Abstract:Because of the increasingly prominent problem of alumina content inhomogeneity in large or super-scale aluminum reduction cells, a transient numerical model for the alumina mixing process was developed for a 400 kA cell, and the relationship between the alumina content distribution and electrolyte flow field was analyzed. In the ANSYS software platform, several numerical simulation cases were presented to display the influence of the feeder configuration on the alumina mixing characteristics. The results showed that a large vortex flow of the molten electrolyte is beneficial for alumina mixing and uniform distribution in the inner areas of the vortexes. The alumina particles reach the inter-electrode zone in 10-15 s from the beginning of the feeding action, and the risk of early precipitation occurs in 10-25 s after the feeding. It was also found that a suitable grouping of feeders could reduce the content fluctuation and gradient. Therefore, a feeding on demand strategy was proposed, and the simulation results showed that although the spatial characteristics are not changed, the uniformity of the alumina content was markedly improved.

Key words: aluminum electrolysis; content distribution; feeder configuration; alumina precipitation