An oxidized gold/silver ore from Mexico has been evaluated at Lakefield Research in order to develop an economically viable treatment flowsheet from the recovery of gold and silver. Initial cyanidation test results indicated that at least 20 kg/t cyanide was required for maximum gold and silver extractions, due to high cyanide consumption by an oxidize zinc mineral present in the ore. A process was developed for the recovery and recirculation of the cyanide from the leach liquors. The proposed flowsheet included direct cyanidation, CCD and Merrill-Crowe, followed by precipitation of the recycling of the regenerated cyanide liquor to the leach circuit. The process was demonstrated during a continuous pilot pant. A mill has been erected recently in Mexico and has been operating using this flowsheet.
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