Influence of the operating parameters over the current efficiency and corrosion rate in the Hall-Heroult aluminum cell with tin oxide anode substrate material

A systematic laboratory study was conducted on current efficiency and corrosion obtained in cryolite-aluminamelts with SnO₂-Sb₂O₃-CuO ceramic inert anodes. The current efficiency (CE) was determined by measuring the total amount of oxygen evolved at the anode andwas found to be ~95%. The influence of operating parameters (inter-electrode distance, temperature and current density) was evaluated. The quantitative interdependencies as well as the ranges of CE optimal values were established (2-3 cm, 940-960 ℃ and 0.7-0.8 A·cm^-2). The corrosion process of these anodes was evaluated by themass lossmethod. The evaluation also took care of the corrosion data, as the problem of the anode corrosion appeared to be themain obstacle for the use of those anodes in the commercial cells. Lowering of the ACD up to 2 cm did not aggravate anode corrosion.