Reduction of lime consumption when treating refractory gold ores or concentrates
First Claim
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1. A precious metal recovery process, comprising:
- 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 in the form of one or more of pyrite, realgar, orpiment, chalcopyrite, and arsenopyrite;
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, whereby an acid level in the first compartment favors the formation of insoluble hematite from iron compounded with the sulphide sulphur;
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 in the precious metal-containing material is oxidized to sulphate sulphur, wherein the aqueous discharge slurry comprises sulphuric acid and a dissolved metal sulphate, and wherein the discharge slurry comprises less than 10 wt. % (dry basis) of the basic iron sulphate;
contacting the discharge solids with an acid consumer to consume at least a portion of the sulphuric acid and the dissolved metal sulphates; and
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
recovering the solubilized 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.
242 Citations
35 Claims
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1. A precious metal recovery process, comprising:
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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 in the form of one or more of pyrite, realgar, orpiment, chalcopyrite, and arsenopyrite; 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, whereby an acid level in the first compartment favors the formation of insoluble hematite from iron compounded with the sulphide sulphur;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 in the precious metal-containing material is oxidized to sulphate sulphur, wherein the aqueous discharge slurry comprises sulphuric acid and a dissolved metal sulphate, and wherein the discharge slurry comprises less than 10 wt. % (dry basis) of the basic iron sulphate; contacting the discharge solids with an acid consumer to consume at least a portion of the sulphuric acid and the dissolved metal sulphates; and 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 recovering the solubilized precious metal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 22, 23)
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10. 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) operating the first compartment under conditions favoring hematite formation and a second compartment of the multi-compartment autoclave under conditions favoring formation of basic ferric sulphate and/or jarosite; (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 in the precious metal-containing material is oxidized to sulphate sulphur, wherein the aqueous discharge slurry comprises sulphuric acid and a dissolved metal sulphate, and wherein the discharge slurry comprises less than 10 wt. % (dry basis) 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 (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A 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) operating the first compartment under conditions favoring hematite formation and a second compartment of the multi-compartment autoclave under conditions favoring formation of basic ferric sulphate and/or jarosite; (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 in the precious metal-containing material is oxidized to sulphate sulphur, wherein the aqueous discharge slurry comprises sulphuric acid and a dissolved metal sulphate, and wherein the discharge slurry comprises less than 10 wt. % (dry basis) 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 sulphate; 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; (f) prior to contact of an acid consumer other than the basic ferric sulphate, allowing at least most of the basic ferric sulphate in the aqueous discharge solids to react, at a temperature of at least about 60°
C., with at least most of the basic sulphuric acid in the aqueous discharge liquid to form ferric sulphate solubilized in the aqueous discharge liquid;(g) separating at least most of the aqueous discharge liquid from the discharge solids, wherein at least most of the solubilized ferric sulphate is in the separated aqueous discharge liquid and wherein the separated aqueous discharge solids comprise sulphuric acid; (h) contacting the separated discharge solids with an acid consumer to consume at least most of the sulphuric acid and dissolved metal sulphate; and recovering the solubilized precious metal.
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Specification