Current Efficiency Measurements in Laboratory Aluminium Cells—XI. Anode Gas Composition and Anode Consumption

Abstract

The anode gas composition and the anode consumption were measured in a small laboratory aluminium electrolysis cell. The anode gas was found to be 100% CO2(g), and the carbon consumption of a prebaked anode decreased slightly with increasing anodic current density towards a value of about 110% of the theoretical consumption. For a graphite anode a slight increase was observed, and the consumptions were higher, in the range 135–150%. From the increase in anode consumption with increasing temperature it was concluded that selective oxidation of prebaked anodes may be the main reason for the excess anode consumption. For graphite anodes, however, the gas evolution and electrolyte stirring may rather be the main cause for the high anode consumption values.