Improved CFD Modeling of the Whole-Cell Side Ledge Behavior in Aluminum Electrolysis Cell

A computational fluid dynamics (CFD) model was developed based on the start-up, operation, and temperature fluctuations of the industrial aluminum electrolysis cell to forecast the shape, thickness, and transient behavior of the whole-cell side ledge. Results indicate a strong correlation between the shape and thickness of the side ledge and melt flow. Driven by electromagnetic force (EMF) and bubble disruption, the side ledge attached to the electrolyte is rough and uneven, whilst the toe adjacent to the metal is flatter. The modeling reliability is validated against autopsy and test data in an industrial cell. During the anode effect (AE), the electrolyte temperature and superheat increase significantly and return to normal after 30 min. The side ledge demonstrates a rapid response to the overheating, with a melting speed of 0.02 m³ K⁻¹ within 30 seconds AE, and the side ledge volume is reduced by 16.9 pct to the minimum value after AE. The side ledge can self-regulate against thermal fluctuation, but it needs a long time to recover. The modeling results also show that during the AE, adjusting the thermal balance by enhancing the external convective heat transfer is insufficient in a short time and that other strategies should be implemented.