Anode Processes on Carbon in Chloride-Oxide Melts

Alkali and alkaline earth metals such as lithium, sodium, magnesium and calcium are produced by electrowinning in chloride melts. Direct cathodic reduction of metal oxides in chloride melts has been proposed for the FFC process. Fundamental data for the anodic process on carbon in mixed chloride/oxide melts are lacking. Anodes of graphite and vitreous carbon (VC) were studied in NaCl-NaO, and in binary melts of the type NaCl-MCl2-MO with 0-7 mol% oxide, (M = Ca, Sr and Ba), using linear polarization, CV and EIS. The gaseous products were Cl2, CO and CO₂ and the exit concentration of carbon oxides were analysed by gas chromatography. In this paper the emphasis is on the NaCl-CaCl2-CaO system.