The Leaching Model Of Ion-adsorbed Rare Earth Ore And Calculation Of Solute Transport

In the current stage of ion-adsorption rare earth mines,the concentration and dosage of leaching agent during leaching are mainly determined by simple laboratory tests and engineering experience.It is easy to overestimate the amount of leaching agent and cause serious ammonia nitrogen in the mining area and its surrounding environment.Exceeded.To reduce the residual amount of leaching agent in the ore body by rationally designing the concentration and amount of leaching agent according to local conditions is a direct means to reduce environmental pollution caused by in-situ leaching technology of rare earth mines from the source.Ion adsorption type rare earth leaching is essentially an ion exchange and migration process.The cup leaching test with the change of liquid-solid ratio is used to explore the relationship between the quality of rare earth ore and the amount of leaching agent during rare earth leaching,and to establish ion exchange experience for ion adsorption type rare earth ore.Model;Analyze the influence mechanism of leaching agent anion on cation exchange,use Langmuir model to describe the influence of anion,describe the cation exchange process with mass effect model,establish a shielding model for rare earth leaching;analyze the effect of impurity cations on rare earth ion exchange Influence mechanism,adopt ion competition exchange analysis method to establish a competitive ion exchange model of rare earth ore considering the influence of impurity ions;use the established exchange model as the source and sink term,and combine the convection-dispersion equation to construct the numerical value of ion adsorption type rare earth leaching process Simulation method to study the influence of liquid-solid ratio,anion and impurity ion on rare earth leaching,and to guide the design of leaching agent concentration and dosage.In the process,the following conclusions were obtained:(1)Using ammonium sulfate as a leaching agent,a cup leaching test with different liquid-solid ratios was carried out.Experiments show that the concentration of added ammonium ions has a negative exponential relationship with the residual rate of rare earths,and an empirical model of ion exchange process for ion-adsorption rare earth ore is established.By comparing with the Kerr model,the proposed empirical model can describe the actual situation of the changing liquid-solid ratio during the rare earth leaching process,and the calculation accuracy of the low-concentration area is better than the existing Kerr model.(2)The effect of different concentrations of ammonium sulfate and ammonium chloride on the test results of rare earth grades was studied.The results showed that the grade of rare earths is negatively correlated with the anion concentration.The amount of shielded rare earth ions varies with the anion concentration in the Langmuir form.Quantitatively,on this basis,a shielding model considering the influence of anions on the leaching of rare earth ions was established.Ammonium sulfate and ammonium chloride are used as leaching agents to extract rare earths.At low ammonium ion concentration,at the same ammonium ion concentration,compared with ammonium chloride,ammonium sulfate is used as a leaching agent to extract more rare earth ions;When the concentration is higher,compared with ammonium sulfate,using ammonium chloride as a leaching ore can extract more rare earth ions.The shielding model can reasonably express the difference between ammonium sulfate and ammonium chloride leaching.(3)Use ammonium chloride(in order to avoid the combination of sulfate and metal ions in the solution to produce precipitation)as a leaching agent to leaching rare earth ore,and analyze the type and content of metal ions in the leaching solution by XRF and ICP-MS testing methods.The results show that when the ammonium ion concentration is low,compared with rare earth ions,the impurity ions such as Ca²⁺,Fe³⁺,Al³⁺,and Cr²⁺in the ore body will preferentially undergo ion exchange reaction with ammonium ions.Combining the law of rare earth ions and impurity ions to compete for exchange of ammonium ions in the solution,based on the shielding model,a competitive ion exchange model considering the influence of impurity ions is established,and calcium ions are used as the main impurity ions for verification and analysis.By comparison with the shielding model,It can be seen that when there is a competitive exchange situation,the accuracy of the competitive ion exchange model is better than that of the shield model.(4)The Kerr model,the shielding model considering the influence of anions on the leaching of rare earths,and the competitive exchange model considering the influence of impurity ions on the leaching of rare earths are used as the source and sink terms,and the convection-dispersion model is used to describe the migration process of ions,and an ionic rare earth is established.Numerical simulation method of leaching process.Under the same working conditions,the peak concentration of the ion penetration curve of the Kerr model is lower.In the case of low concentration and low dosage,the shielding effect of anions promotes the leaching of rare earths,while the presence of impurity ions has a significant inhibitory effect on the leaching of rare earths.