Cathode Voltage Loss in Aluminum Smelting Cells

Abstract

Components of cathode voltage loss and cathode temperatures in aluminum smelting cells were measured using electrically insulated internal probes and thermocouples. In normal operations, the voltage drop between aluminum and lining was insignificant. Lining voltage loss decreased from 0.35 ±.05 v initially to 0.09 ±.02 v with age as the lining graphitized. The collector bar voltage loss ranged from 0.08 to 0.13 v and changed only slightly with cell age. Collector bar to lining contact voltage was as low as 0.06 v shortly after startup but deteriorated with time to 0.35 +.05 v, becoming the major factor in cathode voltage loss. It is postulated that this deterioration is caused by precipitation of very alkaline bath and β-Al₂O₃ at the collector bar interface.