Aluminium electrowinning cells with metal-based anodes and a fluoride-containing molten electrolyte

摘要

A cell for the electrowinning of aluminium comprises a metal-based anode (10) containing at least one of nickel, cobalt and iron is disclosed. The anode (10) may be covered with an applied or an integral hematite-based layer and/or a cerium oxyfluoride-based outermost coating. The cell contains a fluoride-containing molten electrolyte (5) at a temperature below 950 DEG C, in which the anode (10) is immersed and which consists of: 6.5 to 11 weight% dissolved alumina; 35 to 44 weight% aluminium fluoride; 38 to 46 weight% sodium fluoride; 2 to 15 weight% potassium fluoride; 0 to 5 weight% calcium fluoride; and 0 to 5 weight% in total of one or more further constituents. An anode stem (14b) containing nickel and/or iron can be used to suspend the anode (10) in the electrolyte (5) facing a cathode (21,21A,25) that has an aluminium-wettable surface (20), in particular a drained horizontal or inclined surface.