Reduction of lime consumption when treating refractory gold ores or concentrates
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 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) allowing at least most of the reactive iron-containing precipitate in the aqueous discharge solids to react with the acid to form a dissolved iron-containing species;
(d) after step (c), contacting the discharge solids with an 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.
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Abstract
The present invention is directed to a precious metal recovery process in which basic ferric sulphates and/or jarosites are controlled by a number of mechanisms, including control of the oxidation reaction conditions in the first autoclave compartment, hot curing of the autoclave discharge slurry, and/or contacting of the autoclave feed slurry with the hot cured discharge liquid.
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Citations
23 Claims
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1. A precious metal recovery process, comprising:
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(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) allowing at least most of the reactive iron-containing precipitate in the aqueous discharge solids to react with the acid to form a dissolved iron-containing species;
(d) after step (c), contacting the discharge solids with an 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A precious metal recovery process, comprising:
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(a) oxidizing sulphide sulphur in an aqueous feed slurry in an autoclave, the feed slurry comprising a precious metal-containing material, 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 basic iron sulphate in a solid phase;
(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 solid-phase basic iron sulphate, and wherein the aqueous discharge slurry comprises sulphuric acid;
(c) allowing at least most of the solid-phase basic iron sulphate in the aqueous discharge solids to react with the sulphuric acid to form ferric sulphate dissolved in the aqueous discharge liquid;
(d) thereafter separating the aqueous discharge liquid from the discharge solids, wherein at least most of the dissolved ferric sulphate is in the separated aqueous discharge liquid and wherein the separated aqueous discharge solids comprise sulphuric acid;
(e) contacting the separated discharge solids with an acid consumer to consume at least most of the sulphuric acid and dissolved metal sulphates to form a neutralized discharge solids;
(f) contacting a lixiviant, at a pH above about pH 7.0, with the neutralized discharge solids to dissolve at least most of the precious metal; and
(g) recovering the dissolved precious metal. - View Dependent Claims (12, 13, 14)
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15. A precious metal recovery process, comprising:
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(a) inputting a precious metal-containing feed slurry into a first compartment of a multi-compartment autoclave, the precious metal-containing feed slurry comprising a precious metal-containing material comprising sulphide sulphur;
(b) providing, in the first compartment a slurry temperature that is at least about 5°
C. less than a slurry temperature in a second compartment of the autoclave, the second compartment being adjacent to and downstream of the first compartment;
(c) 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 basic iron sulphate, wherein at least most of the sulphide sulphur is oxidized to sulphate sulphur, wherein the aqueous discharge slurry comprises sulphuric acid, and wherein the discharge slurry comprises less than 10 wt. % (dry basis) of the basic iron sulphate;
(d) contacting the discharge solids with an acid consumer to consume at least a portion of the sulphuric acid and dissolved metal sulphates; and
(e) contacting a lixiviant, at a pH above about pH 7.0, with the discharge solids to solubilize at least most of the precious metal; and
(f) recovering the solubilized precious metal. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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Specification