US4571387A — Biological-acid leach process

Claim 1

Independent Claim 69 words

A process for leaching copper from a copper sulphide containing ore, comprising: (a) contacting the ore with an aqueous acid leaching medium containing sulphide oxidizing bacteria, and a bacterial nutrient; and (b) maintaining a suitable oxidation potential, and periodically adding a sufficient amount of bacterial compatible acid to the ore and leaching medium mixture, so as to produce elemental sulphur rather than sulphuric acid from sulphide in the ore.

Claim 2

Dependent Claim 69 words

A process for leaching copper from a copper sulphide containing ore, comprising: (a) contacting the ore with an aqueous acid leaching medium containing sulphide oxidizing bacteria, and a bacterial nutrient; and (b) maintaining a suitable oxidation potential, and periodically adding a sufficient amount of bacterial compatible acid to the ore and leaching medium mixture, so as to produce elemental sulphur rather than sulphuric acid from sulphide in the ore.

Claim 3

Dependent Claim 93 words

A process for leaching copper from a chalcopyrite containing ore, comprising: (a) contacting the ore with an aqueous acid leaching medium containing T. ferrooxidans bacteria, a catalytic amount of silver, and a bacterial nutrient containing carbon dioxide and oxygen; and (b) maintaining the temperature between about 10° C. and 40° C. and the oxidation potential between about 0.54 to 0.66 volts, and periodically adding a sufficient amount of bacterial compatible acid to the ore and leaching medium mixture, so as to produce elemental sulphur rather than sulphuric acid from sulphide in the ore.

Claim 4

Dependent Claim 93 words

A process for leaching copper from a chalcopyrite containing ore, comprising: (a) contacting the ore with an aqueous acid leaching medium containing T. ferrooxidans bacteria, a catalytic amount of silver, and a bacterial nutrient containing carbon dioxide and oxygen; and (b) maintaining the temperature between about 10° C. and 40° C. and the oxidation potential between about 0.54 to 0.66 volts, and periodically adding a sufficient amount of bacterial compatible acid to the ore and leaching medium mixture, so as to produce elemental sulphur rather than sulphuric acid from sulphide in the ore.

Claim 5

Dependent Claim 30 words

A process as described in claim 2 wherein the leaching medium contains sufficient thiosulphate and dissolved copper so as to maintain the oxidation potential between about 0.54 to 0.66 volts.

Claim 6

Dependent Claim 33 words

A process as described in claim 3, wherein the ore is mixed with the leaching medium, additionally comprising agitating the mixture while simultaneously sparging with a carbon dioxide and oxygen containing gas mixture.

Claim 7

Dependent Claim 22 words

A process as described in claim 4 wherein the acid in the leaching medium and the acid periodically added are sulphuric acid.

Claim 8

Dependent Claim 35 words

A process as described in claim 3, 4, or 5 wherein the leaching medium has a pH between about 1.5 and 3.0 and sufficient acid is periodically added to maintain the pH within that range.

Claim 9

Dependent Claim 35 words

A process as described in claim 3, 4, or 5 wherein the leaching medium has a pH between about 2.0 and 2.5 and sufficient acid is periodically added to maintain the pH within that range.

Claim 10

Dependent Claim 39 words

A process as described in claim 5 wherein the leaching medium contains about 100 to 4,000 milligrams of dispersed silver per kilogram of chalcopyrite, about 10 to 30g/L of dissolved copper, and about 2 to 25 g/L. of thiosulphate.

Claim 11

Dependent Claim 32 words

A process as described in claim 8 wherein the leaching medium has a pH between about 1.5 and 3.0 and sufficient acid is periodically added to maintain the pH within that range.

Claim 12

Dependent Claim 31 words

A process as described in claim 8, wherein the leaching medium has a pH between 2.0 and 2.5 and sufficient acid is periodically added to maintain the pH within that range.

Claim 13

Dependent Claim 170 words

A process for leaching copper from a chalcopyrite containing ore, comprising: (a) grinding the ore to a particle size of less than about 200 mesh; (b) mixing the ore with an aqueous leaching medium in an amount to obtain a mixture having 2% to 60% by weight of the ore, the leaching medium being acidified with sulphuric acid to a pH between about 1.5 and 3.0, and containing T. ferrooxidans bacteria, a bacterial nutrient, about 100 to 4,000 mg of dispersed silver per kilogram of chalcopyrite, about 10 to 30g/L dissolved copper, and about 2 to 25g/L thiosulphate; (c) agitating the ore and leaching medium mixture while simultaneously sparging with carbon dioxide enriched air; (d) maintaining the temperature between about 10° C. and 40° C., and the oxidation potential between about 0.54 to 0.66 volts, and periodically adding a sufficient amount of sulphuric acid to the mixture to maintain the pH between 1.5 and 3.0, so as to produce elemental sulphur rather than sulphuric acid from sulphide in the ore.

Claim 14

Dependent Claim 170 words

A process for leaching copper from a chalcopyrite containing ore, comprising: (a) grinding the ore to a particle size of less than about 200 mesh; (b) mixing the ore with an aqueous leaching medium in an amount to obtain a mixture having 2% to 60% by weight of the ore, the leaching medium being acidified with sulphuric acid to a pH between about 1.5 and 3.0, and containing T. ferrooxidans bacteria, a bacterial nutrient, about 100 to 4,000 mg of dispersed silver per kilogram of chalcopyrite, about 10 to 30g/L dissolved copper, and about 2 to 25g/L thiosulphate; (c) agitating the ore and leaching medium mixture while simultaneously sparging with carbon dioxide enriched air; (d) maintaining the temperature between about 10° C. and 40° C., and the oxidation potential between about 0.54 to 0.66 volts, and periodically adding a sufficient amount of sulphuric acid to the mixture to maintain the pH between 1.5 and 3.0, so as to produce elemental sulphur rather than sulphuric acid from sulphide in the ore.

Claim 15

Dependent Claim 26 words

A process as described in claim 11 wherein the pH of the leaching medium is between 2.0 and 2.5 and is maintained between 2.0 and 2.5.

Claim 16

Dependent Claim 36 words

A process as described in claim 12 wherein the ore is ground to a particle size of less than about 325 mesh, and wherein carbon dioxide enriched air contains from 0.1 to 10% of carbon dioxide.

Claim 17

Dependent Claim 43 words

A process as described in claim 3, 5 or 12 wherein the silver is added to the leaching medium in the form of a silver containing substance selected from the group consisting of silver, silver sulphide, silver nitrate, silver chloride, or silver sulphate.

Claim 18

Dependent Claim 37 words

A process as described in claim 11, 12, or 14 wherein the ore is mixed with the aqueous leaching medium in an amount to obtain a mixture having about 20% to 30% by weight of the ore.

Claim 19

Dependent Claim 29 words

A process as described in claim 3, 5 or 12 additionally comprising maintaining an air pressure above the ore and leaching medium mixture of between 0.5 to 10 atmospheres.

Claim 20

Dependent Claim 27 words

A process as described in claim 3, 5 or 12 additionally comprising maintaining an air pressure above the ore and leaching medium mixture of about 1.0 atmosphere.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1989-02-17	1989-08-19	1990-02-18	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1993-02-17	1993-08-19	1994-02-18	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1997-02-17	1997-08-19	1998-02-18	$7700.00	Window Closed / Lapsed

Biological-acid leach process

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