Electrochemical Metallurgy in CaCl2-CaO Melts on the Basis of TiO2·RuO2 Inert Anode

Abstract

Molten CaCl2 has been considered as significant electrolyte for novel electrochemical metallurgy processes due to high solubility of oxygen anions. Some novel processes based on molten-salt electrolysis of oxides in molten chlorides have been proposed, typically including FFC process and OS process. An inert anode capable of sustained oxygen evolution is crucial for a green and efficient electrochemical de-oxidation process. Herein we report the results of a promising inert anode candidate, who shows an excellent performance. Several techniques including anodic polarization, cyclic voltammetry, Tafel polarization and electrochemical impedance have been performed to evaluate the anode behavior of the TiO2·RuO2 anode, revealing that the anode is quite stable during anodic polarization and has a more positive corrosion electrode potential. An in situ analysis of anode gases using the mass spectra proved the capability of the sustained evolution of oxygen at the TiO2·RuO2 anode during electrolysis, meaning that this oxides anode could be a potential candidate as inert anode in calcium chloride–calcium oxide melts for green metallurgical processes, as it showed a nearly negligible solubility of ruthenium dioxide when immersed in the melt and a low rate of corrosion even after long time electrolysis.