Process for Leaching Metal Sulfides with Reagents Having Thiocarbonyl Functional Groups

Abstract

This application pertains to methods of recovering metals from metal sulfides that involve contacting the metal sulfide with an acidic sulfate solution containing ferric sulfate and a reagent that has a thiocarbonyl functional group, wherein the concentration of reagent in the acidic sulfate solution is sufficient to increase the rate of metal ion extraction relative to an acidic sulfate solution that does not contain the reagent, to produce a pregnant solution containing the metal ions.

1 .- 59 . (canceled) 
     
     
         60 . A method of recovering at least one base metal from at least one base metal sulfide in a material, the method comprising:
 contacting the material with an acidic solution comprising reagent having a thiocarbonyl functional group, wherein the reagent is thiourea (Tu), and wherein the initial concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 60 mM, to produce a pregnant solution containing base metal ions; and   recovering the at least one base metal from the pregnant solution.   
     
     
         61 . The method of  claim 60 , wherein the thiocarbonyl functional group of the reagent has a sulfur that bears a partial negative charge, bears negative electrostatic potential surface, and has an empty π*-antibonding orbital as its lowest unoccupied molecular orbital. 
     
     
         62 . The method of  claim 60 , wherein the acidic solution comprises at least one oxidizing agent. 
     
     
         63 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 50 mM. 
     
     
         64 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 30 mM. 
     
     
         65 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 20 mM. 
     
     
         66 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 10 mM. 
     
     
         67 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 5 mM. 
     
     
         68 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 2 mM. 
     
     
         69 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 1 mM. 
     
     
         70 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 0.5 mM. 
     
     
         71 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 0.2 mM. 
     
     
         72 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.002 mM to about 0.02 mM. 
     
     
         73 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.2 mM to about 60 mM. 
     
     
         74 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.2 mM to about 50 mM. 
     
     
         75 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.2 mM to about 30 mM. 
     
     
         76 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.2 mM to about 20 mM. 
     
     
         77 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.2 mM to about 10 mM. 
     
     
         78 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.2 mM to about 5 mM. 
     
     
         79 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 0.2 mM to about 2 mM. 
     
     
         80 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 2 mM to about 60 mM. 
     
     
         81 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 2 mM to about 50 mM. 
     
     
         82 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 2 mM to about 30 mM. 
     
     
         83 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 2 mM to about 20 mM. 
     
     
         84 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 2 mM to about 10 mM. 
     
     
         85 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 2 mM to about 5 mM. 
     
     
         86 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 10 mM to about 60 mM. 
     
     
         87 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 10 mM to about 50 mM. 
     
     
         88 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 10 mM to about 30 mM. 
     
     
         89 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 10 mM to about 20 mM. 
     
     
         90 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 30 mM to about 60 mM. 
     
     
         91 . The method of  claim 60 , wherein the concentration of the reagent in the acidic solution is in the range of about 30 mM to about 50 mM. 
     
     
         92 . The method of  claim 62 , wherein the at least one oxidizing agent comprises a source of ferric ions. 
     
     
         93 . The method of  claim 92 , wherein the source of ferric ions comprises ferric sulfate. 
     
     
         94 . The method of  claim 92 , wherein the source of ferric ions comprises ferric ions generated at least in part by bacteria. 
     
     
         95 . The method of  claim 60 , wherein the acidic solution comprises a sulfate solution. 
     
     
         96 . The method of  claim 60 , wherein the acidic solution comprises a ferric sulfate solution. 
     
     
         97 . The method of  claim 60 , wherein the acidic solution comprises a ferric solution. 
     
     
         98 . The method of  claim 60 , wherein the acidic solution comprises a ferric media. 
     
     
         99 . The method of  claim 60 , wherein the acidic solution is replaced with a ferrous sulfate solution. 
     
     
         100 . The method of  claim 99 , wherein the ferrous sulfate solution provides a source of Fe 2+  ions that are actively oxidized to Fe 3+  ions by bacteria. 
     
     
         101 . The method of  claim 60 , wherein the at least one base metal sulfide comprises at least one copper sulfide. 
     
     
         102 . The method of  claim 101 , wherein the at least one copper sulfide is chalcopyrite, covellite, bornite, enargite, a copper sulfide of the formula Cu x S y  wherein the x:y ratio is between 1 and 2, or a combination thereof. 
     
     
         103 . The method of  claim 101 , wherein the at least one copper sulfide comprises chalcopyrite. 
     
     
         104 . The method of  claim 101 , wherein the at least one copper sulfide comprises covellite. 
     
     
         105 . The method of  claim 101 , wherein the at least one copper sulfide comprises bornite. 
     
     
         106 . The method of  claim 101 , wherein the at least one copper sulfide comprises enargite. 
     
     
         107 . The method of  claim 101 , wherein the at least one copper sulfide comprises a copper sulfide of the formula Cu x S y  wherein the x:y ratio is between 1 and 2. 
     
     
         108 . The method of  claim 107 , wherein the at least one copper sulfide of the formula Cu x S y  comprises chalcocite. 
     
     
         109 . The method of  claim 107 , wherein the at least one copper sulfide of the formula Cu x S y  comprises djurleite. 
     
     
         110 . The method of  claim 107 , wherein the at least one copper sulfide of the formula Cu x S y  comprises digenite. 
     
     
         111 . The method of  claim 60 , wherein the at least one base metal sulfide comprises a cadmium sulfide. 
     
     
         112 . The method of  claim 111 , wherein the cadmium sulfide is greenockite. 
     
     
         113 . The method of  claim 60 , wherein the at least one base metal sulfide comprises at least one nickel sulfide. 
     
     
         114 . The method of  claim 113 , wherein the at least one nickel sulfide comprises pentlandite. 
     
     
         115 . The method of  claim 113 , wherein the at least one nickel sulfide comprises violarite. 
     
     
         116 . The method of  claim 60 , wherein the material is an ore. 
     
     
         117 . The method of  claim 60 , wherein the material is a concentrate of the at least one base metal sulfide. 
     
     
         118 . The method of  claim 60 , wherein the method is a leach. 
     
     
         119 . The method of  claim 118 , wherein the leach is a percolation leach. 
     
     
         120 . The method of  claim 118 , wherein the leach is a heap leach. 
     
     
         121 . The method of  claim 118 , wherein the leach is a vat leach. 
     
     
         122 . The method of  claim 118 , wherein the leach is a tank leach. 
     
     
         123 . The method of  claim 118 , wherein the leach is a column leach. 
     
     
         124 . The method of  claim 60 , wherein recovering the at least one base metal ion from the pregnant solution comprises solvent extraction and electrowinning. 
     
     
         125 . The method of  claim 60 , further comprising maintaining the operating potential of the acidic solution above 500 mV vs Ag/AgCl. 
     
     
         126 . The method of  claim 60 , wherein the reagent does not complex/precipitate with the at least one base metal ion. 
     
     
         127 . The method of  claim 60 , wherein the method is run at a temperature between 0° C. and 80° C.