Two-dimensional Infiltration Process Solution Seepage Characteristics And Rare Earth Ion Leaching Process Regulation

Ionic rare earth ore is a vital strategic mineral resource in China,and currently,in-situ solution leaching is the main mining method.The long-term production practice shows that the lack of theoretical guidance on the injection method of this process is the main reason for low rare earth recovery and secondary re-irrigation.Therefore,an in-depth understanding of the solution flow and rare earth leaching pattern during in situ mineral leaching is of great significance in optimizing the mineral leaching process and guiding the efficient leaching of rare earth.In this paper,relying on the National Natural Science Foundation of China projects（52174113,51904119,51874148）,a soil sample from an ionic rare earth mining area in Ganzhou City,Jiangxi Province was used as the test object.A two-dimensional box-type mineral leaching model was designed to investigate solution percolation characteristics and rare earth ions’leaching laws.According to the law of leaching,the solution infiltration process is regulated by an alternate injection method to achieve the purpose of uniform mineral leaching.The main research contents and conclusions are as follows:（1）Use different mass concentrations of MgSO₄ to conduct single-hole injection leaching tests,simulate the concentration difference of leaching agents in different areas of the mine,and research the law of solution seepage and rare earth ion leaching.The results show that the heterogeneity of the ore body structure dramatically influences the solution seepage,the uniform infiltration process of the solution conceals the existence of the preferential flow,and the ore body liquid rate gradually decreases and then tends to be stable.When the single-hole liquid injection is performed,the control range of the single-hole mineral leaching is wider,and the rare earth ions migrate and gather with the solution to both sides of the ore body under the action of convection.The migration amount increases with the increase of the lateral migration distance.At the same time,the wide mineral leaching control range leads to a longer leaching cycle and leaching tailing,etc.Increasing the concentration of leaching agents will promote the migration of rare earth ions.（2）Adopt the method of multi-hole liquid injection and narrow the mineral leaching range of a single hole,simulate the in-situ leaching process,and investigate the solution seepage and rare earth ion leaching law when the intersection and convergence of the solution after liquid injection.The infiltration rate of the solution in the confluence area is higher when the multi-hole injection is performed,and the distribution of the output volume is more uniform than that of the single-hole injection.Porous liquid injection shortens the lateral diffusion distance of the solution,reduces the migration of rare earth ions,and leaches more uniformly.The rare earth ions gather with the solution to the intersection area,so the mass of rare earth leached in the intersection area is the largest,followed by the boundary area,and the area directly below the injection hole is the least.This is of great significance for understanding the distribution of residual rare earth elements in the wasteland and guiding the re-irrigation of the wasteland.（3）According to the general law of in-situ leaching solution seepage and rare earth ion leaching,alternate liquid injection is used to regulate the infiltration process of the solution and make the rare earth leaching more uniform.The continuous change of the seepage direction of the solution during the alternate liquid injection will significantly disturb the ore body,resulting in the blockage of some fluid outlet holes,the relative weakening of the liquid injection intensity,and the increase of the mineral leaching time.However,the degree of migration and enrichment of rare earth ions is further reduced,the leaching of rare earth is more uniform,the concentration of rare earth ions in the overall leach solution is increased,and the amount of leaching agent is reduced.Therefore,in terms of the amount of leaching mineral agent and the treatment of mother liquor,it is better to use alternate liquid injection to leach ore.However,from the perspective of leaching mineral time,the method of alternate fluid injection has no advantage,and the leaching time required is longer.