Optimization of CO2+O2 in-situ leaching parameters for sandstone-type uranium deposits under uncoupled charge blasting

To deeply analyze the impact of uncoupled charge blasting on the effect of uranium resource exploitation, RHT (Riedel-Hiermaier-Thomas) and HJC (Holmquist-Johnson-Cook) material models were first used to simulate the damage range of under different uncoupled charge blasting conditions, then a reaction-flow numerical model for CO 2 + O 2 in-situ leaching (ISL) was establish to evaluate the influence of CO 2 + O 2 ISL on spatiotemporal distribution and production characteristics of uranium. Results show that as the uncoupling charge coefficient increases, the radius of crushing zone gradually decreases, while the radius of fracture zone show a trend of first increasing and then decreasing. When the uncoupling charge coefficient is 1.75, the time to peak uranium concentration of blasting stimulated uranium deposits reduces by 17.44 %, and the leaching rate increases by 4.61 %, indicating that creating a dense fracture network between injection and extraction wells can strengthen the leaching reaction and the seepage process of the leaching solution, resulting in a significant improvement in the efficiency of CO 2 +O 2 ISL. And the CO 2 +O 2 ISL effect is also closely related to matrix permeability, O 2 concentration, HCO 3 - concentration, injection pressure, and fracture aperture. Promoting the continuous formation of high-concentration uranium-containing leaching solution can be achieved by optimizing blasting parameters, reasonably controlling the injection pressure, injecting O 2 in advance, and supplementing HCO 3 - concentration. This study is of great significance for the reservoir stimulation and efficient mining of low-permeability sandstone-type uranium reservoirs.