Continuous leaching of uranium by Thiobacillus ferrooxidans.

The continuous culture of Thiobacillus ferrooxidans and the continuous leaching of uranium by it were investigated by means of an apparatus for single stage continuous culture. For the specific growth rate on ferrous sulfate medium, the optimum pH, temperature and aeration were between 2.3 and 2.7, between 29 and 34°C and above 5.0×10-7 gmole O2/ml•min•atm, respectively. Under the optimum condition “washout” and the highest output of cells and ferric irons were observed at the dilution rate of 0.10 hr-1 and 0.062 hr-1 respectively. The optimum pH for the leaching was 2.0. When the continuous leaching was conducted with 10% by weight of ore on ferrous sulfate medium at 30°C, at pH 2.0 and at 8.5×10-7 gmole O2/ml•min•atm, over 80% of the uranium of unoxidized ore could be leached at the dilution rate of below 0.011 hr-1.