Redox behavior of galena in alkaline condition

Abstract

Electrochemical potential determines types of redox products formed on electrically conducting minerals like galena, which might manipulate process efficiency applied on the target mineral. Therefore, electrochemical behavior of galena has utmost importance for flotation and hydrometallurgical applications. This study was performed to elucidate redox behavior of galena by cyclic voltammetry (CV) technique in a wide potential range. Voltammograms were obtained at pH 9.2 using deoxygenated borate buffer solution in a three-electrode system electrochemical cell. CV tests revealed that redox reactions proceeded reasonably irreversibly on galena electrode. Pb-oxyhydroxides released on the electrode together with sulfoxy species during anodic process while oxygen containing Pb-species reduced to metallic lead at highly reducing potentials. Oxidation product was thought to form a porous layer on mineral surface. Anodic oxidation process of galena obeyed hypothetical polarization diagram. Beyond transpassive surface corrosion, further oxidation of galena proceeded at highly oxidizing potentials at a limit current due to formation of porous Pb-oxide + sulfoxy layer.