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

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.