Blockage and uranium migration via CO.sub.2 + O.sub.2 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.sub.2 + O.sub.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.sub.2 injection, calcite and dolomite did not precipitate. Gypsum is not saturated during the whole test. HCO.sub.3.sup.-, pH and Eh, controlled by CO.sub.2 + O.sub.2 injection are key factors influencing uranium leaching.