CONTACT-ANGLE STUDIES OF GALENA PARTICLES

The wettability of galena particles has been determined from measurements of the equilibrium capillary pressure across a packed bed. Both the macroscopic advancing liquid contact angle, theta(p), and the specific wettable surface area, A(wet), of the galena particles have been obtained. The influence of particle size and surface preparation method on theta(p) has been investigated. The hydrophobic nature of galena is at least partly controlled by hydrodynamics during particle conditioning. The high shear environment experienced during cyclosizing results in galena par particles of greater hydrophobicity compared with those prepared by sieving; these findings are in agreement with the measured notation recoveries. A mechanism has been proposed to explain the relationship between hydrodynamic conditions, surface chemistry, and surface hydrophobicity. X-ray photoelectron spectroscopy studies support this mechanism. (C) 1995 Academic Press, Inc.