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The study indicated that electrochemical experiments can predict not only the general phenomena observed in leaching experiments of chalcopyrite, including the active-passive transition, but also the exact numerical values of potentials where it happens: around 440 mV or around 510 mV. The anodic behaviour of chalcopyrite is characterised by a plateau between these two values, defining the maximum potential where chalcopyrite leaching is fastest., The study indicated that electrochemical experiments can predict not only the general phenomena observed in leaching experiments of chalcopyrite, including the active-passive transition, but also the exact numerical values of potentials where it happens: around 440 mV or around 510 mV. The anodic behaviour of chalcopyrite is characterised by a plateau between these two values, defining the maximum potential where chalcopyrite leaching is fastest.

Previous studies of the kinetic response of chalcopyrite leaching as a function of controlled slurry potential and potentiostatic anodic polarisation results have shown that the mineral passivates at potentials higher than either -440 mV or -510 mV (SCE). The two values have been consistently observed in leaching practice regardless of the geological source of the mineral, indicating that its passivation potential is little affected by impurity content. Steady-state sampled-current voltammetry studies were carried out on chalcopyrite samples in sulphuric acid solutions. The results showed that chalcopyrite active-passive behaviour at high temperatures exhibited considerable hysteresis in response to an externally applied potential. When it is polarised in the positive, anodic, direction from the open circuit potential, the active-passive transition was observed at -510 mV. When polarised in the negative cathodic direction from high passive potentials to the open circuit potential the passive-active transition or deactivation was observed at -440 mV. A potential range exists approximately between 440 and 510 mV where chalcopyrite exhibits thermodynamic bistability and can be either passive or active depending on how it was brought to that particular potential., Previous studies of the kinetic response of chalcopyrite leaching as a function of controlled slurry potential and potentiostatic anodic polarisation results have shown that the mineral passivates at potentials higher than either -440 mV or -510 mV (SCE). The two values have been consistently observed in leaching practice regardless of the geological source of the mineral, indicating that its passivation potential is little affected by impurity content. Steady-state sampled-current voltammetry studies were carried out on chalcopyrite samples in sulphuric acid solutions. The results showed that chalcopyrite active-passive behaviour at high temperatures exhibited considerable hysteresis in response to an externally applied potential. When it is polarised in the positive, anodic, direction from the open circuit potential, the active-passive transition was observed at -510 mV. When polarised in the negative cathodic direction from high passive potentials to the open circuit potential the passive-active transition or deactivation was observed at -440 mV. A potential range exists approximately between 440 and 510 mV where chalcopyrite exhibits thermodynamic bistability and can be either passive or active depending on how it was brought to that particular potential.