Process for leaching low sulphur content materials

Abstract

Disclosed is a process for leaching low sulphur materials for recovery of metals contained in them. The process includes leaching a first low sulphur material containing metal values with a leaching agent produced by bacterial oxidation of a second material by bacterial action thereby liberating metal values from the first material by a substantially indirect bioleaching process.

What is claimed is:  
     
       1. A process for leaching low sulphur content materials for recovery of metals contained in them comprising: 
       leaching a first low sulphur content material containing metal values with a leaching agent produced by bacterial oxidation of a second material thereby liberating metal values from the first material.  
     
     
       2. The process of claim  1 , wherein said low sulphur content material is selected from the group of oxides, sulphates, partially oxidized weathered sulphide ores of base metals, and mixtures thereof. 
     
     
       3. The process of claim  2 , wherein said base metal is selected from the group consisting of copper, cobalt, lead, zinc, nickel and mixtures thereof. 
     
     
       4. The process of claim  1 , wherein said first low sulphur content material is selected from the group consisting of a low sulphur ore, a mixture of low sulphur materials, a mixture of low sulphur ores, a low sulphur content concentrate and a low sulphur content residue. 
     
     
       5. The process of claim  4 , wherein said low sulphur content concentrate or low sulphur content residue is selected from the group consisting of slags, concentrates, tailings, and residues. 
     
     
       6. The process of claim  1 , wherein said first low sulphur content material includes iron. 
     
     
       7. The process of claim  1 , wherein said second material is sulphur. 
     
     
       8. The process of claim  1 , wherein said second material is a mixture of a sulphide and a low sulphur content material. 
     
     
       9. The process of claim  1 , wherein relative amounts of said first low sulphur content material and said second material are controlled to generate a controlled amount of acid for metal dissolution from said first material. 
     
     
       10. The process of claim  9 , wherein said amount of second material accounts for the content of acid consuming minerals in said first low sulphur content material. 
     
     
       11. The process of claim  1 , wherein said first low sulphur content materials and said second materials are mixed together. 
     
     
       12. The process of claim  1 , wherein said leaching process is a heap leaching process and said first low sulphur content materials and second materials are arranged in layers. 
     
     
       13. The process of claim  12 , wherein said first low sulphur content materials and second materials are formed into a heap. 
     
     
       14. The process of claim  1 , wherein said leaching process is conducted in at least one continuous stirred tank reactor. 
     
     
       15. The process of claim  1 , wherein said bacterial oxidation is conducted by sulphur oxidizing bacteria selected from the group consisting of mesophilic bacteria and thermophilic bacteria. 
     
     
       16. A process for leaching a secondary base metal containing material having sulphur content less than 10% by weight, comprising: 
       (a) forming a leaching agent by bacterial oxidation of sulphur; and  
       (b) reacting said secondary base metal containing material with said leaching agent formed by bacterial oxidation of sulphur; and  
       (c) recovering said base metal.  
     
     
       17. A process for leaching a secondary base metal containing material having sulphur content less than 10% by weight, comprising: 
       (a) mixing milled elemental sulphur with a milled base metal mineral containing material to form a mixture;  
       (b) introducing sulphur oxidizing bacteria to said mixture by percolation such that said sulphur is oxidized to form an acidic leaching agent;  
       (c) liberating base metal from said mixture by leaching of the base metal mineral components with said acidic leaching agent; and  
       (d) recovering said base metal.