Abstract:In order to explore the technical feasibility of application of CO2+O2 in-situ leaching (ISL) technology in a sandstone type of uranium deposit in Northwest China, a field condition test of ISL uranium mining was carried out. The test results show that when O2 is added to groundwater, the dissolved O2 content of the leachate residue rises significantly, but there is no significant increase of c(U) in leaching fluid. When CO2 and O2 are added to the groundwater under the condition of original groundwater c(HCO3-) of 300 mg/L, the rise of c(HCO3-) in the leachate is not significant (only rises from 300 mg/L to 350 mg/L), and no significant increase is observed in c(U). By adding NH4HCO3 to make the leaching agent c(HCO3-) to 1 000 mg/L, c(U) in leachate rises straightly with the increase of c(HCO3-), and the peak of c(U) reaches 31.5 mg/L. The correlation coefficient of c(U) and c(HCO3-) is 0.95, and the two parameter shows a strong positive correlation. The research results show that this sandstone type uranium mine cannot meet the requirements of ISL only by CO2+O2 leaching process, by adding NH4HCO3 and keeping c(HCO3-) in solution reaches 800 mg/L, c(U) in leachate can meet the industrial production requirements of ISL (peak value is 31.5 mg/L, and the average concentration is 25 mg/L above). The technically feasible leaching process of this deposit is “CO2 + O2 + NH4HCO3” in-situ leaching.