Patent ID: 6251163
Filing Date: 2001-06-26
Classification: C22B

Abstract:
A process for recovering a precious metal from a feed material comprising a precious metal sulfide, comprising:(a) floating a first portion of the feed material to form a concentrate fraction having a first sulfide sulfur content and a tails fraction;(b) combining at least a portion of the concentrate fraction with a second portion of the feed material that is not floated and having a second sulfide sulfur content to form a combined feed material wherein the second sulfide sulfur content is less than the first sulfide sulfur content and wherein the sulfide sulfur content of the combined feed material ranges from about 6 to about 20% by weight;(c) subjecting the combined feed material to pressure oxidation in an autoclave at a slurry temperature ranging from about 195 to about 225.degree. C. and at a pressure ranging from about 200 to about 600 psi to produce an oxidized feed material comnprising at least most of the precious metal;(d) leaching the precious metal from the oxidized feed material to produce a pregnant leach solution containing at least most of the precious metal in the oxidized feed material and a waste material; and(e) recovering the precious metal from the pregnant leach solution, wherein the concentrate fraction has a sulfide sulfur content ranging from about 5 to about 30 percent sulfur by weight and the second portion has a sulfide sulfur content ranging from about 1 to about 3 percent sulfur by weight and wherein the amount of the second portion in the combined feed material ranges from about 40 to about 95% by weight.