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-r ich mine-tailings impoundment. This surface-sensitive technique provid es chemical information from surfaces of irregularly shaped mineral pa rticles (both conductive and insulators) less than 100 mu m in diamete r, which are considered to be representative of particle surface coati ngs in the tailings pile (after drying). In addition, depth profiles i n the mineral particles were obtained. The combination of speed of ana lysis (1 min), small beam-diameter (2-4 mu m), surface sensitivity (2- 10 nm), trace-element sensitivity, and capability to analyze rough sur faces makes this method useful as a complement to studies of pore-wate r geochemistry and tailings mineralogy, As an example, the behavior of Pb and As in the Kidd Creek tailings dam near Timmins, Ontario, Canad a, was studied, using a combination of surface analyses, and pore-wate r geochemical data.