Abstract: The main purpose of this experiment is to do research on the synergism effect on leaching uranium ore and pyrite by Acidithiobacillus ferrooxidans(At.f) and Acidithiobacillus thiooxidans(At.t). The authors separate and purificate the thiobacillus of sandstone type uranium deposit by the method of enrichment culture, inorganic salt sodium silicate tablet. Through the analysis of the morphological characteristics, physiological and biochemical results of strain and 16s rDNA sequence, the strain status in system development are determined. And by using the method of shake flask culture design ore leaching test, added separated and purified At.f and At.t and mixed At.f and At.t to pyrite leaching system respectively. Measured the change of parameters such as pH, Eh. 40 d later, detected total concentration of iron and sulfate’s ion. meanwhile analyzed the composition and morphology of the surface of slag of pyrite. Designing the uranium leaching experiment based on the results of the leaching of pyrite, after 40 d, Measured the change of parameters such as pH, Eh, total concentration of iron and sulfate’s ion, calculated the leaching rate of tetravalent uranium. The results showed: SW-2 is identified as At.f, SW-3 was identified as At.t. At.f and At.t exisited synergy leaching pyrite and uranium ore, At.f was strong oxidant by oxidizing Fe2+ to Fe3+ before Fe3+ oxidizing UO2 to soluble UO22+ in leaching system. At.t could provide acidic environment for leaching system, the best amount combination of bacteria was 5:1(At.f:At.t), the leaching rate of UO2 was 55.60%, surface morphology of slag of pyrite showed that was a direct oxidation from the bacterial to pyrite. The condition of At.f and At.t that leaching pyrite also had the same significant role in promoting microbiological leaching uranium ore with pyrite as the associated minerals. The results of the study could provide certain support for industrial microbial leaching uranium and provide reference for microbiological leaching minerals with pyrite as the associated minerals.

Key words: Acidithiobacillus ferrooxidans(At.f), Acidithiobacillus thiooxidans(At.t), concentration ratio, leaching rate