Gold recovery from refractory carbonaceous ores by pressure oxidation and thiosulfate leaching
First Claim
1. A process for recovering gold from a refractory sulfidic and refractory carbonaceous auriferous ore having preg-robbing characteristics due to the presence of organic carbon comprising the steps of:
- forming an aqueous ore slurry comprising a refractory sulfidic and refractory carbonaceous ore having preg-robbing characteristics due to the presence of organic carbon;
subjecting the ore slurry to pressure oxidation in an autoclave to produce an oxidized ore slurry;
mixing the oxidized ore slurry with a lixiviant comprising a thiosulfate salt to form a mixture of oxidized ore slurry and lixiviant;
leaching gold from the oxidized slurry in a stirred tank reactor system comprising between two and six agitated leach tanks by maintaining the mixture at a pH between 7 and 8.7 while agitating the mixture with a slurry residence time in each of said tanks of between about 30 and about 120 minutes to produce a leached slurry comprising a solid residue and a gold-bearing leachate; and
recovering gold from the gold-bearing leachate.
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Accused Products
Abstract
A process for recovering gold in which an ore slurry of refractory sulfidic and refractory carbonaceous ore having preg-robbing characteristics due to the presence of organic carbon is subjected to pressure oxidation in an autoclave. The oxidized ore slurry is mixed with a thiosulfate salt lixiviant, which mixture is maintained at a pH between 7 and 8.7 while the slurry is agitated in a stirred tank reactor system having agitated leach tanks. Gold is recovered from the gold-bearing leachate by cementation, adsorption on an adsorbent, or cyanidation.
80 Citations
22 Claims
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1. A process for recovering gold from a refractory sulfidic and refractory carbonaceous auriferous ore having preg-robbing characteristics due to the presence of organic carbon comprising the steps of:
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forming an aqueous ore slurry comprising a refractory sulfidic and refractory carbonaceous ore having preg-robbing characteristics due to the presence of organic carbon; subjecting the ore slurry to pressure oxidation in an autoclave to produce an oxidized ore slurry; mixing the oxidized ore slurry with a lixiviant comprising a thiosulfate salt to form a mixture of oxidized ore slurry and lixiviant; leaching gold from the oxidized slurry in a stirred tank reactor system comprising between two and six agitated leach tanks by maintaining the mixture at a pH between 7 and 8.7 while agitating the mixture with a slurry residence time in each of said tanks of between about 30 and about 120 minutes to produce a leached slurry comprising a solid residue and a gold-bearing leachate; and recovering gold from the gold-bearing leachate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A process for recovering gold from a refractory sulfidic and refractory carbonaceous auriferous ore having preg-robbing characteristics due to the presence of organic carbon comprising the steps of:
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forming an aqueous ore slurry comprising a refractory sulfidic and refractory carbonaceous ore having preg-robbing characteristics due to the presence of organic carbon; subjecting the ore slurry to pressure oxidation in an autoclave under neutral or alkaline conditions to produce an oxidized ore slurry having a pH in the range of between about 6 and 8; mixing the oxidized ore slurry with a lixiviant comprising a thiosulfate salt; leaching gold from the oxidized slurry in a stirred tank reactor system comprising between two and six agitated leach tanks by maintaining the mixture at a pH between 7 and 8.7 while agitating the mixture with a slurry residence time in each of said tanks of between about 30 and about 120 minutes to produce a leached slurry comprising a solid residue and a gold-bearing leachate; and recovering gold from the gold-bearing leachate. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A process for recovering gold from a refractory sulfidic and refractory carbonaceous auriferous ore having preg-robbing characteristics due to the presence of organic carbon comprising the steps of:
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forming an aqueous slurry comprising a refractory sulfidic and refractory carbonaceous ore having preg-robbing characteristics due to the presence of organic carbon; subjecting the ore slurry to pressure oxidation for between about 30 and about 100 minutes in an autoclave at a temperature in the range of between about 185° and
235°
C. and an oxygen overpressure of at least about 20 psi to produce an oxidized ore slurry;cooling the oxidized ore slurry to a temperature between about 40°
C. and about 55°
C.;adjusting the pH of the oxidized slurry to between 7 and 8.7; mixing the oxidized slurry with a lixiviant comprising a thiosulfate salt in a proportion of between about 0.025M and 0.1M thiosulfate ion, copper in a proportion of between about 50 and 100 ppm, and sulfite in a proportion of at least about 0.001M, while maintaining the pH between 7 and 8.7; maintaining the oxidized slurry and lixiviant at a temperature in the range of between 40°
C. and 55°
C. while agitating the slurry in a stirred tank reactor system comprising between two and six mechanically agitated leach tanks with a residence time of the slurry in each tank of between about 30 and 120 minutes to produce a leached slurry comprising a solid residue and a gold-bearing leachate; andrecovering gold from the gold-bearing leachate. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification