Spectroelectrochemistry of Enargite I: Reactivity in alkaline solutions
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Author(s)
Gow, R.
Young, C.
Huang, H.
Hope, Gregory
Takasaki, Y.
Griffith University Author(s)
Year published
2015
Metadata
Show full item recordAbstract
The presence of enargite (Cu3AsS4) is problematic in gold processing not only because it is environmentally hazardous due to its arsenic content but also because it is refractory, causing both cyanide and oxygen consumption to increase. Selective leaching and treatment of the arsenic would prove advantageous prior to applying conventional gold leaching methods. The reactivity of enargite samples from Butte in Montana and Quiruvilca in Peru were spectroelectrochemically studied under alkaline conditions - pH range of 8-13 - using Raman spectroscopy and cyclic voltammetry. Raman spectra of the surface were collected during and ...
View more >The presence of enargite (Cu3AsS4) is problematic in gold processing not only because it is environmentally hazardous due to its arsenic content but also because it is refractory, causing both cyanide and oxygen consumption to increase. Selective leaching and treatment of the arsenic would prove advantageous prior to applying conventional gold leaching methods. The reactivity of enargite samples from Butte in Montana and Quiruvilca in Peru were spectroelectrochemically studied under alkaline conditions - pH range of 8-13 - using Raman spectroscopy and cyclic voltammetry. Raman spectra of the surface were collected during and after potentially cycled voltammograms in order to determine and compare surface species against theoretical EH-pH diagrams constructed from mass-balanced thermodynamic calculations using STABCAL software. Under slightly oxidizing conditions, covellite (CuS) peaks were found in a short matter of time, above ~100mV vs. SHE for pH 9-13, suggesting arsenic leaching specifically occurred. At longer conditioning times, elemental sulfur was observed and tended to passivate the surface. The presence of elemental sulfur suggests that copper was eventually leached from the surface. By operating above pH 12, under slightly reducing conditions near -300mV vs. SHE, arsenic can be selectively leached as thioarsenate (AsS43-) or thiosulfate (AsO43-) without sulfur formation.
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View more >The presence of enargite (Cu3AsS4) is problematic in gold processing not only because it is environmentally hazardous due to its arsenic content but also because it is refractory, causing both cyanide and oxygen consumption to increase. Selective leaching and treatment of the arsenic would prove advantageous prior to applying conventional gold leaching methods. The reactivity of enargite samples from Butte in Montana and Quiruvilca in Peru were spectroelectrochemically studied under alkaline conditions - pH range of 8-13 - using Raman spectroscopy and cyclic voltammetry. Raman spectra of the surface were collected during and after potentially cycled voltammograms in order to determine and compare surface species against theoretical EH-pH diagrams constructed from mass-balanced thermodynamic calculations using STABCAL software. Under slightly oxidizing conditions, covellite (CuS) peaks were found in a short matter of time, above ~100mV vs. SHE for pH 9-13, suggesting arsenic leaching specifically occurred. At longer conditioning times, elemental sulfur was observed and tended to passivate the surface. The presence of elemental sulfur suggests that copper was eventually leached from the surface. By operating above pH 12, under slightly reducing conditions near -300mV vs. SHE, arsenic can be selectively leached as thioarsenate (AsS43-) or thiosulfate (AsO43-) without sulfur formation.
View less >
Journal Title
Minerals & Metallurgical Processing
Volume
32
Issue
1
Copyright Statement
© 2015 Springer International Publishing. This is an electronic version of an article published in Minerals & Metallurgical Processing (M&MP), 32:1, pp 6–13. Minerals & Metallurgical Processing (M&MP) is available online at: http://link.springer.com/ with the open URL of your article.
Subject
Mineral Processing/Beneficiation
Electrochemistry
Resources Engineering and Extractive Metallurgy