Impedance Spectra of a Mineral Galena Electrode: Relationship to Xanthate Flotation

Abstract

The interfacial behavior of galena in conditions similar to those used in flotation was studied by the impedance technique with superimposition of ac and dc potentials. Whatever the values of steady potential and xanthate concentration, the spectra were determined in a large frequency range by the space charge (depletion layer) showing the doping by electron donor impurities. With the highly doped sample studied, the spectra allowed the evaluation of the relative influences of the Helmholtz and space‐charge capacitances, and the determination of the flatband potential. The latter results mainly from the adsorption of OH−. The effect of xanthate additions at moderate anodic potentials shows that it is physisorbed prior to the electron transfer and progressively changes the flatband potential also determined by adsorption of . In the presence of xanthate and at potentials corresponding to flotation conditions the surface oxidation is slower than in the absence of xanthate, and the surface charge at a given anodic potential is reduced.