Influence of mechano-chemical activation on biooxidation of auriferous sulphides

The influence of mechano-chemical activation on biooxidation of auriferous flotation concentrate by a consortium of Acidithiobacilli species has been studied. The investigation revealed that substantial changes in the structure of the sulphides occurred when the concentrate was mechanically activated. The effects of activation were monitored through changes in the j-factor, mineral phases and also by chemical analysis. As a result of the changes in structure of the sulphide minerals, 96.7% biooxidation of the activated concentrate was achieved within 8 days in contrast to 40% in the case of the non-activated sample after 20 days. In the subsequent cyanidation process of the biooxidized residues using carbon-in-leach technique about 98% of gold in the mechanically activated concentrate was recovered whereas 74.6% was realised for the non-mechanically activated concentrate.