NEW DEVELOPMENTS IN COPPER HEAP LEACHING *E. Asselin1 1Department of Materials Engineering, The University of British Columbia, CANADA, (*Presenting author: edouard.asselin@ubc.ca) ABSTRACT Heap leaching followed by solvent extraction–electrowinning (SX–EW) is widely applied to the recovery of copper from oxide minerals and secondary sulfides. However, most global copper resources occur as primary sulfide minerals, particularly chalcopyrite (CuFeS₂), which exhibits slow dissolution kinetics under conventional heap leaching conditions. The principal kinetic limitation arises from passivation phenomena at the mineral–solution interface, including surface film formation, ferric precipitate accumulation, and bulk semiconductor effects, that collectively inhibit electron transfer between the mineral surface and oxidizing species in solution. Recent advances in copper heap leaching have focused on modifying the electrochemical environment of chalcopyrite to overcome passivation. Emerging technologies include catalytic leaching systems based on thiocarbonyl compounds, chloride-assisted leaching approaches that suppress passivating surface films by controlling solution potential, nitrate-mediated oxidative systems that operate at transpassive potentials, and elevated-temperature bio-heap leaching. These approaches aim to sustain chalcopyrite dissolution by dismantling or bypassing surface and semiconductor barriers, manipulating the effective redox potential, or accelerating interfacial reaction kinetics. Several of these technologies have now reached pilot or commercial scale and may enable direct recovery of copper from primary sulfide ores using existing heap leach-SX-EW infrastructure. This paper reviews the electrochemical constraints governing chalcopyrite dissolution, interprets the mechanisms responsible for passivation within a unified resistance framework, and evaluates emerging technologies for economically viable primary sulfide heap leaching in that context. KEYWORDS Copper, chalcopyrite, heap leaching, hydrometallurgy, passivation 1. INTRODUCTION Copper demand is expected to increase significantly over the coming decades due to electrification, renewable energy deployment, and infrastructure development. Copper production has increased at a compound annual rate of approximately 2.9% since 1960, and this trend is expected to continue (Labbé, 2014). While global copper resources remain substantial, an increasing proportion of future supply will originate from low-grade porphyry deposits dominated by chalcopyrite (CuFeS₂) (Mudd and Jowitt, 2018).
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