Effect Of Pressure Gradient And Pore Ratio On Ionic Rare Earth Column Leaching Process

Rare earth elements have been applied in many fields and have high economic value.Therefore,countries have paid more and more attention to rare earth resources,and ion-adsorbed rare earths are rich in medium and heavy rare earths,so they are also listed as precious strategic rare earths in my country.mineral resources.At present,many scholars have done various researches on the existing in-situ leaching technology,and have achieved many results.However,the current rare earth leaching technology still has various problems such as long leaching cycle.A series of researches have been carried out through the combination of experiment,theory and numerical simulation,aiming at the long leaching period of the in-situ leaching process.Through the equilibrium leaching test of ionic rare earth ore,the influence of aluminum sulfate concentration on the leaching effect of rare earth ions was studied,and the Kerr model selection coefficient,a parameter to measure the degree of ion exchange reaction,was determined;through the column leaching test,aluminum sulfate with different pressure gradients was set Solution and ore samples with different void ratios were used to explore the influence of pressure gradient and void ratio on the leaching effect of ion-adsorbed rare earths,and the following research results were obtained:(1)The equilibrium leaching experiment with aluminum sulfate as the leaching agent was carried out,and the equilibrium ion exchange selection coefficient of the reversible reaction Kerr model was determined.Five groups of aluminum sulfate with a concentration of 1g/L-10g/L were used to conduct leaching tests.From the test results,when the aluminum sulfate concentration was less than 8g/L,as the aluminum sulfate concentration increased,the concentration of rare earth ions in the solution also increased.When the concentration of aluminum sulfate exceeds 8g/L,the variation range of the concentration of rare earth ions in the solution is obviously smaller.The Kerr model was used to analyze the test results,and the equilibrium ion exchange selectivity coefficient of the Kerr model was obtained as 0.4876.(2)The column leaching test of aluminum sulfate solution under different pressure gradients was carried out,and it was found that the greater the pressure gradient,the greater the seepage flow rate and the shorter the leaching period.Under different pressure gradients,the concentration of rare earth ions reached the peak concentration at about 30 m L-40 m L of the liquid,indicating that the peak concentration during the column leaching process is only related to the amount of leaching agent entering the ore column.(3)The rare earth ore samples with different void ratios were selected for aluminum sulfate column leaching experiments.The results showed that the larger the void ratio,the greater the seepage flow and the shorter the leaching period.Different void ratios have influence on the appearance time of rare earth ion leaching concentration peak,but have little effect on the size of the concentration peak.According to the rare earth leaching rate curve under different conditions,it is concluded that accelerating the seepage movement within a certain range can reduce the rare earth leaching cycle without affecting the rare earth leaching rate.(4)Numerical model of rare earth column leaching was established by COMSOL software,and the effects of pressure gradient and void ratio on the leaching agent concentration and rare earth concentration during the column leaching process were studied.The results show that the pressure can promote the seepage movement of the leaching agent in the ore pillar.The greater the pressure gradient,the faster the seepage velocity,the earlier the liquid discharge time,and the earlier the rare earth concentration peak.The increase of the void ratio can also strengthen the seepage movement in the ore pillar and achieve the purpose of reducing the leaching cycle.The simulation calculations selected a suitable pressure for the column immersion simulation to reduce the immersion cycle.