Opportunities for Reducing Energy Consumption and Greenhouse Gas Emissions in Mineral Processing and Metal Production
The results from life cycle assessments of various primary metal production processes are used to show that the metal extraction and refining stages (particularly the former) generally make the greatest contributions to the energy consumption and associated greenhouse gas emissions of these processes at higher ore grades, but the contributions of the mining and mineral processing stages become more significant as the ore grade falls. The results further showed that while the light metals (aluminium and titanium) had the highest life cycle-based energy consumption and greenhouse gas emissions per unit mass of refined metal, when the annual production amounts of the various metals are accounted for, steel is responsible for the greatest global amount of energy consumed and greenhouse gases emitted from primary metal production, followed by aluminium. Based on these observations, the major opportunities for reducing energy consumption and greenhouse gas emissions from primary metal production would appear to lie in the metal extraction stages of steel, and to a lesser extent aluminium, production. However, as ore grades fall, opportunites for reducing these impacts in the mining and mineral processing stages will become more significant, particularly in the area of comminution, although these opportunities may be limited in the immediate future. A number of opportunities have been identified in the paper, covering the broad spectrum of process development from embryonic through to fully established. Estimates of their likely impact on energy consumption and greenhouse gas emissions, both from a global and Australian perspective, are made in the paper.