TY - JOUR

T1 - A rest potential study of impurity (As, Au, Ni and Co) bearing synthetic pyrite in alkaline flotation conditions

AU - Babedi, Lebogang

AU - Tadie, Margreth

AU - Von der Heyden, B. P.

AU - Chareev, D. A.

N1 - The authors are grateful to the DSI-NRF Centre of Excellence for Integrated Mineral and Energy Resource Analysis (CIMERA) for providing funding for this research. Special thanks to the Russian Academy of Science's Institute of Experimental Mineralogy for facilitating this collaboration and assisting with the synthesis of the pyrite crystals used in this study. In addition, Dr. Chareev acknowledges the state financial support of the leading scientific schools of the Russian Federation No. NSh-2394.2022.1.5 and the research funding from the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program) that helped establish the experimental lab used to generate synthetic samples for this study. The authors would also like to express their gratitude to the colleagues at Stellenbosch University's Central Analytical Facilities (CAF) for their excellent assistance with the SEM and LA-ICP-MS evaluations. Thanks to Remy Bucher at Ithemba Labs for his help with the XRD analysis of our samples. Additionally, the authors would like to thank the editor and reviewers for reading and evaluating our manuscript.

PY - 2023/11

Y1 - 2023/11

N2 - Pyrite is an important mineralogical component of most sulphide ore deposit classes, where it commonly forms part of the gangue mineralogy, but may also represent an important ore mineral (i.e., auriferous pyrite). Effective and efficient separation of pyrite is thus a crucial step during most ore processing operations, and this is in part influenced by the pyrite mineral chemistry. Here, electrochemical measurements were used to study the reactivity of a series of well-characterised synthetic trace-element substituted pyrite samples under alkaline conditions relevant to industrial flotation. The presence of metals and metalloid impurities (As, Au, Co, and Ni) in pyrite were tested using rest potential measurements to infer oxidation and associated hydrophobicity. In the absence of any collector phases, pure- and Ni-substituted pyrite have the highest rest potential, followed by Co-substituted pyrite and couple-substituted (Co + Au) pyrite, whilst As-substituted pyrite has the lowest measured rest potential. Importantly, the degree of oxidation at the mineral surface correlates linearly with the concentration of each of the substituents, with the largest effect observed when As is the substituent. These results correspond to the semiconducting properties and noble character of each pyrite sample, with n-type pyrite (Au-, Co- and Ni-substituted) associated with noble character and high rest potential, whereas p-type As-substituted pyrite associated with least noble character and lowest rest potential. With the addition of a potassium amyl xanthate collector, the mineral chemistry further had an impact on the probability of dixanthogen formation. Increased substituent concentration in the pyrite lattice decreased the probability of dixanthogen formation, except in a sample where high Au (and moderate Co) was incorporated. These results highlight the importance of developing improved understanding of the impacts of substitution mechanisms on the surface reactivity and flotability of pyrite. Such an understanding will form the foundation for further improved (and engineered) approaches towards reagent design and mixture. This will serve to optimise separation of both gangue and valuable pyrite by using fundamental knowledge to target specific collector bands and flotation domains.

AB - Pyrite is an important mineralogical component of most sulphide ore deposit classes, where it commonly forms part of the gangue mineralogy, but may also represent an important ore mineral (i.e., auriferous pyrite). Effective and efficient separation of pyrite is thus a crucial step during most ore processing operations, and this is in part influenced by the pyrite mineral chemistry. Here, electrochemical measurements were used to study the reactivity of a series of well-characterised synthetic trace-element substituted pyrite samples under alkaline conditions relevant to industrial flotation. The presence of metals and metalloid impurities (As, Au, Co, and Ni) in pyrite were tested using rest potential measurements to infer oxidation and associated hydrophobicity. In the absence of any collector phases, pure- and Ni-substituted pyrite have the highest rest potential, followed by Co-substituted pyrite and couple-substituted (Co + Au) pyrite, whilst As-substituted pyrite has the lowest measured rest potential. Importantly, the degree of oxidation at the mineral surface correlates linearly with the concentration of each of the substituents, with the largest effect observed when As is the substituent. These results correspond to the semiconducting properties and noble character of each pyrite sample, with n-type pyrite (Au-, Co- and Ni-substituted) associated with noble character and high rest potential, whereas p-type As-substituted pyrite associated with least noble character and lowest rest potential. With the addition of a potassium amyl xanthate collector, the mineral chemistry further had an impact on the probability of dixanthogen formation. Increased substituent concentration in the pyrite lattice decreased the probability of dixanthogen formation, except in a sample where high Au (and moderate Co) was incorporated. These results highlight the importance of developing improved understanding of the impacts of substitution mechanisms on the surface reactivity and flotability of pyrite. Such an understanding will form the foundation for further improved (and engineered) approaches towards reagent design and mixture. This will serve to optimise separation of both gangue and valuable pyrite by using fundamental knowledge to target specific collector bands and flotation domains.

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UR - https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=tsmetrics&SrcApp=tsm_test&DestApp=WOS_CPL&DestLinkType=FullRecord&KeyUT=001047540000001

U2 - 10.1016/j.mineng.2023.108277

DO - 10.1016/j.mineng.2023.108277

M3 - Article

VL - 202

JO - Minerals Engineering

JF - Minerals Engineering

SN - 0892-6875

M1 - 108277

ER -