Kinetic and Mechanism Studies Using Shrinking Core Model for Copper Leaching from Chalcopyrite in Methanesulfonic Acid with Hydrogen Peroxide

ABSTRACT

An investigation on copper leaching from a chalcopyrite concentrate in methanesulfonic acid (MSA) and hydrogen peroxide at 75°C was carried out. Periodic additions of H₂O₂ were applied to enhance chalcopyrite dissolution and the reaction mechanism was analyzed using a shrinking core model. The results revealed that compared with the addition of H₂O₂ at the very beginning, periodic additions of H₂O₂ enhanced copper extraction and leaching kinetics, and the rate-determining step shifted from the diffusion of oxidant to the surface chemical reaction. The reaction orders with respect to MSA and H₂O₂ were found to be 0.19 and 1.26, respectively, suggesting the leaching process was highly dependent on H₂O₂ concentration. Calculated activation energy between the temperature range of 25–75°C was 79.8 kJ/mol. Detailed study also indicated the reaction mechanism is diffusion-controlled through a protective sulfur layer at lower temperature and surface chemical reaction-controlled at temperatures higher than 55°C. Overall, the MSA–H₂O₂ leaching system is a green method for chalcopyrite leaching and a possible flowsheet in the industrial application with the periodic additions of H₂O₂.

KEYWORDS:

• Chalcopyrite
• shrinking core model
• methanesulfonic acid
• hydrogen peroxide
• reaction mechanism

Acknowledgments

Freeport McMoRan Copper & Gold’s support to the Department of Mining and Geological Engineering at the University of Arizona is greatly appreciated. A part of Jiajia Wu and Junmo Ahn’s graduate assistantship was provided by Freeport McMoRan Foundation through the Sustaining 21^st Century Mining Education in Arizona program. The corresponding author, Jaeheon Lee, also would like to express his appreciation to Freeport McMoRan and SME foundation for their support to SME Career Development Grant as a recipient of the program.

Disclosure statement

No potential conflict of interest was reported by the author(s).