UBC Theses and Dissertations
Oxidation of galena in ammonium acetate solutions under oxygen pressure Seraphim, Donald Philip
A study of the oxidation kinetics of galena crystals in ammonium acetate solutions under oxygen pressures was carried out toy following the changes in the lead ion concentration toy means of a cathode ray polarograph. The oxidation rate-exhibits a parabalic rate law character similar to the rate growth curves obtained by E. Gulbransen (8) for oxides on metals. The lead is preferentially oxidized and leached from the galena crystal leaving sulphur, which builds up a sulphur film on the surface. Application of the transition state theory (4) shows that the rate controlling step has a low entropy of activation, and a diffusion coefficient of the magnitude associated with the electron diffusion mechanism. The presence of a sulphide layer on the galena crystal has been established.