Kinetics of Ferric Ion Reduction on Chalcopyrite and its Influence on Leaching up to 150 °C

摘要: The reduction kinetics of ferric ion on chalcopyrite in the quaternary H2SO4-Fe2(SO4)3-FeSO4-H2O system were systematically studied by cathodic potentiodynamic polarization (0.5 mV/s) through a wide range solution compositions and temperatures (25–150 °C). Results reveal that all pseudo-polarization plots exhibit reproducible well-defined linear Tafel regions thus temperature dependence various kinetic parameters, such as exchange current density, transfer coefficient rate constant, has been determined. densities Fe3+/Fe2+ couple obtained extrapolating line to reversible potential are order 10−7-10−5 A/cm2 25–150 °C, substantially less than platinum due formation passive film. In general, at same nominal ratio, increasing from 25 150 °C was observed give rise an increase i0, especially when larger amount free ferrous existed solution. Based densities, constants for calculated, further analysis indicates can be well described Arrhenius equation. Experimental evidence clearly shows anomalous independent variation slope with corresponding unexpected increased respect (rather being constant throughout investigated range). Analysis mixed theory acidic iron sulfate leaching control scenario highly depends both composition temperature. importance reaction overall process is progressively ratio under anodic around 1:1, whereas higher ratios control, oxidation reactions.