Two-Step Process of Aspergillus Niger-Chemical Oxidation Joint Leaching of Granite Uranium Ore

To high-efficiently recover uranium from granite-type uranium ore, a two-step process by Aspergillus niger coupling with chemical oxidants was applied to investigate the effects of pre-culture time, leaching time, oxidant type and dosage on uranium extraction. The results show that the highest uranium recovery of 59.34% is achieved in 36 hours of pre-culture and 72 hours of leaching time in the two-step process by Aspergillus niger. The uranium recovery decreases significantly with the increase of pre-culture time and leaching time. Addition of each of MnO₂, NaClO₃ and H₂O₂ results in an increase in uranium recovery. At a dosage of 2.5% MnO₂ by weight of uranium ore, the highest uranium recovery reaches to 74.09%, having an increase of 14.8% compared with the absence of the oxidant.