Studies on Anode Pre-Heating Using Individual Anode Signals in HallhéRoult Reduction Cells

Abstract

The proportional increase in modern cells' amperage and anode size while aiming for low energy input has resulted in slowing the process of anode current pick-up rate. Changes in cell thermal and electrical balance due to anode replacement (while a thick layer of frozen electrolyte is formed under a new anode) causes a slower anode current pick-up rate which may require 4 days to reach the target current. Variations in cell conditions following anode replacement result in increasing cell magnetohydrodynamic instability and prolonged presence of low superheat zones. This increases the possibility of forming local abnormalities, such as anode spikes. As part of a continuous enhancement programme, the latest developed individual anode current monitoring system in DUBAL (EGA Jebel Ali) was used to study the benefits of pre-heating anodes up to 500 °C. The work includes studying the impact of anode pre-heating on current pick-up rate while conducting operations such as anode dressing.