Patent ID: 7572317

Claim:
A process for recovering precious metal from a sulfidic precious metal-bearing material comprising the steps of: forming an aqueous sulfidic precious metal-bearing slurry comprising the sulfidic precious metal-bearing material; subjecting the sulfidic precious metal-bearing slurry to partial oxidation by pressure oxidation to produce an oxidized precious metal-bearing slurry containing elemental sulfur to form a pressure oxidation discharge oxidized precious metal-bearing slurry; neutralizing the pressure oxidation discharge oxidized precious metal-bearing slurry containing elemental sulfur; forming thiosulfate compounds in situ in the pressure oxidation discharge oxidized precious metal-bearing slurry by reacting the elemental sulfur from the partial oxidation with a reactant which reacts with elemental sulfur to form thiosulfate compounds to yield a pressure oxidation discharge oxidized precious metal-bearing slurry containing a thiosulfate-based lixiviant; leaching precious metal from the pressure oxidation discharge oxidized precious metal-bearing slurry with the thiosulfate generated in situ with said pressure oxidation discharge oxidized precious metal-bearing slurry to produce a leached slurry comprising a solid residue and precious metal-bearing leachate; and recovering precious metal from the precious metal-bearing leachate.