Bioleaching of low-grade copper sulfide ore using a colum reactor

The effects of several variables on the column bioleaching of copper sulphide ore have been investigated. The copper ore contained chalcopyrite as the main Sulfide minerals and bornite and chalcocite as the minor minerals. The experiment was carried out using bench-scale column leach reactors designed in Key Lab of Biometallurgy of Ministry of Education, which were inoculated with the pure mesophile bacteria (Acidithiobacillus ferrooxidans) and thermophile bacteria (Sulfobacillus), respectively, and the mixed bacteria which contain both iron- and sulfur-oxidizing bacteria. The results show that the mixed Cultures were more efficient than the pure Cultures alone and the maximum copper recovery 53.64% was achieved using the mixed Cultures after 85 days. The leaching rate of chalcopyrite tended to increase with the increased dissolved ferric iron concentration. The effect of particle size oil the rate of the copper leaching was also investigated, and it was shown that the copper bioleaching rate decreases as the amount of fines increase, which limits the permeability.. thus decreases leaching rate. Jarosite and elemental sulphur formed in the column were characterized by the X-ray and EDS.