Mineral science and processing
The two key unit operations in sulfide mineral processing that depend on interfacial properties are froth flotation and leaching. Flotation is used to separate the valuable sulfides from each other and from unwanted minerals in the crushed ore. Particles to be separated by flotation must have different hydrophobicity, and typically, adequate hydrophobicity for floatability is imparted by chemisorbed sub-monolayers of organic thiols. The focus of research interest is the mineral-thiol interaction, and it is studied primarily by monochromatised Al Kα XPS, synchrotron XPS, and ToF-SIMS.
After a sulfide mineral has been concentrated by flotation, oxidative leaching is the most environmentally acceptable way of extracting the metal. Passivation may be encountered in this hydrometallurgical process because transport of metal ions, or transfer of electrons to the oxidant, may be hindered by a thin altered sulfide layer. It is this buried interfacial layer that is of research interest, and it is investigated by XPS, XAS and threshold Auger electron spectroscopy. Interpretation of near-edge X-ray absorption fine structure spectra is facilitated by simulation of spectra via ab initio calculation of the relevant density of states using codes such as FEFF8 or WIEN2k.
To deduce information about adsorbed or altered surface layers, it is also necessary to understand the unreacted mineral surface and near-surface. Such information is usually obtained by XAS and XPS.
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Professor Alan Buckley and Siew Wei Goh
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Professor Alan Buckley at Beamline 24A of National Synchrotron Radiation Research Centre (NSRRC) in Hsinchu, Taiwan |
