The ability to rank individual mines by comminution energy intensity in an international database was identified as a priority by the Coalition for Energy-Efficient Comminution in 2012 (Napier-Munn, Drinkwater, & Ballantyne, 2012). Providing a tool to compare the comminution energy intensity of a mine against the industry distribution will incentivise an improvement in energy productivity. It is acknowledged that there is a tendency for the mining industry to avoid benchmarking operational performance because of the inherent variability in geology, mining technique and process design at different mines internationally. Therefore, any tool must be simple to understand, comprehensive in nature and flexible in application. Allowing a number of measures for energy intensity to be included in the analysis (e.g. energy per rock milled or metal produced) will provide a fairer comparison between sites.
The cost curve format widely published by financial organisations has been used to visualise the variability in processing energy intensity across the industry. The applications of energy curves are many and varied. It can be used to map the position of the mine as production progresses with year-on-year analysis. Circuit design proposals can be compared to assess the position of the mine on the energy curve when operational. Operational efficiency improvements can be mapped on the curves to visually assess the magnitude of reductions achievable through various strategies. The efficiency with which the various comminution devices achieve size reduction can be mapped down a circuit to identify opportunities for improvement and the magnitude of achievable gains.
This technique allows the current position of the mine to be identified, providing operators with the insight to achieve best practice and move their operation down the energy curve to a more productive and efficient location. A major outcome from the recent 2014 CEEC workshop was to increase the number of mines in the study to greater than 50% of the copper and gold production internationally, while also extending the methodology to other commodities such as platinum and nickel.
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