Effect of Mechanical Activation on Electrochemical Properties of Chalcopyrite in Iron-Containing Sulfuric Acid Solutions

Mechanical activation significantly enhances the leaching of chalcopyrite, a process that is fundamentally electrochemical in nature. Thus, a comprehensive understanding of its impact on the electrochemical behavior of chalcopyrite in leaching systems is crucial. This study examines the effect of mechanical activation on the electrochemical and semiconductor properties of chalcopyrite in H2SO4 solutions containing Fe2+ or/and Fe3+ at pH = 1.5. Mechanical activation was carried out using a planetary ball mill at 700 rpm for durations ranging from 0 to 2.5 h to reduce particle size and induce lattice distortion, thereby increasing its electrochemical activity. In iron-containing electrolytes, mechanically activated chalcopyrite is more readily reduced, releasing Fe2+ and leading to a higher surface concentration of Fe2+, which consequently increases the diffusion coefficient at the solid–liquid interface. Mott–Schottky analysis revealed a decrease in flat band potentials (from 261.7 mV to 131.2 mV in 0.1 mol/L Fe3+ after 1.0 h of activation) and an elevation in Fermi levels. As a result, mechanical activation markedly accelerates the corrosion rate of chalcopyrite in ferric solutions—the corrosion current increased from 40.27 µA to 70.71 µA in 0.1 mol/L Fe3+ after 1.0 h of activation. These findings provide valuable insights for developing strategies to enhance mineral dissolution, and advance the hydrometallurgical processing of chalcopyrite.