Speaker
Mr
YUBIAO LI
(University of South Australia)
Description
Chalcopyrite (CuFeS2) is the most abundant copper-bearing mineral. The dissolution of chalcopyrite in mine waste environments is considered to contribute to the serious environmental issue of acid and metalliferous drainage (AMD) through release of toxic aqueous copper, particularly in the presence of microbes, dissolved O2, aqueous Fe3+ and pyrite, with the latter two being associated with enhanced chalcopyrite dissolution rates. However, to date few studies have attempted to show the spatial distribution of the surface species formed as well as their evolution as means to better understand the dissolution mechanisms. High resolution, both in terms of energy and spatially, scanning photoelectron microscopy (SPEM), has been applied to the evolution of sulfur species on chalcopyrite surfaces leached in pH 1.0 HClO4 solution at 650 mV (SHE) and 75 °C for 5 - 10 days, in the absence and presence of pyrite or with added aqueous iron. Bulk S2-, S22- and Sn2- were found to be present on all samples and oxidation was observed to take place heterogeneously at the sub-micron scale. As compared to chalcopyrite leached for 5 days, surface oxidation did not appear to be increased on extended dissolution to 10 days, however surface roughness increased markedly. Both S0 and SO42-, but no SO32-, were observed when 4 mmol soluble iron was added indicating greater oxidation occurred with greater Fe3+ activity. The greatest surface oxidation was observed when chalcopyrite was in contact with pyrite due to formation of a galvanic couple, with S0, SO32- and SO42- being identified.
| Keywords or phrases (comma separated) | SPEM; chalcopyrite; oxidation; dissolution; sulfur species, galvanic interaction |
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Primary author
Mr
YUBIAO LI
(University of South Australia)
Co-author
Prof.
Andrea Gerson
(University of South Australia)
