Abstract:The concentration and variational trend of As³⁺ and As⁵⁺, the bacterial resistance for the As³⁺ and As⁵⁺ and converting conditions from As³⁺ to As⁵⁺ were analyzed. The additive was used to prompt the bacterial leaching efficiency by changing valence state of arsenic. The results show that the concentration of As³⁺ is larger than that of As⁵⁺ in the lag phase. The concentration of As³⁺ decreases in the log phase, and is lower than that of As⁵⁺. HQ-0211 typed bacteria express better resistance for As³⁺ and As⁵⁺ and remain growing when the concentrations of As³⁺ and As⁵⁺ are above 6.0 g/L and 12.0 g/L, respectively. It is found that Fe³⁺ cannot oxidize As³⁺ singly as strong oxidant in the leaching system, but can cooperate with pyrite or chalcopyrite to do that. The oxidation of As³⁺ is prompted with addition of H₂O₂. The bacterial activity is improved in favor of bacterial leaching efficiency. NaClO restrains the bacterial growth to depress leaching efficiency because of the chloric compounds affecting bacterial activity.

Key words: As³⁺; As⁵⁺; bacterial leaching; arsenic resistance; oxidant; arsenic-bearing gold ore