Key factors determining the bulk ore sorting potential in a caving mine

Abstract

Bulk ore sorting may add significant value to block and panel cave mines where processing feed grades are constrained by limited grade selectivity. The Cadia East gold-copper mine is a panel caving operation utilizing two different on-belt bulk ore sensors to evaluate the potential benefits of the technology. To date, there is limited reported work addressing the applicability of bulk ore sorting systems at a caving mine, where two commodities drive the economics. This indicative study is aimed at investigating the importance of various key factors on the bulk ore sorting potentials of the active and future panel caves of the Cadia East mine. Results show that for only one active cave of the mine, bulk ore sorting may be applied in the ideal scenario where grades are not affected negatively by mixing and the sorting takes place at maximum efficiency. As a general trend for all the caves, when the sorting cut-off grade is increased beyond a certain threshold, a sharp decline is observed in the sorting potentials due to the significant amounts of gold and copper deporting to the sorter rejects. In the case of a significant drop in metal prices, bulk ore sorting may only provide an opportunity to improve cave economics marginally. Results obtained by investigating the spatial change in sorting potential show that the portions of the caves with low metal grades are favourable for bulk ore sorting. In the scenario where bulk ore sorting is focused on low-grade portions, it is demonstrated that improvements in the economics of the future caves may additionally be achieved. However, as the low-grade portions represent a very small volume in the orebody, applying ore sorting on the plant conveyor may not be viable.