Bulk ore sorting cut-off estimation methodology: Phu Kham Mine case study

As part of the evolution of ore sorting technology for large-scale production operations, Bulk Ore Sorting (BOS) is applied to projects that mine tens of millions of tons per year. BOS systems aim to remove as much non-economic material as possible prior to milling. Mass recovery, metallurgical recovery and consequently plant throughput fluctuate according to deposit characteristics, mining method, equipment efficiency and the cut-off grade applied at both the mine and BOS stage. This case study presents a calculation methodology which determines cut-off grade combinations for the mine and BOS to maximize the financial return for both brownfield and greenfield projects. From this information it is possible to calculate the mass balance, including the BOS stage, in a new process flow sheet. The assumptions made, and production data used (such as volumes, costs and grades) for this case study were those realized in 2014 by Phu Kham Mining, a world-class copper and gold operation situated in Laos.