Induced polarization: Some early non-linear aspects of electrode impedance

An investigation into the early non-linear characteristics of the electrode impedance of natural sulphide minerals can provide information which could identify the processes controlling the induced polarization phenomenon. Chalcocite behaviour which is initially dominated by diffusional processes at the onset of non-linearity, later becomes reaction resistance controlled. The onset of non-linearity in pyrite and chalcopyrite is much delayed. Although both minerals appear diffusion-controlled initially, pyrite is later kinetics-controlled while the large phase angle characteristic of chalcopyrite even at high current densities is indicative of dominant fixed layer effect. The sign of the stable diffusing ion responsible for causing the observed non-symmetric features of the electrodic process has been identified as positive.