Well-controlled stirring tank leaching to improve bio-oxidation efficiency of a high sulfur refractory gold concentrate

For the high sulfur refractory gold concentrate with 41.82% sulfur and 15.12 g/t gold, of which 82.11% was wrapped in sulfide, a well-controlled stirring tank leaching was carried out to improve the bio-oxidation efficiency. Results show that bio-oxidation pretreatment can greatly improve the gold recovery rate of high-sulfur refractory gold concentrate, and at the optimum pH 1.3 in this study, compared with the process without pH control, the oxidation rate of sulfur increased from 79.31% to 83.29%, while the recovery rate of gold increased from 76.54% to 83.23%; under this condition the activity of mixed culture could be sustained and the formation of jarosite could diminish. The results also displayed that for the high sulfur refractory gold concentrate, the recovery of gold is positively correlated with the oxidation rate of sulfur, and the recovery rate of gold increases with the increase of sulfur oxidation rate within a certain range.