Toward optimisation of electrolytic reduction of solid chromium oxide to chromium powder in molten chloride salts

Electrochemical reduction of solid Cr2O3, in the form of an assembled cathode of porous pellets attached to a current collector, to chromium powder was investigated in molten CaCl2 and a molten equimolar mixture of CaCl2 and NaCl. The study focused on the influence of pellets preparation conditions, cell voltages and temperatures on the reduction process. Analyses were reported of the characteristics of the current-time plots of the constant voltage electrolysis under different conditions, cyclic voltammograms of solid Cr2O3 in the molten equimolar mixture of CaCl2 and NaCl, the microstructures and elemental compositions of the reduced pellets. Particularly, attention was given to the intermediate product of the electrolysis, calcium chromites of various stoichiometries, aiming to achieve a better understanding and optimisation of the reduction process. (C) 2004 Elsevier Ltd. All rights reserved.