A fundamental DFT study of chalcopyrite surface evolution due to impurity divalent ions during leaching process. (1st June 2018)

• Record Type: Journal Article
• Authors: Li, Yubiao; Wei, Zhenlun; Xiao, Qing; Gao, Huimin; Song, Shaoxian
• Is Part Of: Minerals engineering. Volume 121(2018)
• Page Start: 205
• Page End: 211
• Publication Date: 2018-06-01
• Subjects: Chalcopyrite -- Surface -- Passivation layer -- Divalent ions -- Density functional theory; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2018.03.007
• Languages: English
• ISSNs: 0892-6875

Abstract

Highlights: DFT was used to study the effects of Mg 2+ and Ca 2+ on CuFeS2 (0 0 1)-S surface. Mg 2+ and Ca 2+ ionswere adsorbed at S sites while SO4 2− was adsorbed at Fe sites. The S–Mg–SO4 –Fe and Ca–SO4 –Fe layers passivated CuFeS2 leaching rates significantly. Abstract: Chalcopyrite leaching process is hindered predominantly due to the passivation layers formed on its surface. The impurity salts normally present in the leaching systems may influence chalcopyrite leaching process. In this work, density functional theory (DFT) was carried out to investigate the influence of Mg 2+ and Ca 2+ on chalcopyrite (0 0 1)-S surface using Materials Studio. The results indicated that the presence of CaSO4 contributed to the breakage of S–S bonds on chalcopyrite (0 0 1)-S surface. Although Ca 2+ was not found to bond with any of the S atoms derived from broken S2 2− bond, a stable structure of Ca–SO4 –Fe was formed. Similarly, the adsorption of MgSO4 on chalcopyrite (0 0 1)-S surface contributed to the breakage of S2 2− bond, forming a complex and stable structure of S–Mg–SO4 –Fe as new passivation layers due to the bonding effects between Mg 2+ and a S atom from the broken S2 2− bond. The formation of these new structures covered on chalcopyrite (0 0 1)-S surface, further reducing chalcopyrite leaching rates. This study, therefore for the first time, reveals the influencing mechanisms of Mg 2+ and Ca 2+ sulfates on chalcopyrite leaching at an atomic level.