Minerals, Metals and Sustainability

Meeting Future Material Needs

WJ Rankin

• Editore: CSIRO PUBLISHING
• Anno: 2011
• ISBN:
  9780643104228
• Argomento: Tecnologia e ingegneria
• Categoria: Ingegneria mineraria

Minerals, Metals and Sustainability examines the exploitation of minerals and mineral products and the implications for sustainability of the consumption of finite mineral resources and the wastes associated with their production and use. It provides a multi-disciplinary approach that integrates the physical and earth sciences with the social sciences, ecology and economics.

Increasingly, graduates in the minerals industry and related sectors will not only require a deep technical and scientific understanding of their fields (such as geology, mining, metallurgy), but will also need a knowledge of how their industry relates to and can contribute to the transition to sustainability.

Minerals, Metals and Sustainability is an important reference for students of engineering and applied science and geology; practising engineers, geologists and scientists; students of economics, social sciences and related disciplines; professionals in government service in areas such as resources, environment and sustainability; and non-technical professionals working in the minerals industry or in sectors servicing the minerals industry.

1     Introduction

The supply of the goods and services used by humans depends on access to materials obtained by exploiting the non-renewable resources of the Earth’s crust, particularly metallic and non-metallic minerals, rocks, coal, oil and gas. This book is about materials made from metallic and non-metallic minerals and rocks, their production and recycling, and the environmental and social issues associated with their production and consumption. Mineral-derived materials and fossil fuels form one major group of materials, the other being those derived from living matter. The latter, while not derived from the crust, rely on the crust as the ultimate source of the nutrients they require.

The greatest challenge facing the world is to ensure that all people can have a good standard of living and quality of life without continuing to degrade the environment. The Earth’s resources are finite and its land and water ecosystems have finite capacities to cope with the wastes produced by human production and consumption. Every year, the people of the United States, for example, consume more than 21 billion tonnes of resources of all kinds – about 80 tonnes per person per year, consisting of 76 tonnes of non-renewable resources and 4 tonnes of biomass (Adriaanse et al., 1997). Only 19 tonnes are used as direct inputs to processing; the rest is waste. Further quantities of wastes are produced during processing of the direct inputs and during the use and ultimate disposal of the products made from them. Other developed countries have similar, though lower, patterns of consumption. The per capita consumption of materials in the European Union in the latter half of the 1990s, for example, was 49 tonnes per year (Moll et al., 2005).

How to deal with the problems caused by this unprecedented level of production, the associated consumption of resources and disposal of the wastes produced, is a global challenge. This challenge will only grow as living standards in China, India, Brazil and many other developing countries continue to rise. The concept of sustainable development, usually defined as development that meets the needs of the present without compromising the ability of future generations to meet their own needs, arose as an attempt to address these issues. Sustainable development principles have had growing influence on the development of environmental and social policy in many countries in recent decades. They have been adopted and promoted by international organisations, particularly the United Nations, the International Monetary Fund and the World Bank. Sustainable development, or sustainability, is an important theme of this book.

Non-renewable resources pose a unique challenge for sustainable development, in particular how global material needs can be satisfied sustainably when so many sources of materials are non-renewable and when their production and consumption results in huge quantities of wastes, many of which are environmentally harmful. The primary aim of this book is to examine systematically the issues raised by this dilemma, and possible solutions. The focus is on the environmental aspects of mineral and metal production and use. The overarching concern is environmental sustainability and its implications for non-renewable mineral resources. A second aim of the book is to provide a comprehensive overview of the science and technology underlying the production and consumption of materials produced from minerals. It is not the intention to provide a detailed examination of the key mineral-related disciplines of geology, mining engineering and metallurgy. These are very adequately covered in more specialised texts. The aim is to give an integrated overview of the science and technology, and combine it with an overview of the socio-economic nature of the minerals industry and its environmental impact. A third aim is to examine some of the social and economic aspects of sustainable development, in particular the role of the minerals industry in wealth creation and the impact of mining on communities. These are vitally important considerations. However, they are not the main focus of this book. Understanding these, and developing solutions to the social problems caused by mining, draws more on the social sciences and requires treatment from a different perspective. Nevertheless, social and economic aspects are discussed where appropriate to provide a more balanced view.

The book is anchored firmly in the traditional sciences of chemistry, physics, geology and biology, and in engineering. There are 17 chapters, which are best read sequentially. Chapters 1 to 3 introduce the concept of materials and their sources, how materials are utilised in society (with particular focus on inorganic materials from the Earth’s crust) and the environmental basis of our existence. Chapter 4 introduces the concept of sustainability and examines its interpretations and the issues it raises for the use of non-renewable resources. Chapter 5 discusses the geological basis of the minerals industry and Chapter 6 describes the structure and nature of the industry. Chapters 7 and 8 review the technologies by which mineral resources are extracted from the Earth’s crust and processed to make materials for use in construction and manufacturing. Chapters 9 and 10 examine the usage of energy and water by the minerals industry, with important environmental implications. Chapters 11 and 12 survey the types and quantities of wastes resulting from the production of mineral and metal commodities, the human and environmental impacts of waste dispersion, and how wastes from mining and processing are managed. Chapter 13 examines the recycling of mineral-derived materials and the role of secondary materials in meeting material needs. Chapter 14 surveys the future sources of minerals and the factors that will determine their long-term supply. Chapter 15 surveys the socio-economic and technological factors that will determine the long-term demand for mineral-derived materials. Chapters 16 and 17 look to the future. Chapter 16 discusses how the quantities of wastes formed during the production of mineral and metal commodities can be reduced, or eliminated, through technological developments and socio-political changes. Finally, Chapter 17 addresses the concept of stewardship and the role the minerals industry should play in the ongoing transition to sustainability.

The chemical and physical basis of materials is quantifiable. We can talk about the quantities of various elements and minerals in the Earth’s crust; the quantities of products made and wastes produced, and their composition (in terms of mass or volume per cent, for example); the quantities of energy and water required for different operations; the concentrations of elements in ores; the quantities of substances recovered or lost during processing; the size of mines and the capacity of various pieces of equipment; and so on. Wherever appropriate, quantitative as well as qualitative aspects of topics are examined in order to enable a better appreciation and deeper understanding of the issues. SI units are used; a brief review of these, and some useful numerical concepts, is given in Appendix I. An elementary knowledge of chemistry and physics has been assumed. Concepts which are particularly relevant are reviewed briefly in Appendix II.

REFERENCES

Adriaanse A, Bringezu S, Hammond A, Rodenburg E, Rogich D and Schütz H (1997) Resource Flows: The Material Basis of Industrial Economies. World Resources Institute: Washington DC.

Moll S, Bringezu S and Schütz H (2005) Resource Use in European Countries. Wuppertal Institute: Wuppertal, Germany.

2 Materials and the materials cycle

2.1 NATURAL RESOURCES

All the material needs of humans are met ultimately from the Earth’s natural resources. Natural resources are the naturally occurring substances and systems that in their relatively unaltered state are useful to humans and that provide the basis for our physical existence. They include:

• the atmosphere;

• water (oceans, rivers, lakes and water in aquifers);

• forests and forest products (timber and other forms of biomass);

• land in its natural state;

• fresh and salt water fisheries and their products;

• minerals, fossil fuels (natural gas, oil and coal);

• non-mineral energy sources (wind, tidal, solar and geothermal).

The capacity of all parts of the environment to undertake the essential role of absorbing, treating and recycling wastes created by humans can also be considered a natural resource. These are also called environmental resources or ecosystem services. Cultivated products, while not being natural resources, are reliant on natural resources (air, water, minerals etc.) for their production.

Some natural resources are renewable by natural processes while others are not. Living renewable resources such as fish and forests can regenerate (restock themselves) whereas non-living renewable resources such as wind, tides, solar radiation and geothermal heat do not need regeneration. They are essentially an infinite resource though they are available only at a finite rate. For example, wind might be available in a particular location at an average velocity of 10 km h^-1 but it is available, at least from a human perspective, for ever. Renewability, however, requires appropriate management of a resource, particularly in the case of living resources. If a living resource is consumed at a rate that exceeds its natural rate of replacement, the stock of the resource will decrease, become subcritical and eventually collapse. Changes to a system or related system can have irreversible effects on renewable resources. Sulfur dioxide emitted from coal-burning power stations can produce acid rain (discussed in Section 3.4.5) which causes dieback of trees in forests; heavy metals from the wastes of mining operations may enter fresh water systems and cause harm to wild-life; global warming may cause reduced rainfall in some areas, resulting in loss of forest or other biomass and wildlife. The unprecedented destruction of many renewable natural resources in recent decades poses a major challenge to achieving sustainability.

The main types of non-renewable natural resources are rocks, minerals and fossil fuels from the crust of the Earth. Rocks and minerals are used for making many useful materials such as construction products, metals and alloys, and specialty materials with vast numbers of uses. Fossil fuels are burned to produce heat to generate electricity and power machines and vehicles and, in the case of oil, to make hydrocarbon-based materials, particularly plastics. Fossil fuels are usually consumed in use (when they are burned); rocks and minerals are transformed into other solid materials. In both cases, however, when they have been extracted from the Earth’s crust and used, the original resource is no longer available. While geological processes can generate new stocks of coal, oil, gas and minerals in the Earth’s crust by the same processes that have occurred in the past, the time scale on which this occurs (tens to hundreds of millions of years) is far too long for these resources to be considered, in the human context, as renewable.

2.2 MATERIALS, GOODS AND SERVICES

In the technical sense, materials are substances which are used by humans to create goods. These consist of structures (such as buildings, dams and roads); vehicles (cars, trains, ships and aeroplanes); machines; electrical and electronic equipment and other devices (for both commercial and consumer use); works of art; and other objects (Bever, 1986). All materials are ultimately derived from the Earth’s natural resources.

The variety and complexity of materials used by humans has increased throughout history. Originally, natural materials such as wood, stone, leather and bone were the main materials used; we now also use complex electronic materials, plastics, synthetic building materials, coating materials (e.g. paints, enamels and polymers) and countless others. History is often divided into periods named after materials, as shown in Table 2.1. People started using stones around 32 000 years ago for hunting, cutting, chopping, grinding seeds and building shelters – the Stone Age. This does not mean, of course, that stone replaced wood and other plant materials, which were used previously. However, the use of stone was a new technology that expanded possibilities, both by using it for building to replace wood and using it for new applications such as knives and axes to cu...