Modeling studies of electrolyte flow and bubble behavior in advanced Hall cells.

摘要

Much research has been carried out in recent years by corporations and university/government labs. On materials for use in advanced Hall-Heroult cells. Attention has focussed on materials for use as wettable cathodes and inert anodes and much has been achieved in terms of material development. Comparatively less attention has been devoted to how these materials might be incorporated in new or existing cells, i.e., to how the cells should be designed and redesigned, to take full advantage of these materials. The present paper describes an effort, supported by the US Department of Energy, to address this issue. The primary objectives are cell design where electrolyte flow can be managed so as to promote both the removal of the anode gas bubbles and the convection of dissolved alumina in the inter-electrode region, under conditions where the anode-cathode distance is small. The principal experimental tool has been a ''water'' model consisting of a large tank in which simulated anodes can be suspended in either the horizontal or vertical configurations. Gas ''generation'' was by forcing compressed air through porous graphite and the fine bubbles characteristic of inert anodes were produced by adding butanol to the water. Velocities were measured using a laser Doppler velocimeter. Velocity measurements with two different anode designs -- one that is flat and the other that has grooves -- are presented. The results show that the electrode configuration has a significant effect on the fluid flow pattern in the inter-electrode region. Furthermore, this study shows that rapid fluid flow is obtained when the cell is operated with a submerged anode. 4 refs., 12 figs.