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PROCESS FOR REDUCED ALKALI CONSUMPTION IN THE RECOVERY OF SILVER

  • US 20070292326A1
  • Filed: 06/11/2007
  • Published: 12/20/2007
  • Est. Priority Date: 06/15/2006
  • Status: Active Grant
First Claim
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1. A precious metal recovery process, comprising:

  • (a) oxidizing an aqueous feed slurry in an autoclave, the feed slurry comprising a silver-containing material and sulphide sulphur, wherein at least most of the sulphide sulphur is oxidized in the autoclave to sulphate sulphur and wherein at least a portion of the sulphate sulphur is in the form of a solid-phase reactive sulphate;

    (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 silver and at least most of the solid-phase reactive sulphate and wherein a liquid phase of the aqueous discharge slurry comprises an acid;

    (c) allowing at least most of the solid-phase reactive sulphate in the aqueous discharge solids to react with the acid to form liquid-phase reactive sulphate, wherein, after step (c), at least a portion of the solid-phase reactive sulphate comprises silver and the discharge solids have a sulphate content of no more than about 2 wt %;

    (d) after step (c), contacting the discharge solids with an acid consumer while maintaining a temperature of the discharge solids of at least about 80°

    C. to convert at least most of the solid-phase reactive sulphate to a nonreactive iron-containing species; and

    (e) thereafter recovering at least most of the silver from the discharge solids.

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