Bio-oxidation process and apparatus

Abstract

Disclosed is a process and apparatus for conducting bio-oxidation processes for the extraction of metals from metal containing materials in which aeration means, preferably a diffuser means, is employed within a bio-oxidation reactor to maintain bacterial viability and suspension of metal containing materials by introduction of an oxygen containing gas to a non-mechanically agitated reactor.

The claims defining the invention are as follows:  
     
       1. A process for recovering metals from materials containing them by bio-oxidation comprising;
 a) treating, in a non-mechanically agitated reactor, a slurry comprising a metal containing material with bacteria capable of promoting extraction of metals from said metal containing material; and,  
 b) introducing an oxygen-containing gas to the slurry within the reactor by aeration means.  
 
     
     
       2. The process of  claim 1 , wherein said oxygen-containing gas is introduced to said slurry in bubbles of controlled size. 
     
     
       3. The process of  claim 2 , wherein said aeration means includes at least one diffuser selected from the group consisting of tubular, dome-shaped, doughnut shaped and disc shaped diffusers. 
     
     
       4. The process of  claim 1 , wherein said reactor is rakeless. 
     
     
       5. The process of  claim 1 , wherein gas introduced to the reactor further includes carbon dioxide. 
     
     
       6. The process of  claim 1 , wherein said bacterial culture includes at least one microorganism selected from the group consisting of  Thiobacillus ferroxidans , and  Thiobaccillus thiooxidans, Leptospirillum ferroxidans, Sulphobacillus thermooxidans, Sulpholobus brierleyi, Sulpholobus BC  and  Sulpholobus acidocaldarius.    
     
     
       7. The process of  claim 1 , wherein said metal containing material contains at least one metal selected from the group consisting of non-ferrous base metals, precious metals and rare earth metals. 
     
     
       8. A reactor system for bio-oxidation treatment of metal containing materials comprising at least one rakeless reactor having a reactor volume provided with aeration means for introducing an oxygen containing gas to the reactor volume for maintaining said metal containing material in suspension and bacterial viability. 
     
     
       9. The reactor system of  claim 8 , wherein said at least one reactor is a tank or vat. 
     
     
       10. The reactor system of  claim 9 , wherein said at least one reactor includes a reservoir lined with a liquid impermeable barrier. 
     
     
       11. The reactor system of  claim 9 , wherein said at least one reactor has a feed end and a discharge end with a base of the reactor having a descending slope towards the discharge end. 
     
     
       12. The reactor system of  claim 8 , wherein said aeration means includes at least one diffuser. 
     
     
       13. The reactor system of  claim 12 , wherein each diffuser is placed adjacent the base of the reactor. 
     
     
       14. The reactor system of  claim 12 , wherein said diffuser is selected from the group consisting of a tubular, dome shaped, dougnnut shaped and disc diffuser. 
     
     
       15. The reactor system of  claim 8 , wherein said aeration means is located in a pipeline communicating with said at least one reactor.