The overlooked mechanism of chalcopyrite passivation

Ren, Zihe; Chao, Chih-Wei; Krishnamoorthy, P.R.; Asselin, Edouard; Dixon, David G.; Mora, N.

doi:10.1016/j.actamat.2022.118111

Cited by 14 publications

(2 citation statements)

References 35 publications

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“…Regarding the implied chemical reactions, the analyses of the residues showed that, when the leaching was efficient, solid elemental sulfur and jarosite formed, as commonly reported in other works. Moreover, these results are in accordance with the mechanism recently proposed by Ren et al, which envisages the formation of a passivating p–n junction due to a nanoscale layer of covellite. The attrition effect could indeed result in the removal of this thin surface layer, followed by a dissolution of the covellite, which would no longer be inhibited by the p–n junction, to form the usual reaction products.…”

Section: Discussionsupporting

confidence: 92%

“…An alternative approach to the passivation model is linked to the electronic properties of chalcopyrite, which as a semiconductor exhibits a band gap that may hinder electron transfer and oxidation, especially since the energy range of this band gap coincides with the standard redox potential of common redox couples such as the ferric-ferrous couple . A recent experimental investigation from Ren et al offers an explanation that combines the two phenomena. The proposed mechanism involves the formation of a covellite-like external layer due to preferential iron dissolution, with p-type electronic properties.…”

Section: Introductionmentioning

confidence: 99%

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Hydrometallurgical Processing of Chalcopyrite by Attrition-Aided Leaching

Dakkoune

Bourgeois

et al. 2023

ACS Eng. Au

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We report the investigation of a chalcopyrite leaching process that implements millimeter-sized glass beads that are stirred in the leach reactor to combine particle grinding, mechanical activation, and surface removal of reaction products. The paper focuses on demonstrating the impact of the so-called attrition-leaching phenomenon on the leaching rate of a chalcopyrite concentrate and provides a first understanding of the underlying mechanisms. For this purpose, we have compared the copper leaching yield for different configurations under controlled chemical conditions (1 kg of glass beads and 84 g of chalcopyrite concentrate in 2.5 L of H2SO4-H2O solution, pH = 1.3, E h = 700 mV vs SHE, and T = 42 °C). On top of elemental analysis of the leach solution with time, we provide a full characterization of the solid residue based on X-ray diffraction, elemental analysis, and sulfur speciation. We demonstrate that glass beads led to a remarkable enhancement of the leaching rate in conditions where particles were already passivated by simple leaching and even when large amounts of solid products (elemental sulfur and jarosite) were present. An in-depth evaluation of particle size distribution showed that particle breakage occurred during a rather short time (a few hours) at the beginning of the runs, transforming the initial particles with d 4/3 = 30 μm to finer particles with d 4/3 = 15 μm. Then, particle breakage almost stopped, while an attrition phenomenon was evidenced, inducing the formation of very fine particles (<1 μm) and aggregates concomitantly with copper leaching.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%