Surface analysis of particles in mine tailings by time-of-flight laser-ionization mass spectrometry (TOF-LIMS)

Time-of-flight laser-ionization mass spectrometry was applied to study the chemical composition of mineral particle surfaces in a sulphide-rich mine-tailings impoundment. This surface-sensitive technique provides chemical information from surfaces of irregularly shaped mineral particles (both conductive and insulators) less than 100 mu m in diameter, which are considered to be representative of particle surface coatings in the tailings pile (after drying). In addition, depth profiles in the mineral particles were obtained. The combination of speed of analysis (1 min), small beam-diameter (2-4 mu m), surface sensitivity (2-10 nm), trace-element sensitivity, and capability to analyze rough surfaces makes this method useful as a complement to studies of pore-water geochemistry and tailings mineralogy, As an example, the behavior of Pb and As in the Kidd Creek tailings dam near Timmins, Ontario, Canada, was studied, using a combination of surface analyses, and pore-water geochemical data.