Innovations in Measurement of Mineral Structure and Surface Chemistry in Flotation: Past, Present, and Future

摘要

This paper surveys the development of surface analytical methods that have contributed fundamental understanding of the flotation process and the ability to measure changes in mineral structure, surface chemistry and reagent uptake in single minerals and now between flotation feeds, concentrates and tails in synthetic and real plant samples. The early applications and past development of new techniques, i.e., XPS (or ESCA), Auger spectroscopy, scanned probe microscopies (STM, AFM), ion beam techniques (ToF-LIMS, ToF-SIMS) and vibrational spectroscopies (FTIR, Raman) to mineral processing are briefly surveyed. In current practice, further innovations in methodologies and principal component analysis applied to ToF-SIMS, contact angle estimation and vibrational spectroscopies (ATR FTIR, TIR Raman, SFG) with examples are reported including cases where the techniques have been combined with electrokinetic and electrochemical analyses (i.e., spectroelectrochemistry). Differences in hydrophobic/hydrophilic surface species on specific mineral phases, which can control recovery and grade, can now be analysed statistically using ToF-SIMS to diagnose problems in grinding, conditioning (physical and reagent) and interfering species on surfaces of value minerals. In future, new methods based on synchrotron techniques offering information on surface structure, amorphous phases and analysis of diffraction and composition on single particles (＜2 μm) are being developed for location of toxic and penalty impurities.