Study On Electrolytic Process Optimization And Cell Improvement Of 8 KA Neodymium Electrolytic Cell

Rare earth neodymium（Nd）,as an important national strategic material,is widely used in permanent magnet materials,catalytic materials,polishing materials and other high-tech industries.Fluoride molten salt electrolysis is an efficient method to prepare rare earth metals,compared with the traditional smelting method,it has the advantages of high temperature stability,high thermal conductivity,large specific heat capacity and environmental friendliness.However,it is challenging to produce rare earth Nd metal with high efficiency and high qualified rate due to the limitation of electrolytic cell technology and technical means in the process of fluoride molten salt electrolysis.How to improve the relevant electrolytic process,improve the electrolytic efficiency,the recovery and purity of Nd metal is still an urgent problem to be solved in the field of rare earth electrolysis.Based on the three key factors which have an important effect on the efficiency of electrolysis:the proportion of fluoride molten salt,the temperature of molten salt and the structure of electrolytic cell.Therefore,this paper aims to improve the output and purity of rare earth Nd metal by optimizing the above electrolytic process elements,so as to achieve low cost,high efficiency and energy saving rare earth electrolytic production.Specific research work is as follows:（1）Electrochemical workstation is used to monitor the electrical characteristics of molten salt system in the process of molten salt electrolysis.The effects of different proportions of fluoride molten salt and electrolytic temperature on molten salt system are studied firstly via the electrochemical characteristics（such as CV,CA,SWV and LSV）.Under the optimal electrolytic conditions of 10:1（Nd F₃:Li F）fluoride ratio and 1323.15 K molten salt electrolytic temperature,the molten salt system has the strongest reduction,the number of active sites increases,and the conductivity of the molten salt system is better,and the side reactions are less,which is conducive to the formation of Nd metal.In addition,the feasibility of the electrolysis condition is further verified by industrial production.Under these conditions,the recovery of Nd reached the highest value of 93.92%,and the internal impurity content of Nd decreased to the lowest value of 0.386%.The optimization of electrolytic conditions not only improves the electrolytic efficiency,but also lays the foundation for the simulation optimization of the key equipment in the subsequent electrolytic process.（2）Based on the coupling effect of multiple physical fields,COMSOL Multiphysics software is used to simulate 8 k A Nd electrolytic cell under the optimal electrolytic conditions.The influences of anode and cathode distance and cathode penetration depth on the distribution of electric field,current density and temperature field of electrolytic cell are investigated,and the optimization of the cathode structure performance of fluoride molten salt electrolytic cell is realized.The results show that when the optimal distance between the anode and the cathode is 85 mm,and the optimal depth of the cathode inserted into the liquid surface is 450 mm,the current density reaches 1.46×10⁵（A/m²）,the recovery rate of Nd metal is increased from 93.92%to 96.44%,and the internal impurity content of Nd metal is decreased from 0.386%to 0.321%,which improves the production efficiency of electrolytic cell and the purity of Nd metal,and verifies simultaneously the reliability of simulation.（3）In order to solve the practical problem of excessive electrolysis temperature caused by anode and cathode corrosion in electrolytic process,and it is difficult to adjust it to return to the optimum temperature,the method of simulation and industrial design is adopted to further improve and optimize the anode and cathode structure of Nd electrolytic cell.The results show that the coupling of electric field effect is the best when the anode height is 490 mm,the anode and cathode distance is 85 mm,and the cathode is inserted into the liquid surface depth is 440 mm,and the current density reaches to 1.48×10⁵（A/m²）.The reduced range of electrolytic temperature via the depth of cathode insertion into the liquid surface of the new electrolytic cell has been expanded from 0～50 K initially optimized to 0～125 K.The recovery rate of Nd metal increases from 96.44%to 98.18%,and the internal impurity content of Nd metal decreases from 0.321%to 0.226%,which It effectively solves the problem that too high electrolytic temperature cannot be controlled to return to the optimal electrolytic temperature,and further improves the production efficiency and the purity of Nd metal.