Benchmarking comminution energy consumption for the processing of copper and gold ores

A survey of the comminution energy requirements of gold and copper producing mines has been conducted to provide reliable benchmarking data which can be used to compare comminution energy consumption across different mine sites. The total gold and copper production of the mines included in the study equated to 15% and 24% respectively of global production and all of Australian production. The comminution energy per unit metal product has been presented in a graphical form similar to a cost curve. This simple technique allows individual mines to be ranked with respect to energy consumption and clearly displays the potential energy and cost benefits of moving down the graph into more efficient operating regimes. Assuming similar specific energy requirements for other sites, comminution of gold and copper ores can be expected to consume about 0.2% of global, and 1.3% of Australia’s electricity consumption. Efforts to reduce this figure should be aimed at the top third of consumers as they are responsible for 80% of the total consumption. Analysis of the contribution of circuit efficiency, ore competence, grind size and ore grade showed that ore grade was the greatest determinate of specific comminution energy. Therefore, concentrating the ore via gangue rejection or grade engineering prior to grinding is likely to achieve the largest positive effect on comminution energy efficiency.