Electrolysis of cryolite-alumina melts and suspensions with oxygen evolving electrodes

Abstract

The development of inert anodes for aluminium reduction cell has been a challenging issue for industries. The inert anodes use can be environmentally friendly, energy-efficient and economic. It has been previously discussed by the researchers that the inert anodes can only be fully efficient when used in vertical electrode cell along with a wettable cathode in lowtemperature melts. Currently, Cu-based alloys have been considered as promising candidates (along with the Fe-Ni alloys) as the inert anodes material in aluminium reduction cells with low-temperature electrolytes. When it comes to the wettable cathode, TiB2 is widely considered as promising materials although other materials such as carbon, tungsten, graphite are tested to analyse the cathode behaviour of the material in various conditions. The lowtemperature alumina suspension electrolytes are considered to reduce the impurities in aluminium produced, so it is important to examine the behaviour of alumina in the melts. Metallic anodes tend to contaminate the produced aluminium with their corrosion products and introducing alumina suspension particles in the electrolyte could resolve this problem by suppressing the convective transfer of corrosion products In this thesis, the anode behaviour of Cu-Al based electrodes, cathode behaviour of tungsten electrode in low-temperature KF-AlF3 melts are tested. Along with that, the alumina dissolution and sedimentation rate in KF-AlF3 melts at different conditions are tested.