Recovery of elemental sulfur and metal values from tailings from copper recovery processes

Claim 2

A process for recovering copper, molybdenum and elemental sulfur from copper sulfide ore concentrates or tailings containing copper, molybdenum, elemental sulfur, pyrite and other impurities which comprises: a. subjecting the concentrate or tailings to froth flotation to collect elemental sulfur, copper and molybdenum values in a float concentrate and reject the remainder of the tailings; b. performing a liquid-solids separation on the float concentrate of step (a); c. leaching the residue of step (b) with a solvent for sulfur to dissolve elemental sulfur; d. performing a liquid-solids separation on the slurry of step (c); e. recovering elemental sulfur from the filtrate of step (d); f. leaching the residue of step (d) with ferric chloride to selectively dissolve copper therein; g. performing a liquid-solids separation on the slurry of step (f) h. recovering copper from the filtrate of step (g); and i. recovering molybdenum from the residue of step (g).

Claim 3

The process of claim 1 in which in step (c) the solvent for sulfur is ammonium sulfide.

Claim 4

The process of claim 2 in which in step (e) the filtrate of step (d) is evaporated to recover elemental sulfur and regenerate ammonium sulfide.

Claim 5

The process of claim 1 in which in step (h) the copper is recovered from the ferric chloride leach solution by sending the solution to the leaching step of a hydrometallurgical circuit for the recovery of copper from its sulfide ores in which the ore is leached with ferric chloride and/or cupric chloride to produce a leach solution comprising cuprous chloride, cupric chloride and ferrous chloride.

Claim 6

The process of claim 1 in which the concentrate of step (a) contains gold and before step (i) the residue of step (g) is leached with cyanide to solubilize gold before the residue is sent to step (i) and gold recovered from the cyanide solution.

Claim 7

In the process for recovering copper from copper sulfide ore concentrates in which the concentrate is leached in a main leach step to produce a leach slurry comprising cuprous chloride, cupric chloride, and ferrous chloride in solution which latter is separated from the residue or tailings containing undissolved materials such as molybdenite, and elemental sulfur, some copper, and impurities and the solution further processed to recover copper, the improvement by which the elemental sulfur, copper and molybdenum in the tailings are selectively separated and recovered, comprising: a. subjecting the tailings to froth flotation to collect the elemental sulfur, and copper and molybdenum values in a float concentrate and reject pyrite, jarosite, if present, and other impurities; b. performing a liquid-solids separation on said float concentrate; c. leaching the residue of step (b) with a sulfur solvent to dissolve elemental sulfur; d. performing a liquid-solids separation on the slurry of step (c); e recovering elemental sulfur from the filtrate of step (d) f leaching the residue of step (d) with ferric chloride to selectively dissolve copper therein; g performing a liquid-solids separation on the slurry of step (f); h recovering copper from the filtrate of step (g); i subjecting the residue of step (g) to froth flotation and recovering the float concentrate containing elemental sulfur and molybdenum values; j leaching the float concentrate of step (i) with a sulfur solvent to solubilize elemental sulfur produced by the ferric chloride leach followed by liquid-solids separation and recovery of sulfur from the solution; and k recovering molybdenum from the residue of step (j).

Claim 8

In the process for recovering copper from copper sulfide ore concentrates in which the concentrate is leached in a main leach step to produce a leach slurry comprising cuprous chloride, cupric chloride, and ferrous chloride in solution which latter is separated from the residue or tailings containing undissolved materials such as molybdenite, and elemental sulfur, some copper, and impurities and the solution further processed to recover copper, the improvement by which the elemental sulfur, copper and molybdenum in the tailings are selectively separated and recovered, comprising: a. subjecting the tailings to froth flotation to collect the elemental sulfur, and copper and molybdenum values in a float concentrate and reject pyrite, jarosite, if present, and other impurities; b. performing a liquid-solids separation on said float concentrate; c. leaching the residue of step (b) with a sulfur solvent to dissolve elemental sulfur; d. performing a liquid-solids separation on the slurry of step (c); e recovering elemental sulfur from the filtrate of step (d) f leaching the residue of step (d) with ferric chloride to selectively dissolve copper therein; g performing a liquid-solids separation on the slurry of step (f); h recovering copper from the filtrate of step (g); i subjecting the residue of step (g) to froth flotation and recovering the float concentrate containing elemental sulfur and molybdenum values; j leaching the float concentrate of step (i) with a sulfur solvent to solubilize elemental sulfur produced by the ferric chloride leach followed by liquid-solids separation and recovery of sulfur from the solution; and k recovering molybdenum from the residue of step (j).

Claim 9

The improved process of claim 6 in which in step (c) the sulfur solvent is ammonium sulfide.

Claim 10

The improved process of claim 7 in which in step (e) the filtrate of step (d) is evaporated to recover elemental sulfur and regenerate ammonium sulfide.

Claim 11

The improved process of claim 8 in which in step (e) the filtrate is evaporated at a temperature of at least about 95° C.

Claim 12

The improved process of claim 6 in which in step (h) the copper is recovered from the ferric chloride leach solution by recycling the latter to said main leach for recovery of copper.

Claim 13

The improved process of claim 6 in which the concentrate of step (a) contains gold and before step (i) the residue of step (g) is leached with cyanide to solubilize gold before the residue is sent to step (i) and gold recovered from the cyanide solution.

Claim 14

The improved process of claim 6 in which in step (f) the residue is ground to about 95 percent being about -325 mesh to expose interlocked copper sulfide ore before it is leached with ferric chloride.

Claim 15

In the process for recovering copper from copper sulfide concentrates in which the concentrate is leached in a main leach circuit to produce a leach solution comprising cuprous chloride, cupric chloride, ferrous chloride and soluble metal impurities, the solution further processed for copper recovery, the improvement by which elemental sulfur, copper and molybdenum in the tailings from the main leach are selectively separated and recovered which comprises the following: a. recovering elemental sulfur from the tailings by solubilizing the sulfur with a solvent for sulfur followed by recovering elemental sulfur from the solution; b. recovering copper from the residue from the sulfur solvent leach of step (a) by leaching the sulfur depleted residue with ferric chloride to selectively solubilize copper; and c. recovering molybdenum from the residue from the ferric chloride leach of step (b).

Claim 16

In the process for recovering copper from copper sulfide concentrates in which the concentrate is leached in a main leach circuit to produce a leach solution comprising cuprous chloride, cupric chloride, ferrous chloride and soluble metal impurities, the solution further processed for copper recovery, the improvement by which elemental sulfur, copper and molybdenum in the tailings from the main leach are selectively separated and recovered which comprises the following: a. recovering elemental sulfur from the tailings by solubilizing the sulfur with a solvent for sulfur followed by recovering elemental sulfur from the solution; b. recovering copper from the residue from the sulfur solvent leach of step (a) by leaching the sulfur depleted residue with ferric chloride to selectively solubilize copper; and c. recovering molybdenum from the residue from the ferric chloride leach of step (b).

Claim 17

The process of claim 13 in which the recovered solubilized copper is returned to the main leach circuit for recovery of elemental copper.

Claim 18

The process of claim 13 performed continuously with the main leach.

Claim 19

The process of claim 13 in which in step (a) the sulfur solvent is ammonium sulfide.

Claim 20

The process of claim 16 in which ammonium sulfide is used in an amount by weight equal to about the amount of sulfur in the tails.

Claim 21

The process of claim 16 in which elemental sulfur is recovered from the sulfur solution by evaporation and ammonium sulfide is regenerated by dissolving the offgases in water.

Claim 22

The process of claim 13 in which the tailings of step (a) contain gold and before step (c) the residue of step (b) is leached with cyanide to solubilize gold before the residue is sent to step (c) and gold recovered from the cyanide solution.

Claim 23

The process of claim 13 in which prior to step (a) the tailings are concentrated by froth flotation to reject impurities such as pyrite and jarosite.

Claim 24

In a hydrometallurgical process for recovering copper from copper sulfide ore concentrates in which the concentrate is leached in a main leach step with ferric chloride and/or cupric chloride to produce a leach slurry comprising cuprous chloride, cupric chloride and ferrous chloride in solution which latter is separated from the residue or tailings containing undissolved materials such as gold, molybdenite, elemental sulfur, some copper, and impurities, and the solution further processed to recover copper, the improvement by which the tailings are concentrated into a small bulk containing substantially all of the materials to be recovered and the elemental sulfur, gold, copper, and molybdenum in the concentrated tailings are selectively separated and recovered, comprising the following steps performed in the recited order: a. concentrating said tailings by subjecting them to froth flotation to collect the elemental sulfur and copper, gold and molybdenum values in a float concentrate having a greatly reduced solids volume and to reject jarosite if present, and other impurities in a barren gangue; b. performing a liquids-solids separation on said float concentrate; c. leaching the residue of step (b) with a sulfur solvent to dissolve elemental sulfur; d. performing a liquid-solids separation on the slurry of step (c); e. recovering elemental sulfur from the filtrate of step (d); f. leaching the residue of step (d) with ferric chloride to selectively dissolve copper therein; g. performing a liquid-solids separation on the slurry of step (f); h. recycling the filtrate of step (g) to said main leach step for copper recovery; i. leaching the residue of step (g) with cyanide to solubilize gold therein; j. performing a liquid-solids separation on the slurry of step (i); k. recovering gold from the solution of step (j); l. subjecting the residue of step (j) to froth flotation and recovering the float concentrate containing molybdenum values, and elemental sulfur produced by the ferric chloride leach; m. leaching the float concentrate of step (l) with a sulfur solvent to solubilize the elemental sulfur produced by the ferric chloride leach of step (f); n. performing a liquid-solids separation on the slurry of step (m); o. recovering sulfur from the filtrate of step (n); and p. recovering molybdenum from the residue of step (n).

Claim 25

In a hydrometallurgical process for recovering copper from copper sulfide ore concentrates in which the concentrate is leached in a main leach step with ferric chloride and/or cupric chloride to produce a leach slurry comprising cuprous chloride, cupric chloride and ferrous chloride in solution which latter is separated from the residue or tailings containing undissolved materials such as gold, molybdenite, elemental sulfur, some copper, and impurities, and the solution further processed to recover copper, the improvement by which the tailings are concentrated into a small bulk containing substantially all of the materials to be recovered and the elemental sulfur, gold, copper, and molybdenum in the concentrated tailings are selectively separated and recovered, comprising the following steps performed in the recited order: a. concentrating said tailings by subjecting them to froth flotation to collect the elemental sulfur and copper, gold and molybdenum values in a float concentrate having a greatly reduced solids volume and to reject jarosite if present, and other impurities in a barren gangue; b. performing a liquids-solids separation on said float concentrate; c. leaching the residue of step (b) with a sulfur solvent to dissolve elemental sulfur; d. performing a liquid-solids separation on the slurry of step (c); e. recovering elemental sulfur from the filtrate of step (d); f. leaching the residue of step (d) with ferric chloride to selectively dissolve copper therein; g. performing a liquid-solids separation on the slurry of step (f); h. recycling the filtrate of step (g) to said main leach step for copper recovery; i. leaching the residue of step (g) with cyanide to solubilize gold therein; j. performing a liquid-solids separation on the slurry of step (i); k. recovering gold from the solution of step (j); l. subjecting the residue of step (j) to froth flotation and recovering the float concentrate containing molybdenum values, and elemental sulfur produced by the ferric chloride leach; m. leaching the float concentrate of step (l) with a sulfur solvent to solubilize the elemental sulfur produced by the ferric chloride leach of step (f); n. performing a liquid-solids separation on the slurry of step (m); o. recovering sulfur from the filtrate of step (n); and p. recovering molybdenum from the residue of step (n).

Claim 26

The improved process of claim 21 in which the sulfur solvent of step (c) is ammonium sulfide.

Claim 27

The improved process of claim 22 in which elemental sulfur is recovered from the sulfur solution by evaporation and ammonium sulfide regenerated by contacting the off-gases with water.