Electrodeposition of liquid metals from molten salts

Abstract

Many important metals are being produced by electrolysis in molten salts (aluminium, sodium, rare earths and other reactive metals). Also industrial electrorefining of aluminium takes place in a molten salt electrolyte. Current efficiency for metal deposition, specific energy consumption and environmental issues are important topics for considering the success of such processes. A wide range of electrolytes including molten salts can be used to electrowin reactive metals. New electrochemical processes are proposed for recycling of metals in molten salts. Controlled laboratory experiments were carried out to study electrolytic deposition of the liquid metals aluminium, magnesium, lead, iron and titanium alloys from molten salt electrolytes. An important feature is the fact that metals are soluble in molten salts. The excess electrons associated with the dissolved metal are in some cases responsible for the presence of electronic conduction in mixtures of molten salts and dissolved metals. In other cases the metal dissolves under the formation of a subvalent species. Diffusion and charge transfer kinetics related to metal deposition processes in molten salts were studied by using electrochemical techniques.