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

Claim 2

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 sequentially comprise the following: (a) removing elemental sulfur from the tailings; (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 3

The process of claim 1 wherein the sulfur is removed by solubilizing the sulfur followed by recovering elemental sulfur from the solution.

Claim 4

The process of claim 1 wherein the sulfur is removed by means of volatilization.

Claim 5

The process of claim 1 in which the recovered solubilized copper is returned to the main leach circuit for recovery of elemental copper.

Claim 6

The process of claim 1 performed continuously with the main leach.

Claim 7

The process of claim 1 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 8

The process of claim 1 in which prior to step (a) the tailings are concentrated by froth flotation to reject impurities such as pyrite and jarosite.

Claim 9

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) removing elemental sulfur from the tailings by volatilizing the sulfur; (b) recovering copper from the residue from the sulfur volatilization 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 10

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) removing elemental sulfur from the tailings by volatilizing the sulfur; (b) recovering copper from the residue from the sulfur volatilization 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 11

The process of claim 8 in which the recovered solubilized copper is returned to the main leach circuit for recovery of elemental copper.

Claim 12

The process of claim 8 performed continuously with the main leach.

Claim 13

The process of claim 8 in which in step (a) the sulfur is volatilized at temperatures between about 300° C. and 600° C.

Claim 14

The process of claim 8 in which in step (a) the sulfur is volatilized at temperatures between about 400° C. and 500° C.

Claim 15

The process of claim 8 in which in step (a) sulfur is volatilized under partial vacuum.

Claim 16

The process of claim 8 in which in step (a) sulfur is volatilized by heating for up to 15 minutes.

Claim 17

The process of claim 8 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 18

The process of claim 8 in which prior to step (a) the tailings are concentrated by froth flotation to reject impurities such as pyrite and jarosite.

Claim 19

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 liquid-solids separation on said float concentrate; (c) recovering elemental sulfur from the float concentrate of step (b) by volatilizing the sulfur and recovering the sulfur from the vapor; (d) leaching the residue of step (c) with ferric chloride to selectively dissolve copper therein; (e) performing a liquid-solids separation on the slurry of step (d); (f) recycling the filtrate of step (e) to said main leach step for copper recovery; (g) leaching the residue of step (e) with cyanide to solubilize gold therein; (h) performing a liquid-solids separation on the slurry of step (g); (i) recovering gold from the solution of step (h); (j) subjecting the residue of step (h) to froth flotation and recovering the float concentrate containing molybdenum values, and elemental sulfur produced by the ferric chloride leach; (k) heating the float concentrate of step (j) to volatilize the elemental sulfur produced by the ferric chloride leach of step (d); (l) recovering sulfur from the vapor from step (k); and (m) recovering molybdenum from the residue of step (k).

Claim 20

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 liquid-solids separation on said float concentrate; (c) recovering elemental sulfur from the float concentrate of step (b) by volatilizing the sulfur and recovering the sulfur from the vapor; (d) leaching the residue of step (c) with ferric chloride to selectively dissolve copper therein; (e) performing a liquid-solids separation on the slurry of step (d); (f) recycling the filtrate of step (e) to said main leach step for copper recovery; (g) leaching the residue of step (e) with cyanide to solubilize gold therein; (h) performing a liquid-solids separation on the slurry of step (g); (i) recovering gold from the solution of step (h); (j) subjecting the residue of step (h) to froth flotation and recovering the float concentrate containing molybdenum values, and elemental sulfur produced by the ferric chloride leach; (k) heating the float concentrate of step (j) to volatilize the elemental sulfur produced by the ferric chloride leach of step (d); (l) recovering sulfur from the vapor from step (k); and (m) recovering molybdenum from the residue of step (k).

Claim 21

The improved process of claim 17 in which the sulfur is volatilized at temperatures between about 400° and 500° C.

Claim 22

The improved process of claim 18 in which the sulfur is volatilized under partial vacuum.

Claim 23

The improved process of claim 30 in which the sulfur is volatilized by heating for up to 15 minutes.

Claim 24

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) recovering sulfur from the float concentrate of step (b); (d) leaching the residue of step (c) with ferric chloride to selectively dissolve copper therein; (e) performing a liquid-solids separation on the slurry of step (d); (f) recovering copper from the filtrate of step (e); and (g) recovering molybdenum from the residue of step (e).

Claim 25

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) recovering sulfur from the float concentrate of step (b); (d) leaching the residue of step (c) with ferric chloride to selectively dissolve copper therein; (e) performing a liquid-solids separation on the slurry of step (d); (f) recovering copper from the filtrate of step (e); and (g) recovering molybdenum from the residue of step (e).

Claim 26

The process of claim 21 wherein the sulfur recovery of step (c) is accomplished by: leaching the residue of step (b) with a solvent for sulfur to dissolve elemental sulfur; a liquid-solids separation is performed on the slurry; and elemental sulfur is recovered from the filtrate.

Claim 27

The process of claim 22 in which the solvent for sulfur is ammonium sulfide.

Claim 28

The process of claim 23 in which elemental sulfur is recovered and ammonium sulfide is regenerated by evaporation of the filtrate.

Claim 29

The process of claim 21 wherein the sulfur recovery of step (c) is accomplished by volatilization of the sulfur at temperatures above the melting point of sulfur; and elemental sulfur is recovered from the vapor.

Claim 30

The process of claim 25 in which the sulfur is volatilized at temperatures between about 300° C. and 600° C.

Claim 31

The process of claim 21 in which in step (f) 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 32

The process of claim 21 in which the concentrate of step (a) contains gold and before step (g) the residue of step (e) is leached with cyanide to solubilize gold before the residue is sent to step (g) and gold recovered from the cyanide solution.

Claim 33

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) recovering sulfur from the float concentrate of step (b); (d) leaching the residue of step (c) with ferric chloride to selectively dissolve copper therein; (e) performing a liquid-solids separation on the slurry of step (d); (f) recovering copper from the filtrate of step (e); (g) subjecting the residue of step (e) to froth flotation and recovering the float concentrate containing elemental sulfur and molybdenum values; (h) recovering sulfur from the float concentrate of step (g); (i) recovering molybdenum from the residue of step (h).

Claim 34

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) recovering sulfur from the float concentrate of step (b); (d) leaching the residue of step (c) with ferric chloride to selectively dissolve copper therein; (e) performing a liquid-solids separation on the slurry of step (d); (f) recovering copper from the filtrate of step (e); (g) subjecting the residue of step (e) to froth flotation and recovering the float concentrate containing elemental sulfur and molybdenum values; (h) recovering sulfur from the float concentrate of step (g); (i) recovering molybdenum from the residue of step (h).

Claim 35

The process of claim 29 wherein the sulfur recovery of step (c) is accomplished by leaching the residue of step (b) with a solvent for sulfur to dissolve elemental sulfur; a liquid-solids separation is performed on the slurry; and elemental sulfur is recovered from the filtrate.

Claim 36

The process of claim 30 in which the solvent for sulfur is ammonium sulfide.

Claim 37

The process of claim 31 in which elemental sulfur is recovered and ammonium sulfide is regenerated by evaporation of the filtrate.

Claim 38

The process of claim 29 wherein the sulfur recovery of step (c) is accomplished by volatilization of the sulfur at temperatures above the melting point of sulfur; and elemental sulfur is recovered from the vapor.

Claim 39

The process of claim 33 in which the sulfur is volatilized at temperatures between about 300° C. and 600° C.

Claim 40

The improved process of claim 29 in which in step (f) the copper is recovered from the ferric chloride leach solution by recycling the latter to said main leach for recovery of copper.

Claim 41

The improved process of claim 29 in which the concentrate of step (a) contains gold and before step (g) the residue of step (e) is leached with cyanide to solubilize gold before the residue is sent to step (g) and gold recovered from the cyanide solution.

Claim 42

The improved process of claim 32 in which in step (e) the filtrate is evaporated at a temperature of at least about 95° C.

Claim 43

The process of claim 33 wherein the sulfur is volatilized at temperatures between about 400° C. and 500° C.

Claim 44

The process of claim 33 wherein the sulfur is volatilized under partial vacuum.

Claim 45

The process of claim 33 wherein the sulfur is volatilized by heating for up to 15 minutes.

Claim 46

The improved process of claim 29 in which in step (d) 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.