In order to augment the supply of uranium for electricity generation, bioleaching is being considered for exploiting a low-grade uranium ore (with 0.024% U3O8 of Turamdih Mines, Jharkhand, India). This ore contains silicate and magnetite as the main minerals and uraninite and hematite as minor minerals. At NML, efforts have been made to use Acidithiobacillus ferrooxidans (Ac.Tf) initially on bench scale in shake flask and then in column to recover uranium. In shake flasks, ~98% uranium dissolution was achieved in 30days at 1.7pH, 35oC temperature and 20% (w/v) pulp density. In a laboratory scale column containing 2.5kg ore, uranium bio-recovery of 55.48% was obtained in 30 days at 1.7pH. To scale up the process, the bio-leaching experiments carried out on 80kg ore showed uranium recovery of 69.8% as against a recovery of 55.12% in control set at 1.7 pH in 50 days. Bio-recovery of uranium has been correlated with the change in redox potential (Eh) and ferric ion concentration
