Holographic Simulation Of Electric Field In High Current Rre Erth Mlten Salt Electrolyzer

As an important strategic resource in China,rare earth plays a very important role in various fields.With the development and application of new materials in China,the demand for rare earth metals is also increasing.In recent years,with the rapid development of rare earth industry in China,the electrolytic process of rare earth metals is becoming more and more mature,and the capacity of single electrolytic cell is becoming larger and larger.How to comprehensively and accurately understand the electric field distribution in electrolytic cell is of great significance to improve the electrolytic cell.In this thesis,according to the actual electrolysis process of 6k A single-cathode electrolytic cell,considering the effect of double electric layer on the electrode surface,the distribution of bubbles generated by the electrode and the structure of the cell on the electric field,the whole electric field holographic mathematical model of crucible,electrode and melt is established,which is of great significance to the improvement of the cell type of rare earth electrolytic cell.In this thesis,laf3-LiF rare earth electrolyte is taken as the research object,and the method of combining experiment and numerical simulation is adopted to measure the double electric layer capacitance of molten salt electrolyte system laf3-LiF when the La2O3 content is 2.0wt%through experiment.Comsol finite element software was used to establish the crucible-electrode-melt electric field model,and the electric field and flow field of molten salt electrolysis cell under different current conditions were simulated.The influence of parameters such as tank material on electric field distribution in molten salt electrolysis process is revealed,which provides theoretical basis for the optimization of molten salt electrolysis production.The main research contents are as follows:（1）In this thesis,the capacitance of laf3-LiF rare earth electrolyte system measured by electrochemical experiments is equivalent to the double layer capacitance.The capacitance of molten salt electrolyte system LaF₃-LiF measured by AC impedance method is 29.4μF when the La₂O₃ content is 2.0wt%.The capacitance of molten salt electrolyte system LAF₃-LIF is 27.8μF.（2）Taking 6k A rare earth electrolytic cell as the research object,Comsol finite element software was used to establish the electric field model of rare earth electrolytic cell,and the influence of three different graphite materials as crucible on the current efficiency of rare earth electrolytic cell was analyzed.It was found for the first time that a part of the current returned to the bottom of the cathode through the graphite crucible and the metal receiver at the bottom to form a loop.This part of the current did not participate in the actual electrolysis and was a part of the current loss.At the same time,the metal receiver indirectly becomes the anode when the circuit is formed,which may be the main reason for the oxidation loss of the metal receiver.When the crucible is semi-graphitic,semi-graphitized and graphitized,the current on the cathode surface is 5643.2a,5643.9A and 5644.6A,respectively.The current efficiency is 94.0533%,94.065%and 94.0767%respectively.By analyzing the simulation results,further optimization is made for the energy saving link.（3）Graphitized material is used as crucible material,and the distribution of electromagnetic field is simulated.The study shows that the main area of electrolysis is between anode and cathode,and the main distribution area of magnetic field generated by current,and the magnetic field is distributed in the circumferential direction,and the radial and axial components are zero.Then the equivalent double layer capacitance measured in the experiment was brought to the model of rare earth electrolytic cell,and the curve of anode and cathode potential change was obtained under different current conditions.With the increase of current,the anode surface potential also increased,and the double layer had more obvious influence on the cell voltage.（4）The flow field-electric field coupling numerical simulation of rare earth electrolytic cell under different current conditions was carried out by coupling the electric field to the flow field,and the cell voltage change of rare earth electrolytic cell was obtained.The cell voltage increased by 0.02V before and after coupling of rare earth electrolytic cell under 4000A condition.The cell voltage increases 0.03V before and after the coupling of 6000A rare earth electrolytic cell;The cell voltage increases by 0.05V before and after coupling of 8000A rare earth electrolytic cell.The cell voltage increases0.06V before and after the coupling of 10000A rare earth electrolytic cell;The voltage of12000A rare earth electrolytic cell increases by 0.07V before and after coupling.The coupling simulation analysis of electric field and flow field provides a theoretical basis for the development of large rare earth electrolytic cell.