Sidewall materials for Hall-Heroult process

The performance of current sidewalls made of carbon and silicon based materials relies on the existence of a frozen electrolyte layer. The development of the Hall-Heroult cell technologies such as inert anodes and wettable cathodes, call for new sidewall materials since the frozen ledge may no longer be applicable. Nickel ferrite has been identified as a possible sidewall material, particularly in relation to its resistance to cryolite and air attack. The presentation proposes some strategies to tackle the combined corrosive action of cryolite, molten aluminium and oxygen upon sidewalls. A multi-layer approach is proposed that optimizes both the chemical and heat flux requirements of a sidewall. Issues relating to joining of materials, process control, manufacturing, maintenance and cost need to be addressed before new sidewall designs can be implemented.