Comparative Performance of Uranium Bioleaching from Low Grade Indian Apatite Rock in Column and Bioreactor

Uranium ore from the Narwapahar mines, Jharkhand, India (∼0.047% U3O8), rich in apatite content (5%) was investigated for bio-processing in lab-scale columns and bioreactor. With a load of 2.0 kg ore in column at pH 1.7 using A. ferrooxidans and L. ferrooxidans, uranium recovery of 57% and 66% was achieved, respectively in 40 days in comparison to 39% in chemical leaching. Bio-leaching studies with the Narwapahar ore carried out in a 2L bioreactor at 10% (w/v) pulp density at pH 2.0, rpm 150 and 35oC yielded 57% and 63% uranium recovery by 10% (v/v) enriched culture of A. ferrooxidans and L. ferrooxidans, respectively in 5 days. In another set of experiments, biogenic ferric sulfate generated in the bioreactor was mixed with the ore slurry and 90.3% uranium biorecovery was achieved in 10 h at pH 2.0, 20% (w/v) pulp density of <45 μm particles and 40oC with L. ferrooxidans as against 87% leaching at 35oC with A. ferrooxidans.