Froth flotation: The adhesion of solid particles to flat interfaces and bubbles

Abstract

The adhesion of a spherical particle to a liquid-air interface has been investigated experimentally, and equations derived for the force and work required to detach the particle from the interface as functions of the solid and liquid densities, the surface tension and the angle of contact. The critical centrifugal force required to detach and submerge siliconed glass beads (radii 0·02–0·1 cm) from air-liquid interfaces was in good agreement with theory. The liquids used were water, and 10 per cent and 25 per cent ethanol in water. Similar measurements with aggregates of approximately equal sized beads showed that the adhesive strength of the aggregate decreased as the number of beads increased, reaching a limiting value of about 50 per cent of the adhesive strength of the individual beads, when ten beads were present in the aggregate. The bearing of the results on the process of attachment and the adhesion of mineral particles to air bubbles in froth flotation cells is discussed.