A Review of Factors Affecting Carbon Anode Consumption in the Electrolytic Production of Aluminum

Abstract

Anode consumptions were determined in the laboratory in a miniature electrolytic cell in which the test electrode is fully immersed in the electrolyte. The test is carried out under conditions simulating those of industrial reduction cells, and the results parallel those of plant-scale tests. The correlation between the laboratory and plant consumption data is demonstrated. Laboratory studies led to better understanding of many factors affecting anode consumption. The mechanism is reviewed. Results are presented for (1) anode materials, (2) anode processing variables, and (3) cell operating practices. Of considerable interest are the consumption rates obtained with special cokes such as needle, fluid, and high-temperature cokes, and with coal-tar and petroleum pitches containing very low amounts of quinoline-insolubles. Anode consumption exhibits a minimum with increasing binder content. It can be significantly modified by the use of certain additives. Major changes in aggregate size distribution have marked effects on consumption in both the prebaked-type and Soderberg electrodes. The effect of electrolyte temperature and composition and some of the reduction cell variables on anode consumption are briefly discussed.