Effect of pH value on activation of bioleaching bacteria and dearsenification of gold ore concentrates

The activation of bacteria and dearsenification of high-As gold ore concentrates for leaching were studied experimentally the way there were six different initial pH gradients set in shaking flasks, i.e., 1.3, 1.5, 1.7, 1.8, 1.9 and 2.1. In the phase of bacterial activation, the bacteria HQ-0211 in the range from 1.3 to 1.9 are more adaptable to activate faster with better oxidation effect. In the phase of dearsenification of high-As gold ore concentrates, the optimum initial pH value for bioleaching is in the range from 1.7 to 1.9, with short stagnation and fast oxidation. When the pH value becomes higher, e.g., up to 2.1, the bacteria will quickly come into their decline phase, so unavailable to bioleaching. With the lower initial pH value in the range from 1.3 to 1.5, the bacteria will fit the long stagnation phase with slow oxidation/dearsenification.