Impact of Cast Iron Degradation and Cathode Block Erosion on the Current Path in the Cathodic Assembly of Aluminum Production Cells

Carbon-cast iron electrical contact degradation is still considered as one of the main cause for the CVD increase over the lifetime of the electrolysis cell. A thermoelectric finite element model was developed to evaluate the effect of the carbon-cast iron electrical contact degradation and the cathode erosion on the CVD and the current distribution inside the cathodic assembly. Chemical degradation data from laboratory and industrial samples were used to calibrate the cast iron and the contact resistivities. Results demonstrate that the carbon block erosion and the contact degradation at the cast iron interface have a direct impact on the current distribution at the carbon block surface. Both factors increase the CVD when taken separately but the contact degradation outperforms the carbon block wear when taken together.