Impact of the existence of carbonate minerals on the performance of CO2+O2 during in situ leaching in uranium deposits

Uranium is a strategically important economic mineral, with sandstone uranium mines typically utilizing CO 2 +O 2 in situ leaching. Previous research predominantly examines seepage processes and chemical mechanisms of in situ leaching. Few studies have addressed how carbonate mineral dissolution-precipitation impacts uranium recovery or strategies to reduce dead zones. To this end, a multi-physical (stress-seepage-chemistry) model is proposed. The model is implemented and solved by COMSOL Multiphysics (5.4a) with suitable boundary conditions and parameters. The presence of carbonate minerals in uranium deposits facilitates uranium leaching. Higher initial carbonate concentrations correlate with increased uranium recovery and reduced dead zones where the leach solution cannot penetrate. Increased deposit permeability encourages the dissolution and precipitation of carbonate minerals while reducing dead zones. Higher injection rates do not improve uranium recovery but promote the dissolution and precipitation of carbonate minerals near the injection well and decrease dead zones because of the overall rise in deposit permeability. Appropriately reducing the production rate enhances uranium recovery, but does little to address the dead zones. This work evaluates the impact of different parameters (CO 2 concentration, O 2 concentration, permeability, carbonate mineral concentration, injection rate, and production rate) on uranium recovery, establishing a foundation for optimizing the in situ leaching strategy.