Electrochemical Production Technology. Plasma chemistry: educational manual 9786010426641

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Electrochemical Production Technology. Plasma chemistry: educational manual
 9786010426641

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AL-FARABI KAZAKH NATIONAL UNIVERSITY

K. K. Kabdulkarimova G. D. Orazbayeva Y. A. Aubakirov

ELECTROCHEMICAL PRODUCTION TECHNOLOGY. PLASMA CHEMISTRY Educational manual

Almaty «Qazaq university» 2017 1

UDC 544 (075.8) LBC 24.5 я 73 K 11 Recommended for publication by the decision of the Faculty of Chemistry and Chemical Technology Academic Council, RISO of the Kazakh National University named after Al-Farabi (Protocol №4 dated 26.05.2017); educational-methodical section of chemical-technological specialties and specialties of professional education, the arts and services of Republican Educational Methodical Council (REMS) of higher and postgraduate education of MES RK at SKSU M. Auezov (Protocol №1 dated 21.03.2017) Reviewers: doctor of Chemistry, Professor S.A. Tungatarova doctor of Chemistry, Professor B.S. Selenova candidate of Chemistry, Ass. Professor A.M. Argimbayeva

Kabdulkarimova K.K. K 11 Electrochemical Production Technology. Plasma chemistry: educational manual / K.K. Kabdulkarimova, G.D. Orazbayeva, Y.A. Aubakirov. – Almaty: Qazaq university, 2017. – 318 p. ISBN 978-601-04-2664-1 The educational manual is constructed in accordance with the requirements of the credit technology program. It contains curriculum (syllabus), theoretical materials on chemical current sources, on the technology of application of chemical and electrochemical coatings, on the production of metals and metallic coatings, on installations and apparatus for electrochemical and chemical processes, on plasma-chemical reactors, on production of gaseous products. There is the analysis of plasma chemical processes and their classification. The educational manual contains individual tasks of students self-independent work (SIW), test questions and assignment for submission of summative assessment on all the topics of the lecture course, a glossary, the tasks of students self-independent work with the teacher (SIWT) and a list of the recommended literature. The educational manual is recommended to students of technological professions of chemical profile and may be useful to specialists, who work in area of technology of inorganical materials recycling and metallurgy. Publishing in authorial release.

UDC 544 (075.8) LBC 24.5 я 73 ISBN 978-601-04-2664-1

© Kabdulkarimova K.K., Orazbayeva G.D., Aubakirov Y.A., 2017 © Al-Farabi KazNU, 2017

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INTRODUCTION

In this age of electricity and chemistry the electrochemistry holds a special place, combining «electrical» and «chemical» sciences and technologies. Electrochemistry, electrochemical processes and technologies are used so widely in all industries, without them it is impossible either the existence or the further development of civilization. Galvanic processes and production have a special place among the diverse areas of the applied electrochemistry. The electrodeposition of coating by metals and alloys that are protecting a variety of products from corrosion, allow tens and hundreds of times to increase their life in mechanical engineering, aviation, rocket production and shipbuilding, power generation, and instrument engineering, in electrical engineering, electronics and microelectronics, sanitary engineering, medical, furniture, jewelry, food and other industries. Such deposited from electrolytes, metal (electrolytic, galvanic) coatings can simultaneously perform some other various functions: for example, put a nice decorative look on the product, magnetic properties, to increase hardness, wear resistance, heat resistance, electrical conductivity, to restore worn out parts of vehicles and machinery, put properties of blackbody or mirrors on the surface of the metal and non-metal products. Modern man encounters everywhere evidences of the power of electrochemistry:  it is the basis of corrosion science and technology to control corrosion loss. To do this, the methods of the cathode, anode, and cathodic protection are used;  chemical current sources is extensive section of Electrochemistry deals with the development of various systems of electrical elements, batteries, electric accumulators, fuel elements, electrochemical generators, as well as their production technology. Their functions are of an extremely 3

diverse – from the life support of space stations, motor power of submarines and radio equipment to charging of watches, cameras, mobile phones, video technique, etc. Research and development of fuel cells for the automotive industry, for space objects and other objects of modern and future technology are the most important objectives of electrochemical science and technology. In practice all non-ferrous metals, the annual production of which are about 30 million tons, are obtained and then purified to high purity by electrochemical means. It may be mentioned the metals such as aluminum, copper, nickel, lead, zinc, cadmium, magnesium, sodium, potassium and other rare metals and alloys. Electrochemical synthesis of simple and complex inorganic compounds is well known and widely used in chemical industry. It is impossible without electrolysis to produce hydrogen and oxygen of high purity, to produce chlorine, fluorine, alkali, various oxidants and reductants (chlorates, perchlorates, potassium permanganate, manganese dioxide, sodium dithionite). The purpose of this tutorial is to familiarize students with the preferred fields of application of electrochemical technologies in modern manufacturing and services, in which electrochemical technologies are used. The course does not provide a detailed answer to the question of how it is done, and it is limited to the most general ideas about this. The content of the textbook and the distribution of allotted training time on the topics are shown in the syllabus.

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1. CURRENT STATE AND PROSPECTS OF DEVELOPMENT OF ELECTROCHEMICAL PRODUCTION TECHNOLOGIES

Processes are called electrochemical, occurring under the influence of constant electric current and concerned with the conversion of electrical energy into chemical energy or chemical into electrical energy. Chemical energy is converted into electrical energy by operating of electric accumulators and electrical elements. Electrical energy is converted into chemical by the electrolysis of solutions and melts, which is widely used in chemical, metallurgy, metalworking and other industries. By the electrolysis of aqueous solutions of the respective substances together with metals are obtained oxygen, hydrogen, chlorine, alkali, hypochlorite, chlorate, perchlorates, permanganates, persulfates, hydrogen peroxide and other inorganic compounds. Chemical essence of electrolysis is the reductive-oxidative reactions at the electrodes. In metallurgy electrolysis of aqueous solutions is a crucial step in the production of copper, nickel, zinc and others. Also from aqueous solutions it is produced galvanic coating of surface of ferrous metals with nickel, chromium, copper, zinc, gold and other metals which protect the products from corrosion and give them beautiful look. Electrolysis of melts is one of the key processes in the production of aluminum, magnesium, calcium, sodium and other metals that are not deposited on the cathode from aqueous solutions because of their high electric potential. In some industries, the use of electrolysis instead of purely chemical processes has allowed to simplify the technology and get cheaper and clean products. Chemical technology is the science of the most economical and environmentally reasoned methods and process of chemical processing of raw natural materials into consumers items and means of production. Isolation of technology in a special branch of knowledge was started in the second half of the XVIII century, when 5

it was the foundation of chemical technology, as a science and academic discipline. For the first time the term «technology» was used in 1772 by the professor of the University of Gottingen J. Beckman, who published the first complete works, highlighting techniques of many chemical plants, and these works were the first textbooks on chemical engineering. Chemical technology at the end of the XVIII century became a compulsory discipline in the universities, in the higher technical educational institutions in European countries. The main trends of the global chemical industry are: 1. Tightening of environmental regulations. The international program «Responsible Care» was adopted and being implemented, it was developed REACH (Registration, Evaluation and Authorization of Chemicals) – system of Registration, Evaluation of properties and the permission for the production of various types of chemical products, system is aimed at tightening of control over the production of chemicals; 2. The growth of energy costs tends to optimize the costs to ensure the competitiveness of products is forcing major companies to transfer production of basic chemicals in countries with more liberal laws and low-cost resources. In the construction of logistic schemes are taken into account not only the factors of placing markets, areas of extraction of raw materials, the availability of cheap energy but also technological solutions; 3. Consolidation in the new cluster of chemical industry, agriculture and power production; 4. The transition to safe and effective technologies, specialization profile of companies in value-added products; 5. The rapid development of technologies, their frequent turnover. The main focus of the new technologies is to ensure the quality of products, reducing the consumption of raw materials, energy, reduce the number of stages of chemical processes 6. The emphasis is on small lines, producing small-tonnage chemical products. The effectiveness of specialized lines is supported by ultra-high prices for unique products, and the acceleration of technological cycle reduces the time during which companies provide payback of their investments; 6

7. The increasing of production concentration through the development of transnational companies. 8. Growth of petrochemical industry significance. In developed countries, the growth rate of the production of basic petrochemical products is 1.5-2 times higher than the growth rate of gross domestic product. This is due to the rapid development of scientific and technological progress in the industry that allows to create new materials with predetermined properties, to introduce energy saving technologies, increase efficiency. 9. The increase in the proportion of the gas material (methane, propane, butane). In the United States, Canada, Germany, Saudi Arabia, Algeria, Chile and some other countries «gas chemical wing» is at the forefront of petrochemicals. 10. The role of chemical energy is increasing essentially. Its aims are to provide a highly effective way to accumulate energy in the energy-intensive materials such as hydrogen and methane, which are easily transported and can store energy for a long time; 11. The hydrogen resources are unlimited and renewable. Environmental and commodity issues are completely removed when using hydrogen technology. One of the most important tasks of modern technology is the development of processes, eliminating harmful emissions into the atmosphere and water. The main direction of solving environmental problems is the integrated use of raw materials and accelerating the introduction of low-waste processes. The most important areas of basic and applied researches in the field of chemical technologies include:  chemical safety and environmental protection;  new high-chemical processes, including catalytic, membrane, metallurgical, electrochemical processes, and processes connected with the use of high energy and physical methods of acceleration of chemical reactions;  new processes of comprehensive and in-depth chemical processing of minerals, oil, gas and solid fuels;  chemical energy and the creation of new chemical current sources and energy conversion systems;  chemical informatics. 7

Thus, electrochemistry, electrochemical processes and technologies are used so widely in all industries, without them it is impossible either the existence or the further development of civilization. Future is for electrochemical nanotechnology, for coatings by metals and alloys, including those containing Nano dispersed particles of the second phase, for the coating consisting of layers of different metals of thick thousandths of a micron, for composite electrochemical coatings. These coatings can allow to give completely new unique properties to coated things and that cannot be obtained by other methods. Chemical current sources are extensive section of Electrochemistry, dedicated to the development of various systems of electrochemical cells, batteries, electrochemical generators, as well as their production technology. The use of chemical current sources is extremely diverse – from the life support of space stations, supply of submarines engines and radio to delivery of watch and implantation into the human body to stimulate its cardiac activity. Finer processes in living organisms – cells, the membranes, nerve fibers and neurons. Implanted fuel cells, which use components of the ultrafiltration of blood, are constant sources of energy for supplementary instruments, monitoring the patient's health. Perspective is a biological fuel cell that provides the function of heart prosthesis. In the future, it acquires special significance of electrolysis process for the removal of urea from the human body by way of its oxidation in nephritic dialysis system. This project will bring a truly portable artificial kidney machine. Despite its considerable age, electrochemistry is one of sciences that are undergoing rapid development with great prospects for the future. According to the forecasts of a number of leading scientists, the role of electrochemistry in the global industry will rapidly increase. It is believed that, as there is the depletion of fossil fuels, humanity enters into an electrochemical atomic era. Electricity generated by nuclear power plants will be used to generate hydrogen by electrolysis of water. Hydrogen will replace natural gas and will be used in hydrogen-oxygen electrochemical generators. In practice, the processes of water electrolysis in the photo electrochemical systems will be implemented, that convert solar energy into electricity. 8

Outstanding contribution to the development of electrochemistry and its applications made Michael Faraday (laws of electrolysis), G. Davey (obtaining metal potassium by electrolysis), S. Arrhenius (theory of electrolytic dissociation), and others. Nobel laureates for works in the field of electrochemistry were: S. Arrhenius (Sweden, 1903, theory of electrolytic dissociation), J. Heyrovsky (Czechoslovakia, 1959, polarographic analysis), R. Markus (USA, 1992, theory of charge transport through the interface). Among Russian and Soviet scientists outstanding contribution to the development of electrochemistry made B.Yakobi (opening electroplating), A.N. Frumkin (role of the double layer in the kinetics of electrochemical reactions), V.G. Levich (physicochemical hydrodynamics). Electrochemists and physical chemists from Moldova are A.N. Frumkin (born in Kishinev in 1895), L.V. Pisarzhevsky, Yu.S. Lyalikov (electroanalysis), Yu.N. Petrov (metals electrochemical machining), B.R. Lazarenko (spark processing of metals).

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2. THE LARGEST CHEMICAL COMPANIES IN THE WORLD

BASF SE, «Badische Anilin- & Soda-Fabrik» is the Germany's and world largest chemical concern. Headquarter is in town Lyudvigsfan in Rhineland-Pfalz in the south-west of Germany. It was founded in 1865. BASF – The Chemical Company is the leader in the global chemical industry. Its portfolio ranges from oil and natural gas, as well as chemicals, plastics, special chemicals, agricultural products and products of fine chemistry. Dow Chemical Company is an American chemical company, and the second in the world in terms of sales after BASF. It was founded in 1897. Dow Chemical manufactures industrial, household and agricultural chemicals, plastics, pharmaceuticals, chemical products for military use, focusing mainly on semi-finished products for other plants and not on the consumer products. Royal Dutch Shell is the British-Dutch oil company, the second largest company in the world, according to the rating Forbes (2009). Shell conducts geological exploration and production of oil and gas in more than 40 countries. Oil reserves in 2009 amounted to 5.69 billion barrels (770 million tons), gas – 49.1 trillion cubic meters feet (1.38 trillion cubic meters. m). Shell is also fully or partially owns more than 50 petroleum processing plants. In particular, the company 12 owns one of the largest petroleum processing plant in Europe Pernis in the Netherlands, a capacity of 10 000 tons per day, the plant "Stanlow" in the UK with capacity of 12 million tons per year, three petroleum processing plants in France, with total capacity of 40,790 tons per day. Shell owns the world's largest network of petrol stations, which has more than 55 thousand stations. In addition, Shell owns a significant amount of chemical plants, as well as production of solar panels and other alternative energy sources. BP plc to mBP plc until May 2001, the company was known as British Petroleum – British oil and Gas Company, the second largest 10

traded oil and Gas Company in the world. The foundation of BP is due to the discovery of oil reserves in the Middle East in the early twentieth century. The company is producing oil and gas in many parts of the world, both on land and offshore. BP's proven reserves in 2011 amounted to 17.748 million Barrels of oil equivalent. BP owns petroleum processing plants and petrochemical facilities, a network of gas stations produces oil under the brand Castrol. The company also holds stakes in 10 gas pipelines and five regasification terminals in the North Sea. In addition, the company owns a 47% part in a gas pipeline in Alaska, as well as a number of receiving terminals for liquefied natural gas in the Gulf of Mexico.

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3. RAW MATERIALS AND ENERGY RESOURCES OF THE CHEMICAL INDUSTRY

Industrial raw materials can be primary and secondary. The primary raw material is a raw material that has passed the primary processing (such as mined minerals, raw cotton). The primary industrial raw materials can be natural and artificial (synthetic), produced in the chemical industry. The wide range of petroleum products can be used as the primary raw materials for chemical purposes: the waste hydrocarbon gases of different processes, different liquid products or even raw oil. Secondary raw materials are waste products, physically or obsolete items to be processed. Traditional forms of secondary raw materials are waste and scrap metal, waste polymers, textiles, paper. They are easy to collect and recycle. As the secondary raw materials more fully waste are used in metallurgy, pulp and paper industry, in the manufacture of building materials. Some products are made entirely or almost entirely of recycled materials, they are some types of paper and cardboard, products of broad economic consumption from polyethylene (boxes, buckets, watering hoses, films, etc.). The main raw material for the chemical industry is fossil mineral raw materials occurring in the interior of the earth. Mineral raw materials are extracted from the subsurface minerals. Typically, mineral raw materials are divided into three types: ore, non-metallic and fuel. Ore mineral raw materials referred to rocks, from which the metals are produced. Minerals ores contain mainly metal oxides and sulfides (less native metals), and the other compounds constituting the waste rock. Typical examples are iron, copper, chromium, titanium and other ore. Ores, which contain compounds of different metals, are called polymetallic. Non-metallic mineral raw materials are rocks used in the production of chemicals, construction and other non-metallic 12

materials and are not source of metals. These include phosphate rock, sulfur-containing raw materials, salt, sand, clay, limestone, etc. Fuel mineral raw materials are combined by one thing in common – flammability. Brown and hard coal, oil, natural gas, oil shale, peat, shale gas are fossil fuels. This raw material is predominantly organic on the composition. Combustible feed can be attributed to energy chemical. As a result of processing of coal is prepared coke, aromatic hydrocarbons, synthetic dyes, pharmaceuticals, chemical fibers, plastics, fertilizers. Oil is a raw material for producing various types of fuel (gasoline, diesel and jet fuel, fuel oil), lubricating oils. Agricultural raw materials are divided into raw materials of plant and animal origin. Plant raw material is a raw material of natural origin: wood, sugar cane, sugar beets, potatoes, corn, cotton, flax, sunflower and rubber plants, herbs, wood, etc. Animal raw materials are these raw materials of animal origin: wool, fats, furs, raw skin, animal bones, meat, fish, milk, etc. The sources of plant and animal raw materials are resources of the natural habitat: land, forest, water. Plant and animal raw materials are divided into edible and technical. Food raw material is processed into food products; technical raw material is processed into products for domestic and industrial use. For example, the solid and liquid vegetable oils are used in the manufacture of soap; wood is used in the production of charcoal, from rapeseed oil is obtained biodiesel, and from animal bones is obtained bone flour. Starch, together with a conventional use in the production of paper and paperboard, is used to create biodegradable polymers. Depending on the state of aggregation are distinguished solid, liquid and gaseous raw materials Water and air are used in large quantities as raw material in the chemical technology. Water is commonly used as a source of raw material in electrochemistry, production of salts and halogens and many brunches of organic chemicals industry. Air is used as a raw material for producing nitrogen, oxygen, argon, and several other elements. In the economy of industrial production it is important the classification of raw materials by qualitative attributes. The quality of 13

raw materials affects the nature and mode of production, technical and economic performance of chemical companies. The economic potential of the country is largely determined by the availability of natural resources of raw materials, their diversity, the level of development of primary industries and agriculture. Environmental classification of materials is based on the signs of its renewability. On this basis raw materials can be divided into nonrenewable and renewable. Non-renewable raw materials are raw materials which are not completely recovered or are being recovered slower than their use by man. Non-renewable raw materials are in the first place, all mineral resources: metal ores, fossil fuels and building materials. In the production process the non-renewable raw material is completely eliminated (e.g. fossil fuels) or scattered (such as metals). Depletion of oil and gas resources is the biggest problem of the 21st century. Renewable raw materials are the resources that are reproduced under the influence of natural processes (e.g. photosynthesis) or conscious effort of man. Renewable raw materials are of plant and animal origin (biomass), some minerals (such as salts precipitated in the lakes), air, water. The flow-rate temp of the raw material must comply with the rate of its consumption, otherwise it will be nonrenewable. Any production, including chemical, has waste. The Chemical industry is the industry that consumes large quantities of raw materials, water, and energy, therefore, in the course of processing is a large amount of by-products which cannot always be used as a secondary raw material, they are accumulated in the form of waste. Some waste productions require complete waste destruction (this applies in particular to the production of organic products) because they are highly toxic. Production remaining should be considered as waste, which are almost impossible to use at this stage of the technology and which should be neutralized and stored or buried. The other type of waste that can be recycled at the present stage of technology development should be called technological residue or secondary material resources (SMR). Large quantities of solid and liquid wastes are in the chemical, petrochemical and refining industries. Most of them are not used; they are collected in storages, stored in the dumps, which leads to environmental pollution. At the 14

same time, this waste is the large reserve of material resources; their recycling can significantly improve technical and economic performance of the processes. The secondary material resources are significant source of chemical raw materials. SMR may fully or partially replace primary raw materials in some chemical processes. Waste reusing expands the raw material base, saves non-renewable sources of raw materials, prevent pollution, and improve economic performance. The raw material base of the chemical industry is diverse, many raw materials are interchangeable, and so the problem of raw material selection is important. The main criterion to the selection of raw materials is cost-effectiveness. Thus, the chemical industry is not only a consumer of resources, but also as an industry to conserve natural raw materials.

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4. EFFICIENT AND INTEGRATED USE OF RAW MATERIALS

Mineral resources are unevenly distributed across the planet. Their location depends on the structure of the earth’s crust. Some minerals occur spatially more uniform than others. Limestone, salt, iron ore, coal slate are available almost everywhere, while the oil, natural gas, diamonds are concentrated in suitable quantities only in certain areas. The raw material factor for the chemical industry is decisive. The specific share of raw materials in the cost of production ranges from 45% to 90%. Therefore, the problem of raw material and its rational and careful use is very important for the chemical industry. By selection a source of raw materials it must be taken into account the current and future conditions of its production, including the local conditions. The main areas of the rational use of raw materials and fuel and power resources are: 1. The use of cheaper raw materials. 2. The use of waste as secondary material resources. 3. The integrated use of raw materials. 4. The use of renewable raw materials. 5. The use of concentrated material. 6. The right organization of transport and storage of raw materials and fuels. 7. The replacement of food raw material by non-food raw material. 8. Chemicalization of production. The search of available and cheap raw materials is a very important issue. First of all, local raw material must be used, that does not require long-distance transportation. This reduces the cost of its transportation. For a long time it was thought that the main type of fuel and raw materials for the chemical industry is coal. However, the transportation of oil and gas through pipelines is more convenient and 16

cheaper than transporting coal by rail. Using waste from other industries also reduces the cost of raw materials. Integrated use of raw materials means the use of all components of the raw materials for the production of different products. By the integrated use of raw materials is no production waste: everything in the raw materials is used. An example of complex use of raw materials is the processing of fuels (coal, oil, slate coal), non-ferrous metals, vegetable raw materials. Thus, by the coal coking besides the desired product - metallurgical coke is prepared coke gas and coal-tar, by their processing are prepared many valuable substances (aromatic hydrocarbons, phenols, pyridine, ammonia, etc.). Using such materials as products is resulted in lower cost of coke. Integrated use of raw materials is due to the combination of productions – combination of several industries within the same enterprise. Thus, by the conversion of natural gas is produced along with hydrogen (synthesis of ammonia), carbon dioxide which in the process of synthesis of ammonia is not applicable. Therefore, production of ammonia and getting carbamide (urea) is combined: 2NH3 + CO2 → (NH2)2CO + H2O. The complex use of raw materials allows to minimize the technological loss of raw materials and to utilize fully production wastes. This allows to expand the resource base, to increase the volume and range of products, to reduce the cost of raw materials and energy, and to reduce pollution by industrial emissions. The complex use of raw materials leads to a reduction of capital investments in production, reduce production costs and improve technical and economic indices of production. The use of secondary material resources saves raw materials and reduces the traditional environmental pollution. Mineral resources, oil and other organic raw materials are exhaustible. Prices are gradually rising; measures are stricter to protect the environment. These factors determine the search of renewable raw materials. As an alternative to fossil fuels are still widely used plant biomass, produced in the process of photosynthesis, and biodegradable waste. From the Biomass can be obtained not only many products of petrochemical synthesis, and unique compounds, for example, biologically active substances. From plant material are obtained alcohols, organic acids, amino acids, fertilizers, and bioplastics. A promising area of biomass use is the production of synthetic fuels – Bio alcohol, biodiesel and biogas. 17

Plastics (synthetic resins) are currently indispensable material in the industry and household. They are a serious competitor of metal, glass, and ceramics. Consumed plastics inevitably go to waste over time. Most polymers are not biodegradable, causing environmental contamination and disposal problems. Other promising materials for biodegradable plastics are cellulose, chitin, and chitosan. However, the creation of a new industrial chemistry on renewable plant raw materials is the deed of the future. So far, the main raw material for organic synthesis remains oil. Application of concentrated raw materials. Chemical production tend, as a rule, to use possibly more concentrated raw material in which there is the high content (concentration) of various substances. The use of such materials allows to intensify the process and get products of better quality at lower cost. The use of concentrated raw materials in some processes, reduces fuel costs for heating the reacting mass, while in other processes can effectively be used the heat of reaction. The concentration of the mineral components in the raw materials affects the costs associated with the processing of raw materials. For the processing of less concentrated raw materials is needed greater apparatus volume. Natural raw materials are not always concentrated, so it is pre-enriched in mineral processing plants or in the chemical process. Changing of food raw material by non-food raw materials is important for solving the food problem. For example, the ethyl alcohol used in large quantities in the production of synthetic rubber, synthetic fibers, plastics and the like, can be obtained from food raw material (grains, potatoes, sugar beets, sugar cane), or from wood hydrolysis or hydration of ethylene, which is obtained from oil and natural gas. For getting 1 ton of ethanol it is necessary to process about 10-11 tons of potatoes or 4 tons of grain. At present, the possibility of using as a raw material for the production is seen biofuels of wood, lignin, agricultural wastes and algae. Plant raw material and raw animal material has displaced substantially by mineral and synthetic dyestuffs, paints, drugs, fragrances and other materials. Food raw materials are displaced by materials derived from natural gas, oil and coal. For example, in household chemistry the use of soap (made from vegetable and animal fats) is reduced every year worldwide, and the use of synthetic 18

detergents is increased (the feedstock for their production are petrochemical products). The main areas of the rational use of raw materials and energy resources may include:  improving the structure of the fuel and fuel-energy balance;  more thorough and high-quality preparing of materials to its direct use in industry;  correct organization of transportation and storage of raw materials and fuel – preventing losses and reduction in quality;  integrated use of raw materials;  chemization of production;  the use of production waste;  re-use of raw materials and others.

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5. PREPARATION AND ENRICHMENT OF RAW MATERIALS

Raw materials for processing into finished products must meet certain requirements. This is achieved by complex of transactions that make up the process of preparation and enrichment of raw materials. Methods of preparation and enrichment of raw materials depend on its aggregate state. Preparation of solid materials comprises grinding, classification, drying. Preparation of liquid materials is its cleaning from solid and gaseous impurities. As the purification methods from solid impurities are used settling, filtration, and centrifugation. Gaseous impurities may be removed by heating or intensive mechanical stirring. The gaseous raw material is subjected to pre-treatment from liquid and solid contaminants. To do this, methods similar to those methods of cleaning of liquid materials from solid impurities are used and it is used cleaning in electrostatic precipitators. Enrichment of mineral products is a set of processes of primary processing of mineral raw materials, having the aim of separation of the valuable minerals from the waste rock, as well as the mutual separation of the valuable minerals. Enrichment is the overriding intermediate link between mining and the use of recovered materials. By enrichment it is possible to obtain as final commercial products (asbestos, graphite, etc.) and the concentrates, which are suitable for further chemical or metallurgical processing. All existing methods of enrichment are based on differences in physical or physico-chemical properties of the individual components of the mineral. There is, for example, gravity, magnetic, electrical, flotation, the bacterial and other ways of beneficiating. Classification of enrichment processes: Mineral processing is carried out at the processing plants, which are highly mechanized enterprises with complex technological 20

processes. The processing plants are usually built in areas of extraction of raw materials. By the enrichment of raw materials at the place of its production transport costs are reduced for the transportation to the place of processing. According to the purpose the processes of mineral processing are divided into preparation, basic (enrichment) and supplemental (final). The preparatory processes are intended to uncover or open grains of useful components (minerals) that are part of the mineral and dividing it by size classes that meet the technological requirements of subsequent enrichment processes. Preparatory processes include crushing, grinding, screening and classification. Crushing and grinding is the process of destruction and reducing the size of the pieces of mineral raw materials (minerals) by the action of external mechanical, thermal, electrical forces, aimed at overcoming the internal cohesive forces binding the particles of solids. Conventionally, it is assumed that during the fragmentation get particles larger than 5 mm, and during the grinding – smaller than 5 mm. Crushing is carried out in special crushing plants. Screening and classification are used to separate the minerals in the products of different sizes – size fractions. Screening is carried out by dissipation of minerals in a sieve and sieve with calibrated holes (hole size is from millimeter to several hundred millimeters). Screening is carried out by special machines – screening. Classification of the material by size is produced in the water or air and is based on using difference in sedimentation rate of particles of different sizes. Large particles settle quicker and concentrate at the bottom of the classifier; the fine particles settle slowly and are removed from the apparatus by water or air flow. Received in the classification large products are called sand and small products are called the sink or a thin product. The classification is used to separate the small and thin products on grain of size of not more than 1 mm. Basic (enriching) processes. The main enriching processes are used for the precipitate of the initial mineral resource of one or more mineral components. The starting material in the beneficiating process is separated into respective products – concentrates, intermediate products and waste. 21

Concentrates are concentration products, which contains the bulk of valuable components of high content of valuable components, and a low content of waste material and contaminants. Waste are products with low content of valuable components, further extraction of which is not possible technically or economically impractical. Intermediate materials are a mixture of aggregates with open grains of useful components and gangue. Intermediates are characterized by a low containing mineral components compared with the concentrate and higher containing mineral components in comparison with the waste. The quality of mineral resources and enrichment products is determined by the content of valuable components, impurities, accompanying elements, as well as humidity and grain size. Main final operations are thickening of effluent, dewatering and drying of the enrichment product. The choice of the dewatering method depends on characteristics of the material that is dehydrated, (initial moisture content, particle size and mineralogical composition) and the requirements for the final moisture. Often the desired final moisture is difficult to achieve in a single step, so in practice the dewatering operations are used by different methods (centrifugation, thickening, filtration, and heat drying) in several stages. Final operations. In addition to technological processes for the normal functioning of the processing plant should be provided the manufacturing service processes: intrashop transport of minerals and its processing products, the factory water supply, electricity, heat, process quality control of raw materials and processed products.

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6. ENERGY BASE OF CHEMICAL INDUSTRY

Energy is one of the most important production needs. Any process is unthinkable without the expenses of energy and energy resources. Energy is spent not only for carrying out chemical reactions, but also for material transportation, crushing and grinding of solids, gas compression, filtering, etc. Kazakhstan has large reserves of energy resources (oil, gas, coal, uranium) living through the sale of natural energy reserves (80% of exports – raw materials, and the share of industrial exports is declining annually). The energy consumption by chemical production is estimated by its power consumption. Power capacity of industry is the amount of energy to obtain a unit of production. Energy consumption is determined by the number of kilowatt-hours (kWh), kilojoules (kJ), calories (kcal) or the same amount of fuel (tons, kilograms, cubic meters) expended per unit mass or volume of the product. For example, kWh / t, MJ / t, Gcal / t, r / t, kg / m3, and the like. Energy consumption for the preparation of various chemical products is not the same: there are the productions of high and low energy consumption. The criterion of energy efficiency is the ratio of all kinds of energy, equal to the ratio of the amount of energy theoretically required per unit of production (Wtheor), to the amount of energy spent on it (Wpr). The chemical technology uses almost all types of energy: electrical, thermal, chemical, light, nuclear. Type of used energy depends on the process. The most widely used are thermal energy, electrical energy, and fuel energy. Thermal energy is used:  for the various physical processes which are not accompanied by chemical reactions (heating, melting, drying, evaporation, distillation, etc.);  for the heating of the reactants to realize endothermic reactions. By type of used thermal energy the processes are divided into high, medium and low temperature and cryogenic 23

processes. High-temperature processes take place at temperatures above 500ιC. These heat-treatment processes are gasification, conversion of natural gas and others. The energy required for these processes is obtained by burning various fuels (natural gas, coal, coke, fuel oil, coke and generator gas) directly into technological devices. Medium- temperature processes occur at temperatures 150-500°C and low temperature processes at temperatures less than 150°C. Such processes include thermal pyrolysis and cracking, evaporation, distillation, drying, heating and others. Low-grade energy is used for space heating, hot water utilities, ventilation. Major energy sources, providing heat to medium and low-temperature processes are steam and hot water. Cryogenic processes occur at temperatures below 120 K (minus 153°C). They are used for liquefying and hardening gas and air separation. Electrical energy is used for electrochemical processes (electrolytic solutions and melts) and electro thermal processes (heating, melting, sublimation, syntheses at high temperatures). In addition, the electrical energy is used for electrodeposition of dusts and mists (in the electrostatic precipitators), for the control and automation of chemical and technological processes. Electrical energy is also used to illuminate and produce mechanical energy. Kazakhstan was a net exporter of electricity until 2010, but after 2010 is a net importer, that is, Kazakhstan consumes more electricity than produces. North Kazakhstan exports electricity at Ekibastuz regional hydro-electric power plant RHEPP-1 in Russia and the South Kazakhstan buys it from Kyrgyzstan and Uzbekistan. The total installed capacity of all power plants in Kazakhstan is 20,000 MW, and the actual capacity – 15,000 MW. About 72% of the electricity in Kazakhstan is generated from coal 12.3% – from hydro, 10.6% – from gas and 4.9% – from oil. Thus, the four basic types of power plants generate 99.8% of electricity, and alternative sources generate less than 0.2% Electric power stations are divided into stations of national significance, power stations for industrial use and power stations of the regional use. 24

For the power plants of national importance are large thermal power stations to ensure the production and sale of electricity to consumers in the wholesale electricity market of the Republic of Kazakhstan:  LLP «Ekibastuz HPP-1»; JSC «Ekibastuz HPP -2»; JSC «Eurasian Energy Corporation» (Aksu HPP);  JSC «Zhambyl HPP»;  LLP HPP «Corporation Kazakhmys» as well as the hydraulic power stations of high power used additionally and to control production schedule of UPP RK:  Bukhtarma HES JSC «Kazzinc»;  JSC «AES Ust-Kamenogorsk HPS»;  JSC «AES Shulbinskaya HPP». For power plants for industrial use are TPP, with a combined production of electricity and heat, which are used for electric heating of large industrial enterprises and nearby communities  TPP -3 LLP «Karaganda-Zhylu»;  TPP PVA, TPP -2 JSC «Arcelor Mittal Temirtau»;  Rudny TPP (JSC «"SSGPO»);  Pavlodar TPP -1 JSC «Aluminium of Kazakhstan»;  Shymkent TPP-1,2 (JSC «Yuzhpolimetal») and others. Power stations of regional significance are TPP, integrated with the territory, which is implementing the electrical energy through a network of regional power companies and power transmission companies, as well as heating of the surrounding towns. According to the State program for accelerated industrialinnovative development of Kazakhstan the share of renewable energy in total energy production by 2015 has to exceed 1%. The mechanical energy is required for physical operations: crushing, grinding, mixing, centrifuging, the pumps, compressors, fans, conveyors, etc. Chemical energy released in an exothermic chemical reaction is a heat source for heating the reagents used for the reaction. Chemical energy is also used in electrochemical cells and batteries, where it is converted into electrical energy. 25

The light energy is used to perform a variety of photochemical reactions: synthesis of the elements of hydrogen chloride, halogenated organic compounds, and others. The photovoltaic phenomenon in which light energy is converted into electrical energy, have been used for automatic control and process control. As it is known almost all forms of energy on our planet have the original source - the sun's energy. The sources of energy used in chemical plants, may be different. Practical use of energy resources is determined, above all, by their reserves, as well as the geographical location, accessibility, the possibility of transformation of the energy and transfers it in the distance, cost and other factors. Placing of chemical plants, having large energy consumption depends on the availability of cheap fuel and electricity. In this regard, there is the importance of local fuels, which are usually cheaper than imported. However, in some cases, the use of transported gas over long distances by pipeline may be more advantageous than the use of local fuels. Energy resources are divided into renewable and nonrenewable, fuel and non-fuel, primary and secondary. Renewable energy resources are derived from solar energy. Many of them do not practically depend on how they are used. These are solar energy, hydropower, wind energy, geothermal energy. Biomass energy (energy of photosynthesis) is renewable resource. Depending on the origin there are fossil fuels (oil, natural gas, coal, oil shale, black dirt, wood, etc.) and artificial fuel (coke, charcoal, motor fuel, generator, coke gases, and others). By aggregation fuel is divided into solid, liquid and gaseous. Solid fuels are brown and hard coal, anthracite, black dirt, oil shale, wood and products of their processing: coke, charcoal, black dirt briquettes. Liquid fuels include petroleum and its processing products: gasoline, kerosene, diesel, fuel oil. Gaseous fuels include natural and associated petroleum gas, generator, coke gas, biogas, hydrogen and others. Energy value of fuel is determined by the amount of energy that can be produced by burning it. The main characteristic of the fuel is its heating value. The importance of using fuel has its composition. Solid and liquid fuel 26

consists of combustible matter and ballast. Ballast is moisture, nitrogen and inorganic compounds (silicates, carbonates, sulfates, phosphates, etc.). The heat of combustion is determined by the chemical composition of combustible material. The composition of the solid and liquid fuels is carbon, hydrogen, oxygen, nitrogen, sulfur, ash and moisture. The elements represent standard symbols C, H, O, N, S, ash and water symbols A and W, respectively.

27

7. QUESTIONS FOR SELF-CONTROL ON TOPIC «RAW MATERIALS AND ENERGY RESOURCES»

1. What grounds are classified raw materials of chemical industry? 2. What are the main raw materials of the chemical industry? 3. What are the secondary material resources? Give examples. 4. What is the integrated use of raw materials? Give examples. 5. What is the purpose of the complex processing of raw materials? 6. What is the enrichment of raw materials and for which it is carried out? 7. Basic methods of enrichment of solid materials. The essence of each method. Equipment. 8. What is the role of energy and fuel in the conduct of technological processes? 9. The main types of energy used in the chemical industry. 10. What are the main types of energy resources? Which ones are the most promising? 11. What are the renewable and nonrenewable energy resources? 12. What are the secondary energy resources? How are they classified by type of energy? 13. What is the role of secondary energy resources in fuel economy and energy? 14. What methods are used for the efficient use of secondary energy resources? 15. What is the essence of energy technologies? 16. Give examples of energy and technological schemes of processing of solid fuels. 28

17. Give examples of the use of energy technology systems in the heat of chemical reactions. 18. What are the minerals of Kazakhstan and fields of their applications? 19. What are the long-term raw materials on the territory of Kazakhstan?

29

8. THE LOW-WASTE AND NON-WASTE TECHNOLOGIES

Waste-free and low-waste technologies are one of the modern trends of development of industrial production. Development of enterprises with non-waste and low-waste technology is the present and future of the industry. Waste-free technology is technology implying more rational use of natural resources and energy in production that protects the environment. Waste-free technology is principle of the organization of production in general, involves the use of raw materials and energy in a closed loop. Closed loop means chain: raw resources → production → consumption → secondary resources. This formulation should not be taken absolutely, that is, it is not said that production is possible without producing waste. To imagine a completely waste-free production is impossible, and this does not exist in nature. However, the waste must not interfere the functioning of natural systems. In other words, we have to develop criteria for the undisturbed state of nature. Creation of waste-free production relates to a very long and complex process, the intermediate stage of which is low-waste production. In accordance with the current legislation the enterprises, violating sanitary and environmental regulations, have no right to exist and need to be upgraded or closed, i.e. all modern companies should be non-waste and low-waste. When create a waste-free production it has to be solved complex organizational, technical, technological, economic, and psychological and other problems. For the development and implementation of waste-free production can be identified a number of interrelated principles. The basic principle is consistency principle. In accordance with principle each individual process or production is considered as an 30

element of a dynamic system of total industrial production in the region and at a higher level as part of eco-economic system in general, including in addition to material production and other economic activities of man, the environment (population of living organisms atmosphere, hydrosphere, lithosphere, biogeocoenoses, landscapes), as well as man and his environment. Another important principle of the creation of non-waste production is the complexity of resources using. This principle requires maximum using of all components of the raw materials and energy potential. As it is known, practically all the raw materials is complex, and an average of more than one third of the amount are related elements that can be removed only by its complex processing. So, even now, almost all silver, bismuth, platinum, as well as more than 20% of gold are obtained simultaneously with the processing of complex ores. Requirement to limit the impact of production on the natural and social environment, taking into account planned and purposeful growth of its volumes and environmental excellence, it is not less important principle need to be included. This principle is primarily concerned with the preservation of the natural and social resources such as air, water, land surface, the health of the population. The general principle of the creation of non-waste production is also the rationality of its organization. Decisive here are the requirement of reasonable use of all components of the raw materials, minimize energy, material and labor intensity of production and the search for new raw materials and environmentally sound raw and energy technologies, what it is largely due to reduction of negative impacts on the environment and the harm caused, including related branches of the national economy. The main way to achieve this is to develop new and improve existing technological processes and production. Humanity must address the issue of non-waste and low-waste production, for the rising rates of accumulation of waste the population can be filled up by landfills and industrial waste and be left without drinking water, enough clean air and fertile land. Thus, the main shortcomings of existing technologies are their negative impact on the environment and high energy consumption. The problem of interaction of electrochemistry and ecology is two31

way: on the one hand – this is the development of methods that reduce the burden of electrochemical technologies on the environment and on the other hand – the development of electrochemical methods of environmental protection. Often, in these conditions, «customer» of the development of new technologies is legislation prohibiting conduct of certain processes, such as in the case of electrochemical chromium-plating technology from compounds of Cr(VI). Therefore, the improvement of existing electrochemical technologies in reducing the burden on the environment is one of the main directions of their development. Power supply of various industries is constantly growing, the cost of energy production increases, and proven reserves decrease. The result is a rise in the cost of electricity, which in turn leads to a situation in which the energy intensity of production becomes the determining factor. Reducing energy consumption of different electrochemical technologies from production of aluminum from the melt to the methods of corrosion control is one of the most important technological challenges. However, the broadest possibilities of electrochemical technologies, high «degree of freedom» of process control as compared to chemical processes (by changing not only the composition of the solution and temperature, but also the current density or potential) should lead (and leads) to the continuous expansion of the scope of the electrochemical technologies of their use in electronics and microelectronics to mechanical engineering. The close relationship of electrochemical, electronic and microelectronic technologies is an essential feature of modern technology and technique. The basis of waste-free production is complex processing of raw materials, using all of its components, because the waste of production is the unused portion of the raw material. Of great importance in this case is the development of resource-saving technologies and to link geographically related businesses so that the waste of one company is the raw material for other businesses. Low-waste technology is an intermediate step before the creation of non-waste technology, implying approximation of process to the closed loop. By low-waste technology the harmful effects on the environment do not exceed the level allowed by the sanitary authorities, i.e. maximum permissible concentration (MPC). At the same time on technical, economic, organizational or other reasons, 32

part of the raw materials can go into waste and sent to long-term storage or disposal. Waste of production and consumption are secondary material resources (SMR), which can now be reused in the national economy. However, the question arises, which allowed part of raw materials in the low-waste production can be directed to long-term storage or disposal? In this regard, a number of industries have already quantitative assessment of disposability. Thus, in the non-ferrous metallurgy is widely used complexity factor, determined by the proportion of mineral substances (%), extracted from the reprocess relative to the entire quantity. In some cases it exceeds 80%. In the coal industry is introduced a coefficient of non-waste production: Knp = 0,33· ( Кbt + Кbz + Кbg), где Кbt, Кbz, Кbg where Кbt, Кbz, Кbg are utilization rates, respectively rocks formed during mining operations, passing water to be abstracted from coal mining (slate) and use dust and gas wastes. It is known that coal mining is one of the most material-intensive and environmentally challenging processes in the national economy. For this industry it is found that production is a non-waste production, if the disposability ratio exceeds 75%. Perhaps, as a first approximation for practical purposes the value of the coefficient of non-waste (or complexity factor), equal to 75% or more, can be taken as a quantitative criterion of low-waste, and 95% – non-waste production and in a number of other material-intensive sectors of the economy. At the same time, of course, it should be considered toxic waste. Main existing directions of waste-free and low-waste technology in selected industries: Metallurgy In the ferrous and nonferrous metallurgy by the creation of new enterprises and the reconstruction of existing facilities must be the introduction of non-waste and low-waste technological processes, providing cost-effective, efficient use of raw ore: 1) involvement in the processing of gaseous, liquid and solid production waste, reduction of emissions and discharges of hazardous substances with waste gases and waste water; 33

2) by mining and processing of ferrous and non-ferrous metals – the widespread introduction of the use of large-tonnage dump solid waste of mining and processing industry as building materials, stowing mines, road surfaces, wall units, etc. instead of specially produced mineral resources; 3) full processing of all the ferroalloy slag, as well as a significant increase in the scale of processing of steel slag and non-ferrous metals waste; 4) a sharp reduction in fresh water consumption and reduction of waste water through the further development and implementation of waterless technological processes and drainage systems, water supply systems; 5) improving the efficiency of existing and new processes of capturing components of the flue gas and waste water; 6) at the enterprises of ferrous metallurgy the accelerate of the introduction of resource autogenous processes, including melting in a liquid bath, which will not only intensify the processing of raw materials, reduce the consumption of energy, but also significantly improve the air basin within the area of enterprises by dramatically reducing the amount of waste gases and obtain highly concentrated sulfur-containing gases used in the production of sulfuric acid and elemental sulfur; 7) the development and widespread adoption of high-performance purification equipment in metallurgical enterprises and control devices of various parameters of environmental pollution; 8) the rapid development and the introduction of new advanced low-waste and non-waste processes, meaning non-blast-furnace coke and cokeless processes for the production of steel, powder metallurgy, autogenous processes in non-ferrous metallurgy and other advanced manufacturing processes aimed to reduce emissions into the environment; 9) increasing use of microelectronics in the industry in order to save energy and materials, as well as control of waste and waste reduction. Chemical and petrochemical industry In the chemical and petrochemical industry on a larger scale should be used in manufacturing processes: 34

1) oxidation and reduction with using oxygen, nitrogen, and air; 2) electrochemical methods, membrane separation technology of gas and liquid mixtures; 3) biotechnology, including the production of biogas from residues of organic products, as well as methods of radiation, ultraviolet, electric pulse and plasma intensification of chemical reactions.

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9. ELECTROCHEMICAL PROCESSES – THE BASIS OF ELECTROCHEMICAL TECHNOLOGIES. CLASSIFICATION

Electrochemical Technologies (ECT) are varied and can be divided into several sections according to the selected classifications. For example, it is according to the nature of manufactured products or services. The basis of all electrochemical technologies is electrochemical processes in electrochemical systems at the electrode-electrolyte interface (phase boundary). They are characterized, like other chemical processes, by thermodynamic and kinetic parameters. By detailing approach plays an important role in the «joined-up» of calculations and theoretical predictions of molecular level with experiment. There are the following central issues:  development of molecular models of the structure of interphase boundaries and adsorption layers;  the establishment of kinetics and mechanisms of electro catalytic processes and the creation of models that take into account the molecular structure of adsorbed layers;  the development of microscopic understanding of the mechanisms of formation and growth of new phases and corrosion-electrochemical phenomena;  the creation of the theoretical foundations of electrochemical methods of obtaining materials with desired (nano) structure and properties and determination of the principles of operation of such materials;  identify the specific characteristics of electrochemical phenomena in nanoscale systems. Most above stated fundamental problems existed in electrochemistry phase boundaries over the past 30-50 years. At the same time the wording Nano electrochemical challenges the science is fully obliged to the progress of the last decade. Achievements of 36

electrochemical science determine the current state and directions of perfection ECT. Electrochemical technologies are the technological processes used in the production of goods and services, which are based on electrochemical processes. The main groups of ECT include:  electrochemical energy;  electrochemical metallurgy;  electrochemical technology of chemical commodity products;  electrochemical technology in the manufacture of products and tools in engineering and instrument making industry; electrochemical technology used for corrosion protection of technical objects;  electrochemical sensory;  electrochemical technologies in health care;  electrochemical technology of water. Advantages of electrochemical technologies: 1. By the production of chemical products via electrochemical technology is achieved high selectivity of electrochemical processes, because the processes of oxidation and reduction at the electrodes occur with electrons (instead of complex chemical compounds as reactants). 2. In the electrochemical processes potential is easily changed by varying the current, flowing through the electrode, achieving such values of the reductive-oxidative potential, which provide a unique opportunity for oxidation and reduction processes. 3. Using the diaphragms or ion exchange membranes in electrolytic cells it is possible to receive simultaneously multiple organic products (for example, in the electrolysis of solution СuSO4 prepared O2, H2SO4). Disadvantages of electrochemical technologies: 1. Large power consumption, which is spent on the electrochemical conversion. 2. Relatively low productivity of electrochemical processes (heterogeneous processes occurring at the electrode-solution). 37

As a result, there is relatively high capital cost of the equipment, building. When assessing the contribution to the overall economy of ECT should be noted that only the cost of chlorine and alkali, produced by electrolysis is about 10% of the total cost of production of the chemical industry. From an environmental standpoint electrochemical production is characterized by very toxic products (Cl2 и F2) and use in the manufacture of highly toxic substances: mercury as electrode, asbestos as a diaphragm material, etc. Electrochemical object is a basic element of electrochemical technology. The object may belong to a class of synthetic or natural electrochemical objects. There may be objects that are intermediate. Man-made objects are the electrochemical devices (ECD), natural are corrosion processes. To intermediate could be included nonelectrolytic facilities (operating without external power), which have passing on the surface of the technical facilities spontaneous reductive-oxidative processes. These processes include chemical metallization processes, etching, oxidation, phosphating, chromate, passivation, activation of metals and other similar technological methods. They occur spontaneously without any external power, but the optimal flow conditions are created artificially. Electrochemical objects can be used in two modes: as a current source or electric power consumers. In the first case, in the ECD occurs transformation (conversion) of chemical energy into electrical energy; in the second case, the reverse process occurs – the electric energy supplied from the outside is converted into chemical energy of produced products. In the first case, the ECD is a current source, in the second case, the electrochemical is electrolyser. The ECD are included in electrical circuitry in parallel or gradually. Gradually connected electrolytic cells are calle d series or battery. A separate group of electrochemical objects are the objects, «working» without a supply and discharge of current to the external circuit. One of the main objects of this type is the corrosion process. 38

Electrochemical objects are phenomena may also be the basis of technological operations, in particular in the electroplating. Shortcircuited anode and cathode spaces lead to manufacturing operations that are current-free. These include processes applying conversion coatings. Examples are oxide, phosphate, chromate, oxalate and other coatings. The term electrochemical sensory can be understood as the world of sensors, action of which is based on electrochemical phenomena. Sensors are sensitive elements (sensors – converters of non-electric quantities into electrical quantities). Electrochemical sensors may be included in analytical systems which allow to recognize substances together, simultaneously assessing their concentration. Electrochemical sensors are known for measuring the concentration of substances in different states, which are in different environments. Sensor for pH measurement is an example of a potentiometric electrochemical sensor. The potential of the indicator electrode is measured, which by some law related to the concentration of hydrogen ions (Е = –0,059рН). Using electrochemical sensors are measured the concentration of substances in liquid media, gases, molten media, for example, measure of the concentration of oxygen in the molten metal. Using electrochemical sensors are measured, in particular, the concentration of drugs; the important tasks in criminal investigation technique are solved. There are two basic types of sensors that use liquid electrolytes: amperometric and potentiometric. The earliest example of amperometric gas sensor is an oxygen sensor Clark, who was used to measure the concentration of oxygen in the blood. Amperometric sensors produce a signal which is related to analyte concentration according to the law of Faraday. Amperometric gas sensors have an advantage over other types of sensors, as they are distinguished by small size, low power consumption, high sensitivity. However, they are relatively cheap. Because of this amperometric gas sensors are ideal as portable instruments of control of toxic and explosive gases. Ion-selective electrodes (ISE) belongs to a group of potentiometric chemical sensors. They are based on measuring the surface potential of the indicator electrode in contact with the environment to be analyzed. Well-known glass pH electrode is a typical representative of ISE. 39

Figure 1. Ion selective electrodes (glass electrodes)

Glass electrode is usually a glass bulb with a wall thickness of 0.06-0.1 mm, filled with a solution of an acid or salts, in which for the contact platinum wire was immersed. The surface of the glass of bulb in the solution acquires the potential, value of which depends on the concentration of hydrogen ions in solution. Therefore, glass electrodes are used to measure pH. In solutions with the same concentration of hydrogen ions on the inner and on the outer surface of the glass electrode also occur potentials different from each other. This potential difference is called potential asymmetry. Potential asymmetry can make a difference of a few millivolts in the case of thin electrodes made of soft glass to hundredths of a volt at the thick electrodes of refractory glass. To reduce the potential asymmetry the glass electrode is maintained in the water or in the 0.1 n hydrochloric acid. In the pH range from 2 to 9 glass electrodes can be regarded as an ideal hydrogen electrode; its potential depends linearly on the pH of the solution. In acidic solutions with a pH below two are deviations from the true pH value, increasing with the acidity of the solution. In alkaline solution deviations are more significant and sometimes begin with a pH 9. An ion-selective electrode (potentiometric sensor) is used under conditions where the mass transfer is limited and therefore the current is linearly dependent on the concentration of the analyte. This type of sensors was developed in many different models and it is used for a 40

wide range of analyte, such as CO, nitrogen oxides, Н2S, О2, glucose, unique gases of type hydrazine and others. Signal produced by the sensor is the electromotive force, which depends on the analyte concentration and is described by the Nernst equation: E = E0 + RT/nF·ln[Ox]/[Red], where E – electrode potential, 0 E – standard electrode potential measured in volts; R – universal gas constant and equal to 8.31 Dzh / (mol · K); T – absolute temperature; F – Faraday constant equal to 96485 Кl· mol –1; n – number of electrons involved in the process; [Ox], [Red] the concentrations of oxidized and reduced forms of the substance involved in the halfreaction. If in the formula of Nernst the numerical values of the constants R and F will be substituted, and go from natural logarithms to decimal, then the formula is E = E0 + 0,059/n lg [Ox]/[Red]. The use of electrochemical sensors (to detect chemical products): environment (industrial emissions, gas), metallurgy (oxygen, hydrogen, carbon monoxide (II)), agriculture (humidity, pesticides, herbicides), petrochemicals, medicine (glucose, urea, pH, infective disease). Use of the solid electrolyte instead of the liquid, allows the construction of electrochemical sensors for use by high temperature. They can operate by potentiometric and amperometric principles. An important advantage of this type of sensors is that they operate in harsh conditions, which sensors with liquid electrolytes do not match. Classification of the electrochemical production:  electrolysis of melts;  production of chemical power sources (batteries, electrochemical cells (batteries), fuel cells, etc.);  galvanic coatings;  electrolysis of aqueous salt solutions;  refining of non-ferrous metals;  obtaining non-ferrous metals from ores;  obtaining the alkali, alkaline earth and other light (aluminum, magnesium) metals;  production of chlorine and alkali;  decomposition of water;  decorative and anti-corrosion coating of metals  complex use of ores. 41

10. THE ELECTROCHEMICAL METALLURGY

10.1. The electrolysis of aqueous solutions Variety of chemical products can be produced by electrolysis of aqueous solutions and molten environment. Hydro electrometallurgy and galvanotechnics are based on electrolysis of aqueous solutions. Hydro electrometallurgy is the extraction of metals from aqueous solutions of their salts by electrolysis. Electrolysis is usually the final stage in a series of metallurgical processes. Tonnage chemical products such as hydrogen, chlorine, sodium and potassium hydroxides are obtained by electrolysis of aqueous solutions of sodium and potassium. By methods of aqueous solutions electrolysis is carried energy synthesis of many organic and inorganic substances - hypo chlorites, chlorates, perchlorates, per chloric acid, permanganates, manganese dioxide, and adiponitrile, antidetonators, such as tetraethyl lead, hydroquinone, fluorinated of organic compounds and several others. Copper, zinc, cadmium, manganese, chromium, lead, tin and noble metals are prepared and refined by electrochemical methods. Electrochemical methods are increasingly being implemented in wastewater treatment equipment, in particular for the desalination of highly mineralized water electrolysis to regenerate the individual salts, acids and alkalis. Electrochemical methods are increasingly being implemented in wastewater treatment equipment, in particular for the desalination of highly mineralized water by electrolysis to regenerate the individual salts, acids and alkalis. Electrochemical methods are developed in the industry faster than with chemicals due to their obvious advantages. In electrochemical processes, in many cases the equipment is simpler and more compact compared to alternative chemical processes. 42

The apparatus consists of an electrolytic cell, the cathode, anode, electrolyte and a DC source (battery or alternator). Electrochemical methods for the preparation of a number of products are characterized by a smaller number of manufacturing steps and operations, cheaper raw materials and greater depth of its conversion, simultaneous formation (in a separate form) of valuable products. These benefits often are responsible for the lower cost of the products. One of the main advantages of electrochemical methods is the purity of the resulting products.

Figure 2. Equipment (electrolyzer) for electrolysis of aqueous solutions of electrolytes (solutions of salts and hydroxides)

The main disadvantage of electrochemical processes is the high energy intensity, so energy costs are a major article of the product cost price. Therefore, for the electrochemical industry it is particularly important to reduce energy consumption by improving the technology, as well as the rational, economical use of electricity. Electrolysis of sodium chloride solution Electrolysis of NaCl solution is the simplest and most economical method for simultaneous production of three major chemical products – chlorine, hydrogen and sodium hydroxide, using cheap and available natural resources. This is the most large-scale electrochemical production. The overall reaction in the electrolytic cell may be expressed by the equation: 43

2NaCl + 2H2O → 2H2 + 2NaOH + Cl2 Chlorine is used on a large scale as a raw material for the production of chlorinated solvents and plastics, synthetic rubber, chemical fiber, pesticides. In metallurgy, chlorine is used for chlorinating roasting of ores, in textile, pulp and paper industry – for cleaning and bleaching of cellulose, pulp and tissues. Large amounts of chlorine are for cleaning and sterilization of waste water and drinking water. Sodium hydroxide is used in the manufacture of many chemical products, particularly in industrial organic synthesis, in the pulp and paper industry, in the manufacture of artificial fibers, in metallurgy (aluminum production), in the petrochemical industry, and others. The values of hydrogen as the fuel of the future and chemicals are very high. Electrolysis of NaCl solution is carried out in two ways, different in character of the electrode processes and in hardware design: 1. Electrolysis with a solid cathode and filter diaphragm: By the implementing the process at the cathode in accordance with the values of the electrode potentials occur the following processes: At the cathode, the hydrogen is released: К:

2Н2О + 2е¯ 2Н → Н2

→ 2ОН¯

+ 2Н

(1) (2)

Material for the cathode is steel, in which hydrogen is released at a relatively low overvoltage (0.3 V). In actual electrolysis conditions (concentrated solution of NaCl, containing NaOH, the temperature 900С) the actual potential of hydrogen evolution is about – 0,845V. Reduced capacity up to 0.3 – 0,4V can be achieved using porous graphite cathodes, for hardening and hydrophobization of impregnated by polytetrafluoroethylene and activated by copper or silver salts. Accumulating in the cathode space hydroxide ions form neutral molecules of sodium hydroxide 44

ОН¯

+ Na+ → NaOH

(3)

At the anode chlorine is released: А: 2СІ– - 2е¯

→ СІ2

(4)

The material of the anode is ruthenium oxide system (composition of ruthenium and titanium oxide, deposited on titanium base), possessing strength and chemical inertness in relation to oxygen is a by-product formed at the anode: А: 4 ОН– - 4е¯

→ О2

+

2Н2О

(5)

Figure 3. Facility for electrolysis with a solid cathode and filter diaphragm

In addition, in the volume of the electrolyte of the anode space as a result of chlorine hydrolysis are chemical side reactions: СІ2 + Н2О ↔ НОСІ + НСІ СІ2 + ОН– ↔ НОСІ + СІ– НОСІ + ОН– → ОСІ– + Н2О

(6) (7) (8)

Resulting from this sequential reaction the hypochlorite anion undergoes anodic oxidation А: 6ОСІ– - 6е¯ + 3Н2О → 2ОСІ3– + 4СІ– + 3О2 + 6Н+ 45

(9)

Figure 4. Electrolysis of sodium chloride solution having a solid cathode and a filter diaphragm

Side reactions reduce the current output (current output – is expressed as a percentage ratio of the quantity of actually electricity spent (Qfact) to the theoretically necessary (Qtheor). Вт = (Qfact / Qtheor)·100%)) of basic products and increase supplies rates in energy. Therefore, the conditions of electrolysis and electrolyte concentration should provide minimal side reactions and achievement of maximum current output of desired products. Electrolysis is implemented in electrolyzers of continuous movement with vertical filtering diaphragm by countercurrent of electrolyte action and OH –ions. Due electrolyte backflow and OH– ions, the latter does not face the anode compartment and the side reactions (5), (7) - (9) for which they are responsible, are extremely minimized. Bath carcass can be divided into cathode and anode spaces of a porous diaphragm from asbestos. From the cathodic space is continuously withdrawn hydrogen and sodium hydroxide solution, and from the anode space – chlorine. The formed chlorine-gas contains 95 - 96% Cl2. Chlorine – gas is cooled to 20°С (by this the water is condensed) and further it is dried by 46

washing with concentrated sulfuric acid. Cathode product – sodium hydroxide solution contains 120-140 g / l NaOH and 170-180 g / l of undecomposed NaCl. The solution is evaporated, and the NaCl goes into the solid phase, because its solubility sharply reduced with increasing of concentration of NaOH. After evaporation and melting of solutions is prepared anhydrous sodium hydroxide, containing 92-95% NaOH, and 2-4% NaCl. 2. The electrolysis without a diaphragm with a liquid mercury cathode On mercury cathode the electrode reactions (1) and (2) come with a large over-voltage – discharge capacity of 1.7-1.8 V. Sodium is allocated on mercury cathode with great effect of depolarization and potential discharge Na + on mercury is well below of standard and is 1.23 V. The phenomenon of depolarization of mercury cathode is provided by the fact that the discharge of sodium ions is by the formation of a chemical compound – sodium amalgam: К: Na+ + nHg + e– → NaHgn which is continuously withdrawn from the surface of the anode, dissolves in excess mercury. On the perforated graphite (or ruthenium oxide) anode chlorine is released: A: 2Cl– - 2e– → Cl2 Sodium amalgam, containing 0.1 - 0.3% of sodium (Na), is output from the electrolyzer and is decomposed by the heated water in a separate reactor-decomposer. In the decomposer is an electrochemical reaction corresponding to the process in a short-circuited galvanic element NaHg n [NaOH] in which amalgam serves as the cathode Na

+

H2O → Na+ + OH– + ½ H2 Na+ + OH– → NaOH

Deep cleansing concentrated NaCl solution is put into the inclined elongated electrolyzer, on the bottom of which by gravity, by countercurrent to brine, is moving mercury serving as cathode. Above 47

mercury is a horizontal oxide ruthenium (or perforated graphite) anode, immersed in the brine. The anode fluid comprising unreacted NaCl, is derived from the electrolyzer together with the chlorine-gas, from which is separated in the separator and purge columns. Chlorine is put into drying, and non-chlorine brine after purification from mercury and impurities, is saturated by rock salt and is returned to the electrolytic cell. Sodium amalgam flows from the electrolytic cell in sloping decomposer-reactor, where moves as countercurrent to distilled water, which is supplied in an amount to obtain a 45% NaOH solution. At the bottom of the decomposer are placed graphite comb plates, forming with amalgam the short-circuited galvanic cell NaHgn [NaOH]. Separated sodium hydroxide is discharged in separators from hydrogen and transmitted to consumers. Mercury, arising from decomposer, is pumped by mercury pump into the electrolyzer. Since alkali is not formed in electrolysis step, so in the process with mercury cathode is excluded side reaction (5), (7) - (9) and the process is characterized by high current are excluded and energy are excluded.

Figure 5. Scheme of electrolysis of NaCl solution with ion-exchange (cation exchange) membrane which separates the cathode and anode spaces 48

However, electrolysis method with mercury cathode requires especially thorough cleaning of the circulating brine source, as impurities of magnesium, iron, calcium, and other metals reduce hydrogen overvoltage on mercury cathode, which can lead to a breach of the cathode process and explosions. Electrolysis with mercury cathode gives highly concentrated chemically pure solutions of sodium hydroxide which are required for a variety of consumers, primarily in the production of synthetic fibers, in the synthesis and preparation of ion exchange materials and others. However, the use of mercury is harmful to human health. To obtain chemically pure solutions of NaOH it was started to apply electrolysis of NaCl solution with ion-exchange (cation exchange) membrane which separates the anode and cathode space. This method is more difficult according to hardware design and operation of equipment, but it is much safer than mercury method. Membrane method of electrolysis, as well as the diaphragm, can be considered as low-waste technology process. Gaseous products – chlorine and hydrogen by either method are distinguished by high purity. During electrolysis with a mercury cathode a third product – a sodium hydroxide solution is highly concentrated NaOH and is chemically pure. Due to the purity of the obtained products, a simple and compact hardware design, as well as one-step process the electrolysis of NaCl solution is the only way in the world to produce chlorine and the main method of producing sodium hydroxide. 10.2. Basics of electrolysis of alloys Alloys electrolysis is widely used for the production of light, refractory and rare metals, fluorine, chlorine and boron, for refining the metals and for receiving the alloys. New field of application of the electrolysis of molten electrolyte is the separation of isotopes. Electrolysis of melts is one of the most energy-intensive industries of Applied Electrochemistry. Thus, the production of aluminum by electricity consumption takes the first place among all the products produced electrochemically. Energy consumption for production of 1 kg of sodium is about 14 kWh, magnesium – 18, calcium – 30, lithium – 60 kWh. Therefore, the production of such metals should be placed 49

in areas with cheap energy, i.e. near the large hydroelectric power plants. Metals and alloys produced by electrolysis of molten environment, have one significant advantage over metals and alloys, separated from the aqueous solutions, they contain much less gas. For electrolysis of alloys is typical the flow process at high temperatures. In most cases, the required temperature is created by the heat generated in the electrolyzer by the flowing current. This eliminates the need for external heating. The difference of electrolysis of molten environment from the electrolysis in aqueous solutions is due to profound differences in the physicochemical properties of electrolytes in melt form and in the form of aqueous solutions. The electrolysis of molten salts is carried out at temperatures slightly above their crystallization temperature. At such temperatures, the structure of melts retains some resemblance to the structure of solids. Such properties of substances such as the volume and specific heat, ordering of the crystal structure and al., do not change significantly during the melting. This is because the nature of the chemical bonding of crystalline substances in the solid state – ionic, covalent, metal – stored for substances in molten form. The processes occurring in the electrolysis of molten electrolyte The molten electrolytes are dissociated into ions. This is heat dissociation of electrolytes. By an electric current cations are reduced at the cathode, as they receive from it the electrons. Anions of acid residue and hydroxide -anions are oxidized at the cathode as they give it their electrons (as in the electrolysis of aqueous solutions). For example: 1. By the thermal dissociation of sodium chloride are formed ions sodium and chloride: NaCl → Na+ + Cl– Sodium is released at the cathode: 2Na+ + 2e– → 2Na Chlorine is released at the anode: 2Cl– – 2e– → Cl2 total ionic equation 2Na+ + 2Cl– → 2Na0 + Cl02 electrolysis

the overall reaction:

2NaCl 50

2Na + Cl2

2. By the dissociation of potassium hydroxide are formed potassium ions and hydroxide -ions: КОН → К+ + ОН– Potassium is released at the cathode: К+ + 1e– → К Oxygen and water are released at the anode: 4ОН– – 4e– → О2 + 2Н2О Total ionic equation: 4К+ + 4ОН– → 4К0 + О2 + 2Н2О the overall reaction: electrolysis

4К0 + О2 + 2Н2О

4КОН

3. By the dissociation of sodium sulphate melt are formed ions of sodium and sulfate-ions: Na2SO4 → 2Na+ + SО4 2– sodium is released at the cathode: Na+ + 1e– → Na oxygen and sulfur oxide(VI) are released at the anode: 2SО42– – 4e– → 2SО3 +О2 total ionic equation: 4Na+ + 2SО42– → 4Na 0 + 2SО3 +О2 the overall reaction: electrolysis

4Na2SO4

4 Na 0 + 2SО3 +О2

Laws of electrolysis of melts of the electrolyte: 1. In the electrolysis of molten of salts and alkali at the cathode is deposited the metal. 2. Anoxic acid anions are oxidized at the anode, giving corresponding compound, for example, chloride-anion form chlorine. 3. Oxygenate acid anions form the corresponding oxide and oxygen. Electrolysis basis consider on the example of the production of aluminum: Electrolysis of cryolite-alumina melts is the main method of producing aluminum. The process of alumina production by electrolysis of aluminum in a melt of cryolite was invented simultaneously by two authors (P. Eru (France) and Ch. Holl (USA) in 1886) and to date, in principle, remains unchanged. 51

Modern life is unimaginable without aluminum. This brilliant light metal, perfect conductor of electricity has become in the last few decades the most widely used in various industries. Meanwhile, it is known that aluminum in free form is not found in nature, and up to XIX century science did not even know about its existence. Only in the last quarter of the XIX century, the problem of industrial production of aluminum metal in free form has been resolved. Kazakhstan has large reserves of bauxite (Kazakhstan ranked 15th in the world of reserves of bauxite), but bauxite is of low quality with high content of iron and silicon. The raw material for Pavlodar Aluminum Plant is Turgai bauxite. Bauxite is a rock composed mainly of aluminum hydroxide, iron oxide, mineral components oxide. Bauxite has received its name from the French town where it was first discovered. Currently, at alumina refineries, processing bauxite, in addition to the basic product – alumina, from the raw materials are extracted rare metals – gallium and vanadium. Furthermore bauxites contain significant amounts of iron, silicon, titanium, and small amounts of rare metals such as scandium, germanium, etc. Consequently, bauxite is a valuable raw material. The basic unit is the electrolyser. Alumina has a high melting point (2049°С). The temperature in the bath in the normal technology mode of electrolysis from is 950°С to 965°С. Therefore alumina in the electrolyte is not melted, but dissolved. Corundum Al2O3, when dissolved in cryolite (Na3AlF6), is split into cations Al3+ and anions O2-. In the liquid aluminum cathode occurs the reaction of ions reduction of trivalent of aluminum – aluminum is released. at the cathode 2Al3+ + 6e– → 2Al0, which is periodically poured by vacuum bucket and sent to the foundry department. at the anode 3О2– – 6е– → 3О0, on carbon anode occurs oxidation of carbon produced by oxygen, emitted carbon and carbon gases CO and СО2 – i.e. there is combustion of anode sole, their calcine by combustion are replaced with new anodes. Electrolysis of cryolite-alumina melt is carried out at the anodes of carbonaceous materials, so final anodic product is not oxygen, but CO and СО2. 52

Total reaction of alumina decomposition in industrial electrolysis can be represented as: 2Al2O3 + 3C → 4Al + 3CO2 Al2O3 + 3C → 2Al + 3CO By continuous electrolysis process the replacing of anodes is performed by established pattern and replacement cycle, that depends on the quality of the anodes and competent conducting of the technological process. In practice, the daily rate of anodes combustion is 1,5-1,7 cm, which corresponds to a replacement cycle of 25-26 days. Anode exhaust gas is mainly a mixture of СО2 and CO. Simplistically electrolysis process can be written in the form: Al2O3 + 2C → 2Al + CO2↑ + CO↑ Thus, in the process of electrolysis are spent alumina and carbon anode and the electricity needed not only for the process – the expansion of alumina, but also to maintain a high operating temperature. It is consumed some fluorides which evaporate and are absorbed into the refractory facing. Mass from of the extracted aluminum at the cathode can be calculated at the first law of Faraday: M = k·I·t. For example, the amperage 200 кА for 24 hours, theoretically obtained: Mt = 0,3354·200·24 = 1610kg⁄24 hours. In practice, the metal weight (Mpr), by weighting, is always less than the theoretically calculated due to unavoidable losses during reversed reactions, «burning» of the metal. Ratio ηt = Mpr/Mt is called output current. By industrial electrolysis, the current efficiency is always less than unity, and the resulting mass is practically according to the formula: Mpr = ηt·k·I·t. 53

The current efficiency depends on many factors and is from 0.82 to 0.96. Mostly the current efficiency is expressed as a percentage: ηt = (Mpr/ Mt )·100%.

Figure 6. Production of aluminum by electrolysis

Aluminum is a silvery-white metal with a bluish tint. The density of aluminum at room temperature is 2,7g/cm3, electrolyte is 2,95g/cm3. At a temperature of 950-960°С aluminum density of the process is already 2,3g/cm3, and the electrolyte is 2,1g /cm3. The differences between these values are enough that the aluminum is on the hearth of electrolyzer, and the electrolyte is on top. By reducing the temperature the electrolyte density is growing faster than the metal’s, and there may come a time when their densities become close. Then there will be mixing of aluminum with the electrolyte, and metal will pop up to the surface, closing the electrolyzer. It is considered the difference in density of metal and the electrolyte must not be less than 0.2 g /cm3. Aluminum melting temperature is 660°С. The Al properties depend on the amount of impurities. With increasing of their content decreases the ductility and strength properties increase. Table 1 shows some brands of aluminum (grade), which are determined by the content of impurities. The main impurities are iron and silicon, coming mainly from the raw material, and by the hearth fracture iron enters the cathodic aluminum from blooms. 54

Table 1 Brands (grade) of aluminum Brand

Aluminum, Not less

А85

Impurities, not more Iron

Silicon Copper Zinc

Titanium Others Amount

99,85

0,08

0,06

0,01

0,02

0,01

0,02

0,15

А8

99,80

0,12

0,10

0,01

0,04

0,02

0,02

0,20

А7

99,70

0,16

0,16

0,01

0,04

0,02

0,02

0,30

А7Э

99,70

0,20

0,10

0,01

0,03

0,04

0,03

0,30

А0

99,0

0,50

0,50

0,02

0,08

0,03

0,03

1

The basis of the electrolyte is the solution of alumina in molten cryolite plus additions of fluorides. In practice, cryolite-alumina melt is not used, because cryolite has a rather high melting point – 10100С. Supplements of some salts can significantly reduce it, which has a positive effect on the process. The electrolyte composition, except cryolite (Na3AlF6)) and alumina (Al2O3), include aluminum fluoride (AlF3 12-14%), calcium fluoride (CaF2 4-6%), other additives are considered background, that are received with the feedstock. To characterize the composition of the electrolyte is used the term «bath ratio» (BR). This is the number of moles of sodium fluoride (NaF), per one mole of aluminum fluoride (AlF3). The chemical formula of cryolite Na3AlF6 can be written in another form: Na3AlF6 = 3NaF·AlF3. Then BR of cryolite is determined: 3NaF⁄AlF3 = 3. Electrolyte with BR = 3 is called neutral. If electrolyte contains an excess of AlF3, so BR is less than three – this electrolyte is called acidulous. If BR is more than 3, it contains an excess of NaF, this electrolyte is called alkalinous. In recent years, an electrolyte is used that contains in its composition about 15% excess of AlF3, corresponding BR 2,3-2,5. 55

Electrolyzer includes the following main blocks: 1. The cathode device. It includes cathode casing, insulating layer, a layer of refractory, hearth and board lining. 2. Anode device. 3. The current supply system – the anode and cathode bus system. 4. The fume hood system. A number of electrolytic cells connected in a circuit called series. The anode device is designed for supplying current to interpolar space. It consists of a collector beam, which is used as a frame for the mounting of automatic feeding of alumina (AFA), mechanisms of lifting shelters (MLS) and anodes (MLA). On the beam collector is anode bus-system with two rows of anode blocks, the amount of which depends on the current strength and reaches 48 pieces. Mounted anode consists of an anode block and anode holder, connected by cast iron thimble in nipple block nests. Anode holder consists of aluminum rod and steel wall bracket, contact between them is carried out by welding through the bimetallic plates or friction welding. Anode rods are pressed to the anode tires with special clamps (locks), forming an electrical contact. The anode bus system with Clamps and mechanisms of anode lifting is the anode frame which is in the process of electrolysis (anode combustion) is lowered. For redrawing of anode frame is used device for the temporary suspension of the anodes (TSA). Service of anode device consists of the following operations:  replacement of the anodes;  hauling of anode frame;  maintenance of the anode carbon;  elimination of the deviations on the anode carbon. The cathode unit consists of a cathode housing, insulation, refractories and lining (hearth and board). At the bottom of the casing is laid the layer of insulation, which is used to reduce heat loss and protect the cathode enclosure from the high temperature. Then a layer of refractory is laid, perceiving the effect of penetrating electrolyte. Bottom blocks have a groove into which the cathode bars (blooms) are 56

inserted from opposite sides. Removal of the current from the electrolyte cell is passed through them. Fastening of cathode rods in the groove block is performed by pouring of molten synthetic pig iron. Fettling of interconnect and peripheral joints is made of the bottom mass. Welds is the weak point of the hearth, and their quality largely determines the period of service of the electrolyzer. One of the tough requirements of the modern electrolyzer is to maintain a certain distance of the anode-cathode (between the anode sole and the metal mirror), which is called interpolar distance (IPD). Typically, the IPD is about 5.5 cm. The main requirement of the effective conduct of the process of electrolysis process is to maintain the purity of the IPD, i.e. smooth soles of anode carbon and a lack of cakes, sediment on the hearth. By changing the IPD is controlled voltage on the electrolytic cell. The relationship between the amperage, voltage, and resistance, is expressed by Ohm's law: I = U/R, where I – current intensity, А (amper) U – Voltage, В (volt) R – Resistance, Оm (Оm). The current in the electrolysis series usually varies very slightly. That is, the control voltage on the bath can be changed by interpolar distance. If it is needed to raise the voltage at the electrolyzer, the anode carbon is twisted, increasing interpolar distance (IPD). To reduce voltage, respectively reduce the IPD.

57

11. HYDROELECTROMETALLURGY IN PRODUCTION. ELECTROMETALLURGY SIGNIFICANCE OF COPPER, ZINC AND LEAD 11.1. Methods of processing of copper containing raw materials

Metallurgical industry is one of the oldest. Metallurgy is called the science and technology area involved obtaining metals from ores and other metal-containing materials.

Figure 7. Metallurgical plant shop

Since ancient times eight metals are known: gold, silver, copper, tin, lead, mercury, antimony and iron. Currently it is produced and consumed about 80 metals. Despite advances in technology, delivering new synthetic materials, a set of properties inherent in metals remains unsurpassed. The demand for metals is increasing from year to year. They are used in all sectors of the economy. Annual world production of major non-ferrous metals is in the tens of millions of tons. Some metals are produced in small quantities, but they are needed by new industries. 58

Continued growth in smelting of metals depletes stock of raw materials. Even now, some ores are threatened by shortage of raw materials. Therefore, one of the main tasks at the current stage of development of metallurgical production is the integrated use of raw materials and the introduction of resource-saving technologies. From electrochemical point of view metals are elements having in reactions processes prevail tending to recoil electrons, unlike nonmetals, tending to join them. The large number of metals, the differences in their properties, methods of preparation and consumption determines the need for classification of individual groups. In modern conditions it is used industrial classification of metals, which reflects the historically established structure of the steel industry and, as a consequence, the structure of training technical personnel of our country. According to the classification all industrial metals are divided into two groups: ferrous and nonferrous. Ferrous metals include iron and its alloys, manganese and chromium, whose production is closely associated with the cast iron and steel metallurgy. All other metals are nonferrous metals. The name «non-ferrous metals» is rather conventional, since actually only gold and copper have strong color. All other metals, including black, are gray in color with various shades – from light gray to dark gray. Non-ferrous metals are divided into five groups: 1. Major heavy metals: copper, nickel, lead, zinc and tin. Their names they got from the large scale of production and consumption, large («heavy») specific mass in the national economy. 2. Small heavy metals: bismuth, arsenic, antimony, cadmium, mercury and cobalt. They are natural satellites of major heavy metals. Typically they are prepared simultaneously but produced in much smaller quantities. 3. Light metals: aluminum, magnesium, titanium, sodium, potassium, barium, calcium and strontium. Metals of this group have the lowest density (specific gravity) among all the metals. 4. Precious metals: gold, silver, platinum and platinum group metals (palladium, rhodium, ruthenium, osmium, iridium). This group of metals is highly resistant to environmental and corrosive environments. 59

5. Rare metals. They are subdivided into sub-groups: a) high-melting metals: tungsten, molybdenum, tantalum, niobium, zirconium and vanadium; b) light rare metals: lithium, beryllium, rubidium, cesium; c) the trace metals: gallium, indium, thallium, germanium, hafnium, rhenium, selenium, tellurium; g) rare-earth metals, scandium, yttrium, lanthanum and the lanthanides; d) radioactive metals: radium, uranium, thorium, actinium, and the trans uranium elements. In the steel industry are used almost all kinds of minerals. The main raw material for the production of metals are ore – subsurface rock containing in its composition metal or metals in amounts which at the present level of enrichment and metallurgical technology can be economically extracted into marketable products. Ores consist of minerals – natural chemical compounds, classified as ore (valuable) and waste rock. Lean materials are minerals that do not contain extractable components; these rocks mostly represented by quartz, carbonates, silicates, aluminum silicates. Although from the metallurgical point of view waste metal is of no value, waste technologies should make full use of raw materials. Waste rock can be successfully applied in the preparation of a number of construction materials (cement, slag, slag paving and so on.). The composition of the ore is determined by chemical analysis. Besides the chemical composition, for practical purposes it is necessary to know type of minerals presented in the raw materials (mineralogical composition), and the distribution of all components of the raw material between minerals (phase composition). Depending on the type of presented metal-containing minerals, nonferrous metal ores are divided into groups: 1) sulfide, wherein the metal is in the form of sulfur compounds. An example of such ores can serve copper, copper-nickel and lead-zinc ore; 2) oxidation, in which the metals are present in the form of various oxygen-containing compounds (oxides, carbonates, hydroxides and the like). This group includes aluminum, oxidized nickel, tin ores, ores of rare metals; 3) mixed, wherein the metal may be either in the sulfide or oxidized form (copper ore); 60

4) native, containing metals in a free state. In the native state in nature there are gold, silver, copper, platinum and mercury. According to the number of present metals ores are classified into monometallic and polymetallic (complex). Most non-ferrous ores are polymetallic and contain at least two valuable components. The most complex by composition are copper, copper-nickel and leadcopper-zinc ores. They contain 10-15 valuable metals. During the processing of complex composition of ores it is necessary to achieve a complete integrated use of all its valuable components, i.e. non-waste technology. Ores, as well as other minerals form natural clusters, which are called land deposit. The content of valuable elements in deposits is significantly higher than their average content in the earth's crust. The most common metal in the nature is aluminum (7.5%), the most rare polonium and actinium (Clark of them is close to 10-15). Table 2 The prevalence in the crust of some metals %: Al Fe Ca Na K Mg Ti Cu Zn Ni

7,50 4,70 3,40 2,64 2,40 1,94 0,58 0,01 0,02 0,018

W Mo Pb Sn U Se Pt Ag Au Re

7 · 10-3 1 · 10-3 8 · 10-4 6 · 10-4 5 · 10-4 8 · 10-5 2 · 10-5 4 · 10-6 5 · 10-7 1 · 10-7

Since most non-ferrous ores are poor, ore are usually enriched, i.e., increase the metal content in the raw materials arriving at the metallurgical processing. The main method of enrichment used in nonferrous metallurgy is flotation. Prior to the enrichment the raw material passes mechanical preparation: crushing, grinding, screening. One of the largest metallurgical complex of Kazakhstan is UstKamenogorsk metallurgical complex, which consists of zinc plant with a capacity of 190'000 tons / year; lead plant with a capacity of 144'000 tons / year; the refining copper plant, with capacity of 61

70 000 t / year (of refined copper cathode, expandable up to 87500 tons / year) and industry. The production site is located in the city of Ust-Kamenogorsk; all production units have a common infrastructure. Zinc plant uses a standard technology: roasting, leaching and solution purification, electrolysis – with small features. The original plant was built in the 60s of the last century for the growth of the power of the old zinc factory (now decommissioned) and gradually expanding, today has reached 190'000 tons of zinc production in commercial types of products a year (metallic zinc, zincaluminum alloy, zinc sulfate). The raw material for the plant are sulfide zinc concentrates of Maleyev mining plant (with zinc content on average 53.5%), and other enterprises. Concentrates are processed in burning furnace of fluidized bed with blast air, oxygen enriched. The exhaust gases of the burning furnace are captured and transferred to the sulfuric acid by contact method, and zinc calcine, the product of kilning is leached with spent electrolyte. From the obtained solution after purification from copper and cadmium is obtained cathode zinc by electrolysis. These waelz-fume and sullage fumes processing of zinc slag from lead production in the slag-sublimation installation are leached in spent electrolyte, cleaned of chlorine impurities, arsenic and antimony, and transferred to the cinder leaching cycle. Zinc cathodes are melted in an induction furnace into ingots, blocks or Jumbo or used for the production of alloys and shipped to ultimate customers. To melting process of lead concentrates ISASMELTТМ process is applied since 2012. In 2010-2013 the company [Engineering Dobersek GmbH] was involved in a new project of modernization of a lead plant for the Kazakhstani metallurgical producer with an annual capacity of 100 000 tons of refined lead billet. The existing lead smelting process was modernized by replacing the standard sintering machine to a modern blast furnace. Engineering Dobersek GmbH was responsible for the overall project of smelting works, basic and detailed design, as well as the supply of the following auxiliary systems and equipment:  charge preparation;  water cooling system; 62

 gas cleaning system;  ventilation and heating of smelting works;  sullage pouring machine;  system of lead bullion production. The scope of the project also included the construction management and commissioning of the supplied equipment and staff training. One of the key components was a machine for lead slag pouring, which produces slag billet for loading into existing shaft furnace to recover. Engineering Dobersek GmbH has designed fully automatic two-line bottling machine of capacity of 45-60 tons / year. The temperature of the filling of lead slag is about 1150°C. Cooling slag occurs via air by natural convection, forced convection, and then at the end of the car by spraying water for cooling the slag briquettes to a temperature below 300°C. The exhaust gas of lead plant is very effectively captured, then cooled, cleaned and sent to a sulfuric acid plant. The modernization of lead plant has significantly reduced harmful emissions into the environment. In the process ISASMELTТМ is used stationary furnace with a refractory lining and a submerged lance. The furnace is continuously loaded by concentrates, fuel and fluxes. Air enriched with oxygen, is fed through an immersion lance and creates highly turbulent bath.

Figure 8. Shop floor of lead smelting plant

The advantage of this process is the combination of several process steps in a single unit, the possibility of more complete removal 63

of volatile impurities, flexibility in the processing of raw materials, high specific capacity coupled with low capital and operating costs. Important indicators of the process efficiency are to engage in process larger volumes of recycled materials. The melting process ISASMELTТМ is the most cost-efficient for fuels, it allows to develop secondary energy sources (steam), which is used for industrial needs. Modern equipment and full automation of the technological process, from preparation of the furnace-charge to the melting process, significantly reduce the share of manual labor. Slag subliming was processed at the zinc plant with extraction of zinc, whereas waste slag was dumped in piles. A small number of blister copper after matte converting was shipped to customers. Black lead was refined and purified from copper, tellurium, arsenic, antimony, bismuth, gold, and silver, and the billet were shipped to consumers. The quality of the produced lead is of 99,985%. The refinery shop, which is an integral part of the lead plant, use the following processes: the production of Dore melt from silver crust, collected during the refining of lead; hydrometallurgical or electrolytic refining of Dore melt to produce gold, silver and platinum group metals. Gold is produced in bars, whereas silver is produced in bars and in powder form. The company's Kazzinc bars of gold and silver with a purity of 99.95% corresponds to the brand "DEER" standard LBMA (London Stock Exchange precious metals). Upgraded manufacturing processes of lead allow to eliminate these shortcomings in the production of lead: – significant consumption of imported coke impossibility of processing copper products (copper cementation) of the zinc plant and their accumulation that presents a threat to the local environment; – production of gas with low sulfur content and their release into the atmosphere because of the inefficiency of their utilization. ISASMELT ™ process was implemented at Kazzinc according to the project «New Metallurgy». Power of the lead plant comprise 144000t of refined lead per year («YKCUK»), 7'000 t of blister copper per year, as well as small quantities of selenium, indium, tellurium, thallium, mercury and antimony concentrate. 64

Copper Plant was built in 2011 by Kazzinc. At one site, along with lead and zinc plants as a result was formed a unique technological scheme that will result in complex extraction of raw materials the maximum number of useful components in the production of high commodity availability. Technological scheme of the copper plant combines advanced technology with well-organized melting processes, and includes the following process stages: – melting of copper concentrates and intermediate products, using modern technology Isasmelt (Australia); – Electrofusion to produce matte and slag in the furnace of firm Demag (Germany); – Conversion of copper matte with Pierce Smith converters of firm Outotec (Finland / Sweden); – Anode refining of blister copper in furnaces of the company Maerz Gauchi (Germany); – Electrolysis to produce refined copper cathode on technology Isa Process (Australia). Oven Isasmelt melts copper concentrates and copper-containing current middling to produce matte-slag melt, separation of which is performed in an electric furnace to obtain a matte containing copper, gold and silver. Copper matte is processed in the converter Pierce Smith to produce blister copper. Dust and slag generated during operation of the system Isasmelt, are transported to processing plants Kazzinc for further additional recovery of valuable components by enrichment and hydrometallurgical methods. Dust-free gas is directed to the utilization of sulfur dioxide in the new sulfuric acid plant. Blister copper after anode refining is sent to electrolysis to produce refined copper of purity of brands IOC MOOK (copper content of 99.97 and 99.99%, respectively). The refining industry. Silver zinc foam, obtained during the desilverization process by lead refining, is processed by electro thermal method to obtain silver-lead. Silver-lead is processed in cupellation furnaces to release Dore bead. Dore bead is undergone electrolytic refining to produce refined silver. Refined gold is conducted on the technology developed by Kazzinc on two technological schemes: anodes electro refining from gold bullion, chemical dissolution of gold bullion, followed by 65

selective precipitation of pure gold. Refined gold is produced in the form of bars (99.99% of the content of Au). Refinery production Power is up to 52 t / per year of gold and 990 t / per year of silver, both metals have been registered on the London Good Delivery Exchange precious metals (Brand Deer). Gold and silver in the form of copper electrolyte slime are transferred to the cupellation Department for receiving Dore bead. Electrochemical metallurgy produces commodity metals in compact form or in the form of metal powders. All electrometallurgical technologies of compact metal derivation belong to one of the types of technologies to produce metals: electroextraction or electro refining. Electroextraction allow to produce metals from aqueous, nonaqueous solutions and from melts in which in the preparatory operations of processes are entering ions of extractable metals. Almost all non-ferrous metals are obtained using a greater or lesser degree of electrolysis. The main «working» electrochemical reaction takes place at the cathode under the scheme: Мn+ + ne– → M, where Мn+ – a metal ion, which is in the electrolyte, M – the product of the electrochemical reaction. It is the target product of the electrochemical technology. The purpose of the technologies of this class is to provide marketable metals. Using the electrolytic it is prepared copper, aluminum, magnesium, nickel, zinc, cadmium, silver, gold and other metals. The electrolyte in this electrochemical process can be aqueous or non-aqueous solution or melt of appropriate salts. By electrolysis of melts it is obtained electrochemically active basic metals (aluminum, magnesium, etc.). Semi-precious metals and precious metals are often obtained by the electrolysis of aqueous solutions. By electroextraction are used insoluble anodes. This means that instead of oxidation of the metal at the anode is oxidized of an electrolyte component. When using aqueous solutions such oxidizing agent is a water molecule (H2O). When using chloride solutions or melts on the anode can be oxidized chloride ion with chlorine separation. In the electrolysis of chloride – containing melts is formed chlorine. In the second case (electro refining) anodes are soluble and they participate in the anodic electrochemical reaction on scheme: 66

M → Мn+ + ne–, where M – metal of soluble anode, e– – electrons go into the electric circuit, as in the anodic electrochemical reaction electrons are the reaction product. Electro refining is the process of obtaining pure metal, suitable for technical purposes usually prepared by pyro metallurgical method of so-called crude metal. Pyro is the technology of high-temperature processing of raw material, resulting in that metal cannot be obtained with sufficient purity with permissible specific financial cost. Therefore, it is used metal pre-purification operation based on electrochemical technique. 1) One of the metals – the products of the electrochemical industry is copper. Copper is soft, ductile and malleable red metal, it is easily taken mechanical processing. It is easily rolled into thin sheets and drawn into wire. Density at 20°C the thermal conductivity of copper is 0.941 cal / cm · sec · °C, the electrical resistance of 1,68 · 10-6 Ом·см, the specific heat 0.092 cal / g · °C. Copper is diamagnetic. The melting point of copper is 1083°С. Boiling point is 2325°С. The most important property is electrical conductivity (the first is silver). Impurities decrease conductivity, so high purity copper is used in electrical technology. Also, copper has a high thermal conductivity. The high electrical conductivity of copper put it in first place among non-ferrous metals consumed by the modern electrical industry. Chemically, copper is not so active, although it may be connected directly to the oxygen, sulfur, halogens and some other elements. At ordinary temperatures and dry air, copper remains inert but in moist air containing СО2, copper is oxidized and copper is covered with a protective film of basic carbonate СuCO3·Cu(OH)2, which is a toxic substance. Copper and its sulphide are well to dissolve gold and silver; they simultaneously are removed by the refining of blister copper. Additive copper to structural steels increases their yield strength, corrosion resistance and increases the hardenability. To improve the corrosion resistance of iron, it is added thereto to 0.5% copper. The simultaneous presence of titanium (0.08-0.15%) and copper (0.350.5%) in the iron significantly increases the wear resistance of parts made therefrom. 67

The largest amount of copper is used in the electrical industry. This is explained by the fact that pure copper is one of the best conductors of electricity. Conductivity of copper determines the spending more than 50% of the copper for the wire, tire collectors, and others. All requirements to the metal specified by electrical industry satisfy the copper obtained after electro refining. Electrical copper is used in the production of cables, wires, and other products used in electrical engineering. Pressed and forged products of high quality are made of electrolytic copper. Copper is an essential metal, which largely kept the modern civilization. In terms of production and consumption in the world, copper is the second after aluminum, ranking second in the production of non-ferrous metals (aluminum, copper, lead, zinc, nickel). Most of the world's copper reserves are concentrated in the South and North America. The largest copper reserves in the world have Chile and the US, so the state of the copper market largely depends on the situation in the American continents. In addition to Chile and the United States, the main holders of copper reserves are 17 countries, which together have more than 80% of proven reserves. Table 3 presents data on stocks of copper in the countries, having the richest deposits of this metal. Table 3 Countries with the largest proven reserves of copper and content in the base metal ore (Source: USGS, Mineral commodity Summaries) Country Chile USA China Кazakhstan Poland Zaire Zambia Uzbekistan Indonesia Iran

Part of world supplies,% 19,88 12,66 6,65 6,15 3,69 3,23 2,99 2,58 2,55 1,69

Supplies thousand/tons 119599 76176 40000 37000 22200 19400 18000 15500 15366 10150 68

Content of Cu in ore,% 1,01 0,65 1,0 0,45 1,85 3,97 2,75 0,40 1,28 1,10

As can be seen, from the CIS countries the largest copper reserves have Kazakhstan and Uzbekistan, of the European countries – Poland. The main copper raw materials are sulphide ores. From sulfide ores are smelted currently 85-90% of all primary copper. The sources of producing copper are ores, products of their enrichment – concentrates – and secondary raw materials. The share of secondary raw materials now is about 40% of the total copper output. Copper ore is almost entirely related to polymetallic. Monometallic ore copper is not in nature. The precious associated rocks of copper in ore raw materials are about 30 elements. The most important are: zinc, lead, nickel, cobalt, gold, silver, platinum group metals, sulfur, selenium, tellurium, cadmium, germanium, rhenium, indium, thallium, molybdenum, and iron. The value of copper ore significantly increases because of the presence of noble metals and some rare metals – selenium, tellurium, rhenium, bismuth and others. Pyro metallurgical copper can contain up to 200 g of gold, and 2 kg of silver per ton of copper. Electrolysis allows to highlight these noble metals in the form of sludge. Sludge is a powdered solid metal that can be recycled for further separation and production of pure silver and gold. The cost of gold and silver produced in the process of copper refining is completely compensated for the costs of electrolysis. This process scheme is the following: in the anodic process occurs dissolution of copper from its transition into the electrolyte according to the scheme: M → Мn+ + ne–. From the electrolyte by the cathodic reaction is obtained pure cathode copper deposit: Мn+ + ne– →M. Growing on the cathode copper deposit has a columnar structure, which may be affected by the introduced special substances in electrolyte – growth regulators, and other settings for the electrolysis. Present in the draft anode metal atoms of silver, gold do not oxidize in the selected mode, form own crystal structure and form a slurry. Particles of sludge are deposited on the bottom of the cell, are collected by special methods and passed to other stages of the process. By the refining the blister copper it is produced per ton of parent metal to 1 kg of silver and to 200 of gold. 69

11.1.1. Marking of copper, basic concepts and terms Leading steel companies supply products to dozens of countries. International Cooperation and Globalization copper market requires manufacturers to comply strictly with relevant standards on the composition and properties of the alloys. The single copper market also involves the use of a single system of alloys marking. By marking specialist can immediately determine the method of production of the alloy, guaranteed level of properties and the possible scope of application. One of the major systems of copper marking, widely used by all producers and consumers is the marking of the USA, which is based on the basic technological features of the manufacturing process. When choosing international system of the copper labeling it is also taken into account the authority of the United States in the global production and consumption of copper. In recent years, the use of labeling system UNS (The Unified Number System – Unified Numbering System) is being expanded, which was jointly developed by ASTM, SAE (Society of Automotive Engineers) and several other organizations to unify the different systems of notation. In the latest editions of ASTM standards is indicated parallel ASTM and UNS markings. ASTM Standards for all copper alloys begin with the letter «B». The system UNS marking consists of the letter and five numbers. The letter indicates the class of alloy; figures show the alloy brand within the class. Marking of copper alloy starts with the letter «C» (copper) and is written as СХХХХХ where XXXXX – a five-digit numeric number. Alloys with the number less than 80000 are treated by pressure, more than 80000 – casting. Marking S1 ХХХХ corresponds to copper of varying degrees of purity, the rest – its alloys. The above marking system of copper is described in a number of standards, the main of which is the standard ASTM D 224-98 «Standard Classification of Coppers». This standard is marked «International» and it applies to products of refined copper. The text of the standard specifies that it is useful for the initial contacts and for alloy choice of specific production. This standard gives a number of 70

terms describing a method of producing copper and its brief characteristics, such as: – on purification method (refining): 1) chemically refined copper – copper chemically treated; 2) electrolytic copper – electrolytically refined copper (because of the importance cathode copper is rendered in a separate standard ASTM B 115); 3) fire-refined copper – copper fire refining. On the method of casting and processing in the liquid state (Casting or Processing): – deoxidized copper - casting from deoxidized copper; – oxygen-free copper - oxygen-free copper electrolytic; – specific grades of copper and properties of products from it (Specific Kinds of Copper and to Products): 1) deoxidized copper, high-residual phosphorus – deoxidized copper with high residual phosphorus content; 2) oxygen-free copper, extra low phosphorus – oxygen-free copper with an extremely low content of phosphorus and others. Oxygen-free copper (OF) is copper with an oxygen content of not more than 0.001%. It is also stipulated in the standard key indicators that define this brand of metal (mostly the limit the phosphorus content). – For example: Brand Cu – DHP (deoxidized copper, high – residual phosphorus) – residual phosphorus content in the range of 0.015 to 0.040% (this copper is not prone to hydrogen embrittlement and has a relatively low electrical conductivity of the high content of phosphorus); – Brand Cu – DLP (deoxidized copper, low-residual phosphorus) – deoxidized copper with low residual phosphorous content, has agreed amount of phosphorus – from 0.004 to 0.012%; Brand Cu – OFXLP (oxygen free copper, extra low phosphorus) – oxygen-free copper with a phosphorus content of 0.001 to 0.005%. The full composition of each brand, controlled properties, their level and other requirements are specified by other standards. More information about composition and other requirements, determining the level of properties, are registered for copper of responsible 71

marking. For example, for the oxygen-free Cu OFE mark, which is in the electronics industry, the total content of harmful impurities As, Bi, Mn, Sb, Se, Sn, Te should not exceed 0.004% and phosphorus not more than 0.0003% (ASTM B – 4). Also, stricter demands are to copper, which is used to make heat exchange units (ASTM B 359 – 98). Recommended alloys C10100 (OFE), C10200 (OF), C10300 (OFXLP) and a number of others that are also used for the manufacture of electronic industry, have a minimum copper content at the level of 99,99% (OFE) and 99,95% (OF, OFXLP). For relatively less responsible products, the level of requirements on the composition is correspondingly less. In addition to brands with a very low content of impurities, they are allowed to use less pure copper. For example, for seamless tubes of general purpose ASTM B 68 - 99 "Standard Specification for Seamless Copper Tube, Bright Annealed", which is subjected to bright annealing, are recommended copper С 10200, С 10300, С 10800, С 12000, С 12200. Requirements for the composition according to ASTM B 68 - 99 are shown in Table 4. Table 4 The composition of the copper for the manufacture of seamless pipes according to ASTM B 68-99,0 wt. % Element

С10200

С10300

С10800

С12000

С12200

Сu min

99,95

Cu+P min

-

-

-

99,90

99,9

99,95

99,95

-

-

P

-

0,001…0,005

0,005…0,012

0,004… 0,012

0,015…0,04

As copper in large quantities is for the manufacture of wire products, one of the main controlled properties is electrical conductivity (electrical resistance). The US standards and technical documents of other countries electrical conductivity of the copper often indicate in the percentage IACS (from the International Annealed Copper Standard). In this system, for 100% is taken conductivity at 20C of pure copper wire with a diameter of 2 mm after 72

annealing at 500°C for 30 min. It corresponds to the conductivity 58 m/(Оm·mm2) (specific electrical resistance 0,017241 mk·Оm·m). Mechanical voltage (strength characteristics) in ASTM standards measured in ksi (kilopound per square inch – kp per square inch). 1 ksi = 6,9N / mm2. If in the standard is used metric system, it is additionally marked with the letter «M» – В 395M – 95. The level of the properties is determined by the condition of the metal (cold deformation and annealing). For example, the standard ASTM B 272 – 01 «Standard Specification for Copper Flat Products with Finished (Rolled or Drawn) Edges (Flat Wire and Strip)» determines the next series of states (Temper): – O61 (annealed – annealing process) – H00 (eight hard – 1/8 hardness) – H01 (quarter hard – 1/4 hardness) – H02 (half hard – 1/2 hardness) – H03 (three-quarter hard – 3/4 hardness) – H04 (hard – hard) – H06 (extra hard – superhard) – H08 (spring – a spring). In European countries, the main system of standardization is European norms (EN). One option of marking to EN is numeric-alphabetic system, partly is analogue of marking UNS USA. The European standard EN 1982: 99 «Copper and copper alloys. Ingots and casting» casting copper alloys are designated as ССХХХК. Here, the characters «CC» – «copper casting», characters «XXX» – alloy number. For example, the alloy CuSn12 (BrO12) according to EN is designated as CC483K. Wrought copper alloys to EN are designated CWXXXA, CWXXXC (on copper wrought – copper deformed). XXX – alloy number which is dependent on impurity doping. Pure (refined) copper corresponds to the brand CW004A. In addition to the alphanumeric system in a number of EN standards is used marking similar marking ASTM (ASTM 224-98 et al.). It is sometimes referred to trade marks. It is used almost the same system of letter symbols of the method of cleaning and other process parameters and characteristics of copper. For example, Table shows the labeling and composition of copper, which is for products for 73

general use (standard EN 1652: 1998 «Copper and copper alloys – Plate, sheet, strip and circles for general purposes»). Table 5 Marking and composition of copper, by weight % for general purpose rolling according to EN 1652: 1998 Marking Symbolical Cu-ETP Cu-FRTP Cu-OF Cu-DLP Cu-DHP

Cu

Bi

O2

P

Pb

˃99,90 ˃99,90 ˃99,95 ˃99,90 ˃99,90

˂0,0005 ˂0,0005 ˂0,0005 -

˂0,04 ˂0,100 -

˂0,013 ˂0,04

˂0,005 ˂0,005 ˂0,005 -

Numerical CW004A CW006A CW008A CW023A CW024A

Practice shows that the majority of manufacturers of copper and its products mainly use ASTM and EN (trade marks) or states national standards, primarily Germany, due to its prominent role in the production of refined copper. For example, for the manufacture of electrical products it is often used copper grades E – Cu57 and E – Cu58 (German standard DIN 1787-73). The numbers in the marking point to the electrical conductivity of copper 57 (58) m/(Оm·mm2). This designation (E-Cu) usually is indicated in technical documentation. Relevant copper grade EN – CW004A – almost never is used to describe these products. According to interstate standards DSTU GOST 859-2003 «Copper. Marking» copper marking on chemical composition and metallurgical processing methods are divided into the following five groups: – fire refining copper, which is melted in the usual manner, containing 99,5 ... 99,7% Cu; – cathode electrolytic copper 99,93 ... 99,97% Cu; – remelted deoxidized copper with controlled content of deoxidizer (phosphorus) 99.5 ... 99.9% Cu and oxygen content 0.01% and phosphorus 0.0012 ... 0.06%; – oxygen-free copper, smelted in an inert atmosphere 99,95 ... 99,99% Cu; – Evacuated copper 99,95 ... 99,99% Cu. 74

Copper Marking is generally denoted by the letter "M" followed by figures, indicating the degree of purity and the letter, indicating the degree of purification: c – cathode; r – refined and deoxidized; ph – deoxidized phosphorus; f – oxygen-free copper. The numbers which characterize the degree of purification of the copper varies from 00 - most pure copper comprising Cu > 99.99% to 3 with copper Cu > 99.93%. In many cases such a low impurity content is not required, which reduces the cost of the metal while maintaining a high level of physical and mechanical properties. Corresponded standards for each group of products specified maximum content of impurities, taking into account their impact on the basic properties that are required for the metal of the product. For example, for copper pipes used for construction, for the manufacture of heat exchangers and other purposes, it is recommended copper grades M1r and M2P. According to the European standard BS EN 12449: 1999 for general-purpose pipes is allowed a maximum impurity content of 0.1% weight when the content of phosphorus is of 0.015 ... 0.04% by weight. The hardness mark of copper on GOST depends not only on the mark, but on the profile type and method of production. For example: soft state corresponding to 50 ... 55 HB, semi – solid-75 HB, solid – of 70 to 95 HB. Numbers, characterizing the degree of copper purity, are changed from 00 – pure copper, having Cu > 99,99 % to 3 with the copper content Cu > 99,93 %. Thus, in the world, there are several standards systems for copper composition, and transferring one marking into another without the appropriate documentation is impossible. In promotional materials often it is indicated a trademark without reference to a particular standard. Normally, the leading copper producers are working on a specific order, which necessarily mean grade of copper, and the standard by which it is produced. Marking of copper to some extent differ by the content not only of the main element, but acceptable levels of impurities, in which customers are very interested. To ensure this requirement, the 75

company must have a well-functioning and well-developed technology to produce a given composition of copper in all parameters according to customer requirements. Influence of impurities on the copper properties Many index marks of copper are different in impurity content in hundredths of a percent. It means that there is marked influence of small amounts of impurities on the basic physical and mechanical properties of copper. Because of the production copper always contains a number of impurities; the main ones are bismuth, antimony, lead, sulfur, oxygen. By the nature of the interaction with copper all impurities can be divided into three groups. The first group includes the impurities, soluble in the solid copper (aluminum, iron, nickel, zinc, silver, etc.). With a small content, typical for metal commercial-purity, these elements have little effect on the properties of copper, although they somewhat reduce electrical and thermal conductivity. The second group contains elements, which are substantially insoluble in copper and form a low melting eutectic with it. Such impurities include bismuth, lead, antimony. The insoluble impurities adversely effect on the physical-mechanical and technological properties of copper, and the effect manifests itself even at very low contents of these elements. Bismuth by content of more than 0.001% by weight allocates in the form of brittle layers along the grain boundaries. By hot forming such layers are melted, copper becomes hot-brittle, and deformed workpiece is destroyed along the grain boundaries. At low temperatures, the fragile layers provoke cold brittleness. Antimony is more soluble in copper than bismuth, and thus dramatically reduces the thermal and electrical conductivity of copper. Lead also forms a fusible separation at the grain boundaries, and because of the low melting point, this leads to a strong hot brittleness of copper in the hot plastic working. The third group consists predominantly of nonmetallic elements which form chemical compounds with copper (oxygen, sulfur, phosphorus, arsenic, selenium, etc.). The solubility of oxygen in the copper is small, all the oxygen contained in the copper is in the form 76

of separate hard and brittle particles Cu2O, formed copper oxide creates a eutectic (Cu+Cu2O), which grain boundary separation reduce plasticity and deformability of the metal. Cu2O particles tend to form clusters, which lead to the destruction of the copper by treatment pressure both hot and cold. To form the eutectic (Cu2S+Cu) is sufficient minimum amounts of sulfur, while allocating it deteriorates ductility of the hot plastic working and the corrosion resistance of copper. Hydrogen is an extremely harmful element, its high content causes so-called «hydrogen disease». Hydrogen reacts with oxides contained in copper, to form water vapor (Cu2O + H2 = H2O + 2Cu). Under the vapor pressure of water inside the metal occur microfissures, and on the surface – bubbles from metal distention. Hydrogen affects weak on copper, deoxidized by phosphorus. Thus, all the impurities to some extent degrade the properties of copper. Even those impurities that do not affect the technological plasticity and strength of copper significantly reduce indicators of physical properties. Most impurities degrade the entire set of properties and firstly characteristics of electrical and thermal conductivity. Furthermore, most of these impurities enter into chemical reaction with each other and reinforce their negative influence. Hydrogen is particularly impairs the properties of the copper containing increased amounts of oxygen. When sharing the presence with oxygen, antimony, and arsenic sharply decreases the electrical conductivity. Thus, the task of metallurgists is to maximize reduction of impurities in copper, particularly harmful, because to remove them completely from metal is technically impossible. Continuous improvement of the quality requirements of the metal leads to the legislature (at the level of standards) limit of the content of impurities in the copper, which is used in major industries. 11.1.2. Methods of production of high-grade copper Metals are the main type of steel production. In non-ferrous metallurgy, depending on the used technology and the composition of the resulting metal it is distinguished rough and refined metals. Marketable products, supplied to the consumer for further use for its intended purpose, as a rule, are refined metals. 77

Metals contaminated with impurities are called crude metals. The copper and nickel may have contaminants, and valuable items – associated rocks of basic metal. Harmful impurities decrease characteristic properties of the metal (conductivity, ductility, corrosion resistance, etc.) and make them unsuitable for direct use. Conversely, precious metals, selenium, tellurium, germanium, indium, bismuth and many others represent a value in itself, and must be simultaneously selected in the appropriate product that is of great economic importance. Crude metal are necessarily purified from impurities – refining. The quality of crude metals, in some cases is established by industry standards and technical specifications that regulate the relationship between producers and crude metal plant where they go for refining. The ultimate objective of copper metallurgy, like any other metal production, is the production of metals from the feedstock in free metallic state or in the form of a chemical compound. In practice, this problem is solved by using special metallurgical processes, ensuring the separation of waste material components from valuable constituents of raw materials. Production of metal products from ores, concentrates or other metal-containing raw material is a difficult task. It becomes much more complicated for copper and nickel ores, which are generally relatively poor and complicated composition polymetallic raw materials. During the processing of the raw materials by metallurgical methods, it is necessary simultaneously with producing base metal to provide a comprehensive selection of other valuable components into independent commercial products with a high degree of removal. Ultimately, metallurgical industry should make full use of all components of the feedstock and the creation of non-waste (boardless) technology. As previously stated, the majority of copper ores consist of compounds of copper, iron and gangue, so the ultimate goal of metallurgical processing of ore is to obtain a metallurgical product due to the complete removal of gangue, iron and sulfur (in the case of processing of sulphide raw materials). To obtain sufficiently high purity metals from complex polymetallic raw materials with a high degree of complexity of its use 78

it is not sufficient to apply a metallurgical process or a metallurgical plant. This task is far realized in practical terms by using multiple processes of gradual separation of the components of the feedstock. The whole complex of used metallurgical processes, training and support operations is formed in the flow chart of the site, department, department or enterprise. All enterprises engaged in processing of copper, are characterized by multi-technological schemes. The basis of any metallurgical process is the principle of the transfer of the processed raw materials in a heterogeneous system consisting of two, three and sometimes more phases, which must be different in composition and physical properties. Thus one of the phases should be enriched by extractable metal and depleted by impurities, while other phases, on the contrary, depleted by the main component. Differences of some physical properties of the resulting phase (density, aggregate state, wettability, solubility, etc.) provide a good separation of them from each other by simple processing methods, such as sedimentation or filtration. Modern metallurgical process should ensure: 1) high degree of use complexity of the feedstock; 2) high specific performance of steel vehicles; 3) minimum energy costs; 4) maximum use of secondary energy resources; 5) the use of equipment which is simple, cheap and easy to use, start-up, commissioning and maintenance; 6) the high degree of comprehensive mechanization and automation; 7) the high productivity; 8) safe and harmless working conditions; 9) the elimination of emissions; 10) the maximum cost-effectiveness. The high degree of complexity of the use of raw materials is the main and perhaps the most important requirement to modern technology and it must be understood in the broadest sense. The concept of comprehensive utilization of raw materials should be included as much as possible high recovery of valuable components 79

of the ore: copper, nickel, zinc, cobalt, sulfur, iron, precious metals, rare and trace elements, as well as the use of the silicate ore. Processed sulphide ores and concentrates have sufficiently high calorific value and are not only a source of valuable components but also process fuel. Consequently, the concept of the integrated use of raw materials should be included the use of its domestic energy capacity. Copper ores and concentrates have the same mineralogical composition and differ only in the ratio between the different minerals. Consequently, the physical-chemical basis of metallurgical processing is completely identical. For processing copper raw material to produce copper metal is used the pyro and hydrometallurgical processes. The total production of copper in the pyro metallurgical methods share accounts for about 85% of world production of this metal. Pyro metallurgical technology provides raw material processing (ore or concentrate) on the blister copper with subsequent refining mandatory. If we take into account that the bulk of the copper ore or concentrate is composed of sulphides of copper and iron, the ultimate goal of pyro metallurgy of copper - obtaining blister copper – achieved by the almost complete removal of gangue, iron and sulfur. The most common technique involves the mandatory use of the following metallurgical processes: – smelting on matte; – converting of copper matte; – fire and electrolytic refining of copper. In some cases, before the melting is carried out preliminary oxidative roasting of sulphurous materials. Roasting is used for partial removal of sulfur and transferring of iron sulfides, and other elements easily in slagging oxides during subsequent melting. As a result, most of the roasting sulfides becomes oxides, some of which escapes in the form of oxides. The degree of removal of some of the elements in the firing process,% (of their content in the raw materials): As Sb Bi Se Te Pb Zn 60…80 20…40 10…15 25…50 25…50 5…10 5…7 80

Copper matte, containing depending on the starting ore materials and processing technology from 10 to 70 ... 12 ... 75% copper, are processed preferably by recycle conversion. The main purpose of conversion is receiving blister copper by oxidation of iron and sulfur and other associated components. Noble metals (silver, gold), the bulk of the selenium and tellurium remain in the crude metal. Blister copper is the end product, typically and has a chemical composition shown in Table 6. Table 6 The chemical composition of the blister copper after converting Сu

S

Fe

Ni

Pb

As

Sb

Bi

Sn

Zn

97,599,5

0,030,35

0,010,15

0,10,5

0,050,26

0,030,3

0,030,2

tо 0,05

tо 0,1

tо 0,03

Au

Ag

0,003 0,002 0,04 0,3

Se

to 0,1

The blister copper is produced in the form of ingots weighing up to 1200 kg and anodes, which run on the electrolytic refining. Copper refining is produced by fire and electrolytic methods. The purpose of fire refining in a preliminary (before electrochemically) stage of production is reduced to a partial purification of copper from impurities, having high affinity for oxygen and its preparation for the subsequent electrolytic refining. Fire refining method of molten copper is to maximize removal of sulfur, oxygen, iron, nickel, zinc, lead, arsenic, antimony and dissolved gases. For immediate technical application blister copper is not suitable, and therefore it is necessarily subjected to refining to clean of contaminants and the associated recovery of precious metals, selenium and tellurium. Small inclusion (few parts per million of copper particles) elements such as selenium, tellurium and bismuth can significantly degrade the electrical conductivity and the workability of the copper properties that are particularly important for the industry that produces cabling and wiring products, which is the largest consumer of refined 81

copper. Electrolytic refining is considered a major process that allows to obtain the copper that meets the most stringent requirements of electrical engineering. The essence of electrolytic refining of copper is that the anode alloy (cast, usually of fire refining copper) and cathodes – thin matrix of electrolytic copper – halt alternately in an electrolytic bath filled with electrolyte and through the system direct current is passed. During the electrolytic refining are solved two main tasks: – deep cleaning of copper from impurities; – the passing extraction of related valuable components. In the electrolytic refining of copper is expected to receive copper of high purity (99,90 ... 99.99% Cu). According to GOST highest grade of electrolytic copper should contain no more than 0.04% of impurities. It should be noted that the higher content of the precious metal in the initial copper, the lower the cost of electrolytic copper. To perform electrolytic refining of copper, anodes cast after fire refining, are placed in an electrolytic cell filled with electrolyte sulfate. Between the anodes in the baths are thin copper sheets – the cathode substrate. Electrolyte is aqueous solution of copper sulfate (160 ... 200 g / l) and sulfuric acid (135 ... 200 g / l) with impurities and colloidal additives, the flow of which is 50 ... 60 g / t Cu. Most of all as colloidal additives are used carpenter's glue and thiourea. They are introduced to improve the quality (structure) of cathode deposits. Operating temperature of the electrolyte is 50 ... 55°C. By copper electrolysis often operation is at a current density of 240-300 A/m2. When the tubs are in direct-current network there occurs electrochemical dissolution of copper at the anode, migration of the cations through the electrolyte and depositing it on the cathode. Impurities of copper mainly are distributed between slurry (solid residue at the bottom of bath) and the electrolyte. Figure 8 shows a diagram of the process of electrolytic refining. 82

Figure 9. Scheme of electrolytic refining process of copper 1 – anode; 2 – cathode; 3 – electrolyte; 4 – cuttings. Dissociating: CuSO4 → Cu2+ + SO42Anode: Cu - 2e– → Cu2+ Cathode: Cu2+ + 2e– → Cu

11.1.3. Composition of the electrolyte by copper refining The electrolyte, used for copper refining should be highly conductive and provide production of dense and pure copper sediment. To ensure the cathode layer of copper by ions, the copper concentration must be sufficiently high, its decline, particularly at high current densities results in intensive formation of dendrites. Refining may be carried out in a solution of copper sulfate, but the electrical resistivity of the electrolyte is large, increasing the specific energy consumption. Therefore, in the electrolyte is added sulfuric acid H2S04, having a high electrical conductivity. In addition, it prevents the formation of colloidal particles of copper hydroxide or its basic salts that can be adsorbed by growing precipitate contaminating it, as well as changing the discharge mechanism. Sulfuric acid is regenerated simply, and it is inexpensive and accessible. At various enterprises ion concentration Cu(II) in the electrolyte is 35-50 g / dm3 and sulfuric acid – 120-200 g / dm3. Such an electrolyte has high conductivity, it provides acceptable specific energy consumption; at higher concentrations increases the viscosity of the electrolyte and sludge, as well as the probability of a salt passivation of anodes. In copper refining electrolyte are always present impurities that go into it from the anodes. According to the degree of influence of 83

impurities on the electrolysis process and the quality of the cathode deposit are allowed their different concentrations. The maximum allowable concentration of nickel ions is considered to be 20-25 g / dm3, although in some plants because of the specific raw materials, it reaches 36 g / dm3. For antimony maximum allowable concentration is 0.4-0.5 g /dm3. As the concentration of antimony grows, the refining effect decreases. The arsenium content in the electrolyte is recommended to keep 0). The energy is stored in the metal as a free energy. This determines the thermodynamic instability of metals, i.e. the ability of metals transition in an oxidized state, characterized by lower energy of Gibbs. Corrosion is accompanied by the release of energy, and the transition of this energy into thermal energy (in space and time) is random. Heat is dissipated into space, its practical use is impossible. Corrosion products also tend to disperse in the space, which leads to an increase of entropy (ΔS) system. So, from the standpoint of thermodynamics the corrosion processes: Metal + corrosive environment → corrosion products can be described as: ΔG 10? 6. What is used to prevent corrosion or reduce its speed? 7. What are ways to protect metals from corrosion? 8. What is doping and what is its role in the protection against corrosion? 9. What types of protective coatings are used and what methods and techniques are used for their application? 10. What kind of metals must be that are used as cathode coatings? 11. What metals can be used as anode coatings? 12. What is the protection against corrosion and how it is achieved? 13. What is the meaning of the cathode electrochemical protection and how it is implemented? 14. What is the purpose of the anode cathodic protection?

Laboratory work № 12 Galvanic cell Objective: On the basis of the table of redox potential to make battery cells and calculate the emf. Necessary tools and materials: 1. Copper-Zinc galvanic cell. 2. The voltmeter. 3. Galvanometer. 284

4. The electrolyser or cups. 5. Electrolytic key. 6. Copper and Zinc plate. Solutions: 1. Solutions of zinc sulfate – 0,01 М и 1 М. 2. The copper sulfate solutions – 0,01 М и 1 М

Figure 14. The circuit of copper-zinc galvanic cell

A device for directly converting chemical reaction energy into electric energy is called galvanic cell. Consider the work of copperzinc cell. The element is composed of a zinc plate, immersed in a zinc sulfate solution and a copper plate, immersed in a copper sulfate solution. Both solutions are in contact with each other. They are separated by a partition from porous material permeable sulfate ions. By using the galvanic cell takes the overall reaction: Zn + CuSO4 = ZnS04 + Сu. Here, the oxidation processes and reduction are separated in space, and to carry out the recovery process of copper ions, electrons pass from the oxidant through the conductor, i.e. create a current through an external circuit. The zinc electrode is the source of the electrons flowing in an external circuit, referred to as negative (anode), a copper electrode – positive (cathode). The equations of electrode processes occurring during operation of the cell: 285

The anode, oxidation: The cathode process, reduction:

Zn – 2е– = Zn2+ Сu2+ + 2е– = Сu°

The galvanic cell can be written in the form of a short circuit electrochemical: А(–) Zn | ZnS04 || CuSO | Cu А(–) Zn | Zn2+ || Сu2+ | Сu°

(+) К (+) К

where a bar denotes the boundary between the electrodes and the solution, two features – the boundary between the solutions, in parentheses electrodes marks, the anode is written on the left, the cathode - to the right. A necessary condition for the work of the cell is the difference between potentials of its electrodes. Lower potential electrode is an anode. The electromotive force of the galvanic cell (EMF) – a positive value and is defined as the difference between the potentials of the cathode and the anode. EMF = Еc – Еа. Completing of the work: Experiment 1. Preparation of electrochemical cells One of micro glass should be filled with 1M solution of zinc sulphate, and the other –1M solution of copper sulfate. Connect cups by electrolyte bridge, filled with a saturated solution of potassium chloride in the mixture with agar-agar. To lower narrow zinc plate in zinc sulfate solution, and in copper sulfate solution - copper plate. To connect lowered plate with a galvanometer or other recording device by the electric wire. To watch the deflection of galvanometer, indicating the occurrence of an electric current. Experiment 2. Preparation of the concentration galvanic cell Fill micro glasses with zinc sulfate solution of various concentrations: the first cup – 1M ZnS04, second – 0,01M ZnS04. Connect cups by Electrolyte Bridge. Lower into each cup zinc strips and connect them by the wire with a galvanometer. Does galvanometer needle deviate? (Repeat the experience with a solution of copper sulfate – 0.01 M and 1 M). 286

Write the equation of chemical reactions at the electrodes of electrochemical cells, and the total equation of a chemical reaction resulting in an electric current in this element. In what direction are moved electrons in the external circuit? Write down from the application to the laboratory practical the numerical values of the standard electrode potentials of copper and zinc, and calculate the EMF of copper-zinc element. What ions and in which direction do move in the solution? Calculate the emf of silver concentration cell. Submit a written report to the teacher for approval of the done work. Control questions: 1. The cell consists of zinc metal, immersed in 0.1 M zinc nitrate solution, and the metal lead, immersed in a 0.02M lead solution. Make a diagram of the cell, write the equations of electrode processes and calculate the electromotive force (EMF) of the process. 2. Define the electrode potential, hydrogen electrode, the electromotive force, cell. 3. Nickel plates are omitted in aqueous solutions of salts: magnesium sulfate, sodium chloride, zinc chloride, lead nitrate. What salts will the nickel react with? 4. Make a galvanic cell in which the nickel and steel plates placed in solutions of their salts. Write the electrode reactions, equation of the currentproducing reaction, calculate the EMF and the equilibrium constant. 5. Make circuit, write equation of electrode processes and calculate the electromotive force of cell, consisting of silver and lead plates immersed in a solution of its own ions with the concentration (activity) [Ag+] = [Pb2+] = 1 mol / l. Will the EMF be reduced to 10 times when the concentration (activity) of each ion? 6. Make circuit of operation of the closed electrochemical cell formed by iron and lead, immersed in 0.005 M solutions of their salts. Calculate the EMF and Аmax of this cell. 7. Calculate the EMF of element in which there is a reaction: Zn+ Sn2+ = Zn2+ + Sn при [Zn2+] = 10-4 mol/l, [Sn2+] = 10-2 mol/l. 8. EMF of the galvanic cell formed by nickel, immersed in a salt solution with a concentration of nickel ions, 10-4 mol / l, and silver, immersed in a salt solution, equal to 1.108 V. Determine the concentration of silver ions in the solution of its salt. 9. Make a diagram of the concentration of the galvanic cell at [Ag+] = 10-2 mol/l by one electrode and [Ag+] = 10-4 mol/l – by the other. Indicate which of the electrodes an anode is, and which is – cathode. 287

10. Determine the concentration of ions Cu2+ in solution, if by 298 К EMF of element, wherein the reaction takes place Zn + Cu2+ = Zn2+ + Cu, equal 1,16В and [Zn2+] = 10-2 mol/l. 11. EMF of the galvanic cell, composed of two hydrogen electrodes, is equal to 0.271 V. What is the pH of the solution, in which is immersed the anode, if the cathode is immersed in a solution of pH = 3? 12. Which of the electrode is negative and which is positive in concentration element, formed by aluminum electrodes at a concentration (activity) Al3+ ions in one 0.01 mol / L, in another – 0.1 mol / l. Calculate the EMF element.

Laboratory work № 13 Production and study of battery Objective: Introduction to the work of lead-acid battery, the scheme of the process of charging and discharging Necessary tools and materials: 1. Galvanometer or a digital voltmeter; 2. The lead electrodes; 3. DC power supply; 4. The bunsen beaker of 50 ml Solutions: 1. Solution H2SO4 4,0 М Completing of the work: Production and study of the work of the lead battery 1. Assemble the model of lead battery. Fix the lead electrodes in tube, put them in a glass, fill the glass 1/2 of the volume of sulfuric acid. Charge the battery; connect to the lead plates of a constant current source. A few minutes pass an electric current, and then disconnect the power source. Check the charged battery, connect the electrodes to a voltmeter, and note the presence of a potential difference. 2. Draw device, record observations of the process of charging and discharging the battery. 3. Write anode and cathode reactions occurring when the battery is charging. Specify the electrodes charges. 288

4. Write anode and cathode reactions occurring at discharging the battery. Specify the electrodes charges.

Figure 15. The scheme of the lead-acid battery operation: a – charge; b – discharging:

The content of the report: 1. Identify the sources of energy that may be. 2. Record the classification of lead-acid batteries, describe their device. 3. Describe the principle of labeling of the battery. 4. Write the form of electrolyte, the normal density of the electrolyte, mixing rules. 5. Draw the diagram (Fig. 15) of charging, discharging the battery, describe the process. 6. List the characteristics of lead-acid batteries. 7. Operations that are carried out in the technical operation of the process of the battery. 8. List the possible failure of lead-acid batteries. Control questions: 1. What electrode in a lead acid battery is the anode, which - cathode? What is the quantitative correlation of their potentials? 2. What processes do occur at the electrodes of acid battery during charging and discharging? 3. How can determine the concentration and weight of the solution with the help of hydrometer? 4. How much water should be added to 100 ml of 40% nitric acid solution of density of 1.307, for the preparation of 15% solution? 289

Laboratory work № 14. PREPARATION OF ACID ELECTROLYTES - BATTERY SULFURIC ACID Objective: 1. Learn the process of preparation of the acid electrolyte solution of a given concentration. 2. To master the techniques of determining the density of the electrolyte. Necessary tools and materials: 1. Hydrometers, densitometer or thicktometer. 2. The glass cylinder. 3. Glass or ebony sticks. Solutions: Concentrated sulfuric acid of density of 1.84 g / ml Completing of the work: 1. Get from the teacher control solution of sulfuric acid. Determine its density and concentration. For this purpose, into glass cylinder pour 2/3 volume of stock solution. Carefully lower the hydrometer into the liquid, without letting it go until it becomes clear that it floats – otherwise it can be broken at the bottom of the hydrometer cylinder. After that, taking away his hand, give areometer the right position: it must be vertical in the center of the cylinder and not to touch its walls and bottom. 2. Make indication on the hydrometer divisions, taking the density of the scale value, which coincides with the level of the liquid (at the lower meniscus!). Write indication in a notebook. After measuring the hydrometer should be removed from the liquid, washed well and dried. 3. Using the application table, find the percentage content of acid in the solution. If this value is not in the table, and there are close value to it, then the percentage concentration found by interpolation on two well-known extreme values is calculated intermediate value. 4. Determine the volume of the solution, and, knowing its density, to calculate the weight of the solution. Knowing the value of the data, determine the ratio of solution and water needed for the 290

preparation of the electrolyte solution of the desired concentration (the concentration of values take from the instructor). Remember that to dilute sulfuric acid, the acid should be added to the water, and not vice versa!

Figure 16. Density hydrometer

5. Prepare the final electrolyte solution (using distilled water only). By measuring the density using a hydrometer, check the concentration using the application table. The prepared solution at the end of class pass to the teacher. 6. Form the work, bringing all the experimental and calculated data. Control questions: 1. 2. 3. 5. 6. 7.

Purpose of batteries (battery). How different are batteries depending on the components? What are the batteries by design? What is the lead-acid battery? What is the electrolyte lead-acid battery? What is measured density of the electrolyte, its value depending on the temperature of the environment with? 8. What are the processes taking place in the lead-acid battery during discharge? 9. What are the processes taking place in the lead-acid battery during charging? 10. What are the characteristics of a lead battery? 291

11. 12. 13. 14. 15. 16. 17. 18. 19.

What factors does the capacity of the electrolyte depend on? What is the technical operation of the battery? What are methods of charging the battery? How is checked the technical condition of the battery, which measurement is carried out? How to determine the extent of discharging the battery? How to store the battery? What kind of phenomenon is called sulfation? The processes of self-discharging of the battery. The basic malfunctions of the battery.

Laboratory work № 15 Electroplating. The electrolytic copper plating Objective: 1. Learn the copper plating technology; 2. Get practical skills in copper plating of brass products. Necessary tools and materials: 1. Bars of brass (10 х 20sm). 2. Bars of copper sheet (10 х 20sm). 3. The copper wire. 4. Bath of polyvinyl chloride. 5. Milliammeter. 6. Rheostat. 7. Measuring Microscope. 8. Sandpaper. 9. The current source. Solutions: 1. Electrolyte №2 (ml bluestone CuSO4 · 5H2O 160+ concentrated sulfuric acid, H2SO4 (к) 60 + thiourea CS(NH2)2 4,0). 2. CuSO4 · 5H2O 160-230g/l. 3. Ethanol. 4. Conc. sulfuric acid, H2SO4 . 5. Thiourea CS(NH2)2 60-78g/l . Completing of the work: 1. Cut Copper plates (10 х 20sm). 2. Fix the plate on the copper plug. 292

3. In a bath of PVC to fix the plug and cross bar, in which will hang products for copper plating. 4. Process brass rods using emery paper. 5. Process brass parts by ethyl alcohol. 6. Pour the solution number 2, which is designed for a brilliant copper plating and it is not necessary to stir. 7. Details hung on a cross-beam. 8. Attach the connecting devices to the cross – to the negative pole of the power source and plug into the positive – puton in the chain. 9. Adjust the settings using the rheostat and milliammeter (current density of 1-2 A / dm2). 10. Time 5, 10 and 15 minutes. 11. Exclude part of the solution for the passage of the required period of time. 12. Measure coating thickness. 13. Write and analyze the results. Key points: Copper plating is a process of electroplating copper layer of thickness of from 1 micron to 300 microns or more. Applications parts with copper plating depend on whether the copper coating used alone or copper coating acts as underlayer (substrate) for applying other coatings electroplating. Copper plating is copper coating on another material. Copper is deposited by electroplating on steel, as an intermediate layer under the coating of nickel, chromium or silver (variant of this method is electroplating). Steel and brass are coated with copper to produce artistically designed products. Sometimes the copper coating is applied to the steel to prevent carburization (carburization) of surface. In the solutions it is essentially used copper salt for electroplating – sulfate and cyanide in the form of the coordinate compounds. Great value takes metal copper plating in the electrical field. Due to copper plating low price compared to coated with silver or gold, copper coatings are often used in the copper plating electrical tires, contacts, electrodes and other elements of working under stress. There are 2 types of copper electrolytes: – sour; – alkaline. 293

In acid electrolytes cannot be got firmly coupled copper coating on the steel and zinc products, since in this case iron and zinc in contact with the copper are dissolved – impaired adhesion with coating. To resolve this particularity – it is necessary the first thin copper layer (2-3 microns) apply in an alkaline electrolyte, and further increase coverage in a cost-effective acid electrolyte to the desired thickness. Zinc products of complex shape it is better to coat with copper in alkaline (cyanide) electrolytes. The acid electrolytes of copper plating. The most common electrolytes are of two types – sulfates and boron hydrofluoric. The greatest use is made of sulfuric acid electrolytes, characterized by the simplicity of the composition, stability and high output current (up to 100%). Before the copper plating of parts in acidic electrolytes they are pre-coppered in cyanide electrolytes or precipitated thin underlayer of nickel. The disadvantage of these electrolytes is the impossibility of direct coating zinc and steel parts due to the contact separation of copper having poor adhesion to the base metal, as well as their small scattering power and precipitation is of coarser structure in comparison with other electrolytes. Alkaline electrolytes of copper plating. By alkaline electrolyte of copper plating are cyanide, pyrophosphate and other electrolytes. Cyanide copper electrolytes have high throwing power, fine-grained structure of the precipitation, the possibility of direct copper plating of details. The disadvantages include low current density and instability of the composition due to the carbonation of free cyanide by the carbon dioxide of air. In addition, cyanide electrolytes are characterized by reduced current yield (less than 60-70%).

Figure 17. The electrolytic copper plating 294

Control questions: 1. 2. 3. 4. 5. 6. 7.

Advantages and disadvantages of alkaline electrolytes Advantages of acidic electrolytes What is the purpose of the copper plating? Why is used copper plating with chemical heat treatment? For what purpose is carried out copper plating by technical processing? Disadvantages of acidic electrolytes Disadvantages of alkaline electrolytes

295

18. TASKS FOR STUDENT SELF-INDEPENDENT WORK (SIW)

Task 1. Students self-independent work (SIW) №1 1. Composition of copper-pyrite concentrate. 2. Distribution of lead on smelting products. 3. How should be designed electrochemical cells to have proceeded this reaction: Mg + 2H+ = Mg2+ + H2? №2 1. Composition of copper sulphide concentrate. 2. Material balance of sinter smelting process. 3. How should be designed electrochemical cells to have proceeded this reaction: 3H2 + 2Bi3+ = 6H+ + 2Bi0? №3 1. Preparation of charge (in copper production). 2. Electrolysis of zinc sulphate solution. 3. How should be designed electrochemical cells to have proceeded this reaction: Zn + 2Ag+ = Zn2+ + 2Ag? №4 1. Agglomerated firing 2. Productivity of agglomerating machine. 3. How should be designed electrochemical cells to have proceeded this reaction: Cd + CuSO4 = CdSO4+Cu? №5 1. Composition and output of matte. 2. The main dimensions of the shaft furnace and air communications. 3. How should be made galvanic cells to have proceeded in them this reaction: Sn + Cu2+ = Cu+ Sn2+? №6 1. The rational part of raw materials of the agglomerating roasting. 2. Shaft smelting reduction of agglomerate. 3. How should be designed electrochemical cells to have proceeded this reaction: Zn + Hg2SO4 = ZnSO4+ 2Hg? 296

№7 1. The reflectivity smelting of copper batches. 2. Characteristics of lead ore base. 3. How should be designed electrochemical cells to have proceeded this reaction: Pb + Hg(NO3)2 = Pb(NO3)2 + Hg? №8 1. Electric smelting of copper ores and concentrates. 2. Schematic diagram of the processing of lead concentrates. 3. How should be designed electrochemical cells to have proceeded this reaction: 2Ag+ + H2 = 2Ag+ 2H+? №9 1. The refining of blister copper. 2. Reactions and autogenous methods for lead production. 3. How should be designed electrochemical cells to have proceeded this reaction: Mn + 2HCl = MnCl2 + H2? № 10 1. Theoretical basis and practice of converting copper matte. 2. Firing in zinc metallurgy. 3. How should be designed electrochemical cells to have proceeded this reaction: Fe + Pb2+ = Fe2+ + Pb? № 11 1. Hydrometallurgy of copper. 2. Refining of lead bullion. 3. How should be designed electrochemical cells to have proceeded this reaction: 3H2 + 2Au3+ = 6H+ + Au? № 12 1. Recycling of industrial products of lead production. 2. Agglomerated firing. 3. How should be designed electrochemical cells to have proceeded this reaction: Zn + NiSO4 = ZnSO4 + Ni? № 13 1. Characteristics of zinc ore base. 2. Protection of the environment. 3. How should be designed electrochemical cells to have proceeded this reaction: 2Al + 3CuCl2 = 2AlCl3 + 3Cu? № 14 1. Zinc Pyro metallurgy. 2. Theoretical basis and practice of firing sulfide batches. 297

3. How should be designed electrochemical cells to have proceeded this reaction: Zn + Fe2+ = Zn2+ + Fe? № 15 1. Zinc Hydrometallurgy. Zinc sulphate solution purification from impurities. 2. Preparation of the charge. Methods of agglomerating of fine materials by granulation, briquetting, sintering. 3. How should be designed electrochemical cells to have proceeded this reaction: Mg + Zn2+ = Mg2+ + Zn? Task 2. Students self-independent work (SIW) №1 1. Signs for classification of chemical industry raw materials. 2. The secondary material resources. Give examples. 3. Which metal will be dissolved at the operation of following corrosive elements? Make the equation of electrochemical processes on the cathode and anode sections and determine the type of depolarization. How much will be reduced weight of corrosion metal at a current of I A for the time τ m? Galvanic corrosion Cr | HCl | Cu

I, А 5

τ, m 15

Result: ∆m, г 0,54

№2 1. The main types of chemical industry raw materials. 2. Integrated use of raw materials. Give examples. 3. Which metal will be dissolved at the operation of following corrosive elements? Make the equation of electrochemical processes on the cathode and anode sections and determine the type of depolarization. How much will be reduced weight of corrosion metal at a current of I A for the time τ m? Galvanic corrosion

I, А

τ, m

Result: ∆m, г

Fe | H2SO4 | Zn

7,5

20

3,02

№3 1. Raw material enrichment and for why it is carried out? 2. Role of the energy and the fuel to conduct processes. 3. Which metal will be dissolved at the operation of following corrosive elements? Make the equation of electrochemical processes on the cathode and anode sections and determine the type of depolarization. How much will be reduced weight of corrosion metal at a current of I A for the time τ m? Galvanic corrosion Mg | HCl | Sn

I, А 7 298

τ, m 15

Result: ∆m, г 0,78

№4 1. Basic methods of enrichment of solid raw material. The essence of each method. Equipment. 2. The main types of energy resources. Which ones are the most promising? 3. Which metal will be dissolved at the operation of following corrosive elements? Make the equation of electrochemical processes on the cathode and anode sections and determine the type of depolarization. How much will be reduced weight of corrosion metal at a current of I A for the time τ m? Galvanic corrosion Fe | H2SO4 | Ni

I, А 5

τ, m 20

Result: ∆m, г 1,74

№5 1. The main forms of energy used in the chemical industry. 2. Renewable and non-renewable energy resources. 3. Which metal will be dissolved at the operation of following corrosive elements? Make the equation of electrochemical processes on the cathode and anode sections and determine the type of depolarization. How much will be reduced weight of corrosion metal at a current of I A for the time τ m? Galvanic corrosion Sn | H2SO4 | Cu

I, А 6

τ, m 30

Result: ∆m, г 6,64

№6 1. Secondary energy resources. How are they classified by the type of energy? 2.What is the nature of energy technologies? 3. Which metal will be dissolved at the operation of following corrosive elements? Make the equation of electrochemical processes on the cathode and anode sections and determine the type of depolarization. How much will be reduced weight of corrosion metal at a current of I A for the time τ m? Galvanic corrosion Ag | NaCl, H2O, O2 | Cu

I, А 5

τ, m 35

Result: ∆m, г 3,47

№7 1. The role of secondary energy resources in the fuel and energy savings. 2. Examples of energy technological schemes of processing of solid fuels. 3. Which metal will be dissolved at the operation of following corrosive elements? Make the equation of electrochemical processes on the cathode and anode sections and determine the type of depolarization. How much will be reduced weight of corrosion metal at a current of I A for the time τ m? Galvanic corrosion Fe | H2O, O2 | Ni

I, А 6 299

τ, m 15

Result: ∆m, г 1,56

№8 1. What are the minerals in Kazakhstan and the field of their applications. 2. Prospective raw materials in Kazakhstan. 3. Which metal will be dissolved at the operation of following corrosive elements? Make the equation of electrochemical processes on the cathode and anode sections and determine the type of depolarization. How much will be reduced weight of corrosion metal at a current of I A for the time τ m? Galvanic corrosion Zn | H2O, O2 | Cu

I, А 7

τ, m 20

Result: ∆m, г 2,82

№9 1. The chemical reactions occurring under the effect of electrical energy, or serving as source of electrical energy. 2. The use of cheaper raw materials and better use of it. 3. Which metal will be dissolved at the operation of following corrosive elements? Make the equation of electrochemical processes on the cathode and anode sections and determine the type of depolarization. How much will be reduced weight of corrosion metal at a current of I A for the time τ m? Galvanic corrosion Ni | H2O, H2S | Ag

I, А 2

τ, m 30

Result: ∆m, г 1,09

№ 10 1. Historical stages of development of electrochemical technology. 2. Preparation of very pure metals by electrolysis of solutions or molten salts. 3. The Galvanic cell is composed of two metal electrodes:

Electrode I V2+V

The molar concentration potential-ions с, mol/l

Electrode II +

Ag | Ag

Electrode I

Electrode II

0,01

0,001

a. Determine the nature of the anode and cathode. b. Pick electrolytes and write circuit (electrochemical system) of Galvanic cell. c. Record equation of electrode reaction (cathode and anode) and the overall reaction defining the work of Galvanic cell. № 11 1. Technological schemes of the electrochemical industry. 2. Value of hydro electric industry in the production of non-ferrous and rare metals. The application of these processes in various industries. 3. The Galvanic cell is composed of two metal electrodes:

300

Electrode I Cd2+ |

Cd

The molar concentration potential-ions с, mol/l

Electrode II Cr3+

Electrode I

Electrode II

0,02

0,05

| Co

a. Determine the nature of the anode and cathode. b. Pick electrolytes and write circuit (electrochemical system) of Galvanic cell cell. c. Record equation of electrode reaction (cathode and anode) and the overall reaction defining the work Galvanic cell. № 12 1. Properties and use of chlorine and alkali. The requirements for the composition of the solution for the electrolytic method of production of chlorine and alkali. Preparation of a concentrated alkali and fused sodium hydroxide. 2. Overview of hydro electric industry processes. Applications and advantages of these processes. Electrolytic refining of copper. 3. The Galvanic cell is composed of two metal electrodes:

Electrode I

Electrode II

Pb2+ Pb

Cd2+ | Cd

The molar concentration potential-ions с, mol/l Electrode I

Electrode II

0,001

0,5

a. Determine the nature of the anode and cathode. b. Pick electrolytes and write circuit (electrochemical system) of galvanic cell. c. Record equation of electrode reaction (cathode and anode) and the overall reaction defining the work of galvanic cell. № 13 1. The value of hydro and hydro electric industry in the production of metals. 2. The history of the emergence and development of the processes of electrodeposition of metals. 3. The Galvanic cell is composed of two metal electrodes:

Electrode I Sn2+

 Sn

The molar concentration potential-ions с, mol/l

Electrode II Ag+

 Ag

Electrode I

Electrode II

0,2

0,001

a. Determine the nature of the anode and cathode. b. Pick electrolytes and write circuit (electrochemical system) of galvanic cell. 301

c. Record equation of electrode reaction (cathode and anode) and the overall reaction defining the work of galvanic cell. № 14 1. Areas of application and prospects of development of the electrochemical production (HIT). HIT manufacturing technology, the system of notation, used materials. Special labor protection measures in the production and operation of CCS. 2. Removing of cadmium from waste of hydrometallurgical nickel production. 3. The galvanic cell is composed of two metal electrodes:

Electrode I

Electrode II

In3+ | In

Sn2+ | Sn

The molar concentration potential-ions с, mol/l Electrode I

Electrode II

0,05

0,5

a. Determine the nature of the anode and cathode. b. Pick electrolytes and write circuit (electrochemical system) of galvanic cell. c. Record equation of electrode reaction (cathode and anode) and the overall reaction defining the work of galvanic cell. № 15 1. The electrolytic production of metal powders. 2. Technology of production of aluminum by electrolysis of melts. 3. The galvanic cell is composed of two metal electrodes:

Electrode I Ag+

| Ag

The molar concentration potential-ions с, mol/l

Electrode II Mg2+

| Mg

Electrode I

Electrode II

0,02

0,5

a. Determine the nature of the anode and cathode. b. Pick electrolytes and write circuit (electrochemical system) of galvanic cell. c. Record equation of electrode reaction (cathode and anode) and the overall reaction defining the work of galvanic cell. Task 3. Students self-independent work (SIW) №1 1. How does the atmospheric corrosion of tinned iron and tinned copper in violation of coverage? Make electronic equations of cathodic and anodic processes. 2. Iron barrels, covered with lead inside, used for the transportation of concentrated sulfuric acid, but after the release of the acid the barrels often completely destroyed as a result of corrosion. How can this be explained? What is the anode, and that – the cathode? Make electronic equation of the corresponding processes. 302

3. Give examples of cathodic and anodic coatings for cobalt. Make the equation of cathode and anode processes in damp air and in a solution of hydrochloric acid in violation of the integrity of the coating. №2 1. Tin soldered with silver. Which of the metals will be oxidized under corrosion if the metals enter the alkaline environment? 2. Iron plated chrome. Which metals of the metals will be corroded in the trouble of the surface layer coating in an atmosphere of an industrial area where the humid air comprises carbon monoxide (IV), sulfur oxide(IV), hydrogen sulphide? To define the chemical reactions. 3. The silver does not displace hydrogen from dilute acids. Why? However, if to silver plate, lowered into the acid, to touch zinc plate, the silver starts the rapid evolution of hydrogen. Explain this phenomenon, write the equation of the anode and the anode processes. №3 1. Nickel is in contact with gold in humid air saturated with hydrogen sulfide. Which metal is subjected to corrosion? Make electronic equations of cathodic and anodic processes during metal corrosion. 2. Aluminum riveted with copper. Which of the metals will be corroded in acidic media? Write down the reaction. 3. What processes do occur at the electrodes during the electrolysis of an aqueous solution of iron(II) chloride: a) on the carbon electrodes; b) with an iron anode? №4 1. What metal coating is called the anode, and what - the cathode? Name some metals which can be used for the anode and cathode coating of iron. Make electronic equations of anodic and cathodic processes that occur during corrosion of iron coated with copper, in the humid air and acidic environment. 2. Why is chemically pure iron more resistant to corrosion than iron? Make electronic equations of anodic and cathodic processes that occur in iron corrosion in acid medium. 3. What metals can be produced by electrolysis of aqueous solutions of their salts? What metals cannot be obtained in this way? By Electrolysis of what compoundings, and under what conditions it is possible to obtain metals: K, Ca, Al? №5 1. Copper does not displace hydrogen from dilute acids. Why? However, if to a copper plate, lowered into the acid, to touch the zinc plate, the copper begins the rapid evolution of hydrogen. Give an explanation for this, making electronic equations of anodic and cathodic processes. Write the equations of occurring chemical reaction. 2. Two iron plates partially covered with a tin, and the other with copper are in the humid air. On which of these plates will be formed rust faster? Why? Make 303

electronic equations of anodic and cathodic corrosion processes of these records. What is the composition of the corrosion products? 3. Why is the expansion potentials acids: H3PO4, HNO3, H2SO4 and alkaline NaOH, KOH very close by values (1,67-1,70 V)? There is a mixture of salts of the equal cations concentration in the solution. In what sequences will be allocated metals in the electrolysis, if the voltage is sufficient to extract all of them: а) Na+ , Sn2+ , Au3+; b) Ni2+, Fe2+, Cu2+; c) Mg2+, Cr3+, Au3+; d) Pb2+, Sn2+, Ca2+; e) Mn2+, Ag+ , Zn2+? №6 1. The silver does not displace hydrogen from dilute acids. Why? However, if to a silver plate, lowered into the acid, to touch zinc plate, the silver starts the rapid evolution of hydrogen. Give an explanation for this, making electronic equations of anodic and cathodic processes. 2. Two zinc plates, one of which is partially covered by nickel were transferred in hydrochloric acid solution. In what case is more intense the zinc corrosion process? Answer motivated, making the equations of the corresponding processes. 3. The electrolysis of sodium hydroxide solution is carried out. Will be the changes in time: a) the amount of alkali; b) the concentration of the solution? Why? Write the reactions occurring at the electrodes. №7 1. Describe the essence of the tyre-tread protection of metals from corrosion. Give some metals which can be used for cathodic protection of iron from corrosion. 2. Give examples of cathodic and anodic coatings for cobalt. Make the equations of cathode and anode processes in damp air and in a solution of hydrochloric acid in violation of the integrity of the coating. 3. A cadmium sulfate solution was skipped 25 A / h of electricity. 42,5g of cadmium was stood out on the cathode. Write the reactions occurring at the electrodes, and calculate the output of cadmium by current. №8 1. What iron is corroded faster – in contact with the tin or copper? Make electronic equations of cathodic and anodic processes during corrosion of iron in these cases. 2. Iron was plated by nickel. Which metal will be corroded in the case of the fracture of surface coating? Corrosion occurs in acidic medium. Make a diagram of the galvanic cell formed in this case. 3. Calculate the theoretical potential of decomposition of aqueous solutions of salts: Fe2(SO4)3, NiSO4, MnSO4 by electrolysis with their platinum anode. What weight of aluminum can be obtained by melt electrolysis А12О3 if over 1 hour flowing current of 20000A, with a current output 85%? №9 1. How does the atmospheric corrosion of tinned and galvanized iron in disruption of coverage operate? Make electronic equations of anodic and cathodic processes. 304

2. Copper does not displace hydrogen from dilute acids. Why? However, if to a copper plate, lowered into the acid, to touch the zinc plate, the copper begins the rapid evolution of hydrogen. Give an explanation for this, making electronic equations of anodic and cathodic processes. Write the equations of occurring chemical reaction. 3. What is the polarization? What factors affect it? How can be reduced the polarization? Electrolysis of ferrous(II) sulfate solution was carried out on the carbon electrodes in the presence of sulfuric acid. At what concentration of hydrogen ions is possible deposition of iron and hydrogen, if the concentration of iron ions is 1 mol / L? № 10 1. How does the atmospheric corrosion of tinned iron and tinned copper in damage of coverage? Make electronic equations of anodic and cathodic processes. 2. If a plate of pure zinc dipped in dilute acid, the starting allocation of hydrogen nearly ceases soon. However, by touching to the zinc by copper wand at the last begins the rapid evolution of hydrogen. Give an explanation for this, making electronic equations of anodic and cathodic processes. Write the equations of chemical reactions. 3. By electrolysis of what combinations (in solution or melt) can be got K, Ca, A1? How much time should be maintained the electrolysis by current intensity of 0.5 A to get 0.5 mol equivalents of each metal? № 11 1. The iron product was plated with nickel. What is this cover - anode or cathode? Why? Make electronic equations of anodic and cathodic corrosion processes of the products by damage of the coating in moist air and hydrochloric (hydrochloric) acid. What corrosion products are formed in the first and second cases? 2. Make the electronic equations of anode and cathode processes with oxygen and hydrogen depolarization with corrosion of magnesium – nickel. What corrosion products are formed in the first and second cases? 3. To obtain 1 m3 of chlorine (NU) in the electrolysis of aqueous magnesium chloride solution was passed through a solution of 2 423 A / h of electricity. Calculate the output current. Make scheme of electrolysis of magnesium chloride solution with graphite electrodes. № 12 1. To a solution of hydrochloric (hydrochloric) acid was put a zinc plate and zinc plate, partially covered with copper. In which case the zinc corrosion process is more intense? Answer motivated, making the equations of the corresponding processes. 2. Why is chemically pure iron more resistant to corrosion than ingot iron? Make electronic equations of anodic and cathodic processes that occur in ingot iron corrosion in humid air and acidic environment. 3. The current was passed through zinc sulfate solution for 30 minutes. 0.25 grams of zinc was stood out. Ammeter showed 0.4 A. What is the error in the indication of the ammeter? 305

№ 13 1. What the metal coating is called the anode, and what - the cathode? Name some metals which can be used for the anode and cathode iron coating. Make electronic equations of anodic and cathodic processes that occur during corrosion of iron coated with copper, in the humid air and in acidic environment. 2. The iron product was plated with cadmium. What is this cover – anode or cathode? Why? Make electronic equations of anodic and cathodic corrosion processes of the products in damage of the coating in moist air and hydrochloric (hydrochloric) acid. What corrosion products are formed in the first and second cases. 3. When passing through the electrolyte solution of 2 A / h of electricity at the anode was oxidized 1,196g sulfide ion. Determine the electrochemical equivalent and a molar mass of sulfur equivalent. № 14 1. Iron product covered with lead. What is this cover – anode or cathode? Why? Make electronic equations of anodic and cathodic corrosion processes of the product in damage of the coating in moist air and hydrochloric (hydrochloric) acid. What corrosion products are formed in the first and second cases? 2. What is the sequence of discharge of ions at the cathode and the anode? What is the difference of electrolysis processes with soluble and insoluble anode? 3. The salt solution Ni(NO3)2 for 2.45 hours was passed by current of 3.5 A. Determine how many grams of weight change of the nickel anode was during this time. № 15 1. What is electrolysis? What processes are including in electrolysis? Which processes do occur by the electrolysis at anode and cathode? 2. In the hydrochloric acid solution were transferred two zinc plates, one of which is partially covered by nickel. In which case the zinc corrosion process is more intense? Answer motivated, making the equations of the corresponding processes. 3. Write the reactions that occur during electrolysis nickel (II) sulfate on the electrodes: a) nickel, b) inert. What should be the amperage that in 10 hours at the cathode was allocated 58 g of nickel by its output at current 60%? Task 4. Students self-independent work (SIW) №1 1. The concept of the plasma, the Debye radius. Classification of plasma. The degree of ionization. Saha formula. The concept and essence of plasma-chemical processes. Historical stages of development. The modern state of plasma-chemical processes. 2. Raw materials for the production of phosphorous fertilizers. The main types, deposits and reserves of phosphate ores. Technical requirements to phosphate raw materials. 306

№2 1. Elementary processes in plasma: classification, the rate of the elementary processes, the collision cross section. Elementary processes of the first kind. The direct and stepwise ionization in the plasma. 2. Characteristics of phosphate concentrates. Economic evaluation of workability of phosphate raw materials. №3 1.The relaxation processes of activated particles in the plasma. Mechanisms of development of electrical discharge. Streamer and spark forms of gas discharges. Generators of low-temperature plasma. 2. Direct use of phosphorite meal as fertilizer. Storage and transportation of phosphate raw materials. №4 1. Types of gas discharges. Breakdown of gas in the AC voltage. Typical designs of discharge sources of low-temperature plasma. Production of hydrochloric acid by plasma process. 2. The production of phosphorus fertilizers. Simple superphosphate. Types and properties of the products. Physical and chemical bases of production. The manufacturing methods and parameters. Basic apparatus. Process calculations. №5 1. Methods of oscillations of charged particle beams. Generators of pulsed highcurrent electron beams. Generators of powerful ion beams. 2. Phosphates and ammonium polyphosphates. Physical and chemical bases of production. The manufacturing methods and parameters. Production of ammonium orthophosphate. Production of ammonium polyphosphate. №6 1. Plasma refining and impurity doping of metals and alloys. Plasma coating and surface treatment. 2. Physical and chemical bases of processes of nitric acid phosphate processing. Decomposition of nitric acid phosphates. Isolation from nitrate solution of calcium ions. №7 1. Specific features of plasma chemical reactions. Quasi-equilibrium plasma chemical processes. The nonequilibrium plasma-chemical processes. 2. The phase distribution of fluorine in various stages of production. Processing of nitrate extraction. №8 1. Principles of organization of plasma-chemical processes. The types of reactions that occurring in the plasma chemistry. 307

2. The main ways of development of the chemistry and technology of mineral fertilizers. №9 1. The methods of no equilibrium excitation of molecules. Chain gas phase processes. Chain chemical processes under external influence. 2. Phosphate fertilizers and trends in scientific and technological research at the present stage. № 10 1. The conversion of methane in low-temperature plasma. Chain plasmachemical conversion of methane. 2. Composition and characteristics of mineral fertilizers; classification of mineral fertilizers. №11 1. Plasma chemical synthesis of nano-dispersed particles. 2. The physical properties of mineral fertilizers; Development of the production of mineral fertilizers. № 12 1. Plasma-chemical methods for the preparation of carbon nanostructures. 2. Natural phosphates: a) the mineralogical composition of the apatite ore and phosphate rock; b) the nature of occurrence of apatite ores and their main field. № 13 1. The beam-plasma technology of hardening and modification of the surface of metal products. 2. General characteristics of phosphate rock and their classification, characteristics of individual phosphate ores and their classification, and the prospects for their use. № 14 1. Applications of the low-temperature plasma in chemical production. Plasmo chemical processing of medical polymers. 2. Properties of condensed phosphates. Hydrolytic cleavage of the cyclic phosphate, differences from salts hydrolysis. Show an example of the homologous series of cyclic phosphate. № 15 1. Plasma-chemical methods of waste treatment. What principle is the basis of plasma-chemical processes? 2. Determine how much of apatite concentrate is necessary to produce 1 ton of 96% phosphoric acid, it is known that apatite concentrate contains 38% of the waste rock, and its degree of conversion is 86%. 308

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1. Applied Electrochemistry / Edited by Tomilov A.P. – M.: Chemistry, 1984.− 520 p. 2. Theoretical Electrochemistry / Edited by Rotinyan A.L. − L: Chemistry, 1981. – 423 p. 3. Vyrapayev V.N., Nikolsky V.A. Chemical current sources – M.: High school, 1989. – 360 p. 4. Dikussar A.I. Fundamentals of electrochemistry and electrochemical technologies. Tutorial / A.I. Dikussar, J.I. Babanova., S.P. Yushchenko. − Tiraspol: Publishing House of the University, 2005. – 187 p. 5. Akhmetov T.G. Chemical technology of inorganic substances. 2 books: Tutorial / T.G. Akhmetov and others − M.: Higher School, 2002. – 688 p. 6. Polak L.S. and others. Theoretical and applied plasma chemistry. − M.: Nauka, 1975. – 304 p. 7. Taganova A.A., Semenov A.E. Lead batteries: stationary, traction, for portable devices: Handbook. − SPb.: HIMIZDAT, 2004. − 120 p. 8. Kafarov V.V. Principles of creating waste-free chemical industries / V.V. Kafarov. − M.: Chemistry, 1982. – 288 p. 9. Sokolov R.S. Chemical Technology: Manual for HEI / R.S. Sokolov V. 1. − M.: Vlados Press, 2000. – 516 p. 10. Valiyev H.H., Romanteyev Y.P. Metallurgy of lead, zinc and related metals: textbook. – Almaty: 2000. – 441 p. 11. Utkin N.I .Production of non-ferrous metals. 2nd ed. − M.: Intermet Engineering, 2004. – 442 p. 12. 12. Snurnikov A.P. Integrated use of raw materials in non-ferrous metallurgy. − M.: Metallurgy, 1986. – 384 p. 13. Baimakov J.V., Jurin A. I. Electrolysis in hydrometallurgy. − M: Metallurgy, 1977. – 336 p. 14. Yakimenko L.M. Production of hydrogen, oxygen, chlorine, and alkalis. – M.: Chemistry, 1981. − 280 p. 15. Fanstein S.Y. Chlorine production by diaphragm electrolysis. – M.: Chemistry, 1984. − 256 p. 16. Volkov G.I. Electrolysis with mercuric cathode. – M.: Chemistry, 1976. − 192 p. 17. Yakimenko, L.N., Pasmanik V.N. The production of chlorine and caustic – M.: Chemistry, 1976. – 437 p. 18. Tsvetkov Yu.V., Panfilov S.A. Low-temperature plasma in the recovery process. − M.: Nauka, 1980. – 248 p. 309

19. Troitsky I.A., Zhelesnov V.A. Aluminum Metallurgy. – M.: Metallurgy, 1977. – 392 p. 20. Khudaibergenov T.E. Metallurgy of light metals: Tutorial. − Almaty, 2001. − 235 p. 21. Shivrin G.N. Metallurgy of lead and zinc. Textbook. – M.: Metallurgy, 1982. − 353 p. 22. Mintsis M.J. Polyakov P.V. Aluminum Electrometallurgy − Novosibirsk: Science, 2001. – 321 p. 23. Yampolsky A.M. Electroplating. − L.: Mechanical engineering, 1978. − 165 p. 24. Vinogradov S.S. Organization of electroplating production. − M.: Globe, 2002. − 191 p. 25. Kopylev B.A. and oth. Technology of phosphoric acid − M.: Chemistry, 1989. – 421 p. 26. Taganova A.A., Bubnov Yu. I. Hermetic chemical sources: Elements and batteries. Methods and the device charge: A Handbook. 2 nd ed., Revised and add. − St. Petersburg: HIMIZDAT, 2002. – 176 p. 27. Davtyan O.K. The problem of direct converting of fuel chemical energy into electrical energy. − M.: Publishing House of the USSR Academy of Sciences, 1947. − 150 p. 28. 28. Khudyakov S.A., Pospelov B.C. // Science and life. – 1990. – № 9. – P. 60-65. 29. Acid processing methods of phosphate raw material / E.L. Yakhontova, I.A. Petropavlovsky, V.F. Karmyshov, I.A. Spiridonova. − M.: Chemistry, 1988. − 288 p. 30. Kopylev V.N. The technology of extraction phosphoric acid / V.N. Kopylev. − M.: Chemistry, 1981. − 224 p. 31. Koshkarbayeva Sh.T., Satayev M.S., Ibragimova G.N., Amanbayeva K.B. Galvanic coatings technology: textbook. − Almaty: Publishing house Evero, 2015. – 128 p. 32. Lukomskii Yu.Ya., Hamburg Yu.D. Physico-chemical bases of electrochemistry. − Publishing house Intellect, 2013. – 448 p. 33. Belenkiy M.A., Ivanov A.F. Electrodeposition of metal coatings. Directory. − М.: Metallurgy, 1985. – 288 p. 34. Zhuk N.P. Course of theory of corrosion and protection of metals. − M.: TTI Ltd. «Alliance», 2006. – 472 p. 35. Rotinyan A.L. and others. Theoretical electrochemistry. − M.: Student, 2013. – 494 p. 36. Mamayev V.I., Kudryavtsev V.N. Nickel plating: textbook ed. V.N.Kudrjavtsev. − M.: D.I. Mendeleev RCTU, 2014. – 198 p. 37. Skopintsev V.D. Oxidation of aluminum and its alloys. − M.: D.I. Mendeleev RCTU, 2015. – 120 p. 38. Hamburg Y.D. Theory and practice of the electrodeposition of metals / Y.D. Hamburg, Dzh. Zalgari: Translation from English. − M.: BINOM. Knowledge Laboratory, 2015. – 438 p. 310

GLOSSARY

Agglomerates – segregation – agglomerated ore concentrate produced during agglomeration. Sintered into small pieces (often powdered) ore is of size 5-100 mm with a low content of minor items. Agglomerates are obtained by firing iron and lead ores, zinc concentrates and others. In the steel industry is the main iron ore raw material to produce pig iron in a blast furnace. Battery is a device for storing energy in chemical form which can be used as electricity. The battery works because two different metals, being in an acid solution, produce electricity. Chemical degreasing – removal from the item surface by treatment in alkaline solutions or organic solvents from the surface of products of fats of vegetable and animal origin. Chemical current source is a device in which chemical energy of active substances during the flow of redox processes is converted directly into electrical energy. Cinders – the final product of roasting ores and concentrates to remove impurities and make technological properties in order to facilitate the extraction of valuable components. Composition of calcine depends on the initial composition of ores and concentrates and baking purposes. Clinker – high-strength brick, obtained from special clay by roasting to sintering and used for paving roads, floors in industrial buildings. Corrosion of metal is spontaneous process of metal destruction under the influence of the environment. Copper extraction – carried out to a deeper copper removal, since it causes serious complications in the subsequent melting of slurry at the silver-gold alloy. Major sludge fraction (scrap), which composition is close to anode copper, is separated by the classification and recycled to melt on the anodes. Dissolution is carried out at heating to 80-90°С and intense aeration of the pulp. Crushing – a separation of the material into small pieces. There are problems of crushing various materials: grain, plastics, solid waste, biological waste, rock. Crushing can be considered part of the grinding process, if it is talked about the need to reduce the size of 2 meters or less to a particle size of units, tens and hundreds of millimeters. Current output is expressed as a percentage ratio of the quantity of actually spent electricity (Qfact) to the theoretically necessary (Qtheor). Dross (skimming, dross) – solid compounds of non-ferrous metals (or removing), formed in smelting and refining, buoy to the surface of the melt and removed by mechanical means. For example, during the melting of cathode zinc at the 500-520°С are formed powder dross on the surface of the melt, that are raked and discharged from the furnace. Dross contains 80-90% Zn, 1-2,5% C1. Zinc in dross is 311

in the following forms: metal (35-40%), ZnO, ZnCl2, ZnCl2 · ZnSO4, ZnS. Furthermore, dross comprises impurities of oxides of iron and manganese. Еlectrolysis – physic-chemical process, consisting in the allocation on the electrode of components of the dissolved substances or other substances that are the result of secondary reactions at the electrodes, which occurs by an electric current through the solution, or electrolyte melt. Electrode – an electrical conductor having electronic conductivity (one conductor of the first kind) and in contact with the ion conductor-electrolyte (ionic liquid, ionized gas, solid electrolyte). Electrochemical processes – processes which take place under the influence of constant electric current and associated with the conversion of electrical energy into chemical energy or electrical into chemical. Electrochemical technologies are the electrochemical processes at the electrochemical systems on the boundaries of electrode-electrolyte (interfacial boundaries). Electromotive force (emf) of the element – the potential difference between the terminals of the electrochemical cell with an open circuit. Electrolytic refining – process for producing pure metal, suitable for technical purposes from the prepared usually by pyro metallurgical method of so-called crude metal. Electroplating – receiving process on the workpiece or substrate (mold) layers of metals from solutions of their salts by the action of a constant electric current, that is electroplating is one of the directions of industrial application of electrolysis. Etching process – the process of removing oxides from surface of metals in solutions of acids and acidic salts or alkalis. Flotation – a method of enrichment of minerals, which is based on the difference in the ability of the minerals to retain in the interphase surface due to the difference in specific surface energy. The hydrophobic (poorly wettable by water) mineral particles are fixed selectively at the interface, typically gas and water, and are separated from hydrophilic (well wetted with water) of the particles. By flotation gas bubbles or oil drops adhere to the poorly water-wettable particles and raise them to the surface. Flotation is also used for water purification from organic substances and solid sediment, separation of mixtures, accelerating sedimentation in the chemical, petrochemical, food and other industries. Fluxes – inorganic substances which are added to the ore in the smelting of metals, to lower the melting temperature and easier to separate the metal from the waste rock. Gangue – minerals not containing extractable components. Galvanostegy – getting on product surface firmly coupled with it thin metal coatings. Galvanoplastics – getting easily separated, relatively thick, facsimile from various subjects, the so-called matrices. Hydro electrometallurgy – extracting metals from aqueous solutions of their salts by electrolysis. Impurity doping – a method for creating alloys with desired properties (alloys slowly exposed by corrosion). The various additives are introduced into metal – chromium, manganese, tungsten, cobalt, and other metals. 312

Low-waste technology is an intermediate step before the creation of non-waste technology, implying approximation process to the closed loop. Mineral processing – a set of primary processing of mineral raw materials processes, having the aim of separation of valuable minerals from waste rock, as well as the mutual separation of the valuable minerals. Non-renewable raw material is a raw material, which is not recovered at all or is recovering more slowly than goes its use by human. For non-renewable raw materials are in the first place, all the mineral resources: metal ores, fossil fuels and building materials. Non-metallic mineral raw material is the rock used in the production of chemical, construction and other non-metallic materials and is not source of obtaining metals. These raw materials are phosphate rock, sulfur-containing raw materials, salt, sand, clay, limestone, etc. Ore mineral raw materials – rocks from which the metals are obtained. Pyro metallurgy – the technology of high-temperature processing of raw material, as a result of which cannot be obtained the metal of sufficient purity with permissible specific financial cost. Renewable raw materials are resources that are at least spending reproduced under the influence of natural processes (e.g. photosynthesis) or conscious effort of man. Renewable raw materials are raw materials of vegetable and animal origin (biomass), some minerals (e.g. salt, precipitating in the lakes), air, and water. Refining is the process of preparation of chemically pure gold of different samples for the banking needs, production, and the jewelry industry. Refining – the final purification of the product from the impurities in the steel, chemical, food and other industries. Refining industry – silver refinery processed semi-finished products, in the form of placer gold, gold concentrates and alloys, produced in heavy concentrate – processing plants (CPP), mining and concentrating plants (MCP) and mining and smelting plants (MSP). Factories and plants are usually located near the mining sites. Refined silver – silver derived from slurry formed in the electrolytic refining of copper and recyclable materials. Refined gold – gold, getting by deep cleaning from impurities. Repulping – dilution with water or circulating solutions of condensed pulp, cake of defend tails for easy transport of the material through pipes and gutters or to create appropriate pulp density to conduct further operations of flowsheet. Thickening and subsequent repulping are used, for example, for washing of flotation reagents or sludge and before the subsequent secondary cleaning or the flotation development of middling product. Retardant – substance capable in small quantities to slow chemical processes or to stop. Sludge – powdered solid metal that can be recycled for further separation and production of pure silver and gold. Slag-sublimation – processed products of slags of lead production at the slag-sublimation installing by leaching in the spent electrolyte, purified from impurities of chlorine, arsenic and antimony (they are transferred to the cinder leaching cycle). 313

Stein – slag molten – (German Stein – Rock), – a mixture of sulfides of iron, nickel, copper, cobalt and other elements. Stein – an intermediate product in the preparation of some non-ferrous metals (Cu, Ni, Pb, etc.) from their sulphide ores. Stein – an alloy of iron sulfide FeS with sulfide of produced metal (e.g. Cu2S). Screen separation is a process of separation of bulk materials by size at the screening surface – sieves. Solid minerals, building materials, abrasives, solid secondary raw materials, certain types of raw material are subjected to screening. them. Sludge –the solid residue after the filters, the pulp containing 12-18% of the liquid phase (damp). The cake may be the concentrate (by enrichment of mineral products) and waste production (in hydrometallurgy). For the final dehydration the cake is sent for drying. Sometimes cake is processed by Waelz, for example, to extract Zn, Pb, Cd, In, and others. Waste-free technology – technology that implies the most rational use of natural resources and energy in production, ensuring environmental protection. Waelz – (Waelz process) (from the German waelzen – roll) processing of polymetallic metallurgical wastes: slag of lead, copper and tin production, cakes of zinc production in order to recover valuable metals. Waelz sublimate – remanufactured metals in the stream of flue gases, which again are oxidized and trapped in the dust cleaning system of gases in the form of fumes (Waelz sublimate). Waste – products with low content of valuable components, further extraction of which is impossible technically or economically impractical. Zinc cake – the insoluble residue obtained after leaching, which is subjected to further processing with a view to additional recovery of zinc from it and other valuable components.

314

CONTENT

INTRODUCTION .................................................................................... 3 1. The current state and prospects of development of Electrochemical Production Technologies .......................................................................... 5 2. The largest chemical companies in the world ....................................... 10 3. Raw materials and energy resources of the chemical industry ............... 12 4. Efficient and integrated use of raw materials ......................................... 16 5. Preparation and enrichment of raw materials ......................................... 20 6. Energy Base of Chemical Industry ........................................................ 23 7. Questions for self-control on topic «Raw materials and energy resources» ...................................................... 28 8. The low-waste and non-waste technologies ........................................... 30 9. Electrochemical processes – the basis of electrochemical technologies. Classification ....................................................................... 36 10. The electrochemical metallurgy ........................................................... 42 10.1. The electrolysis of aqueous solutions................................................ 42 10.2. Basics of electrolysis of alloys .......................................................... 49 11. Hydro electrometallurgy in production. Electrometallurgy significance of copper, zinc and lead............................ 58 11.1. Methods of processing of copper containing raw materials .............. 58 11.1.1. Marking of copper, basic concepts and terms ................................ 70 11.1.2. Methods of production of high-grade copper ................................. 77 11.1.3. Composition of the electrolyte by copper refining ......................... 83 11.1.4. Pyrometallurgical method of producing copper ............................. 92 11.2. Methods of processing zinc-containing raw materials ...................... 97 11.2.1. Refining of crude zinc .................................................................... 99 11.2.2. Leaching zinc calcine ..................................................................... 101 11.2.3. Cleaning zinc-containing solutions from impurities ...................... 106 11.2.4. Electrolysis of zinc sulfate solution and cathode zinc smelting ..... 107 315

11.2.5. Processing of zinc cakes ................................................................ 114 11.2.6. Remelting of cathode zinc.............................................................. 116 11.2.7. Technology of dross processing ..................................................... 118 11.3. The process of lead by means of electrochemical metallurgy ........... 119 11.3.1. Methods of lead-containing raw materials processing ................... 121 11.3.2. Technology and stages of lead bullion refining ............................. 128 11.4. Questions for self-control on topic «Hydro electrometallurgy in production. Electrometallurgy significance of copper, zinc and lead».......................... 133 12. Corrosion and electrochemical technologies of protection from corrosion of major technical objects................................. 136 12.1. Chemical corrosion of metals ........................................................... 138 12.2. Electrochemical corrosion of metals ................................................. 141 12.3. Acid corrosion .................................................................................. 153 12.4. Methods of metals protection from corrosion ................................... 156 13. Electroplating. Basics of coating processing by metals and alloys. Aspects of the creation of low-waste and non-waste galvanic production .................................................................................................. 164 13.1. Preparation of component parts to coating ........................................ 166 13.2. Mechanical methods of surface preparation ..................................... 167 13.3. Chemical and electrochemical methods of preparing surface ........... 168 13.4. Galvanic coating ............................................................................... 173 13.5. Basics of galvanostegy ...................................................................... 184 13.6. Basics of galvanoplastics .................................................................. 186 13.7. Aspects of the creation of low-waste and non-waste galvanic production .................................................................................................. 189 14. Chemical current sources ..................................................................... 193 14.1. Galvanic elements ............................................................................ 193 14.2. Batteries ............................................................................................ 203 14.3. Fuel Cells .......................................................................................... 208 15. Plasma-chemistry Equipment for plasma-chemical processes. Plasma-chemical reactors. Generators of low-temperature plasma ............ 217 15.1. Historical stages of development ...................................................... 217 15.2. The concept and essence of plasma chemical processes ................... 219 15.3. Equipment for plasma-chemical processes. Plasma-chemical reactors .......................................................................... 223 15.4. Low-temperature plasma generators ................................................. 227 16. Natural phosphates in the territory of Kazakhstan. Characteristics of phosphorus ore deposits. The technological scheme of thermal and extraction methods of phosphoric acid production .......................................................................................... 232 316

16.1. Natural phosphates in the territory of Kazakhstan. Characteristics of phosphorus ore deposits ................................................ 232 16.2. Production of phosphoric acid by extraction method ........................ 236 16.3. Phosphoric acid production by the electro thermal method .............. 239 17. Experimental part................................................................................. 243 18. Tasks for Student Self-independent Work (SIW) ................................ 296 REFERENCES .......................................................................................... 309 GLOSSARY .............................................................................................. 311

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Educational issue Kabdulkarimova Kulbanu Kabdulkarimovna Orazbayeva Gaukhar Doldashevna Aubakirov Yermek Aitkazynovich

ELECTROCHEMICAL PRODUCTION TECHNOLOGY. PLASMA CHEMISTRY Educational manual Computer page makeup and cover designer N. Bazarbaeva The website used for front-page designing http://chemistry-chemists.com/ IS No.10968 Signed for publishing 08.06.17. Format 60x84 1/16. Offset paper. Digital printing. Volume 19,75 printer’s sheet. Edition 80. Order No.3464 Publishing house «Qazaq university» Al-Farabi Kazakh National University, 71 Al-Farabi, 050040, Almaty Printed in the printing office of the «Qazaq university» publishing house

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