Thermodynamic analysis and in situ PXRD study of mineralogy phase transformation of arsenopyrite in acid pressure oxidation

Yanhua Liu; Fang Xia; Yi Yang; Miao Chen

doi:10.1016/j.mineng.2023.108486

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Thermodynamic analysis and in situ PXRD study of mineralogy phase transformation of arsenopyrite in acid pressure oxidation

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Thermodynamic analysis and in situ PXRD study of mineralogy phase transformation of arsenopyrite in acid pressure oxidation

Yanhua Liu, Fang Xia, Yi Yang and Miao Chen

Minerals engineering, Vol.205, 108486

2024

DOI: https://doi.org/10.1016/j.mineng.2023.108486

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Abstract

Acid pressure oxidation (POX) is a cost-efficient pre-treatment method for releasing refractory gold from arsenopyrite and pyrite prior to cyanidation. However, ongoing debate surrounds the mechanism of the dissolution, crystallization, and phase transformation during POX, in part due to the lack of thermodynamic data and in situ studies of the acid POX. In this study, we developed Eh-pH diagrams and used in situ powder X-ray diffraction (PXRD) to investigate mineralogical phase changes during acid POX of arsenopyrite. Based on the existing thermodynamic data, we established the Eh-pH diagrams for the Fe-As-S-H2O systems at 225 °C and 100 °C, which correctly predicted the predominant solid phases precipitating during POX of arsenopyrite at a pH range of 0 to 0.5, such as basic ferric sulphate (BFS: Fe(OH)SO4), szomolnokite (FeSO4·H2O), hydronium jarosite ((H3O)Fe3(SO4)2(OH)6) and angelellite (Fe4O3(AsO4)2). FeSO4·H2O solid is the stable phase during annealing stages as predicted by the Eh-pH diagram, which is in line with the observed solid phases using in situ PXRD. The influence of initial concentration of ferric ions and the presence of pyrite on mineral phase change was revealed. Our results confirmed the formation of FeSO4·H2O, BFS and hydronium jarosite during annealing stages, while BFS and/or hydronium jarosite dissolved during curing and cooling process. Especially, the formation of angelellite was observed in the presence of pyrite during cooling process, which is well-agreed with thermodynamic analysis.

Details

Title: Thermodynamic analysis and in situ PXRD study of mineralogy phase transformation of arsenopyrite in acid pressure oxidation
Authors/Creators: Yanhua Liu - RMIT University
Fang Xia - Murdoch University, Centre for Water, Energy and Waste
Yi Yang - RMIT University
Miao Chen - RMIT University
Publication Details: Minerals engineering, Vol.205, 108486
Publisher: Elsevier Ltd.
Identifiers: 991005612270007891
Murdoch Affiliation: Harry Butler Institute
Language: English
Resource Type: Journal article

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Collaboration types: Domestic collaboration
Citation topics: 7 Engineering & Materials Science; 7.229 Mineral & Metal Processing; 7.229.774 Bioleaching
Web Of Science research areas: Engineering, Chemical; Mineralogy; Mining & Mineral Processing
ESI research areas: Geosciences