Law and Mechanism of Different Electric Field Modes Enhancement Alkaline Leaching Sandstone-type Uranium Ore

China’s uranium resources are rich in reserves and deposits, but they are mainly low-grade uranium ores with low content of uranium. Sandstone-type uranium ores are mainly mined by in-situ leaching (ISL), but when the carbonate content is high, their efficient development is often limited by problems such as gas plugging in acid leaching or insufficient neutral leaching efficiency. In this paper, a method for electric field enhancement alkaline leaching sandstone-type uranium ores was proposed. Firstly, shake flask experiments were conducted using different concentrations of sodium carbonate, sodium bicarbonate and potassium permanganate as lixiviant, and the concentration of the optimal lixiviant as 35 g/L sodium carbonate + 15 g/L sodium bicarbonate + 3 g/L potassium permanganate is obtained. At this ratio, through a self-designed electric field enhancement leaching experimental device, the effects of four different electric field modes in enhancing the alkaline leaching of sandstone-type uranium ores were compared within 40 d to systematically study the behavior and laws of uranium in alkaline leaching under different electric field conditions, namely stabilized electric field (continuously energized), alternating electric field (continuously energized but exchanging the direction of the electric field every other day, and the initial electric field direction is the same as the stabilized electric field), intermittent electric field (de-energized for one day followed by re-energized for another day, with a duty cycle of 50%), and non-electric field (not energized). The results show that under the effect of alternating electric field, the leaching efficiency of uranium is the highest, about 51.28%, which is 2.81 times higher than that of the no electric field group. And the leaching mass of the gangue mineral (silicon) is the least under the alternating electric field, which is about 71% that of the no electric field group. The alternating electric field can effectively reduce the deposition of silicate minerals on the surface of uranium ore and enhance the surface activity of uranium ore. The analysis results by inductively coupled plasma emission spectrometer (ICP-OES), field emission scanning electron microscope with energy dispersive spectrometer (SEM-EDS), Zeta potential analyzer, and specific surface area analyzer (BET) demonstrate that the electrokinetic effect primarily enhances the efficiency of alkaline uranium leaching by promoting the dissolution of uranium minerals and gangue minerals, as well as the migration of leached elements. The electric field enhancement alkaline leaching of sandstone-type uranium ores effectively improves the leaching efficiency of uranium, providing a theoretical foundation and technical support for practical field applications.