Comparative Experiments on Acid Leaching and Bioleaching to a Sandstone Type Uranium Ore

Abstract

512 uranium deposit, located in the northwest of China, is one of the largest in-situ leaching uranium mine in China. In the last 2 decades, The V cyclothem Deposit in 11 mining areas were successively mined by acid in-situ leaching. The uranium recovery rate in the roll body was very high, in contrast it was very low in wing body. To compare the efficiency of uranium recovery in No.11-3 mining area, in which the uranium recovery rate was less than 40% by acid leaching in more than 10 years, acid leaching and bioleaching experiments in lab scale were carried out respectively with a native mix cultures isolated and domesticated with the raffinate from this uranium ore in this paper. The experiments mainly focused on the influences of acidity and ferric ion concentration of the solution to uranium recovery. 12 flask bioleaching tests were set up with acidity of 2g/L, 3.5 g/L and 5 g/L , while ferric ion concentration of 0 g/L, 2g/L, 3.5 g/L, and 5 g/L，respectively. The results showed that the average bioleaching rate was 9.8% higher than that of acid leaching. And when the tailings after acid leaching was leached by bacteria culture, uranium concentration in the solution was 115.74% higher than that when in acid leaching. The average leaching rate of uranium increased 5.7%. It concluded that bioleaching is better than acid leaching to this type of minerals.