Mechanical activation modes of chalcopyrite concentrate and relationship between microstructure and leaching efficiency

Abstract In this study, a high-energy planetary mill was used to perform mechanical activation of chalcopyrite in dry-, moist-, and wet-milling modes. Granulometric and microstructural changes of chalcopyrite were characterized, and their effects on Cu dissolution were distinguished. Although water was added during milling to reduce agglomeration, it led to the inhibition of energy transmission. The maximum Brunauer–Emmett–Teller surface area of 8.382 m2/g was obtained in samples subjected to 7 h of moist milling. Dry milling resulted in considerable microstructural changes; the amorphization degree, grain size, and lattice strain of the chalcopyrite were 66.4%, 10 nm, and 0.427 × 10−2, respectively. Samples that had undergone 7 h of dry milling exhibited the highest copper extraction efficiency of 48.9%, which was 81.5 times higher than that for the nonactivated samples. The results of kinetics analysis revealed that the degree of amorphization exhibited a greater reactivity of chalcopyrite than the surface area did, and the enhancement in the leaching efficiency was highly consistent with the mechanical activation parameter. In addition, because of the selective rupturing of the chalcopyrite lattice, a “sulfur channel” appeared on the surface of the dry- and moist-milling samples, which proved that passivation decreased and leaching was enhanced. The results of this study can provide considerable insight on chalcopyrite leaching.