Processing at the Campbell mill is via three-stage crushing and rod and ball mill grinding followed by gravity concentration to recover free-milling gold, with refractory gold recovered by floatation. Flotation tailings are leached and flotation concentrate from both mills is treated by pressure oxidation at the Campbell mill.
Operating two low capacity mills results in high fixed costs for the operation. Lycopodium was engaged to study the feasibility of increasing the throughput of the Campbell mill to 1 Mtpa to enable processing at the Red Lake mill to cease.
The investigation looked at overland conveying of ore and modifications to the crushing and grinding circuit, as well as all downstream processing including increasing the capacity of the concentrate oxidation circuit which was contributing to a process bottleneck.