Abstract:Uranium concentration has a significant positive correlation with HCO3- during CO2+O2 in-situ leaching of uranium process from Mengqiguer sandstone type uranium deposit in Xinjiang. However, after the initial stage of leaching, HCO3- concentration of leaching solution can be not increased effectively by adding more CO2. For most leaching units of Mengqiguer deposit, HCO3- concentration does not yet meet the optimal leaching requirement. So, in a selected mining area of the deposit, a trial of supplementing bicarbonate ammonia combined with increasing of CO2 amount was carried out to enhance leaching intensity. The study results show that effect of enhanced leaching is significant: HCO3- concentration rises from 850 mg/L to 1 200 mg/L, which results in that uranium concentration of pregnant solution of single-well rises by 1.733-44.33 mg/L, and that of mix pregnant solution by 8 mg/L. While pH value of leaching solution is controlled at 6.2-6.3 and SO42- concentration stabilized by reducing O2, precipitation of calcium carbonate and calcium sulfate will not happen during enhanced leaching process. In addition, pumping and injection capacities are not affected passively. This enhanced leaching technology is a further optimization of CO2+O2 leaching process in Mengqiguer deposit, and good leaching effect and economic benefits result from its applications in mining areas.