Column bioleaching of sandstone type uranium ore deposit
Column bioleaching has been performed on sandstone type uranium ore. The column is initially leached with H2SO4 to make the environment acidic and feasible for thiobacillus ferroxidan bacteria growth. The column later injected with acid solution containing 6g/L H2SO4, iron source 1.5g/L (Fe3+ 0.75g/L, Fe2+ 0.75g/L) and bacteria. The leaching results show that the uranium concentration increases rapidly to maximum value 445mg/L and later decreases and reduced to minimum value. Fe3+ and Fe2+ curves shows that initially Fe2+ concentration rises indicating uranium oxidation. Later raise of Fe3+ concentration shows that bacteria growing within column causing oxidation of Fe2+ ions. Flow rate decreases from 6.35ml/hr to 5.37ml/hr at the start of test but later enhance to 8.50ml/hr. Recovery curve shows that total uranium recovered in this test is 83%. Maximum recovery attained within 90 hours which later changes slightly.