Method for treating mineral material having organic carbon to facilitate recovery of gold and silver

Claim 1

A method for processing a mineral material which has a precious metal to reduce the potential for problems with recovery of the precious metal when organic carbon is present, the method comprising the steps of: (a) providing a feed slurry having particulate mineral material slurried with aqueous liquid, wherein (i) said mineral material comprises a precious metal selected from the group consisting of gold, silver and combinations thereof, and organic carbon which has an ability to interfere with recovery of said precious metal, said mineral material also comprising sulfide sulfur in association with said precious metal and from which said precious metal is difficult to separate, and (ii) at least 80 weight percent of particles of said mineral material in said feed slurry are smaller than 38 microns in size, which facilitates oxidative treating of said mineral material to reduce the ability of said organic carbon to interfere with recovery of said precious metal; and (b) oxidative treating of said mineral material in said feed slurry comprising subjecting said feed slurry to an oxidizing environment at a temperature of greater than about 190° C. to produce an oxidized slurry, wherein the ability of said organic carbon to interfere with recovery of said precious metal from said oxidized slurry is reduced; wherein, during said oxidative treating of said feed slurry, at least 96 percent of sulfide sulfur in said feed slurry is oxidized, thereby permitting substantial passivation of said organic carbon to reduce the ability of said organic carbon to interfere with recovery of said precious metal.

Claim 2

A method for processing a mineral material which has a precious metal to reduce the potential for problems with recovery of the precious metal when organic carbon is present, the method comprising the steps of: (a) providing a feed slurry having particulate mineral material slurried with aqueous liquid, wherein (i) said mineral material comprises a precious metal selected from the group consisting of gold, silver and combinations thereof, and organic carbon which has an ability to interfere with recovery of said precious metal, said mineral material also comprising sulfide sulfur in association with said precious metal and from which said precious metal is difficult to separate, and (ii) at least 80 weight percent of particles of said mineral material in said feed slurry are smaller than 38 microns in size, which facilitates oxidative treating of said mineral material to reduce the ability of said organic carbon to interfere with recovery of said precious metal; and (b) oxidative treating of said mineral material in said feed slurry comprising subjecting said feed slurry to an oxidizing environment at a temperature of greater than about 190° C. to produce an oxidized slurry, wherein the ability of said organic carbon to interfere with recovery of said precious metal from said oxidized slurry is reduced; wherein, during said oxidative treating of said feed slurry, at least 96 percent of sulfide sulfur in said feed slurry is oxidized, thereby permitting substantial passivation of said organic carbon to reduce the ability of said organic carbon to interfere with recovery of said precious metal.

Claim 21

A method for processing a mineral material having a precious metal to facilitate recovery of the precious metal by reducing the potential for recovery problems when both sulfide material and organic carbon render the mineral material refractory to precious metal recovery, the method comprising the steps of: (a) providing a feed slurry having particulate mineral material slurried with an aqueous liquid, wherein (i) said mineral material comprises a precious metal selected from the group consisting of gold, silver and combinations thereof; sulfide material, having sulfide sulfur, which is associated with said precious metal and from which said precious metal is difficult to separate to permit recovery of said precious metal; and organic carbon, which has an ability to interfere with recovery of said precious metal, and (ii) at least 80 weight percent of particles of said mineral material in said feed slurry are smaller than 38 microns in size, which facilitates oxidative treating of said mineral material to reduce the ability of said organic carbon to interfere with recovery of said precious metal; and (b) oxidative treating of said mineral material comprising subjecting said feed slurry to an oxidizing environment to produce an oxidized slurry, wherein during subjecting of said feed slurry to an oxidizing environment, at least 96 percent of said sulfide sulfur in said feed slurry is oxidized such that precious metal is freed from association with said sulfide sulfur and the ability of said organic carbon to interfere with recovery of said precious metal is reduced.

Claim 22

A method for processing a mineral material having a precious metal to facilitate recovery of the precious metal by reducing the potential for recovery problems when both sulfide material and organic carbon render the mineral material refractory to precious metal recovery, the method comprising the steps of: (a) providing a feed slurry having particulate mineral material slurried with an aqueous liquid, wherein (i) said mineral material comprises a precious metal selected from the group consisting of gold, silver and combinations thereof; sulfide material, having sulfide sulfur, which is associated with said precious metal and from which said precious metal is difficult to separate to permit recovery of said precious metal; and organic carbon, which has an ability to interfere with recovery of said precious metal, and (ii) at least 80 weight percent of particles of said mineral material in said feed slurry are smaller than 38 microns in size, which facilitates oxidative treating of said mineral material to reduce the ability of said organic carbon to interfere with recovery of said precious metal; and (b) oxidative treating of said mineral material comprising subjecting said feed slurry to an oxidizing environment to produce an oxidized slurry, wherein during subjecting of said feed slurry to an oxidizing environment, at least 96 percent of said sulfide sulfur in said feed slurry is oxidized such that precious metal is freed from association with said sulfide sulfur and the ability of said organic carbon to interfere with recovery of said precious metal is reduced.

Claim 24

The method of claims 20 for processing a mineral material, wherein: during said oxidative treating of said mineral material, less than about 60 weight percent of said organic carbon is oxidized.

Claim 41

A method for processing a gold-bearing mineral material, that is refractory due to the presence of both organic carbon and sulfide material, to liberate gold from the sulfide material and to deactivate, or passivate, the organic carbon present in the mineral material as an adsorbent capable of interfering with recovery of the gold, the method comprising the steps of: (a) providing a feed slurry having particulate mineral material slurried with an aqueous liquid, wherein (i) said mineral material comprises gold; sulfide material, having sulfide sulfur, which is associated with said gold and from which said gold is difficult to separate to permit recovery of said gold; and organic carbonaceous material which is active as an adsorbent of a complex of said gold with a ligand and is capable of interfering with recovery of said gold, and (ii) at least 80 weight percent of particles of said mineral material in said feed slurry are smaller than 38 microns in size, which facilitates oxidative treating of said mineral material to reduce the ability of said organic carbonaceous material to interfere with recovery of said gold; and (b) oxidative treating of said mineral material comprising subjecting said feed slurry to an oxidizing environment at a temperature of greater than about 190° C., a total pressure of greater than about 190 psia, and an oxygen gas overpressure of greater than about 25 psig to produce an oxidized slurry having greater than about 10 grams of free acid per liter of liquid in said oxidized slurry, wherein during said oxidative treating at least 96 percent of sulfide sulfur in said feed slurry is oxidized, and organic carbon in said feed slurry is passivated as an adsorbent of said complex.

Claim 42

A method for processing a gold-bearing mineral material, that is refractory due to the presence of both organic carbon and sulfide material, to liberate gold from the sulfide material and to deactivate, or passivate, the organic carbon present in the mineral material as an adsorbent capable of interfering with recovery of the gold, the method comprising the steps of: (a) providing a feed slurry having particulate mineral material slurried with an aqueous liquid, wherein (i) said mineral material comprises gold; sulfide material, having sulfide sulfur, which is associated with said gold and from which said gold is difficult to separate to permit recovery of said gold; and organic carbonaceous material which is active as an adsorbent of a complex of said gold with a ligand and is capable of interfering with recovery of said gold, and (ii) at least 80 weight percent of particles of said mineral material in said feed slurry are smaller than 38 microns in size, which facilitates oxidative treating of said mineral material to reduce the ability of said organic carbonaceous material to interfere with recovery of said gold; and (b) oxidative treating of said mineral material comprising subjecting said feed slurry to an oxidizing environment at a temperature of greater than about 190° C., a total pressure of greater than about 190 psia, and an oxygen gas overpressure of greater than about 25 psig to produce an oxidized slurry having greater than about 10 grams of free acid per liter of liquid in said oxidized slurry, wherein during said oxidative treating at least 96 percent of sulfide sulfur in said feed slurry is oxidized, and organic carbon in said feed slurry is passivated as an adsorbent of said complex.