Uneven Cathode Wear in Aluminium Reduction Cells

Abstract

The service life of aluminium reduction cells is limited by cathode wear. A typical wear pattern has been reported as a single or double "W" profile. The uneven cathode wear appears to be controlled by multiple mechanisms such as non-uniform current distribution and carbide dissolution. According to our analyses, formation of aluminium carbide that dissolves into a bath film located on the cathode surface is the dominating mechanism. A dynamic model was developed in order to calculate the local carbide formation as well as cathode wear rate. The present model utilizes a simplified geometry where the metal flow, which is driven by the Lorentz force, results in shear stress and motion of the bath film. The simulations demonstrate how the local current distribution and the mass transfer of aluminium carbide from the cathode surface and into the bath film result in uneven cathode wear profiles.