Leaching copper-containing ores

Abstract

A method of leaching copper-containing ores, such as chalcopyrite ores, with a leach liquor in the presence of silver and an activation agent that activates silver whereby the silver enhances copper extraction from copper ores.

The invention claimed is: 
     
       1. A method of leaching copper-containing ores with a leach liquor including:
 (a) forming agglomerates by a step selected from (i) mixing together ore fragments and silver in an agglomeration step, (ii) adding silver to ore fragments and then mixing together ore fragments in an agglomeration step, or (iii) forming agglomerates in an agglomeration step and then adding silver to the agglomerates, with the agglomerates having a low added silver concentration of less than 5  1  g silver per kg copper in the ore in agglomerates, and 
 (b) leaching agglomerates with a leach liquor in the presence of an activation agent that activates silver whereby the silver enhances copper extraction from copper ores, with the activation agent being in the form of any one or more than one of chlorides, iodides, bromides, and thiourea. 
 
     
     
       2. The method defined in  claim 1  wherein the leaching is selected from the group consisting of heap, vat, and tank leaching. 
     
     
       3. The method defined in  claim 1  includes providing a selected concentration or concentration range of the activation agent in the leach liquor. 
     
     
       4. The method defined in  claim 3  wherein the selected concentration or concentration range of the activation agent in the leach liquor results from any one or more of the following positive steps:
 (a) addition of the activation agent to the leach liquor; 
 (b) removal of the activation agent from the leach liquor; 
 (c) addition of the activation agent in the agglomeration step; 
 (d) mixing different ore types having regard to the activation agent in the ores; 
 (e) selection and mixing/blending of water source/type regard to the activation agent in the ores; and 
 (f) other human-intervention into one or more inputs to the method of leaching that can affect the activation agent concentrations in the method of leaching. 
 
     
     
       5. The method defined in  claim 1  wherein the leaching is carried out in the presence of a low concentration or concentration range of the activation agent. 
     
     
       6. The method defined in claim  5   1  wherein the leaching is carried out in the presence of a low concentration of chlorides, iodides, and bromides of up to 5 g/L in the leach liquor. 
     
     
       7. The method defined in  claim 6  wherein the low concentration of chlorides is greater than 0.8 g/L. 
     
     
       8. The method defined in claim  5   1  wherein the leaching is carried out in the presence of a low concentration of chlorides of greater than 0.2 g/L. 
     
     
       9. The method defined in claim  5   1  wherein the leaching is carried out in the presence of a low concentration of thiourea of less than 10 g/L in the leach liquor. 
     
     
       10. The method defined in claim  5   1  wherein the low concentration of chlorides, iodides and bromides is up to 4 g/L in the leach liquor. 
     
     
       11. The method defined in  claim 1  includes adding the activation agent to the leach liquor during the method to maintain a required concentration. 
     
     
       12. The method defined in  claim 1  includes leaching a heap of agglomerates with the leach liquor. 
     
     
       13. The method defined in  claim 12  wherein heap leaching includes bioleaching with microorganisms to assist leaching of copper. 
     
     
       14. The method defined in  claim 12  wherein heap leaching includes controlling heap temperature to be less than 85° C. 
     
     
       15. The method defined in  claim 12  includes controlling oxidation potential of the leach liquor during an active leaching phase of heap leaching to be less than 900 mV versus a standard hydrogen electrode. 
     
     
       16. The method defined in  claim 12  includes recovering copper from the leach liquor in downstream copper recovery steps. 
     
     
       17. The method defined in  claim 16  includes regenerating the leach liquor and recycling the regenerated leach liquor to the heap of agglomerates. 
     
     
       18. The method defined in  claim 12  wherein heap leaching includes controlling the heap temperature to be less than 50° C. 
     
     
       19. The method defined in  claim 1  wherein the added silver concentration in agglomerates is less than 2 g silver per kg copper in the ore in agglomerates. 
     
     
       20. The method defined in  claim 1  wherein the added silver concentration in agglomerates is less than 1 g silver per kg copper in the ore in the agglomerates. 
     
     
       21. The method defined in  claim 1  wherein the added silver concentration in agglomerates is less than 0.5 g silver per kg copper in the ore in the agglomerates. 
     
     
       22. The method defined in  claim 1  wherein added silver concentration in agglomerates is greater than 0.02 g silver per kg copper in the ore in agglomerates. 
     
     
       23. The method defined in  claim 22  wherein the added silver concentration in agglomerates is greater than 0.2 g silver per kg copper in the ore in agglomerates. 
     
     
       24. The method defined in  claim 1  includes steps (a)(i) or (a)(ii) and comprises adding the silver in a solution or in a solid form to chalcopyrite ore fragments. 
     
     
       25. The method defined in  claim 1  includes forming agglomerates by also mixing microorganisms that can assist leaching of copper. 
     
     
       26. The method defined in  claim 1  includes steps (a)(i) or (a)(ii) and comprises adding the silver in a spray or a mist to chalcopyrite ore fragments. 
     
     
       27. The method defined in  claim 1  includes steps (a)(i) or (a)(ii) and comprises adding the silver in an aerosol to chalcopyrite ore fragments. 
     
     
       28. A method of leaching copper-containing ores that includes:
 (a) forming agglomerates of fragments of (i) a copper-containing ore, (ii) silver, (iii) an acid, and (iv) optionally microorganisms, wherein the agglomerate forming step includes any one of (i) mixing together ore fragments and added silver in an agglomeration step, (ii) adding silver to ore fragments and then mixing together ore fragments in an agglomeration step, and (iii) adding silver to the agglomerates after the agglomerates have been formed, and wherein the added silver concentration in the agglomerates is less than 1 g silver per kg copper in the ore in the agglomerates; 
 (b) forming a heap of the agglomerates; 
 (c) leaching the agglomerates in the heap with a leach liquor in the presence of an activation agent that activates silver whereby the silver enhances copper extraction, with the activation agent being any one or more than one of chlorides, iodides, bromides, and thiourea; and 
 (d) recovering copper from the leach liquor. 
 
     
     
       29. A method of leaching copper-containing ores that includes:
 (a) assessing, in a copper-containing ore, the amount of naturally-occurring silver that has catalyst properties for copper leaching;  
 (a)(b) forming agglomerates of fragments of (i) athe copper-containing ore, (ii) an acid, (iii) optionally silver, and (iv) optionally microorganisms, wherein when addition of silver is required, the agglomerate forming step includes any one of (i) mixing together ore fragments and added silver in an agglomeration step, (ii) adding silver to ore fragments and then mixing together ore fragments in an agglomeration step, and (iii) adding silver to the agglomerates after the agglomerates have been formed, wherein the amount of added silver is determined by taking into account catalyst properties for copper leaching of naturally occurring silver in the ore, and wherein the added silver concentration in the agglomerates is less than 1 g silver per kg copper in the ore in the agglomerates; 
 (b)(c) forming a heap of the agglomerates; 
 (c)(d) leaching the agglomerates in the heap with a leach liquor in the presence of an activation agent that activates silver whereby the silver enhances copper extraction, with the activation agent being any one or more than one of chlorides, iodides, bromides, and thiourea; and 
 (d)(e) recovering copper from the leach liquor. 
 
     
     
       30. A method of leaching copper-containing ores that includes:
 (a) forming agglomerates of fragments of (i) a copper-containing ore containing naturally-occurring silver that has catalyst properties for copper leaching, (ii) an acid, and (iii) optionally microorganisms;   (b) forming a heap of the agglomerates;   (c) leaching the agglomerates in the heap with a leach liquor in the presence of thiourea and adjusting the amount of thiourea to provide an amount which activates the silver whereby the silver enhances copper extraction from the copper-containing ore; and   (d) recovering copper from the leach liquor.   
     
     
       31. The method defined in  claim 30  wherein the naturally occurring silver is selected from a group consisting of one or more of native silver, argentite (Ag 2 S), chlorargyrite (AgCl), and silver sulfosalts. 
     
     
       32. The method defined in  claim 31  wherein the silver sulfosalts are selected from a group consisting of one or more of tetrahedrite (Cu,Fe,Zn,Ag 12 Sb 4 S 13 ), pyragyrite (Ag 3 SbS 3 ) and proustite (Ag 3 AsS 3 ). 
     
     
       33. The method defined in  claim 30  includes providing a selected concentration or concentration range of the activation agent in the leach liquor. 
     
     
       34. The method defined in  claim 33  wherein the selected concentration or concentration range of the activation agent in the leach liquor results from any one or more of the following positive steps:
 (a) addition of thiourea to the leach liquor; 
 (b) removal of thiourea from the leach liquor; 
 (c) addition of thiourea in the agglomeration step; 
 (d) mixing different ore types having regard to thiourea in the ores; 
 (e) selection and mixing/blending of water source/type regard to thiourea in the ores; and 
 (f) other human-intervention into one or more inputs to the method of leaching that can affect thiourea concentrations in the method of leaching. 
 
     
     
       35. The method defined in  claim 33  includes assessing the required concentration or concentration range of thiourea for a given ore. 
     
     
       36. The method defined in  claim 35  includes assessing the available water source(s) and relevant conditions and controlling the process so that there is the required concentration or concentration range of thiourea. 
     
     
       37. The method defined in  claim 30  wherein agglomeration step (a) includes forming agglomerates with added silver and the copper-containing ore containing naturally-occurring silver. 
     
     
       38. The method defined in  claim 30  wherein leaching step (c) is carried out in the presence of less than 10 g/L thiourea in the leach liquor. 
     
     
       39. The method defined in  claim 30  includes adding thiourea to the leach liquor during the method to maintain a required concentration. 
     
     
       40. The method defined in  claim 30  includes adding thiourea to the leach liquor continuously or periodically during the course of the method to maintain a required concentration during the method. 
     
     
       41. The method defined in  claim 30  wherein leaching step (c) includes regenerating leach liquor and recycling regenerated leach liquor to the heap, including adjusting the concentration of thiourea in the regenerated leach liquor to maintain the concentration.