Patent ID: 7604783
Filing Date: 2009-10-20
Classification: C22B,Y02P

Abstract:
1. A precious metal recovery process, comprising: (a) oxidizing an aqueous feed slurry in an autoclave, the feed slurry comprising a precious metal-containing material and sulphide sulphur, wherein at least most of the sulphide sulphur is oxidized to sulphate sulphur and wherein at least a portion of the sulphate sulphur is in the form of a reactive iron-containing precipitate; (b) removing, from the autoclave, an aqueous discharge slurry comprising discharge solids and aqueous discharge liquid, the discharge solids comprising at least a portion of the precious metal and at least most of the reactive iron-containing precipitate, and wherein the aqueous discharge slurry comprises an acid; (c) prior to contact of an acid consumer other than the reactive iron-containing precipitate with at least most of the discharge solids, allowing at least most of the reactive iron-containing precipitate in the discharge solids to react with the acid in the aqueous discharge liquid to form a hot cured slurry, the hot cured slurry comprising the discharge solids and a dissolved iron-containing species derived from the reaction of the acid and reactive iron-containing species; (d) after step (c), contacting the discharge solids with the acid consumer; (e) leaching at least most of the precious metal from the discharge solids to form a dissolved precious metal; and (f) recovering the dissolved precious metal.