Assessing the environmental impact of metal production processes

Evaluating both new and existing processes for primary metal production to assess their environmental impacts is often difficult due to the many inputs and outputs involved. Life Cycle Assessment (LCA) is a methodology that can be used for such purposes to identify those parts of the metal production life cycle that have significant environmental impacts. LCA has been used by CSIRO Minerals to assess the “cradle-to-gate” environmental impacts of a number of metal production processes practised either currently or potentially in Australia. The metals considered included copper, nickel, aluminium, lead, zinc, steel, stainless steel and titanium, by both pyrometallurgical and hydrometallurgical routes in some instances. The environmental profile included greenhouse and acid rain gas emissions, solid waste emissions and gross energy consumption. The results for various metals are compared in this paper. New process technologies for primary metal production can be expected to reduce the environmental impacts of metal production, and estimates of likely reductions for technologies involving stainless steel, titanium and aluminium are also presented in this paper.