Refractories for Anode Baking Furnaces

Abstract

Carbon anodes are necessary for the Hall–Herault process with prebaked anodes (Fig. 4.1). We discussed anode baking furnaces in Sect. 2.3 because the furnaces for baking cathodes and baking anodes are the same. They have identical constructions, the same issues with refractories, and the same refractories. One real difference between them is that the service life of a cathode block should be 6–8 years, while the service life of an anode is 30 days; the consequence is the consumption of cathodes and anodes. Another difference is that the raw materials for cathodes are relatively pure, while the butts of spent anodes are utilized in raw materials for anodes, which leads to a significant sodium content in green anodes (from electrolyte). The temperature regime (Fig. 2.28) in anode baking furnaces is more or less the same. Usually, anode producers also produce cathodes; sometimes they keep the furnaces for specialized production, but not always.