Blockage and uranium migration via CO2 + O2 leaching within autoclave: a test study from Mengqiguer deposit in Yili Basin, Northwest of China

Due to high content of carbonate and sulfide in ore, precipitation of calcium compounds is blocking the in-situ leaching system at Mengqiguer sandstone type deposit. Autoclave CO 2 + O 2 leaching tests were conducted in respecting the blockage and uranium migration. Result shows that: Most uranium was recovered within the first hour. Calcite and dolomite precipitated in the initial stage of leaching because of high pH value. As pH decreases rapidly after CO 2 injection, calcite and dolomite did not precipitate. Gypsum is not saturated during the whole test. HCO 3 - , pH and Eh, controlled by CO 2 + O 2 injection are key factors influencing uranium leaching.