The Concentration Of Leaching Solution Affects The Leaching Effect And Mechanism Of Ion-type Rare Earths

Rare earth elements have high economic value,especially medium and heavy rare earth elements.The ion-adsorbed rare earth ore is formed by the adsorption of rare earth elements on the surface of clay minerals in ionic or hydrated cationic state.It is the main source of medium and heavy rare earth elements in the world.In recent years,Chinese and foreign scholars have carried out a series of studies on the exploitation and utilization of such rare earth minerals,and have obtained many useful conclusions on in-situ leaching mining technology.However,there are still a series of problems such as slow leaching speed and low leaching rate in the in-situ leaching process,in which immersion concentration is an important factor.The leaching solution has two processes of molecular diffusion and convection-dispersion in the ionic rare earth ore body.The concentration difference causes the difference between the molecular diffusion speed and the convection-dispersion speed,which directly affects the final leaching efficiency.Aiming at these problems,an ion-adsorbed rare earth ore in Longnan,Ganzhou was selected as the research object.Different concentrations of MgSO₄ solution were used as the leaching agent to analyze the diffusion and migration process of solute in different concentrations of leaching ore in rare earth ore bodies.The influence mechanism of immersion concentration on the leaching efficiency of rare earth ore body,so as to obtain the optimal leaching concentration which is favorable for leaching efficiency.This paper mainly conducts a series of researches by the way of laboratory tests,including the following contents.?1?In order to obtain the basic physical properties of the undisturbed rare earth which can provide reference for remolding soil samples.The wax,the pycnometer method,the drying method and the sieving method were used to test the basic physical parameters of density,gravity,specific gravity,water content and particle size distribution of undisturbed soil.The dynamic viscosity of each concentration of MgSO₄ leaching solution was measured by gravity capillary method,and the concentration was positively correlated with the dynamic viscosity.?2?In order to explore the influence of leaching solution concentration on the solute diffusion rate in the leaching process,the lateral leaching experiment under the simple diffusion method was designed by means of the conductivity sensor.The leaching chemical reaction process was explored by the change of soil conductivity,The results show that when the concentration is less than 5%,the solute transport rate is positively correlated with the concentration,but when the mass concentration exceeds 5%,the solute transport rate begins to decrease.?3?In order to explore the relationship between the concentration and viscosity of the leaching solution and the convection-dispersion rate of the solute during the leaching process,the leaching test was carried out using the constant water head,and five soil conductivity measuring points were set at a certain interval,and through the change of conductivity value in the leaching process,the convection-dispersion speed of solute was calculated,The results show that when the mass concentration is less than 4%,the solute transport rate is positively correlated with the concentration of leaching solution,and when the mass concentration is more than 4%,the solute transport rate is negatively correlated with the concentration.?4?In order to investigate the effect of MgSO₄ leaching solution concentration on rare earth leaching rate,leaching rate and leaching efficiency under diffusion and convection-dispersion coupling,a rare earth tube injection-column immersion test was designed,and each 200ml leaching solution was measured by EDTA titration.The leaching rate,leaching speed and leaching efficiency of rare earth MgSO₄ leaching rare earth were obtained.The optimum concentration of MgSO₄ leaching agent was selected by synthesizing the transport law of leaching agent solute in rare earth ore body and the optimum concentration of leaching solution for rare earth leaching efficiency is 4%-5%.