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US 6,660,059 B2Granted
Method for thiosulfate leaching of precious metal-containing materials
AssigneePlacer Dome Technical Services Limited
InventorsJinxing Ji, Christopher Andrew Fleming, Paul George West-Sells, Ralph Peter Hackl
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Abstract
Processes are provided for recovering precious metals from refractory materials using thiosulfate lixiviants. The processes can employ lixiviants that include at most only small amounts of copper and/or ammonia and operate at a relatively low pH, reduction of polythionates, inert atmospheres to control polythionate production, and electrolytic solutions which provide relatively high rates of precious metal recovery.
Claims67
A process for recovering a precious metal from a precious metal-containing material, comprising:
- (a) contacting the precious metal-containing material with a thiosulfate lixiviant to solubilize the precious metal and form a pregnant thiosulfate leach solution containing the solubilized precious metal and a polythionate;
- (b) contacting the pregnant leach solution with a sulfide-containing reagent to convert at least most of the polythionate to thiosulfate, wherein, in the contacting step (b), the pregnant leach solution has a dissolved molecular oxygen content of no more than about 1 ppm;
- and
- (c) thereafter recovering the precious metal precipitate from the thiosulfate leach solution.
1 more element
A process for recovering a precious metal from a precious metal-containing material, comprising:
- contacting the precious metal-containing material with a thiosulfate lixiviant to solubilize the precious metal and form a pregnant thiosulfate leach solution comprising solubilized precious metal, thiosulfate, and at least one of trithionate and tetrathionate;
- after the contacting step, converting at least most of the at least one of trithionate and tetrathionate in the pregnant thiosulfate leach solution into thiosulfate while maintaining at least most of the solubilized precious metals dissolved in the pregnant thiosulfate leach solution;
- and
- thereafter recovering the solubilized precious metal from the pregnant thiosulfate leach solution.
1 more element
A process for recovering a precious metal from a precious metal-containing material comprising:
- (a) contacting a precious metal-containing material with a thiosulfate lixiviant to dissolve the precious metal and form a pregnant thiosulfate leach solution containing the dissolved precious metal;
- (b) contacting the pregnant thiosulfate leach solution and/or a barren thiosulfate leach solution with a sulfide and/or bisulfide and/or a polysulfide to convert polythionates in the pregnant thiosulfate leach solution and/or barren thiosulfate leach solution into thiosulfate;
- and
- (c) thereafter contacting the pregnant thiosulfate leach solution and/or barren thiosulfate leach solution with an oxidant to solubilize precipitated precious metal precipitates.
1 more element
A process for recovering a precious metal from a precious metal-containing material, comprising:
- (a) contacting the precious metal-containing material with a thiosulfate lixiviant to solubilize the precious metal and form a pregnant thiosulfate leach solution containing the solubilized precious metal, wherein the pregnant thiosulfate leach solution includes polythionates;
- (b) recovering the solubilized precious metal from the pregnant thiosulfate leach solution to form a precious metal product and a barren thiosulfate leach solution;
- (c) contacting at least one of the pregnant thiosulfate leach solution and the barren thiosulfate leach solution with a reductant to convert at least some of the polythionates into thiosulfate;
- and
- (d) after the contacting step (c), contacting at least one of the pregnant thiosulfate leach solution and barren thiosulfate leach solution with an oxidant to remove any remaining reductant.
2 more elements
A process for recovering a precious metal from a precious metal-containing material, comprising:
- (a) contacting the precious metal-containing material with a thiosulfate lixiviant to solubilize the precious metal and form a pregnant thiosulfate leach solution containing the solubilized precious metal and a polythionate;
- (b) recovering the precious metal from the pregnant thiosulfate leach solution to from a precious metal product and a barren thiosulfate leach solution comprising trithionate;
- (c) contacting the barren thiosulfate leach solution with at least one of a (i) polysulfide, (ii) a bisulfide other than a polysulfide, and (iii) a sulfide other than a polysulfide and a bisulfide to convert at least most of the trithionate into thiosulfate;
- and
- (d) thereafter recycling the barren leach solution to step (a).
2 more elements
A process for recovering a precious metal from a precious metal-containing material, comprising:
- (a) contacting the precious metal-containing material with a thiosulfate lixiviant to solubilize precious metals and form a pregnant thiosulfate leach solution containing the solubilized precious metals and polythionates;
- (b) recovering the precious metals from the pregnant thiosulfate leach solution to form a precious metal product and a barren thiosulfate leach solution comprising polythionates;
- (c) contacting at least one of the pregnant thiosulfate leach solution and the barren thiosulfate leach solution with a reductant to convert at least most of the polythionates into thiosulfates;
- and
- (d) after step (c), contacting the at least one of the pregnant thiosulfate leach solution and the barren thiosulfate leach solution with an oxidant to remove at least most of any remaining reductant.
2 more elements
A process for recovering a precious metal from a precious metal-containing material, comprising:
- (a) contacting a heap of the precious metal-containing material with a thiosulfate lixiviant to solubilize precious metals and form a pregnant thiosulfate leach solution containing the solubilized precious metals and polythionates;
- (b) recovering the precious metals from the pregnant thiosulfate leach solution to form a precious metal product and a barren thiosulfate leach solution comprising polythionates;
- and
- (c) after at least one of the contacting and recovering steps, maintaining at least one of the pregnant thiosulfate leach solution and the barren thiosulfate leach solution, respectively, at a temperature of at least about 60° C. to convert at least most of the polythionates into thiosulfates.
1 more element
Dependencies are inferred from the claim text.