The role of LCA in performance assessment in minerals processing

摘要

This paper demonstrates the use of Life Cycle Assessment (LCA) as a basis for assessing potential environmental performance in the minerals industry through a copper case study. The case study is sourced from a demonstration plant of a hydrometallurgical process that converts copper sulfides and oxides to LME Grade A copper using a leach / electrowinning technology. The life cycle approach is supported by a sequential leach extraction protocol to better quantify the potential mobility of metals and complementary anions from solid waste residues. Sequential leach tests showed that the majority of iron and sulfur, the main components of these residues, are unlikely to mobilize under waste deposit conditions. This information was used to modify the potential burdens predicted using conventional LCA practice, giving a more realistic view of the overall potential impact associated with this process. Certain environmental effect scores were sensitive to changing process conditions; the eco-toxicity indicator was affected by changing process feed composition, whilst the global climate change indicator (greenhouse effect) was affected by changes to the current density for electrowinning.