Interactions between zinc sulphide particles under flotation-related conditions

Abstract

Rheological investigations of dispersions of spherical synthetic zinc sulphide particles have been conducted under flotation-related conditions and correlated with interparticle force-distance measurements using “colloid probe” atomic force microscopy. The interparticle interactions observed are discussed in terms of zinc sulphide surface chemistry; the latter was characterised by electrokinetic and X-ray photoelectron spectroscopic measurements. At pH < pHiep of zinc sulphide there is clear evidence of a hydrophobic attraction, in addition to electrostatic and van der Waals forces, affecting interparticle interactions. The presence of copper(II) ions at pH 4 resulted in increased Bingham yield values and interparticle cohesive forces, whereas at pH 10 no such attractive interactions were observed. These findings are discussed in the context of copper(II) ion activation of sphalerite in flotation practice.