Enhancing leaching efficiency of ion adsorption rare earths by ameliorating mass transfer effect of rare earth ions by applying an electric field

Improving the seepage of leaching solution in the ore body and strengthening the mass transfer process of rare earth ions during in-situ leaching are two critical methods to improve the leaching efficiency of rare earth. In this study, 2 wt% MgSO4 solution was used for the indoor simulated column leaching experiment on rare earth samples and an electric field was applied at both ends of the samples. Then the effects of different intensities, initial application time and duration of the electric field on the rare earth leaching system and its mechanism were investigated. The results show that compared with the single MgSO4 solution leaching, applying an electric field with a strength of 6 V/cm can save the leaching time of 30 min and increase the flow velocity of the rare earth leachate by 26.98%. Under the optimal conditions of applying an electric field with a strength of 6 V/cm for 20 min to the leaching system after 10 min of rare earth leachate flowing out, the leaching efficiency of samples increases from 81.20% to 86.05% with the increase of 4.85%. The mechanism analysis shows that when a direct current electric field is applied to the rare earth leaching system, rare earth ions rapidly change from disorderly movement with the seepage into faster and directional movement. In addition, the seepage of the leaching solution is also improved due to the increase of the cross-sectional area of the seepage channel, the polarized water molecules migrate directionally by force from the negative pole, and the movement of the hydrogen is generated by the electrolytic water. More importantly, based on the principle of in-situ leaching process, the layout of injection holes and deflector holes in this process provides a natural site for the electrode layout of the electric field. With the simple equipment and the operation, the rare earth leaching process with the applied electric field has high feasibility in industrial application.