DETERMINATION OF LEACHING RATES OF PRECIOUS METALS BY ELECTROCHEMICAL TECHNIQUES

The leaching rates of gold, silver, palladium and platinum in cyanide solutions have been determined from the corrosion potential and voltammograms of the anodic oxidation reaction. The order of reactivity was Au > Ag > Pd > Pt and the leaching rate was a maximum at about pH 10 for each metal. An assessment was made of the applicability of PAR M342C Softcorr Corrosion Software, devised for computing corrosion currents, to the measurement of leaching rates of precious metals. The software does not yield accurate rates due to the nature of the individual oxygen reduction and metal dissolution processes, but could be applied to rapidly estimate the influence of variation in solution composition on the leaching of an individual metal.