Aiming for zero anode effects

Abstract

The conventional predictor of an incipient anode effect is a high rate of rise of cell voltage. This is used to trigger a fast feed of alumina. Sometimes, however, fast feeding does not start quickly enough to prevent an anode effect. Other indicators can be combined to more accurately trigger the fast feed. These indicators include hysteresis in cell volts vs. current, a rapid fluctuation in anode current distribution, high frequency electrical noise, acoustical noise and pilot anodes. The authors stress the need for a sound, undamaged cathode lining and accurate feeding of high quality alumina. Preemptive anode effect quenches are suggested for cells that do not have automatic feeders.