Patent ID: 7537741
Filing Date: 2009-05-26
Classification: C22B,Y02P

Abstract:
1. A method for treating a polymetallic sulfide ore containing gold or silver, and further comprising a base metal selected from the group consisting of iron, aluminum, chromium, titanium, copper, zinc, lead, nickel, cobalt, mercury, tin, and mixtures thereof, the method comprising: (a) providing a granulated polymetallic sulfide ore containing gold or silver having a particle size of less than about 35 mesh; (b) oxidizing said granulated polymetallic sulfide ore at temperatures of at least about 300° C. to produce oxidized granules having a sulfur content of about 0.5% or less; (c) chloride leaching of said oxidized granules, wherein said chloride leaching involves contacting said oxidized granules with a leaching solution comprising dissolved elemental chlorine, a high concentration of chloride, and a catalytic amount of bromide, to produce a pregnant solution of solubilized metal chlorides and a barren solid; (d) recovering said barren solid from said pregnant solution to produce a purified pregnant solution; and (e) selectively recovering gold or silver from said purified pregnant solution, wherein the method is carried out at atmospheric pressure.