Measurement Of Physical Parameters Of LaF₃-LiF Molten Salt System And The Influence Of Electric Double Layer On Electric Field

As an important strategic resource of our country,rare earth is known as"industrial monosodium glutamate".In recent years,my country's rare earth industry has developed rapidly,and the production process of rare earth metals has become more and more mature.Among them,molten salt electrolysis is the most commonly used process for preparing rare earth metals.In the process of molten salt electrolysis,the composition and physical and chemical properties of the molten salt electrolyte system are important factors that affect the efficiency of electrolysis.The physical and chemical properties of the molten salt electrolyte system are to choose the appropriate electrolyte composition,control the degree of slagging during the electrolysis process,and obtain The basis for the appropriate electrolysis temperature is also the basis for studying the relationship between the electric double layer effect and the physical field in the electrolytic cell.In this paper,the La F₃-Li F rare earth electrolyte is used as the research object.The viscosity,density,surface tension and conductivity of the molten salt electrolyte system La F₃(82wt%)-Li F(18wt%)when the La₂O₃addition amount is 2.0wt%are measured through experiments.And get the fitting formula with temperature.Use COMSOL Multiphysics simulation software to compare the two types of electrolytes La F₃(82wt%)-Li F(18wt%)and La F₃(85wt%)-Li F(15wt%),and calculate the coupling of electric double layer effect and electric field in the electrolysis process.Analyzing the distribution of the electric double layer in the electrolytic cell and the relationship between the electric double layer and the electric field provide theoretical support for the preparation and production of high-purity and high-grade rare earths.In this paper,the physical and chemical properties of the La F₃-Li F molten salt system were studied under high temperature conditions.It was found that the viscosity,density and surface tension of the system decreased with the increase of temperature,and the conductivity increased.With the addition of La₂O₃increasing from 2.0wt%to 2.5wt%,the viscosity,density and surface tension of the system gradually increase,and the conductivity decreases.When the addition amount of La₂O₃reaches 2.0wt%,the system viscosity is too large to be 583mpa S,it is not conducive to the progress of the electrolysis reaction,the density and surface tension reach the maximum value,and then begin to decrease.Considering the optimal addition amount of La₂O₃is 2.0wt%.By mathematically summarizing the data when the La₂O₃addition amount is 2.0wt%,the required parameters for the simulation are:viscosity fitting formula ln=-3.23252+12.84348/T;density fitting formula:?=2705.04239exp(-T/121.34238)+3.13327;conductivity fitting formula:K=-58.08757exp(-T/(2861.21696))+47.82558;surface tension fitting formula:?=0.25567+(0.08927)/(1+10^((1028.7432-T)(-0.01193))).This paper uses COMSOL finite element simulation software to compare two types of electrolytes.It is found that the La F₃(82wt%)-Li F(18wt%)molten salt system is used for simulation.When the La₂O₃addition amount is 2.0wt%,the cell voltage is higher than that of La F₃(85wt%).The Li F(15wt%)molten salt system dropped by about 0.18V,and the melt pressure drop dropped by about 0.43V.When using La F₃(82wt%)-Li F(18wt%)molten salt system,the current density is more consistent with the actual production current density.Controlling the cell voltage reduction and reasonable current density is conducive to the electrolysis process,and energy saving is achieved.advanced optimization.During the simulation and analysis of the electric double layer-electric field coupling model,this paper found that the electric double layer really exists near the electrode interface.When the electrode is coupled to the electric double layer,both the cell voltage and the melt voltage decrease.With the progress of the electrolysis process,a"bump"of potential will occur in the electric double layer area.This"bump"is expressed as the electric double layer potential.The electric double layer potential will cause the voltage drop of other electrolytes in the melt to increase.This is a factor that must be considered when conducting electric field research.