An improved understanding of chalcopyrite leaching kinetics and mechanisms in the presence of NaCl

Copper (Cu) extraction rate from chalcopyrite (CuFeS2) is normally slowed down by the passivation layers formed on CuFeS2 surface. Cost-effective CuFeS2 extraction strategies are therefore strongly expected in both academic and industrial worlds. This study investigated CuFeS2 leaching in the presence of NaCl and the results showed that NaCl played a significantly positive role on Cu extraction in air-saturated solution. Smaller CuFeS2 particle size led to a higher Cu recovery while pH 1.0 was optimum. In addition, the increment of NaCl concentration increased Cu extraction rate and recovery significantly. Moreover, Cu extraction from CuFeS2 was increased apparently with increased temperature, with an approximately 100% Cu recovery being achieved at 348 K and 0.1 M NaCl, within 144 h. XRD indicated that the major products formed were crystalline elemental sulfur (S0) rather than Cu–S like compounds at a NaCl concentration greater than 0.1 M, indicating that crystalline S0 did not inhibit Cu extraction. This study therefore provides a promising strategy of applying seawater in hydrometallurgical processing of chalcopyrite.