矿床地球化学国家重点实验室知识库

The sphalerite oxidative kinetics under hypergene condition was simulated and studied by means of a mixed flow reactor over a pH range of 1.0–7.8, and at dissolution temperatures from 20 to 55°C, ferric ion concentrations from 1.0×10⁻⁵ to 1.0×10⁻² mol/L, O₂ flux of 0.5 L/min, and oxidants of ferric ion and O₂. It is indicated that with ferric ion as oxidant, the oxidation rate of sphalerite increases with increasing ferric ion concentration, temperature and decreasing pH value, and under the studied conditions, the dissolution rates of Zn and Cd are approximately identical, with the values of activation energy being 41.75 and 42.51 kJ·mol⁻¹, respectively, suggesting that the oxidation rate of sphalerite is controlled by chemical reactions on mineral surface. However, with O₂ as oxidant, the oxidation mechanism of sphalerite varies with pH value. Oxidation rate decreases with increasing pH value when pH is lower than 5.95, whereas the increase of pH value results in an increase in oxidation rate when pH value is higher than 7. The oxidation rate of sphalerite can be expressed as:

RZn=101.1663[Fe3+]0.1540⋅[H+]0.2659⋅e−41.75/RTorRCd=101.7292[Fe3+]0.1700⋅[H+]0.2637⋅e−42.5