Claims
- 1. In a method for recovery of precious metals from carbonaceous sulfide ores or concentrates having present organic and inorganic carbon, said recovery employing carbon-in-leach cyanidation of the ores, the improvement comprising first pretreating said ores in an autoclave at a temperature between about 125.degree. and 250.degree. C. with a mineral acid and oxygen sufficient to oxidize said ore so as to minimize chlorine consumption by said ore, thereafter subjecting said ore to a chlorine gas or oxides of chlorine treatment and cyaniding said ore using a carbon-in-leach process.
- 2. The method as defined in claim 1, wherein said pretreating is in the presence of sulfuric acid at a temperature between about 125.degree. and 250.degree. C.
- 3. The process as defined in claim 1, wherein pyritic sulfide is present in the ore in the amount from about 0.2 to 30% by weight based on said ore or concentrate.
- 4. The method as defined in claim 1, wherein the ore also contains base metal sulfides.
- 5. The process as defined in claim 1, wherein a concentrate is being treated which contains from about 3.5% and higher of sulfide sulfur and 1.0% and higher of organic carbon.
- 6. The method as defined in claim 1, in which the chlorine gas is dispersed throughout the slurry at a rate and for a period of time such that the slurry is amenable to gold cyanide recovery.
- 7. The process as defined in claim 1, wherein the ore is wet ground with water to yield a slurry containing said ore of a mesh size of about 60% of -200 mesh, said ore is thereafter pulped to wherein the same contains from about 40 to about 50% by weight of solids; said slurry is heated and treated in an autoclave at a temperature within the range from about 125.degree. C. and up, but less than 250.degree. C., in the presence of oxygen and acid, the pretreated slurry cooled to about 30.degree. C. to 90.degree. C., and thereafter chlorinated.
- 8. The process as defined in claim 7, wherein the pretreatment is in the presence of sulfuric acid of 5 to 40 grams per liter concentration.
- 9. The process as defined in claim 1, wherein after the pretreatment the slurry was cooled to about 35.degree. C. to 40.degree. C., was maintained at this temperature for about four hours and during this time chlorine gas bubbled into and dispersed throughout the slurry for this period for a total chlorine consumption of about 60 pounds of chlorine per ton of solids; the slurry was then treated with lime to raise the pH to between 10.5 and 11.0, and cyanidation was for eight hours with a carbon-in-leach process.
- 10. The process as defined in claim 10, wherein the total chlorine consumption was less than about 120 lbs/ton, and said oxygen pretreatment was sufficient to maintain chlorine consumption by an ore or a concentrate at less than 120 lbs/ton.
- 11. The process as defined in claim 10, wherein total chlorine consumption was less than about 90 lbs/ton and said oxygen pretreatment was sufficient to maintain chlorine consumption by an ore or a concentrate at less than 90 lbs/ton.
- 12. The process as defined in claim 10, wherein total chlorine consumption was less than about 60 lbs/ton and said oxygen pretreatment was sufficient to maintain chlorine consumption by an ore or a concentrate at less than 60 lbs/ton.
- 13. The process as defined in claim 1, wherein gold is recovered from a concentrate or ore.
- 14. In a method for recovery of precious metals from carbonaceous sulfide ores or concentrates having present organic and inorganic carbon, said recovery employing carbon-in-pulp cyanidation of the ores, the improvement comprising first pretreating said ores in an autoclave at a temperature between about 125.degree. and 250.degree. C. with a mineral acid and oxygen sufficient to oxidize said ore so as to minimize chlorine consumption by said ore, thereafter subjecting said ore to a chlorine gs or oxides of chlorine treatment and cyaniding said ore using a carbon-in-pulp process.
Parent Case Info
This application is a continuation of application Ser. No. 07/264,632, filed Oct. 31, 1981, now abandoned.
US Referenced Citations (6)
Continuations (1)
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Number |
Date |
Country |
Parent |
264632 |
Oct 1988 |
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