Oxidation of sulfur-containing substrates by an association of acidophilic chemolithotrophic microorganisms

Quantitative and qualitative changes in the content of elements in the solid and liquid phases occurred as the pulp moved through reactors during biooxidation of an ore flotation concentrate. The association of microorganisms were adapted for utilizing sulfur-containing substrates; however, the rate of their oxidation was insufficient, which led to an increase in the amount of sodium cyanide required for gold recovery. The replacement of one-fourth of the liquid phase of the pulp (density, 13%) with a mineral medium without an energy source, the fractional addition of FeSO₄ · 7H₂O (1 g/l per day), and the improvement of pulp aeration made it possible to increase the content of SO ₄ ²⁻ by 80.7, 86.2, and 58.5%, respectively. When one-fourth of the liquid phase of the pulp (density, 24%) was replaced with a mineral medium without an energy source, the rate of additional oxidation of sulfide minerals increased, which increased the efficiency of gold extraction into solution and gold recovery on charcoal by 3.4 and 3.6%, respectively, and reduced sodium cyanide consumption by 3 kg/ton.