Laboratory-scale performance of a binary Cu–Al alloy as an anode for aluminium electrowinning

A binary Cu–Al alloy (9.4 wt.% Al) has been investigated as a potential inert anode for aluminium electrowinning. Anodes have been tested in a laboratory electrolysis cell both with and without preformed oxides. Electrolysis was conducted in cryolitic electrolytes with anode current densities of 0.5 A cm−2. The anodes operated satisfactorily as measured by electrical parameters. However, substantial corrosion of the Cu-metal substrate was observed. The external oxide generated on pre-treated anodes was porous and allowed the electrolyte to penetrate through to the Cu-metal whereby corrosion was initiated. An untreated anode formed an in situ surface alumina film, but this did not prevent corrosion of the substrate.