Numerical simulation of cathodic voltage drop in Hall-Héroult cell

Abstract

Numerical simulations are widely used to predict cathode voltage drop in Hall-Héroult cells and to determine the qualifications needed for voltage savings. The aim of this study is to investigate the effect of change in the properties of cathode assembly materials with temperature, the effect of the copper insert in collector bar and effect of change in cathode design on the cathodic voltage drop, horizontal current density and potlife. Thermal and electrical measurements were performed on twenty cells to validate the model results. The results proved that resistivity of both collector bar and cathode block is considered the main property that controls the cathodic voltage drop in the cells. While the copper insert has a much higher potential for providing a lower cathode voltage, great effect on the horizontal current density in the cell and increases the expected potlife. However, the choice of cathode assembly materials must be compatible between cathodic voltage drop and horizontal current density. Therefore, these items have been examined for different cases to reach optimal conditions. The results show that select anthracitic with 30% graphite cathode blocks and adjust the resistivity of steel collector bars and cast iron, as well as insert copper in the steel collector bar, are effective in bringing down the cathodic voltage drop, lower the electro-erosion of the cathode block and the expected potlife will be increased.