CONTACT-ANGLE AND SURFACE-ANALYSIS STUDIES OF SPHALERITE PARTICLES

Capillary penetration techniques were used to determine the wettabilit y of sphalerite particles under flotation related conditions. Particle contact angles were determined separately from measurements of wettin g rates (Washburn technique) and equilibrium capillary pressures acros s a sphalerite particle bed. For sphalerite of different size fraction s, particle contact angles ranged from 75 to similar to 90 degrees, wh ereas synthetic ZnS (99.9%) gave values of 46 degrees and 53 degrees. The strong hydrophobic nature of the natural sphalerite samples was du e to inadvertent copper activation and the ensuing formation of sulfur -rich surfaces, determined by bulk chemical and surface analysis (X-ra y photoelectron spectroscopy and scanning Auger microscopy) studies. S canning Auger microscopy also revealed variations in the levels of sur face copper from mineral grain to grain and confirmed the heterogeneou s chemical nature of sphalerite surfaces. The latter enables the conta ct angle variability to be discussed. Copyright (C) 1996 Elsevier Scie nce Ltd