Two-Phase CFD Model of the Bubble-Driven Flow in the Molten Electrolyte Layer of a Hall-Heroult Aluminum Cell

A two-phase computational fluid dynamics (CFD) model has been developed to simulate the time-averaged flow in the molten electrolyte layer of a Hall-Heroult aluminum cell. The flow is driven by the rise of carbon dioxide bubbles formed on the base of the anodes. The CFD model has been validated against detailed measurements of velocity and turbulence taken in a full-scale air-water physical model containing three anodes in four different configurations, with varying inter-anode gap and the option of slots. The model predictions agree with the measurements of velocity and turbulence energy for all configurations within the likely measurement repeatability, and therefore can be used to understand the overall electrolyte circulation patterns and mixing. For example, the model predicts that the bubble holdup under an anode is approximately halved by the presence of a slot aligned transverse to the cell long axis. The flow patterns do not appear to be significantly altered by halving the inter-anode gap width from 40 to 20 mm. The CFD model predicts that the relative widths of center, side, and end channels have a major influence on several critical aspects of the cell flow field. (C) The Minerals, Metals & Materials Society and ASM International 2015