Melt Penetration and Chemical Reactions in 16 Industrial Aluminum Carbon Cathodes

The study shows examples of the distribution of melt components in spent carbon cathodes from 16 industrial aluminum electrolysis cells shut down after 10 to 2534 days. The concentration of the phases was determined by quantitative X-ray diffraction (XRD), and the distribution was found by analyzing series of samples from several vertical cores from each cathode. The results show that the analysis is useful for characterizing phases in spent potlining, and the detailed distribution graphs are suitable for comparing different parts of a cathode, or different cathodes. The composition of the melt in the 16 cathodes changed systematically over time, and the stages in the evolution, the effect of the cathode material type, and the effect of the melt on the lining are discussed.