Salt extraction process–novel route for metal extraction Part 3–electrochemical behaviours of metal ions(Cr, Cu, Fe, Mg, Mn) in molten (CaCl2–)NaCl–KCl salt system

Abstract

The present work is Part 3 of a novel salt extraction process towards the extraction of metal values from slag, low-grade ores, etc. The electrochemical behaviour of different metal ions, Cr(III), Cr(II), Cu(II), Fe(III), Mg(II) and Mn(II) was studied using cyclic voltammetry (CV) at 827°C in (CaCl2–)NaCl–KCl system with a tungsten or glassy carbon electrode. The deposition process of Cr(III) species was found to be consisted of two electrochemical steps, while, in the case of other species, the deposition only involves one step. The deposition potentials and diffusion coefficients were determined from the cyclic voltammetrys. Electrodeposition of chromium was performed using a two-electrode cell under constant voltage, and pure dendrite and nodular-like crystals of chromium were obtained. The present study provides a good understanding of the electrochemical behaviour of these metal ions in molten salts, and thus is helpful to this novel salt process for the recovery of metal values from slag or other materials.