Mechanistic and Kinetic Insights into Chalcopyrite Dissolution Under Simultaneous Mechanochemical Activation

Simultaneous mechanochemical activation was employed to enhance chalcopyrite dissolution in sulfuric acid systems. Unlike conventional sequential activation followed by leaching, this integrated process enables in situ defect utilization and continuous disruption of transient passivation layers. Systematic investigations were conducted under varying reagent compositions and temperatures (25–80°C). Sulfuric acid alone resulted in limited copper extraction, whereas operation at 80°C increased leaching efficiency to 15.93%. The addition of ferric sulfate and hydrogen peroxide further enhanced copper extraction to 32.14% and 32.54%, respectively, representing a 6–7 fold improvement over non-activated systems. Kinetic analysis reveals that copper dissolution is governed by diffusion through a dynamically evolving solid product layer, with apparent activation energies of 28.54 kJ/mol (ferric system) and 35.60 kJ/mol (peroxide system). These values are markedly lower than those reported for conventional leaching systems, demonstrating a mechanochemically induced shift in the rate-limiting step from surface reaction control to solid product layer diffusion. X-ray diffraction and Raman spectroscopy confirm that chalcopyrite largely retains its bulk crystal structure, with minor peak broadening and the formation of elemental sulfur. Scanning electron microscopy reveals selective dissolution of strained crystallites and repeated formation and disruption of sulfur-rich surface films. Overall, this study provides direct mechanistic evidence that simultaneous mechanochemical activation establishes a diffusion-controlled regime via dynamic depassivation, offering a moderate-temperature and potentially scalable strategy for processing refractory sulfide ores.