Electrokinetic-enhanced sulfuric acid leaching of uranium from sandstone uranium ores

Solute transport in conventional acid leaching of sandstone uranium ores is limited by diffusion and convection, resulting in extended leaching cycles. This study described an electrokinetic-enhanced method for leaching sandstone uranium ore with sulfuric acid and was intended to investigate the impacts of potential gradients on leaching efficiency. Electrokinetic horizontal column leaching experiments were conducted on sandstone uranium ore. After 20 h of leaching, the uranium leaching efficiencies were 54.90 %, 56.36 %, 68.33 %, and 82.04 % for potential gradients of 0, 0.5, 1.0, and 2.0 V/cm, respectively. The uranium leaching efficiency of sandstone at a 2.0 V/cm potential gradient was 27.14 % greater than that at a 0 V/cm potential gradient, and the leaching time was decreased by approximately 40 % at the same uranium leaching efficiency. Analyses of the chemical fraction of uranium, XRD and SEM-EDS showed that the applied potential gradient facilitated solute transport during leaching, thus accelerating the leaching efficiency of adsorbed uranium, tetravalent uranium, and uranium encapsulated in lattices of silicates and primary and secondary minerals in sandstone uranium ores. Therefore, electrokinetic action is excellent for enhancing the effectiveness of sulfuric acid leaching of sandstone uranium ores and has broad application prospects.