Patent ID: 8025859

Claim:
A process for the extraction of a precious metal from a sulphide ore or concentrate or other feed material amenable to pressure oxidation, comprising: subjecting the feed material to pressure oxidation to produce a pressure oxidation slurry; subjecting the slurry to a liquid-solid separation step to obtain a pressure oxidation solution and a solid residue containing elemental sulphur and the precious metal; and subjecting the solid residue to cyanidation to leach the precious metal into solution, wherein formation of thiocyanate during said cyanidation is minimized or counteracted by effecting said cyanidation at an elevated oxygen pressure of about 1000 to 10,000 kPa guage with respect to atmospheric pressure so as to reduce duration of the cyanidation while still leaching a major portion of the precious metal during said reduced duration of the cyanidation.