Thermo-Electric Field Analysis And Parameter Optimization Of Rare Earth Electrolysis Process

Rare earth is a kind of rare element with great strategic significance in modern industry.As an important non renewable resource,rare earth is widely used in many advanced fields because of its excellent physical properties.Molten salt electrolysis is widely used to prepare a large number of mixed rare earth praseodymium and neodymium metals.Its working principle is that direct current is applied between the negative and positive poles of the electrolytic cell.Because the rare earth oxide in the electrothermal effect cell is melted into liquid electrolyte at high temperature,the internal redox reaction occurs,that is,the metal ions at the cathode get electrons and are reduced to rare earth elements.The key equipment of molten salt electrolysis is the rare earth electrolytic cell,but the domestic electrolytic smelting equipment generally lags behind the foreign countries,and there is a great waste in the development of rare earth resources.Whether the structural parameters of rare earth electrolyzer are suitable or not plays an important role in the efficient development of rare earth resources.At present,most of the electrolyzer manufacturers test their electrolytic efficiency by manufacturing electrolyzers with different structural parameters.This way has a long development cycle and high cost.Therefore,it is necessary to simulate and analyze the physical field related to praseodymium and neodymium cell electrolysis process according to the reliable theory,and simulate the influence of different structural parameters on the physical field in the cell,so as to provide effective theoretical support for the actual optimization of cell structural parameters.There are many complex physical fields,such as electric field,magnetic field,temperature field,flow field and so on.In these physical fields,electric field is the basic field in the cell,and the temperature field produced by the electrothermal effect is the key to determine whether the electrolytic reaction can occur normally.Therefore,it is necessary to simulate the coupled electric field of rare earth electrolyzer by modeling.In this paper,the 6KA Pr-Nd electrolyzer is taken as the research object,and the multi physical field finite element analysis software COMSOL is used to simulate the electrothermal field coupling of the electrolysis process of 6KA Pr-Nd electrolyzer with different cathode diameter and different depth of the cathode inserted into the electrolyte.Through the way of computer modeling and thethree-dimensional model of praseodymium and neodymium cell is established,with different cathode size and cathode inserted into the electrolyte In order to find out the reasonable structure parameters of the electrolyzer,the influence of different cathode diameter and different depth of the cathode inserted into the electrolyte on the electrothermal field was analyzed.And using the conclusion that the temperature regulation in the cell can be realized by raising and lowering the depth distance of the cathode bar in the cell,the test device of the cell is constructed to verify the rationality of the simulation results.Through a number of simulation experiments,it is concluded that when the diameter of cathode is 80 mm,the insertion depth of cathode is 380 mm,the maximum temperature of the cell is about 1370 k,which can produce enough Joule heat for the 6KA Pr-Nd electrolyzer and achieve good electrolysis efficiency.Several experimental results show that the relative error between the simulated temperature and the actual measured temperature is less than 1%,which proves that the simulation results are more reliable,and can provide some reference for the optimization of cell parameters by using COMSOL numerical simulation.