Investigations of accelerating parameters for the biooxidation of low-grade refractory gold ores

This research was designed to accelerate the biological oxidation rate of low-grade suphidic gold ores. The biological oxidation by tamed Thiobacillus ferrooxidans bacteria with a mixed low-grade refractory gold ore was investigated. These bacteria could well tolerate up to 18.0 g/L of arsenic (III). The effect on the oxidation rate due to the presence of a magnetic field on the culture medium was examined as well as the influence of surfactants (tween-80, tween-20 and emulsifier-OP) and selected ionic metals such as Ag+, Bi3+, Co2+ and Hg2+. The results showed that, based on a 60% oxidation rate for arsenic, the oxidation time was shortened by 83 hours, 90 hours, 98 hours and 100 hours under the optimal conditions of tamed bacteria, magnetized water, concentrations of tween-80 and Ag+ respectively. Under the combination of the above parameters, the biooxidation rate was shortened by 120 hours to achieve a 60% oxidation rate for arsenic. However it did not produce a simple additive effect on the biooxidation.