Research On Seepage-Reaction-Stress Coupling In The Leaching Process Of Ion-Type Rare Earth Ore

Rare earth elements have high economic value.With the rapid development of science and technology,the application in new materials,new energy and other fields has gradually been widely used.The world's demand for rare earth resources is increasing and has become a strategic resource for all countries.Therefore,scholars at home and abroad have done a lot of research on the mining and utilization of rare earth ore,and have drawn many useful conclusions in the in-situ leaching process.However,the current in-situ leaching technology still has a long leaching cycle and recovery rate.The issue of low level restricts the sustainable development of the rare earth industry.Considering the principle of the in-situ leaching process,the leaching process is a seepage process involving the participation of chemical reactions and the action of multiple physical fields.In order to reflect the complex leaching process,it combines geomechanics,chemical reaction kinetics,and porous media.Design stress permeation leaching test in terms of fluid mechanics and solute transport in the leaching process,and control different injection hydraulic pressures and axial pressure confining pressures through infiltration instruments to simulate the environment where in-situ leaching is subjected to stress during the injection process,so as to explore the leaching process The influence of medium injection hydraulic pressure,axial pressure,confining pressure on seepage movement and leaching laws;at the same time,the porous media fluid dynamics,chemical reaction dynamics and rock and soil mechanics are combined through the COMSOL Multiphysics software to establish the seepage-reaction-stress coupling value The model is used to study the temporal and spatial evolution of the distribution of seepage field,concentration field and stress field in the process of column leaching with three different loads of hydraulic pressure,axial pressure and confining pressure.The following are the main research conclusions:(1)First of all,for the column leaching process,the leaching agent flows into the ore column and is subjected to different sizes of hydraulic pressure.Observation from the results of the triaxial penetration experiment shows that when the injection pressure is 10 k Pa,the time for the leaching solution to reach the peak concentration is 339 min,When the injection pressure increases to 50 k Pa,the peak time is 79 min,and the peak concentration of 10k Pa is greater than the concentration at 50 k Pa,indicating that increasing the injection pressure can increase the fluid's seepage velocity in the porous medium of the ore body and help reduce the leaching cycle;But analyzing the RE³⁺peak concentration data in the leachate flowing out of the ore body,it can be concluded that the increase in injection pressure reduces the RE³⁺peak concentration of the leachate to a smaller extent.(2)When the pillar is subjected to axial stress,the ore body will strain in the axial direction.The change in the shape of the pillar makes the internal pore distribution more compact.The analysis of the results of the leaching experiment shows that the increased axis The pressure reduces the permeability coefficient of the pillar.When the axial pressure is 50 k Pa,the time to reach the peak concentration of the leachate is 186min.When the axial pressure increases to 50k Pa,the peak time is 271 min,which prevents the leaching agent from being in the rare earth mine.As the axial pressure increases,the longitudinal depth of the ore pillar's geometric model gradually increases.The position of the leaching solution in the ore pillar has a small distribution gap,and the peak concentration of the leaching solution increases with the increase in axial pressure.The increase of the axial pressure increased,and the RE³⁺peak concentration difference between the axial pressure of 50 k Pa and 250 k Pa was 0.36 g/L,indicating that increasing the axial pressure increased the leaching rate of rare earths.(3)For the leaching process in which the confining pressure acts on the pillar,the mechanism is similar to the coaxial pressure.The geometry and pore structure of the pillar are changed in the radial direction to reduce the permeability coefficient of the pillar.When the confining pressure is 50 k Pa,the leaching liquid The time to reach the peak concentration is132 min.When the confining pressure increases to 50 k Pa,the peak time is 339 min,which has a greater influence on the seepage movement of the extractant than the axial pressure.At the same time,analysis of the simulation results shows that the confining pressure is 50 k Pa The difference between the RE³⁺peak concentration of 250 k Pa and the peak concentration is 0.51g/L.Increasing the confining pressure has a greater effect on the increase of the peak concentration of the leachate than the axial pressure,indicating that increasing the confining pressure can increase the leaching rate to a greater extent.