The development of regrind–flotation pre-treatment of the CIL feed in copper–gold plants

•Regrind–flotation is effective prior to the CIL circuit in copper–gold plants.•This new method recovers copper minerals that are not readily leachable.•It also recovers cyanide consumable copper minerals.•Compared to regrind alone, this method increases total copper recovery.•It also reduces cyanide consumption from the CIL circuit.

This study focused on the development of a new method, regrind–flotation pre-treatment, to improve the performance of the CIL (Carbon-in-Leach) circuit at copper–gold concentrators. Occlusion of gold by iron sulphide gangue minerals and the fine grain size of gold associated with them contribute to the low gold recovery in the CIL circuit. Fine grinding of the CIL feed increased gold recovery significantly from the leaching process. However, fine grinding increased the amount of liberated copper which is cyanide soluble resulting in significantly higher cyanide consumption. A proposed method of regrinding of the CIL feed followed by copper flotation was developed as an appropriate pre-treatment method for the CIL circuit that increased gold recovery while reducing cyanide consumption related to the presence of copper.

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