Simulation And Discussion On The Flow Field And Electric Field In The Rare Earth Molten Salt Electrolysis Cell

Molten salt electrolytic method is an important method for producing RE metals and alloys. It is important of each physical fields inside the electrolysis cell for the stability of production, product quality and production efficiency, especially for flow field and electric field. The research of flow field and electric field in RE electrolysis cell not only provide a theoretical basis for the improvment of the cell, but also lay a good foundation for the research of the new cell. Because of the high temperature and high corrosion resistance of electrolyte in the process of electrolysis, it is difficult for the research of the electrolytic process. In this pape, the software of ANSYS was used for the study of the electrolyte movement and the electric field inside the electrolytic cell by numerical simulation, investigated the distribution of the flow field and electrolyte voltage, and the result of the numerical simulation has been verified by physical simulation, in order to make suggestions for the improvement of cell structrue and the optimizing of operating parameters.The 6 kA RE electrolysis cell of upper cathode was choosed for the rasearch of gas liquid two phase flow by RSM.The results show that, anode gas produced durring the electrolytic process escaped from electrolytic cell near the inner surface of anode by buoyancy. These was no anode gas in the bottom of the cell. Durring the anode gas escaped from the cell, the velocity of the electrolyte reached the maximum, at the distance of 50 mm below the free surface and 5 mm from the inner wall of the anode, it was 1.2 m/s.These was a upwelling near the inner of the anode and a down flow near the cathode in the electrolytsis cell. This trend made a larger vortex phenomenon between the anode and cathode. At the distance of 30 mm below the free surface and 5 mm from the inner wall of the anode, the velocity of the electrolysis reached the maximum, it is 0.9 m/s. At the bottom of the cell, The movement trend of the electrolyte was very weak, the velocity are all less than 0.01 m/s, belongs to flow dead zone. Through the water model experiments for the original cell structure, we found that, the flow trend of the water was very weak at the bottom of the model. The trace particle could accumulation at the edge of the bottom, and verified the conclusion of numerical simulation that, there was a dead zone at the bottom of the cell.In order to improve the flow field at the bottom of the cell, The gas blowed to the bottom of the cell, through gas stirring we found that, these was an anticlockwise vortex at this zone, and the vortex becomes more obviously because of the increase of the speed of the gas. The velocity of the electrolyte in this zone increased more than 10 times. The velocity of the electrolyte reached the maximum, at the distance of 90 mm below the free surface and 25 mm from the inner wall of the anode, it was 1 m/s. Through the water model experiments, we found that, the flow speed of the water at the bottom of the model increased obviously. The distribution of trace particle was more homogeneous, and verified the rationality of the model of gas stirring.Through the numerical simulation to the electric field inside the cell, we found that, the electrolyte voltage gradually inceresed with the electrolytic and increase of the pole pitch, and at the same time, the electrolyte voltage diminishing with the increase of the diameter of the acthode and the increase of the depth of the electrode. The decomposition voltage accounted for over 20%, the structure voltage accounted for over 40%, and the electrolyte voltage accounted for 30-40% of the overall cell voltage.