Abstract:Taking “six-injection and two-pumping” in-situ leaching units in a sandstone-type uranium deposit in Xinjiang as research object, applying combination of numerical simulation and hydrochemical analysis to form initial flow field of CO2+O2 neutral leaching and its relationship with solute transport was studied. The results show that in spindle-shaped flow field with axis of injection-pumping holes, solution front reaches the pregnant holes within 15 days; and concentration changes of SO42- and HCO3- are sensitive and accurate for infiltration of the forward solution of in-situ leaching. It is an ideal tracer for judging the forward flow of solution in initial stage of CO2+O2 neutral leaching. Initial calcium and magnesium carbonates are both in supersaturated state, and their migrations lag behind solution infiltration and is closely synchronized with change in pH value. There is good mutual proof between calculation results of leaching simulation, hydrogeochemical model and actual water chemical monitoring data. The comprehensive application of these methods is more objective and reliable in analysis of in-situ leaching flow field.