Raw materials substitution sustainability 978-3-319-60831-0, 3319608312, 978-3-319-60830-3

Table of contents :
Front Matter ....Pages i-ix
Raw Materials and Sustainability Indicators (Elza Bontempi)....Pages 1-28
Case Study of Raw Materials Substitution: Natural Fillers Substitution in Plastic Composites (Elza Bontempi)....Pages 29-61
Case Study of Raw Materials Substitution: Activated Carbon Substitution for Wastewater Treatments (Alessandra Zanoletti, Elza Bontempi)....Pages 63-77
A New Approach to Evaluate the Sustainability of Raw Materials Substitution (Elza Bontempi)....Pages 79-101

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SPRINGER BRIEFS IN APPLIED SCIENCES AND TECHNOLOGY

Elza Bontempi

Raw Materials Substitution Sustainability

SpringerBriefs in Applied Sciences and Technology Series editor Janusz Kacprzyk, Polish Academy of Sciences, Systems Research Institute, Warsaw, Poland

SpringerBriefs present concise summaries of cutting-edge research and practical applications across a wide spectrum of fields. Featuring compact volumes of 50– 125 pages, the series covers a range of content from professional to academic. Typical publications can be: • A timely report of state-of-the art methods • An introduction to or a manual for the application of mathematical or computer techniques • A bridge between new research results, as published in journal articles • A snapshot of a hot or emerging topic • An in-depth case study • A presentation of core concepts that students must understand in order to make independent contributions SpringerBriefs are characterized by fast, global electronic dissemination, standard publishing contracts, standardized manuscript preparation and formatting guidelines, and expedited production schedules. On the one hand, SpringerBriefs in Applied Sciences and Technology are devoted to the publication of fundamentals and applications within the different classical engineering disciplines as well as in interdisciplinary fields that recently emerged between these areas. On the other hand, as the boundary separating fundamental research and applied technology is more and more dissolving, this series is particularly open to trans-disciplinary topics between fundamental science and engineering. Indexed by EI-Compendex and Springerlink.

More information about this series at http://www.springer.com/series/8884

Elza Bontempi

Raw Materials Substitution Sustainability

123

Elza Bontempi INSTM and University of Brescia Brescia Italy

ISSN 2191-530X ISSN 2191-5318 (electronic) SpringerBriefs in Applied Sciences and Technology ISBN 978-3-319-60830-3 ISBN 978-3-319-60831-0 (eBook) DOI 10.1007/978-3-319-60831-0 Library of Congress Control Number: 2017946960 © The Author(s) 2017 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer International Publishing AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Acknowledgements

The author thanks EIT RawMaterials for the first price assigned in the EU competition, to the idea of COSMOS use as substitute of conventional fillers in polypropylene (PP) (EIT 2016).

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Contents

1 Raw Materials and Sustainability Indicators. . . Elza Bontempi 1.1 Mineral Resources Consumption in Europe . 1.2 Raw Materials and Sustainability . . . . . . . . . 1.3 World Material Consumption . . . . . . . . . . . . 1.4 Embodied Energy and Carbon Footprint. . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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2 Case Study of Raw Materials Substitution: Natural Fillers Substitution in Plastic Composites . . . . . . . . . . . . . . . . . . . . . . . . Elza Bontempi 2.1 A New Sustainable Filler from Waste: COSMOS Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Plastic Industry in Europe. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Alternative Plastic Composites: Increased Sustainability by Substitution of Natural Fillers . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 A Substitute of Antimony, a Critical Raw Material . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Case Study of Raw Materials Substitution: Activated Carbon Substitution for Wastewater Treatments . . . . . . . . . . . . . . . . . . . Alessandra Zanoletti and Elza Bontempi 3.1 Coal Fly Ash Reuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Adsorption Properties of Coal Fly Ash . . . . . . . . . . . . . . . . . . 3.3 Thermal Regeneration of Porous Material . . . . . . . . . . . . . . . 3.4 Advantages of Proposed Material . . . . . . . . . . . . . . . . . . . . . . 3.5 Sustainability of the Proposed Material . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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4 A New Approach to Evaluate the Sustainability of Raw Materials Substitution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Elza Bontempi 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Legal Framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 The SUB-RAW Index . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 Raw Materials Substitution Possibilities . . . . . . . . . . . . 4.4.1 Coal Fly Ash and Portland Cement . . . . . . . . . . 4.4.2 Coal Fly Ash and Activated Carbon . . . . . . . . . 4.4.3 COSMOS and Natural Fillers . . . . . . . . . . . . . . 4.5 Considerations About the SUB-RAW Index . . . . . . . . . 4.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Introduction

In the last few decades, global demand not only for energy but also for materials was increased. The problem of raw materials supply is now widely recognized to be fundamental for the whole world. In particular, raw materials including critical materials have an economic and strategic importance, highlighted also by the European Commission. Raw materials are scarce in Europe, then it is fundamental the development of new policies, devoted to promote materials recovery and recyclability. Future progress in the areas of raw materials substitution will critically depend on the politically developed lines for technology and industrial development. It is possible to identify new resources in by-product materials, but specific methodologies must be developed to quantitatively account for the economic and environmental advantages in raw materials substitution. Additionally, some regulatory framework must be implemented specifically for this aim. This book is devoted to propose a simplified strategy to quantify the sustainability of natural resources substitution. It is based on the introduction of an index, the SUB-RAW index, defined by using only embodied energy and carbon footprint of materials to compare. The simplified approach makes the evaluation of sustainability of raw materials substitution accessible also to political authorities and industries, opening the possibility to assess suitable materials for investments in the green economy. This simple index allows researchers to design new sustainable materials. Perhaps, the development of new materials based on recycled resources can be the more powerful way to respect all the sustainability pillars.

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Chapter 1

Raw Materials and Sustainability Indicators Elza Bontempi

Abstract The first book chapter analyzes the raw materials consumption in Europe and introduces the parameters that characterize these materials. A model is presented to fully connect the raw materials aspects (their characteristics, their availability, and their manufacturing) and the three pillars of sustainability (economic, environmental, and social dimensions) and to show the relationships between them. The world materials production data analysis allows highlighting the problem connected to resources depletion and the need of some strategies to reduce it. For this aim, the use of different indicators other than some aggregated economy indicators, to account the raw material consumption in term of sustainability, is proposed. The use of embodied energy and carbon footprint parameters, accounting for energy and emissions involved in materials production, is envisaged. These data are presented and discussed in connection to elements natural abundance on the crust hearth and in respect to the materials world production. Evident correlations are found among the data. In particular the relationship among embodied energy and materials production can be represented by an equation very similar to demand-price curves, developed in the economy context. Keywords Raw materials

1.1


Sustainability
Embodied energy
Carbon footprint

Mineral Resources Consumption in Europe

Natural resources are essential to maintain and improve lifestyle of all persons living in the industrialized regions. From mineral resources mainly building and other cities infrastructures (as for example transports, roads, public areas, electrical transmission lines, and so on) are realized. Moreover, also other goods, with dimensions lower than a building, are made by using raw materials. For example, in a house several objects are derived from minerals: glass (made from melted quartz E. Bontempi (&) INSTM and University of Brescia, Brescia, Italy e-mail: [email protected] © The Author(s) 2017 E. Bontempi, Raw Materials Substitution Sustainability, SpringerBriefs in Applied Sciences and Technology, DOI 10.1007/978-3-319-60831-0_1

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sand), ceramic plate (realized from clay minerals and worked at high temperatures), salt (sodium chloride) used to cooking, steel utensils, jewels, cellphone, computer (containing over 70 different minerals typologies), and so on. We need minerals to make several other objects, used in other fields. For example in agriculture minerals are necessary to realize not only the machines to work, but also fertilizers. Minerals are used also in cosmetics, defense, energy production, health, and so on. It is not possible to conceive a world without mineral resources: industry would ruin and living standards would fall. In the past century, the increase of population and lifestyle standards has caused a significant increase in human pressure on natural resources. From the early 1900s to 2005, the use of industrial minerals has estimated to be increased by a factor of 27 (Krausmann et al. 2009). However, while global time series data about important socio-economic and environmental indicators (such as GDP, population, primary energy supply, emissions and so on) have been reported in literature, a comprehensive account of global materials extraction and use is available only for the last 10–15 years. For earlier periods, only a dataset, that provides an estimation of global natural resource extraction for the period 1980–2005, can be found in literature (Material flows). During the last century, the exponential increase in global materials use resulted in a fundamental shift in the typology and composition of natural resources, which are used. The economic historian Wrigley (1988) has accounted the shift from an organic economy (i.e. based on fossil fuels) towards a mineral economy, as a typical consequence of the industrial revolution in the 18th and 19th century. In this revolution, for the first time in human history, the materials obtained from the exploitation of mineral resources gained importance as compared to resources obtained from biomass (Krausmann et al. 2009). Moreover, the economy of several industrialized countries, as all the Europe, strongly depends on raw material imports, as their domestic deposits and exploitation activities are limited (Glöser et al. 2015). This remarkable increase of natural resources use, coupled with potential supply restriction (also due to the political instability of some mining area, with a resulting high price fluctuation) have recently attracted the attention of governmental, individual decision-makers, and researchers. For example, the rate of scientific publications about “raw materials” is growing exponentially from 1990. Figure 1.1 reports the publications about “raw materials” in 2016 divided by geographical area [source (ISI-Webofknowledge)]. It appears that Europe researchers have the higher sensibility to this argument (with a number of publications globally higher than 35%). Despite the high number of researchers, China has about 30% of publications in the “raw materials” field. USA, India and Japan have about 8, 4 and 2% respectively. This is probably also due to the EU approach to raw materials management. Europe is-self sufficient in raw materials for construction purpose. However, it is highly dependent on the import of several minerals. On the global level, the amount of natural resources extracted corresponds to the amount of resources used. On the individual country level (in the present case for EU), domestic extraction of resources (DE) is different from domestic resource

1.1 Mineral Resources Consumption in Europe

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Fig. 1.1 Publications on “raw materials” in 2016, divided by geographical area

Fig. 1.2 Material flow accounts in raw material equivalents (Units—Thousand tonnes) for EU (28) [data from (Eurostat)]

use (DMC), as trade has to be taken into account. Figure 1.2 highlights this dependence, by showing the material flow for EU (28) from 2005 to 2014 [data from (Eurostat)]. It appears that EU imported about 21% of resources that are

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used from 2014 to 2008. This data was decreased to about 18% starting from 2009, due to the world financial crisis. In the EU Thematic Strategy on the Sustainable Use of Natural Resources (EC 2005) the EU Commission recognizes that the way in which raw materials are used is rapidly decreasing the planet’s capacity to regenerate the resources, on which the prosperity and growth of population is based. The Commission proposes to improved resource efficiency, for greater decoupling of material use from economic growth. According to the definitions that are used, reserves concern energetic and non-energetic raw materials deposits, which are recoverable with current available technologies and under present economic conditions. Resources concern reserves and other available materials that have been already identified, but cannot yet be extracted and used because of economic or technological limitations. They also include other materials, which have been estimated but not yet discovered (Schaub and Turek 2016). Very recently, securing reliable and unhindered access to certain raw materials was recognized as a growing concern within the Europe. Current supply of raw materials is characterized by high concentrations of these materials extraction on some emerging countries. Additionally, raw material mining is made by some large corporations with significant power in markets. This distortion of raw material market, also caused by restrictions in exports and taxation of specific materials made by some countries, represents a serious threat for Europe economy, because both higher prices and the limited availability of essential raw materials can comprise industrial survival (Glöser et al. 2015). As a consequence, in the raw materials supply chain, also systematic evaluation of availability risks, market vulnerabilities and economic consequences of supply constraints must be considered. The determination of risks associated to raw material availability is a key parameter in quantifying and communicating economic vulnerabilities of natural resources due to uncertain material supplies. For this reasons a list of Critical Raw Materials (CRMs) was compiled by an EU task-force and continuously updated (EC 2011). They are considered on the basis of two parameters: economic importance and supply risk. Figure 1.3 reports the non-metallic mineral consumption in Europe (EU 28), in the last years. It appears that before the economical crisis (in 2008) the amount of mineral resources used in the EU was growing rapidly. As a consequence of the economic recession, and the decline in final consumption expenditure, also industrial production declined rapidly across the EU. This produced a decrease in the mineral consumption, with an adjustment to actual value that currently remains very high. In 2015, the average person in Europe consumed more than 4.2 tons of mineral resources [data from (Eurostat)]. With an average life expectancy of 78 years, mineral resources used during a person’s lifetime result more than 327 tons. All mineral resources are nonrenewable, because nature usually takes hundreds of thousands to millions of years to produce mineral deposits.

1.1 Mineral Resources Consumption in Europe

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Fig. 1.3 Non-metallic mineral consumption in Europe (EU 28), in the last years [data from (Eurostat)]

European Mineral Statistics web-site provides all statistical information about minerals and metals used in Europe. It provides the essential background intelligence for any European minerals-related activities. Production, export and import

Fig. 1.4 Non-metallic mineral consumption (1000 t) in Europe [data from 2015 (Eurostat)]

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tables are reported for all EU members. Figure 1.4 reports non-metallic mineral consumption in the 2015 in EU (Eurostat). As a result of the need of sustainable development, the materials requirements are changing. Because of the building sector was the main area of the raw material consumption the persons involved in suggesting and promoting new green practices and standards, connected with natural resources, have traditionally been designers, architects, civil engineering, and public officials. As a consequence, many of the proposed and realized changes associated with materials have been introduced without the collaboration of materials scientists. Thus, materials science scientists are now dealing with changes, which are forced by people outside the materials community. In view of these constraints, the materials science community has defined and developed new visions on material to design sustainable components, technologies and processes.

1.2

Raw Materials and Sustainability

Sustainable development is development that meets the needs of the present, such as the development of economic prosperity and the establishment of a more equitable society without compromising the ability of future generations to meet their own needs (WCED 1987). During the Earth’s history profound changes in the chemical milieu at the surface occurred. They were generated, for example, by the change in atmosphere composition, due to the cyanobacteria. The corrosive atmosphere formed, due to the oxygen presence, changed the surface chemistry of the Earth. These transformation, however, have occurred relatively slowly, with sufficient time for evolutionary change to keep pace (Schlesinger 1997). With the industrialization and the consequent increasing of human population, the environmental changes, mainly due by human activities using natural resources, have occurred much faster. The Earth is a closed system, with finite, non-renewable resources. With a continuous need to transform the available mineral resources into good, their reduced availability may represent a serious economical and social problems, resulting, for example, in political or military conflicts. This new comprehensive vision, in considering connections among human interactions, environmental effects, and potential conflicts, contributed the concept of sustainability to be considered as a comprehensive goal of development. Then sustainability has originated as a matter that is more and more perceived as permeating every human activity. In this global sustainability vision there are three different dimensions that must be integrated: economic, environmental, and social. Economic interests are the main drivers of the industrial and financial sectors. They address the flow of capitals, the development of markets and commerce, and the political framework for making decisions.

1.2 Raw Materials and Sustainability

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Environmental issues recognize the importance of the living environment and interdependence of humans and natural spheres, the goods and services produced by the world’s ecosystems, and the impacts of wastes production. Socio-political issues, that are devoted to promote ethical issues and human well-being, consider also the connections between society and political institutions, identifying and managing business impacts and environmental changes effects on society. Economic development, environmental degradation, and poverty of some world area are often interrelated, suggesting that approaching sustainable development requires to consider all the sustainability dimensions, not just an environmental or economic perspective alone, with an holistic approaches in politics and policies (Wallimann 2013). Because of the emerging raw materials concerns, connected with their availability, the economic issue of a natural resource is currently the mainly considered parameter. Global distribution of raw materials concentration in deposits, their accessibility as well as the technological difficulty in mining contribute to define the cost of the raw materials. However, also economic and political boundary conditions are fundamental. In this sense, the conditions for availability are not fixed, but may change in the future. Moreover, the sustainable character of a raw material encompasses more than just its economical impacts. It must be considered in the three sustainability dimensions: environmental, economic, and social impacts. The traditional models used to manage, develop and optimize raw materials are no longer opportune, as they frequently do not adequately account the three pillars of sustainability. A new model is needed to fully connect the raw materials aspects and the sustainability pillars and to show the relationships between them. Therefore, this new model is proposed to simultaneously optimize all areas of concern regarding raw materials. This model can be represented as a triangle with vertices indicating the fundamental aspects of raw materials: i.e. their characteristics, their availability, and their manufacturing (see Fig. 1.5). The materials characteristics are related to their composition, which depend on the materials origin, and represent their identity. A raw material is important because, in view of its composition, some constituent elements or compounds can be extracted. Moreover, also the materials properties are fundamental: the physical and chemical characteristics made the raw material suitable for use or extraction of valuable other compounds. Historically, materials have been produced to meet a particular set of performance characteristics, as for example, tensile or compressive strength, insulation or conductive characteristics, hardness and so on. Raw materials manufacturing represents the process of converting raw materials into finished goods. Manufacturing can require low cost technologies (as for example in cement manufacturing) or advanced technologies, which usually employ sophisticated machines (as for example in computer manufacturing). Finally, as highlighted in the previous paragraph, the raw material availability is now a fundamental aspect, that allows putting in evidence, for example, “critical raw materials”. In this model, shown in Fig. 1.5 and describing raw materials fundamental aspects, the sustainability can be represented as another triangle,

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Fig. 1.5 A model to fully connect the raw materials aspects (in blue) and the sustainability aspects (in red) and to show the relationships between them

contained in the first. Indeed, there are three pillars that sustainability seeks to integrate: economic, environmental, and social dimensions. These three pillars can be represented on the sustainability triangle vertices. The three different sustainability dimensions can be correlated at different levels with the raw materials aspects. The aim is to directly links the sustainability issues to the raw materials issues, and allows them to be actively focused in processes that concern raw materials selection and eventual substitution. Each raw materials aspect, reported in Fig. 1.5, it is strictly related to two sustainability dimensions. In the Raw Materials Scoreboard recent initiative (EC 2016), it is reported that raw materials industries provided in 2012 more than four million jobs. However, the importance of raw materials goes far beyond the economic connected activities. Figure 1.5 shows an interconnection between raw materials availability and social and economical dimensions of sustainability. In the last years, the concentration of production of some critical raw materials in few countries and the rapid industrialization of some emerging economies, intensified competition for some resources and caused a huge and fast rise in the prices of some natural resources. For example, rare earths are a class of material that has grown enormously in recent years. In Europe they are used in several sectors, such as generators, batteries, and magnets employed in motors. Europe’s demand for some of these critical materials, needed in several industrial fields, as for example for renewable sources energies, as solar and wind sectors, is expected to increase in the coming years (Rabe et al. 2017). China is the EU’s predominant supplier for rare earths. In recent years, the Chinese government has become very active towards managing its raw materials industries, changing in few years of one and two order of magnitude the

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price of exported critical materials and maintaining export restrictions on some resources. In these circumstances, it becomes difficult to predict, with a certain margin of time, what will be the future levels of raw materials prices and the social implications due to materials availability. For their determination, in fact, several components must be considered: not only availability, supply, and material demand, but also important speculative political and economic phenomena. Finally also the health and safety conditions of people working in raw materials must be considered in the social dimension of sustainability. The connection between raw materials availability and economic level of sustainability is extremely clear: raw materials are the fundamental input in productivity systems. They are the basis for manufacturing all goods, machines and infrastructures, thus they are economically and strategically fundamental. However, the economic importance of raw materials is quite challenging to define and measure, and the proposed approaches to quantify this parameter are several and very different. Indeed, despite that economic value of a material can be connected with its cost, and market price, in the case of raw materials a high economic importance generally means that the raw material is fundamental in the involved industrial sectors. Essentially, the importance of a basic resource is connected with lack of material substitutes. In this context, quantitative evaluation of economic importance of raw materials remains a challenge. The consequence is that even specialty metals, which serve strategically important high added value industrial sectors, but with very tiny supply, can acquire extremely high economic importance (Dewulf et al. 2016). From a social point of view there are several connections with raw materials availability. In developing countries, such as in Africa, raw materials more often produce inequality and conflicts rather than prosperity and well-being. For example, the Democratic Republic of Congo should be very rich thanks to its mineral resources, such as tin, tantalum, cobalt, gold, and wolframite, minerals, which are currently used to produce computers and mobile phones. However, the political corruption, the social inequity and the economical interest of developed countries caused the so-called conflict minerals (Jameson et al. 2016). In developed countries, raw materials scarcity contributes to increases the social resilience. As reported in literature (Sprecher et al. 2015), resilience can be defined as the capacity of a system to tolerate disruptions while retaining its structure and function. In case of criticality of raw materials, it can reflect how the society is able to deal with supply disruptions. It can increases the capability of developing diversity of supply, based not only on better resource management, but also on development of new primary production, and recycling, among others. Raw material substitution is another fundamental issue that binds raw materials properties and social dimension, because technological and scientific advances are fundamental to find substitution possibilities and opportunities. Raw materials characteristics can be directly connected to social and environmental sustainability levels (see Fig. 1.5). It must be considered that the destination use of a raw material depends on its properties. Then on the basis of the materials

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characteristics the area of employ is generally defined. For example, phosphate rocks are used as a source of fertilizers. The application field impacts the environment and social levels, being related to the final users. Some issues, such as labor opportunities, work conditions, and final obtained benefits depend on the materials used (for example the presence of chemical fertilizer allows to increase the productivity and the population growth). Moreover the same material characteristics can be related to environmental pillar of sustainability. For example, the environmental performance of raw materials is typically a key functional parameter, which is now considered and used to evaluate building materials. This is strictly connected with the social level and the well-being, but also to environmental dimension of sustainability. Finally, raw materials manufacturing can be connected to economical and environmental sustainability levels (see Fig. 1.5). Raw materials generally require manufacturing, which is a process that turns these resources into useful goods. Obviously the material manufacturing technologies have been developed to work raw materials in the most suitable and economic way. Material manufacturing is strictly connected with materials chemical composition. For example, in the case of aluminum, its manufacturing process requires several steps. Aluminum is contained in either silicates or oxides, but it is industrially produced starting from a mineral ore, bauxite. The metal extractions require several steps: bauxite purification, alumina electrolysis and final refining. As a consequence the aluminum manufacturing is extremely onerous. On the other hand, the aluminum industry is well-developed due to intense and diffuse use of this metal. Aluminum is not toxic, and it naturally produces a protective oxide coating (aluminum oxide), that is highly corrosion resistant. Additional surface treatments can further improve the material functional properties. Aluminum can be melted, cast, formed and machined as iron, but aluminum is a very light metal with a specific weight about a third that of steel. As a consequence it is diffusely employed in several sectors, from food packaging to transport, from power lines to construction. 90% of the world’s bauxite reserves are concentrated in tropical and sub-tropical regions, then European industries import this key raw material. Moreover, aluminium is recyclable. Irrespective of how many times it is reprocessed and re-used, it is a metal, which can be recycled and remains fundamentally unchanged (EU 2016). For these raisons, and for the high cost of aluminum extraction from its minerals, about 95% of the used aluminum in Europe is recycled. This is an example that highlights the industrial interest and new Circular Economy strategy to assisting in the phasing out of landfilling of recyclable waste. As a consequence, the raw materials manufacturing naturally meet both economical and environmental sustainability criteria. From an environmental point of view, extraction and processing of raw materials must also be considered, because they are often energy intensive activities involving large ecosystems modification and resulting in air, soil and water pollution. Additionally, a not suitable management of manufacturing residuals can

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produce waste and pollution, that impact the environment and the society. For example, the concrete industry requires the use of limited natural resources like crushed rock, rock, water, gravel, and sand. This activity is connected with the cement production. For this aim, clay, limestone and other raw materials are quarried or mined and transported to the manufacturing plant, where they are crushed and milled. To obtain the final cement material (with a defined composition), with specific functional properties, these natural resources are mixed, in fixed proportions (Salas et al. 2016). The concrete production causes 5% of global anthropogenic CO2 emissions (Hendriks et al. 2004). In addition, the cement production accounts for significant emissions of other pollutants, such as carbon monoxide and heavy metals (Lei et al. 2011). In the industrial sector, an interesting example of raw material manufacturing connected with environmental pillar of sustainability concerns gears and gear manufacturing industry. They play a fundamental role in several industrial segments, as gear is one of the basic mechanical components for motion transmission in machines, instruments, and equipments. Billions of gears are manufactured globally every year (Gupta et al. 2016). This sector uses large amounts of mineral-based cutting fluids for lubrication, with possible adverse environmental impacts because they may produce ground contamination. The lubrication involves increased wet chip handling and increased energy consumption. Additionally, an incorrect disposal of produced waste from lubrication can contribute to produce potential health and safety concerns (Debnath et al. 2014). This has pushed the interests in performing machining operations dry or near-dry. For example a micro-lubrication technology, requiring a small quantity of lubricant mixed with air, instead of large quantities of water and mineral oil-based cutting fluids, has been developed. It employs vegetable oils, synthetic ester and fatty alcohols, which are lubricants biodegradable and environmentally friendly and therefore also less dangerous to humans during use (Weinert et al. 2004). In conclusion, it was shown as each raw materials property can be directly correlated with two of the sustainability pillars; as a consequence, the fundamental importance of all these properties makes that a failure of any one leads to the raw material system as a whole becomes unstable. For some raw materials, these conditions are very next.

1.3

World Material Consumption

All world economies are based on consumption of physical resources, which is generally concentrated in urban locations. Currently, cities contain more than half of the global population. They are responsible for 80% of the global economic growth but also for 75% of the resource consumption (Kalmykova et al. 2016). In the last years, the resources use increased in an uncontrolled way, with consequent concerns regarding not only the raw materials availability for the next generations,

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but also the consequence of uncontrolled materials use, as for example ecosystem degradation (due to mining activities), environmental pollution, and climate change. Greenhouse gas (GHG) emissions can be converted in CO2-equivalent emissions, to account with only one parameter all the emitted gases. In particular, the emissions level, in terms of tonnes of CO2-equivalent per gross domestic product (GDP), is a commonly used metric of emissions intensity. It is considered a useful indicator to monitor eventual de-carbonization of a national economy or energy system (WRI). Often the resource use, that can be related to the corresponding emissions, is strongly connected with the GDP, demonstrating overall economy dependency on the materials use (Kalmykova et al. 2016). Figure 1.6 shows greenhouse gas (GHG) emissions per capita (in terms of tonnes of CO2-equivalent per capita), as a function of GDP (reported in current prices, euro per capita) for EU countries. The data are for 2014 (Eurostat). Despite that the emission intensities change across countries, there is a slight correlation between the GDP and the quantity of emissions, with Luxembourg resulting the top EU emitter. Globally, there is an increasing need supported by a political consensus toward to sustainable development, with an high necessity of a decrease of material use and its associated environmental impacts (Wenzlik et al. 2015). It was observed from several years that current levels of per capita material consumption are higher in industrialized countries than in developing countries, then they are unequally distributed among the world (Giljum et al. 2015). It was shown that domestic material consumption per capita can be considered a robust indicator of a society economy, analogous to GDP as indicator for the monetary structure of an economy (Weisz et al. 2006). Figure 1.7 reports the material consumption in terms of non metallic minerals and metal ores (in a scale of 1000 tonnes), for EU countries. The data concern 2014 (Eurostat). A quite good correlation seems to be established among the natural resources use: EU countries generally use both typologies of resources, like Germany, where the economy results to be restarted, after the economic crisis. Some exceptions are evident in Fig. 1.7, like Sweden, that has a large consume of metallic ores (56,268.5 Mtonnes), with a corresponding low use of non-metallic

Fig. 1.6 Greenhouse gas emissions per capita (in terms of tonnes of CO2-equivalent per capita), as a function of gross domestic product (GDP) for EU countries

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Fig. 1.7 Material consumption in terms of non metallic minerals and metal ores (in a scale of 1000 tonnes), for EU countries. The data are for 2014 (Eurostat)

ores (87,386 Mtonnes) and Romania, with an opposite trend. Sweden, in particular, is among the most active metals mining countries in Europe. Indeed this state has modernized its mining legislation which, differently from several enter members states, considers also lead times in the permitting process. Global society uses materials in large amount. World demand for engineering materials has quadrupled in the past 50 years (Allwood et al. 2011). This is not only a problem of developed countries, but it is a global problem: material extraction and use have grown continuously during the 20th century, with an expanded increase evident during the first decade of the twenty-first century (Wenzlik et al. 2015). The need to reduce the materials use on industrialized countries is imperative, but it is not clear the way to decrease natural resources use while maintaining the existing social well-being and economic prosperity. To reach this objective it is necessary to decouple material use from economic growth, so that material efficiency (material use per unit of economic output) must increases at higher rates than GDP (Wenzlik et al. 2015). Some industrialized countries are shifting to developing countries the problem of materials use, generally associated with resources extraction. As a consequence, for industrialized countries, the material-intensive production was increasingly outsourced to other countries, resulting in an apparent reduction of domestic material use. These countries show an increase on the economic material efficiency, with a reduction of their CO2 emissions. For these countries the goal to decouple material use from economic growth was formally reached. For example, analyzing the CO2 emitted from United Kingdom from 2004 to 2014 (Eurostat) with parallel comparison with GDP, it is possible to enhance a divergence on the behavior of these two parameters (see Fig. 1.8): the UK’s consumption-based emissions was continuously decreasing with a slightly pronounced drop in 2008, as a consequence of the world economic crisis. On the contrary GDP has a behavior that is not clearly correlated to the emission: GDP increased from 2004 to 2008. Then it decreases till 2011 (the raison is attributed to the economic crisis), when it starts to increases. This difference can be attributed to

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Fig. 1.8 CO2-equivalent emissions and GDP for UK

the offshore materials production and manufacturing required to meet the physical demands of UK consumption (Wiedmann et al. 2010). The outsourcing material production causes discrepancies in the real evaluation of the pressure on raw materials made by each county: for economists an increased consumption of material and energy services corresponds to increased economic welfare, not considering the sustainability aspect of resource use, that relates the welfare to the service provided by the energy and materials, and not their consumption per se (Allwood et al. 2013). The focus on raw materials consumption is now imperative. For a long time, no data were available to quantify the difference among consumption-based indicators and production-based accounts. From few years these data are available and can be now critically analyzed. Figure 1.9 represents the annual world production of several materials widely used by our society, aggregated by some major categories: metals (and metals

Fig. 1.9 Annual world production of several materials widely used by our society, aggregated by some major categories: metals (and metals alloys), ceramics and glasses, hybrid materials, polymers, and fibers and particulate [data were provided by CES Selector (GRANTA)]

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alloys), ceramics and glasses, hybrid materials, polymers, and fibers and particulate. Several of these materials are sophisticated materials, requiring specific manufacture processes. The scale is logarithmic to allow visualizing all the materials in the same image. It appears that the consumption reaches values larger than 1010 tons per year for several materials, i.e. now exceeding the oil and coal (materials for energy) use. This is extremely interesting, because it is clear that now world is facing with not only the energetic problems (connected with the use of materials for energy), but also with the natural resources (i.e. not energetic resources) expanded use. Construction minerals dominate the world material consumption. They are mainly ceramic (and glass) materials. Figure 1.9 shows that cement and concrete are the most produced materials (on the order of 1010 tons per year). Also plasters and silicates are produced in large amount (about 108 tons per year). In particular, construction materials consumption has been increasing continuously at the country level and exponentially in metropolitan areas (Kalmykova et al. 2016). One outstanding parameter of the use of construction minerals is its localism. Generally, transport costs of these materials are high compared to their production costs. Then import and export are always limited and generally they are comparable to domestic extraction cost of these materials. A peculiar characteristic of the construction minerals production is their dependence on economic growth. This tendency is essentially due to the local use of these materials. Indeed, the trend of domestic consumption of construction minerals over the past three decades strongly correlates with economic growth (Weisz et al. 2006). Periods of active economic growth often result in enhanced construction activities. On the contrary, periods of economic crisis, as that started in 2008, are reflected in a decrease of the construction activities. During these periods, investment in new building and physical infrastructure and thus the use of construction materials usually declines (Weisz et al. 2006). No other materials production other than the domestic material consumption shows similar high dependence. From 1970 to 2000, domestic materials use of construction minerals increased also in several medium and high income countries (Weisz et al. 2006). Chemicals and ores production generally correlates with GDP. In particular, metals consumption has demonstrated to correlate with the GDP of high industrialized cities (Kalmykova et al. 2016). Figure 1.9 shows that the world production of metals (and metal alloys) is extremely high and comparable to that of some construction materials. In particular, iron and its alloys dominate the market of metals production (more than 109 tons per year). Aluminium (and its alloys) is also highly produced (more than 107 tons per year), due to peculiar physical and chemical characteristics of this metal. It is evident in Fig. 1.9 that some metals can be contained in several different alloys (for example Fe and Al), which cannot be all represented in Fig. 1.9, but this is evident in the expanded x-axis metals attribution. Similar considerations can be extended to other materials such as ceramics (alumina and silicates for example).

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Technically and economically, minerals are the fundamental materials for industrial production. They are also diffusely used for building applications. Moreover, some of the materials containing metals (mainly containing heavy metals) are particularly harmful due to their high chemical reactivity and their toxicity. Additionally, wastes and emissions associated to materials production must be carefully considered (Weisz et al. 2006). In European countries, the mining of industrial minerals and ores has long been under national governmental control. However, in the past decades the governmental influence on this market has been decreased considerably mainly due to EU liberalization politics (Weisz et al. 2006). Hybrid materials, as for example composites, foams, honeycombs, and natural materials are also used in several applications. Leather, bamboo, and paper are used in quantities comparable to those of Fe and Al. In addition, the technological improvement of the last years in the synthesis and characterization technologies allowed to develop new generation of materials, obtained combining for example nanoparticles, graphene (Shtepliuk et al. 2016), thin films, core/shell architecture (Cui et al. 2016), and so on, with conventional bulk materials. Hybrid materials present advantages and benefits that can be modulated for example by changing the relative amount of the used materials, for several applications fields, as for example from electronic to medicine. Polymers are a materials category that is now fundamental. Due to reduced reactivity and cost of polymer materials, in respect to metals, the polymer production is increased in the last years. The main diffused polymers, i.e. polyvinyl chloride (PVC), polyethylene (PE), and polypropylene (PP), are produced in quantitates that are comparable to aluminium and its alloys (more than 107 tons per year). Other polymers such as polystyrene (PS), and polyethylene-terephthalate (PET), acrylonitrile butadiene styrene (ABS), and polyamide (PA) are produced in less quantities, but they are realized in the order of 106–107 tonnes per year. In addition it is very interesting to notice that these materials are often used as composites, i.e. comprising a polymer matrix, and the addition of filler, that generally is inorganic. For this reason the different polymers attributions have an expansion on the x-axis of Fig. 1.9. Finally the production of some fibers and particulate materials, that are widely used, is also reported. Fibers, too, are produced in very large amounts. Natural fibers, such as for example cotton, silk, and wool have a fundamental role in human life. As shown in Fig. 1.9, the materials (and their amount) used by industrialized countries are several. Furthermore, the International Energy Agency (IEA 2008) hypnotized that materials request will by 2050 be at least double current levels. To find new possibilities to limit and prevent high consumption of materials resources, some strategies must be achieved. For this aim, clear indicators of materials consumption must be addressed. To opportunely monitor materials flow in national economy and to make a comparison in a transparent and comprehensive way among different materials categories, some aggregated economy-wide indicators have been proposed. In recent years, for example, material flow accounts (MFA) have been devoted to

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analyze the global raw material use associated with a final consumption in the investigated area. Another fundamental indicator is raw material consumption (RMC), also referred as material footprint, which includes upstream flows (Eisenmenger et al. 2016) and accounts direct and indirect consumption of materials. This indicator attributes all material requirements of consumption activities to the consumer. Then it doesn’t take into account where the resources were extracted or where they physically end up. On the contrary, the indicator of domestic material consumption (DMC), reported by Eurostat and applied to evaluate some EU policies, is calculated as the balance of the annual quantity of raw materials extracted from the domestic territory (DE), plus all direct physical imports minus all direct physical exports. This indicator only accounts the amount of materials directly used by an economy (Bruckner et al. 2012). Therefore, RMC can be considered a good indicator to reflect the material flows related to domestic consumption. The difference between RMC and DMC indicators is often interpreted as an estimation of the shifting of activities related to extraction and processing of materials away from the domestic territory to other world regions (often in developing countries), for several reasons (as for example environmental constraints), beyond the actual physical shift of materials. Based on the reported defined indicators, during the last decade, several material flow analyses for different economies in several geographical areas have been realized and are widely available in literature. However, the material flow analysis can be highly dependent by the considered monetary economic structures, and approach to account the data, thus limiting meaningful cross-country comparisons. Additionally, because of the large amount of existing data, the literature on national material flow analyses, for single country, generally considers levels and trends of highly aggregated material flows (Weisz et al. 2006). Then, often, some specific indicators of materials flow have been accounted with high levels of aggregations of considered resources. Unfortunately, high aggregation levels can produces some errors in material categories evaluations, to identify the most suitable aggregation system. Indeed, the subgroups material categories definition involves different types of materials aggregation into one theoretically homogenous flow. This can hide that raw materials use can be dependent from different driving factors, which determine the raw materials level of use (Weisz et al. 2006). This assumption does not hold true, in particular for the category of metals and industrial minerals (Bruckner et al. 2012). Therefore, the material flow accounts analysis is also dependent on the applied system boundaries and methods for estimating missing data. Then meaningful cross-country comparison may be not easy to made, due to a lack of comparability among available data sets (Weisz et al. 2006). Finally, the quantity of used material and their composition can be quite different even among highly industrial economies and incoming countries. Then, a suitable solution to this problem may be to use disaggregated data, which allow separating all materials, with a global vision of raw materials use.

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Embodied Energy and Carbon Footprint

In the complex context of existing data and indicators about raw materials consumption, two simple parameters can be accounted to evaluate the sustainability of the materials use. They are embodied energy and carbon footprint. The total energy used during all stages of a material’s life is defined embodied energy (EE). Embodied energy of an object refers to the total energy used, then the energy involved in raw material extraction, acquisition, manufacture, transport, and all energies involved in the final obtained object life and disposal. If an object is made of a mixture of different materials, such as a composite, or an object made of different parties, the embodied energy of the object must be calculated considering all of the energy inputs from all object components. In addition, also the energy inputs to obtain the final object (that is often defined as manufacture), for example by mixing and combining the single materials, must be included in the total life embodied energy. It is evident that minimally processed materials, as for example some natural resources directly used as building materials (like calcite, sand, and so on), generally have a lower EE than those with extensive or multiple manufacturing processes, as for example plastics composites, made from at least two different materials, that are obtained by industrial processes. All the parameters that must be accounted in EE evaluation not only include manufacturing processes and energy sources, but also national and regional conditions (as for example legislative constraints in manufacturing, emissions, energy cost), recycled content, end-life possibilities, and final life conditions parameters (e.g., cradle to gate, cradle to cradle, etc.…). In view of all these variables, generally it is extremely hard to exactly quantify all the embodied energy of a product; as a result the calculated embodied energy for materials, also depending on variable parameters, can vary widely, sometimes by 100%. The constrains considered in a material life cycle can also contribute to considerable EE variations. For example when a product has high-energy requirements in primary processing, it is better that recycled-content percentages is maximized to reduce the energy required to produce the material. Then the EE of this material will be extremely different if a recycled content is accounted or not considered. As a consequence the evaluation all the material life cycle, in EE calculation, can generate excessively complex approaches, with multiple solutions. Generally, the less variable components of embodied energy are connected with the cradle to gate approach, that is, all the energy required to obtain the final product. They commonly concern primary resource extraction and mining, transport to the manufacturing sites, and processing and manufacturing of final goods. To reduce the variabilities and errors sources, in this work, to account EE of a material, only embodied energy associated to its primary production is considered. This choice is justified also by the book aim, that is devoted to raw materials and their sustainability. As a consequence all the considerations and the proposed

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approaches for materials comparison are mainly devoted to natural resources. Because the book aims to establish some indicators to evaluate sustainability of raw materials substitution, manufacturing of complex products, made by different raw materials, is not accounted. Literature report that EE of raw materials involved in residential building construction typically represents between 30 and 100% of total life cycle energy consumption in this sector. This has caused the great attention devoted near exclusively to EE of building materials. Indeed, one of the main principles of sustainable building, require a great attention to materials EE. The EE of materials used in other applications have been generally ignored. The importance of EE for raw materials, however, is generally greater than that attributed also for materials used in lower amount in respect to building materials. Figure 1.10 reports EE of primary production of elements, as a function of their abundance in the earth’s crust. The scale is logarithmic to allow representing and visualizing all elements in the same figure. EE required to obtain metals from minerals is related to the technological processes and can involve mining, crushing, washing and chemical reactions that produces the refined material from its ore (Gutowski et al. 2013). The most abundant elements on earth crust are Si, Fe, Ca, and Al. They correspond to elements with low EE. On the contrary the most diluted elements, such as for example Rh, Pd, Au, Pt, Os, and Ir shows an EE in the order of 105–106 Mj/kg. These elements, extracted from dilute ores, and that often require several chemical reactions to be purified, are much more energy intensive in respect to most diffused elements. In the centre of the graph of Fig. 1.10, where the higher number of elements can be found, it is possible to find elements with intermediate EE (from 102 to 104 Mj/kg). These elements have middle abundance values (for example U, Ga, V, S, W, Li, and V), i.e. among 0.1 and 100 ppm.

Fig. 1.10 Embodied energy (EE) of elements primary production, as a function of their abundance in the earth’s crust [data were provided by CES Selector (GRANTA)]

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While there is a considerable scatter in the data reported in Fig. 1.10, the difference in the EE among elements that are present in low (less than 0.1 ppm) and high concentrations (higher than 1000 ppm), can be explained by the change in the dominating energy step. For the most abundant elements, for example for iron and aluminium, the energy requirement for extraction is dominated by the chemical reactions step. On the contrary, for metals present in low concentrations on the corresponding mineral (generally they are also less reactive), such as gold and platinum, the energy requirements are dominated by the mining activities and separation steps to extract almost pure element. It can be observed that for these elements generally the EE of primary production increases with increasing dilution of the ore. The elements that are widely diffused, generally show contained EE values. An exception is represented by Al, that, in view of its physical and chemical characteristics, can be recycled. It is evident that Al, which shows an EE higher than other most used metals, such as for example Fe, Mn, Cu, and Zn, should be recycled, instead to extract it from natural resources. Indeed it has high EE requirement in primary processing, but this metal is easily recyclable, then it is not necessary to provide all EE for its primary production, when the material is reused. Carbon footprint or CO2 footprint (CF) refers to the CO2 released during a material or product’s life cycle. Actually not only carbon dioxide is emitted during all life cycle of a material, but also other gases, that can contribute to increase global warming. There are several greenhouse gases (GHG) (as for example not only carbon dioxide, but also methane, and nitrous oxide). For simplification about greenhouse gas emissions account, all GHG can be converted in CO2-equivalent emission. Because each GHG has a characteristic global warming potential and can persist for a different time in the atmosphere, these parameters are taken into account in the GHG conversion to equivalent CO2. Considering not only primary production of a material, but also its whole life cycle, GHG emissions are often directly correlated to the embodied energy of the material, because they generally depend on the fossil fuels combustion required in its production and manufacture. For example, many of the most used metals originate from compounds containing sulfur. Generally this element is converted into oxides during processing. The reduction reaction often is realized by using carbon, which yields a final output, including carbon dioxide gas emission. Thus, the reaction can produce a certain amount of carbon dioxide (basically 1 mol of carbon dioxide is produced form 1 mol of metal) in addition to the carbon dioxide associated with the energy required for metal extraction (which depends on the nature of the energy source) (Gutowski et al. 2013). Then the increased required energy for metal extraction is reflected in the increase of GHG produced. Preparing engineering materials from ores or biomass (for example plastic materials) is an energy intensive process. As a consequence, an eventual increase in material demand will involve an increase in energy demand, and this will entail an increased emission of greenhouse gases. As already explained for EE, this work will consider the carbon footprint connected with raw materials primary production.

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Fig. 1.11 Industrial CO2 emissions (IEA 2008)

The International Energy Agency (IEA 2008) has reported that 56% of industrial carbon dioxide emissions are generated from production and processing of just five materials: cement, steel, paper, plastic, and aluminium (Fig. 1.11). That gives an idea of the emissions related to raw materials primary production. In general the carbon dioxide intensity of material production is dominated by the energy intensity of production (Gutowski et al. 2013). The ratio of carbon dioxide emitted (emission term) to that from energy use (energetic term) varies by material and technology, but is generally in the range of 1:1 to 1:10. Considering both parameters, EE and CF, it is possible to summarize that basically these two parameters account for energy (EE) and emission (CF) involved in a material synthesis. Materials require energy for their production (energy generally derived primarily from fossil fuels combustion processes), so generally the greenhouse gas emissions, due to materials realization, result directly associated with their EE. As a consequence, CF figures generally correspond to EE figures: it means that if a product has a high EE, it will probably have a high CF. There are some exceptions to this. For example, aluminum has an high EE, yet CF is not correspondingly because the primary power source for aluminum manufacture is relatively clean hydroelectric energy (Calkins 2009). Another exception concern concrete production: gas emissions for concrete are about twice the embodied energy, as, during the concrete production, almost the same amount of CO2 is released in the conversion of limestone to lime as in the fossil fuel combustion to heat the limestone (Calkins 2009). Figure 1.12 shows the EE and CF of materials, reported as a function of their annual world production. Both axis scales are logarithmic.

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Fig. 1.12 a Embodied energy (EE) and b carbon footprint (CF) of elements primary production, as a function of their annual world production [data were provided by CES Selector (GRANTA)]

It appears, that, in general, there is an inverse correlation between the production and the EE of materials. Similar correlation exists also for CF and materials production. In accord with data already reported and discussed in Fig. 1.9, materials for building applications (concrete, asphalt, plaster, and Fe alloys) are the most produced ones. In particular, cement, asphalt, and concrete are near the bottom of the energy-intensity scale (and also carbon-footprint-energy scale). The building ceramic materials have low EE and CF, due to few procedure need to obtain and produce them from natural resources. Also polymers and other metals are produced in large quantities. They require higher energies, in respect to building materials, for their production, due to the polymer manufacture. Higher energies and emissions

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are involved in the production of other materials, as for example high pure metals, and precious material, such as diamond, and gold alloys. The technologies involved in the production of several industrial minerals, to obtain, for example, high purity metals, involve some steps that are more complex than the minimal procedures mandatory for the manufacturing of building materials. In addition the final obtained metals are characterized by high differences between the mass of the extracted gross ore and the mass of the obtained products (Giljum 2008). This explains the considerable energies involved in the production flows of materials requiring complex extraction steps and or manufacturers. It increases the consequent GHG emissions that are accounted as equivalent carbon dioxide. Data reported in Fig. 1.12 show that, generally, the materials production takes into account also energetic (and emissive) characteristics of these materials: it appears that many of the high production volume materials are low-energy-intensity materials. Data in Fig. 1.12a, reported in logarithmic axis, can be approximated by an exponential equation, that can be represented as: y ¼ c  xð0:4Þ where c is a constant, depending on the dimensions of entities reported on the two axis. Similar data fit may be done also for data reported in Fig. 1.12b. This curve is very similar to demand curve (in the economy context), that often can be represented as an exponential equation. In the economic law, the price of a good is represented as a function of quantity demanded. An increase in price of a good, almost always generates a decrease in the quantity demanded of that good (Khanacademy). As a consequence, on the demand-price curve, it results that a lower price leads to a higher quantity demanded and vice versa. For example, it was found that the gasoline demand curve, with quantity on the horizontal axis and the price per gallon on the vertical axis, has a behaviour very similar to that reported in Fig. 1.12a. Equations of demand curves are generally different for each product. Considering the EE as a sort of economic index of materials, it can be assimilated to a price variable; in this manner the equation found and represented as data fitting in Fig. 1.12a can be explained in terms of market demand law. This simplified assumption implicates a basic linearity among energy use and money flow, that is in principle reasonable. Some materials appear to be an exception to this law: for example, diamond, aluminum and its alloys, gold and silver dental alloys, and finally also kaolin, mica, bamboo, and some high purity metals. When materials are below the fitting line, it means that they are produced in quantities that are lower than expected ones. This is probably due to the fact that these materials are used in lower quantities, in respect to theoretical possible amounts, on the basis of curve relating EE and quantity of produced materials. This may stimulate to find other applications for these materials, that are low-energy materials.

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On the contrary, materials that are above the fitting line, are used in larger quantities, in respect to the expected ones (always considering the curve relating EE and quantity of produced materials). This can be reasonably explained for some precious materials, as for example dental alloys and diamond: people are willing to spend more for some goods related to medical applications and for emotive reasons. Concerning aluminum and its alloys, it is very important to remember that Al is generally recycled, because of the high EE required for its primary production. Then, to obtain aluminum and its alloys it is not necessary to use all the EE for their primary production. The production of secondary aluminium can allow to decrease the EE for its production till to two orders of magnitude. This is in accord with the quantity of Al (and its alloys) produced, that, considering the reduction of EE of two orders of magnitude, can be better approximated by the fitting line reported in Fig. 1.12a. Data shown in Fig. 1.12 allow to conclude that EE and CF are very interesting parameters, that can allow to connect the sustainability dimensions of raw materials to economy factors. Then more attention should be paid to their evaluation and analysis in connection with materials production and use. An historical analysis of EE and CF data demonstrated that technological advances have produced significant reductions in the energy intensity of materials, particularly for those produced in high volumes. Additional improvements must also account constrains due to the thermodynamics (Gutowski et al. 2013). However other ways to reduce the EE for elements (or generally for materials) production exist. The reported EE refers only to primary production, not accounting recycled content, which in some cases, may represent a fundamental fraction of supply. As a consequence, as already shown for Al, the materials reuse can reduce their embodied energy for secondary production. For example, in addition to the example already reported (for Al), also the production of secondary steel can allow to decrease the EE for its production: secondary steel EE can be halved in respect to the primary energy intensity. This cannot be applied to all materials, because some constraints on the quantity of secondary materials and on the quality and characteristics of recycled materials that must be processed, exist (Gutowski et al. 2013). For example, there is no known way to efficiently recycle cement. Material substitution can be another suitable method for reducing material energy requirements. The principle is based on substitution in the use of a material with high EE, by means of another with a lower energy intensity. For example, substituting concrete with more sustainable coal fly ash concrete not only reduce the materials EE, but can allow to reduce also its CF. Coal fly ash is a by-product of the combustion of coal in thermal power plants. Its employ in concrete production has been proven to provide several mechanical and environmental benefits in building industry. It was also shown that fly ash concrete production can involve a carbon dioxide emission reduction of 36% in respect to classical concrete (Zhang et al. 2016).

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The raw materials substitution, and in particular the preservation of natural resources, is the main aim of this book. In particular, this will be extensively discussed in the next chapters. Besides, owing to the strong correlation highlighted in Fig. 1.12 between annual material production and energy intensity (and also carbon footprint intensity), that can be also interpreted as the market law of demand, it is evident that raw material substitution can also save money associated to materials production. Anyway, despite that this concept is simple, in principle, material substitution is a complicated procedure, that necessitates of more constraints in respect to simple recycling of the primary material. Indeed, a material is used in a defined field, due to its chemical, physical, and functional properties, that are specific of the considered material; as a consequence it can be extremely hard to find a suitable material substitute, in view of the differences in materials properties. This makes the materials substitution often a theoretical concept, but with fascinating and stimulating perspectives for the materials research and design. The material design is another possibility to reduce the request and use of raw material, and, in particular, of high-energy intensity raw materials. Indeed, it is possible greatly reduce material energy requirements, by a suitable design, that limits the use of high-energy intensity materials and promotes their efficient use. This can be obtained by some design strategies focalized on materials optimization, reusing high energy intensity materials or designing products with less of these materials through light-weight design or dematerialization (Allwood et al. 2013). It is necessary also to promote design strategies able to recover materials at their end life. For example, for smartphone a general idea involving modular design has been proposed, promoting new concepts of easily replaceable parts. With the goal of also reducing the growing amounts of e-waste, the approach aims to replace or upgrade constituent blocks, rather than all the smartphone. This concept is known as “material efficiency”, that means using less raw material (Allwood et al. 2013). Additionally, material design must to make products last longer. This requires new thinking about how the materials are used. Finally, because materials EE and annual world production correlates so closely (see Fig. 1.12), it is possible to deduce that economy laws can help, in the next future, to direct the market towards important reduction in demand request of high energy intensity raw materials. Considering the annual world production of elements, normalized by their EE, it is possible to exacerbate the difference among elements which are used in high amount, and having low EE, and elements which are used in low amount and having high embodied energy. The ratio among the elements annual world production and corresponding EE is plotted versus the elements abundance in earth’s crust, in Fig. 1.13. The scale is logarithmic for both axes. This figure highlight an evident correlation existing among elements use, on the basis of primary energy required for their production, and their abundance. Antimony is displayed in blue in Fig. 1.13, because this critical raw material will be diffusely considered and its substitution will be discussed in the next chapter.

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Fig. 1.13 Annual elements world production divided by corresponding embodied energy (EE), as a function of elements abundance [data were provided by CES Selector (GRANTA)]

In conclusion, to analyze global material use and to further evaluate progress concerning dematerialization and sustainable use of resources, global material production and use rather than highly aggregated indicators can be examined. In was shown that embodied energy and CO2 footprint analyses can represent a simplified and easily accessible method of evaluating a raw material or a natural resource sustainability or to compare two different materials, because they allow to directly balance two basic parameters of sustainability (energy and emission). Evaluating the material flows tacking into account embodied energy and carbon footprint would be a promising next step to improve the environmental relevance of the material flow indicators. This, however, require a the use of database (as for example CES Selector (GRANTA), used in this book), than can easily take into account also energetic (EE) and emissive (CF) information about materials. Indeed some of these information may change rapidly, due for example to the change in materials manufacture, availability, and so on. Then it is fundamental periodical data update.

References Allwood JM, Ashby MF, Gutowski TG, Worrell E (2011) Material efficiency: a white paper. Resour Conserv Recycl 55:362–381. doi:10.1016/j.resconrec.2010.11.002 Allwood JM, Ashby MF, Gutowski TG, Worrell E (2013) Material efficiency: providing material services with less material production. Philos Trans R Soc London A Math Phys Eng Sci. doi:10.1098/rsta.2012.0496 Bruckner M, Giljum S, Lutz C, Wiebe KS (2012) Materials embodied in international trade— global material extraction and consumption between 1995 and 2005. Glob Environ Chang 22:568–576. doi:10.1016/j.gloenvcha.2012.03.011

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Chapter 2

Case Study of Raw Materials Substitution: Natural Fillers Substitution in Plastic Composites Elza Bontempi

Abstract In the frame of European problems of raw materials availability, this chapter describe a new technology (COSMOS) that allows to produce safe materials, starting from toxic ash waste (derived from municipal solid waste incineration). It is shown that this technology was evolved in the years to reduce its environmental costs and to use local available by-products for stabilization. The by-products and wastes that can be used in the COSMOS technology are coal fly ash, flue-gas desulfurization residues, rice husk ash, silica fume, and wood ash. The sustainability of the obtained COSMOS materials is demonstrated on the basis of their embodied energy and carbon footprint values. These parameters are reported and discussed also for several natural and engineered materials used as fillers, with great attention also to their cost. Results show that the new proposed material is comparable to calcium carbonate, in term of sustainability. A rapid analysis of the European plastic market and the results about mechanical performances of the obtained composites, highlights the possibility to reuse COSMOS filler as a substitute of calcite and talc, in polypropylene composites. Embodied energy and carbon footprint of the already available polypropylene composites and the new proposed ones are presented and discussed. In this context, Ashby plot is used to investigate possible substitution of polypropylene fillers that are unsustainable or very expensive, exploring the potential of one material to replace another. Finally, in view of its thermal properties the COSMOS filler is proposed as a substitute of antimony, one critical raw material, that urgently need alternative.














Keywords COSMOS Fillers Polypropylene composites Fly ash Sb Biomass ash Coal ash Flue-gas desulfurization residues Rice husk ash Silica fume













E. Bontempi (&) INSTM and University of Brescia, Brescia, Italy e-mail: [email protected] © The Author(s) 2017 E. Bontempi, Raw Materials Substitution Sustainability, SpringerBriefs in Applied Sciences and Technology, DOI 10.1007/978-3-319-60831-0_2

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2 Case Study of Raw Materials Substitution …

A New Sustainable Filler from Waste: COSMOS Technologies

Every year about 11 billion tons of solid waste are collected worldwide and the European Union alone generates about 3 billion tons of waste (Eurostat). Highly dependent on imported raw materials, Europe must reduce the amount of waste generated by improving its resource efficiency through recycling, avoiding waste and using unavoidable waste as a resource, when possible. On the basis of developed policy on waste management, in Europe, from 1995 to 2013, the global amount of waste produced per capita (500 kg/year) results almost constant. Moreover the waste landfilling shows a negative trend, with a reduction at about one half of the waste designated to landfill in 2013, in comparison to data of 1995 (from about 300–130 kg/per capita). An opposite trend is found for waste incineration (with an increase from 67 to 127 kg/per capita, comparing data from 1995 to 2014). Waste incineration, that is acquiring a prominent role for domestic waste management in several EU countries, is at present exceeding the amount of waste that is landfilled. Municipal solid waste incineration (MSWI) is now considered an efficient technique to recover energy and to manage waste. Indeed, it allows to widely reduce the total waste volume and mass to be disposed in landfill (Zacco et al. 2014). During 2014, in Europe, 122 kg per capita of waste were incinerated (Eurostat), i.e. the 25% of the waste generated in the same year. Data about waste production and management in Europe show that, generally, where high incineration rate is reached (more than 35% of the total waste produced), as for example in Norway, Sweden, Germany, France, Austria, and Netherlands, the fraction of waste incinerated is constant considering the past years (some countries also exceed 50% waste incinerated, in respect to total waste generated). On the contrary, countries where the incineration rate is lower than 25%, the amount of waste incinerated, in respect to the waste generated, is continuously increasing with time (see Fig. 2.1). As a consequence, in the next years, the incineration of waste is expected to rise in several European countries. MSWI technology induces environmental issues, mainly connected to the treatment and management of solid by-products generated by waste combustion. These residues include bottom ash, fly ash, and scrubber residue. Generally MSWI fly ash and air pollution control (APC) residue are not differentiated. Fly ash is the thinnest fraction of the particulate contained in combustion flue gas. After combustion, fly ash is caught by electrostatic precipitators without any other treatment of the gaseous stream (Zacco et al. 2014). APC residues are instead a product deriving from the injection of an alkaline material inside a scrubber system, in order to reduce the content of acid gases, particulates and flue gas reaction products. Fly ash can be incorporated inside the APC residue. Thus fly ash and APC residues are considered as an unique by-product of MSWI processes. This by-product is commonly called MSWI fly ash. MSWI fly ash is generally composed of sulphate and

2.1 A New Sustainable Filler from Waste: COSMOS Technologies

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Fig. 2.1 Percent of waste incinerated, in respect to the waste generated, in Europe from 1995 to 2013 [data from (Eurostat)]

aluminosilicate glass and it is quite rich in terms of soluble salts. The most abundant crystalline compounds generally detected in MSWI fly ash are CaClOH, NaCl, KCl, CaCO3 and CaSO4. Moreover, also amorphous phases are always present (Zacco et al. 2014). The typology and concentration of the contaminants found in this waste are quite various, depending on the solid waste original composition, the plant operational conditions, the incinerator typology and the air pollution system design. MSWI fly ash may contain high concentrations of leachable heavy metals such as As, Cd, Hg, Pb and Zn (Le Forestier and Libourel 1998) and can contain organic micro-pollutants (PCDD and PCDF) (Zacco et al. 2014). Because of the dangerous effects produced on humans and environment, MSWI fly ash is generally landfilled, after a partial stabilization with cement. On the other hand, because Europe faces issues with raw materials depletion, there is an increasing need to encourage resource conservation. As a consequence, the materials recycling represents a large and significant contribution to protect the environment (Brunner and Rechberger 2015) and a way to reach the objectives established in the framework of COP21 meeting (COP21). The need to reuse valuable materials contained in toxic fly ash has been reported and discussed in the literature (Funari et al. 2015). However, the papers on this subject are mainly dedicated to the recovery of precious metals and earth elements that represent only a limited content in these wastes.

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In this frame, the COSMOS project (it was realized in 2011–2013), financed by European Commission, developed a new method for MSWI fly ash stabilization and explored the stabilized material recovery possibilities. The stabilization technology was based on the use of colloidal silica and other fly ashes (i.e. coal fly ash and flue-gas desulfurization (FGD) residues). In the following the required ingredients for the COSMOS process, which are mixed to obtain the MSWI fly ash stabilization, are briefly analyzed; they are: colloidal silica, coal fly ash, and flue gas desulphurisation (FGD) residues. Colloidal silica is a concentrated stable dispersion of dense particles of amorphous silicas, generally monodispersed with size ranging from about 5 to about 1500 nm. Colloidal silica is composed of discrete particles, thus it is different from silica glass, because despite both are amorphous, the structure of the glass is macroscopically continuous (Bergna 1994). Colloidal silica is used in the form of a gel, made of a network of interconnected pores with a silicon dioxide core where water is entrapped. The silica surface can be covered by silanol groups (Iler 1979). The surface silanol groups are responsible for physically adsorbing water molecules and holding them in place by hydrogen bonding. The silanol hydroxyl groups, the water entrapped in the core, and the physically adsorbed water together represent the moisture content in the dispersed silica gel particles (Kamath and Proctor 1998). The high dispersion of its particles makes colloidal silica very reactive. In the COSMOS process the commercial colloidal silica that was used has a particles dimension less than 10 nm. Coal fly ash is a by-product originated from the flue gases of furnaces at pulverized coal power plants. It is predominantly an inorganic residue; however, its characteristics can be different, depending on several factors, such as on the coal source, the temperature and the method of combustion of power plants, the technology of emission control devices, and the ash storage and handling (Zacco et al. 2014). Therefore, coal fly ash shows a wide variation in its physicochemical and mineralogical properties. This material is generally composed of crystalline and amorphous phases. Crystalline phases are mullite, quartz, magnetite, hematite and anhydrite. Glass is found as amorphous constituent. Coal fly ash is sometimes reused in building application, to produce concrete (as reported in Chap. 1). Coal fly ash can be reused in other applications (that will be discussed in Chap. 3), to increase the sustainability of the obtained material (see also Chap. 4). Coal fly ash is used in the COSMOS stabilization technology to mainly improve the mechanical characteristics of the obtained filler (Bontempi et al. 2010). Flue gas desulphurisation (FGD) residues are a by-product generated by the air pollution control equipment in coal-fired power plants. They are formed as a consequence of the required pretreatment made on coal, in combustion plant, to reduce sulphur amount. Indeed, coal contains large quantities of natural sulphur and its burning produce severe air pollution problems, because sulphur-bearing impurities are transformed into gaseous SO2, that is an atmospheric pollutant and a precursor to acid rains. For this reason, in Europe, coal power plants are forced to remove sulphur oxides from the flue gases, before releasing them to the atmosphere (Zacco et al. 2014). FGD residues generally contain calcium sulfite and calcium

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hydroxide. As a consequence, flue gas desulphurisation residues are used, as an inexpensive calcium hydroxide source, in the COSMOS stabilization technology. FGD were chosen to promote the carbonation reaction, which naturally takes place with atmospheric carbon dioxide. The reaction mechanism occurring during the stabilization, is due to the amorphous colloidal silica reactivity. The adsorption of metal ions seems take place on the silica surface, and can be explained on the basis of the surface complex formation model. The hydrolysis of silicon dioxide produces hydrous oxide surface groups –SiOH (the silanol groups). When colloidal silica is added to a solution containing leachable metals, the sorption of metal ions on silica can occur by the cation exchange reaction through the substitution of protons from silanol groups on the surface by the metal ions contained in the solution (Srivastava et al. 2006). This reaction mechanism can be represented as: mðSiOHÞ \ [ mðSiO Þ þ mH þ An þ þ mðSiO Þ \ [ AðOSiÞðmnmÞ þ and the overall reaction can be written as: þ An þ þ mðSiOHÞ \ [ AðOSiÞðnmÞ þ mH þ m

where An+ is the metal ion with n+ charge, SiOH is the silanol group on SiO2 surface, and mH+ is the number of protons released (Bosio et al. 2014a). To verify the efficacy of the stabilization procedure, leaching solution of MSWI fly ash and stabilized samples are prepared and analyzed. Leaching tests consist in the realization of an aqueous leaching of the material which must be analyzed, to verify the presence of soluble heavy metals. The tests are generally realized following the European Committee for Standardization normative (EN 2002). Some results of leaching tests, made on a MSWI fly ash sample and corresponding stabilized material, are shown in Table 2.1. Analysis were made by means of inductively coupled plasma (ICP) spectroscopy. Data show that the main soluble heavy metals, present in MSWI fly ash are Pb and Zn. Generally Hg, Cd, Co, Mn, Se and V are below instrument detection limits. Data reported in Table 2.1 also show that the stabilization treatment reduces the amount of soluble Pb ad Zn. The amount of leachable Si, in the stabilized material, is increased due to the use of amorphous silica as stabilizing agent. Figure 2.2 shows Pb and Zn concentrations in the leaching solutions of stabilized samples, as a function of added silica gel amount. The zero point of the silica corresponds to concentration of metals in the MSWI fly ash leaching solution, i.e. in the leaching solution of fly ash, before stabilization (Bosio et al. 2013). Data of Fig. 2.2 are presented in logarithmic scale, due to the change of about two orders of magnitude in the metals’ leaching, as a function of the quantity of employed silica gel. These data show that the quantity of leachable metals depends on the content of

2 Case Study of Raw Materials Substitution …

34 Table 2.1 Concentration of elements detected in the leaching solutions of MSWI fly ash sample and corresponding stabilized material. Analysis were made by means of inductively coupled plasma (ICP) spectroscopy

Element

MSWI fly ash (mg/l)

Stabilized material (mg/l)

As Ba Be Bi Ca Cd Co Cu Fe Hg K Li Mn Mo Ni P Pb S Sb Se Si Sn Ti TI V Zn Zr