Abstract: A process for separating Co from Ni in an aqueous solution comprises subjecting the solution to extraction and using kinetic differences between Ni and Co in the extraction for achieving at least a partial separation of Co from Ni. This is effected by controlling the duration of the extraction so that a major portion of Co and a minor portion of Ni is extracted from the solution to produce a loaded extractant, enriched in Co and depleted in Ni compared to the feed solution, and a Co-depleted raffinate containing Ni. In a further embodiment, the invention utilizes kinetic differences between Ni and Co during striping for effecting separation of Ni and Co. The loaded extractant can be subjected to a bulk stripping or a selective stripping operation to obtain Co and Ni solutions from which Ni and Co can be recovered. The process may be incorporated in a hydrometallurgical process for the extraction of Ni and/or Co from an ore or concentrate containing Ni and Co.

Abstract: A process for separating Co from Ni in an aqueous solution comprises subjecting the solution to extraction and using kinetic differences between Ni and Co in the extraction for achieving at least a partial separation of Co from Ni. This is effected by controlling the duration of the extraction so that a major portion of Co and a minor portion of Ni is extracted from the solution to produce a loaded extractant, enriched in Co and depleted in Ni compared to the feed solution, and a Co-depleted raffinate containing Ni. In a further embodiment, the invention utilizes kinetic differences between Ni and Co during striping for effecting separation of Ni and Co. The loaded extractant can be subjected to a bulk stripping or a selective stripping operation to obtain Co and Ni solutions from which Ni and Co can be recovered. The process may be incorporated in a hydrometallurgical process for the extraction of Ni and/or Co from an ore or concentrate containing Ni and Co.

Abstract: A process for the extraction of a precious metal, such as gold or silver, from a sulphide ore or concentrate or other source material comprises subjecting the source material to pressure oxidation to produce a pressure oxidation slurry. The pressure oxidation slurry is flashed down to a lower temperature and pressure and is then subjected to a liquid/solid separation to obtain a pressure oxidation solution and a solid residue containing the precious metal. The solid residue is then subjected to cyanidation to extract the precious metal. The formation of thiocyanide during cyanidation is minimized or counteracted by effecting the cyanidation at an elevated oxygen pressure and a reduced retention time, such as 30 to 90 minutes. A method for the reduction of copper cyanide formation during cyanidation leaching is also provided.