Biooxidation of a Refractory Gold-Bearing Concentrate at Decreased Retention Time

The goal of the present work was to perform biooxidation of a gold-bearing pyrite-arsenopyrite flotation concentrate under unfavorable conditions (decreased retention time). For this purpose, biooxidation of the concentrate containing 51% pyrite and 13% arsenopyrite was carried out in a continuous mode with a retention time of 5 days (i.e., under conditions corresponding to those used in industrial biooxidation facilities) and 3 days (i.e., under conditions unfavorable for the biooxidation). Reducing the retention time led to a decrease in the oxidation degree of sulfide minerals in the concentrate. Application of an additional carbon source (carbon dioxide) made it possible to neutralize the negative effect of reducing the retention time. Thus, it was shown that it is possible to significantly increase the rate of the biooxidation process by using carbon dioxide as an additional carbon source for the microbial population of the biooxidation reactor.