Effect of Changes in Anode Top Cover Composition on Anode Butt Quality

Abstract

In Hall-Héroult reduction cells, alumina and/or crushed bath is used to cover anodes and plays a major role in controlling cell heat dissipation and preventing anode air burn. Changes in anode cover granular size and composition result in varying anode protection level and crust hardness which consequently affect the anode butt quality cleanliness process. Growth in high purity metal production to meet market requirements led to the increase of the stockpile of anode crushed recycled material (ACRM) at EGA’s Jebel Ali smelter. The work in this paper demonstrates the impact of lowering alumina content in anode top cover material to reduce ACRM generation while monitoring its effect on the anode butt cleaning process using state of the art EGA anode rod tracking system (ARTIS) and butt analyzer. In addition, the study presents the outcome of statistical models of bath area on a butt and prescribes the main contributors to anode butt quality cleaning effectiveness.