Material flow and energy required for the production of selected mineral commodities

Environmental impact assessments of industrial processes are based on the amount of raw materials, residues and energy in the production of commodities. A materials flow analysis of these amounts and an environmental impact analysis are usually the first steps in a product life cycle assessment. In the extraction of mineral resources, these various amounts say a great deal about the environmental impact of a process: for example, for the production of one tonne of aluminium about 5 t of ore and 3 t of rock are mined and transported, and about 16,000 kWh/t electrical energy are used. These analyses reveal the situation for the production of a specific mineral commodity but they also provide an indication of where it is possible to improve the process efficiency. The enormous diversity of mineral deposits, characterised by various parameters, including geometry, size, depth, mineral composition and grade, together with the numerous extraction and processing methods, results in very different mass flow diagrams for different deposits using different extraction and processing methods. It is usually risky to draw general conclusions about the materials flow for a natural resource on the basis of data for one or only a few known deposits and the processes involved. Given (a) the importance of mineral commodities in supplying the needs of humankind, (b) the importance of mineral extraction for industrial processes, (c) the need to protect our environment, and (d) the fact that these resources are all limited to one extent or the other, there is also an enormous need to establish a reliable and objective database as the basis for further analyses.