Patent ID: 6372099
Filing Date: 2002-04-16
Classification: C25C

Abstract:
A cell for the electrowinning of aluminium by the electrolysis of alumina dissolved in a molten fluoride-containing electrolyte, comprising:one or more anodes, each having a metal-based substrate and an electrochemically-active iron oxide-based outside layer, in particular a hematite-based layer; and means external to the anode's electrochemically-active outside layer(s) for feeding to the electrolyte a sufficient amount of iron species so that the electrochemically-active iron oxide-based layer remains dimensionally stable, the cell having an operating temperature that is sufficiently low so that the required concentration of iron in the electrolyte is limited by the reduced solubility of iron species in the electrolyte at the operating temperature, which consequently limits the contamination of the product aluminium by iron to an acceptable level.