Experiments on the flotation of fine particles: The influence of particle size and charge

Abstract The dispersed-air flotation of polystyrene particles of size 4–20 μm has been studied under conditions in which the effect of particle diameter on the rate of flotation could be analysed. The particle charge was controlled by electrolyte addition. The particle charge had a drastic effect on the flotation rate, an increase by an order of magnitude being observed when the zeta potential was reduced from 60 to 30 mV. The flotation rate was found to vary as the 1.5 power of the particle diameter, and this exponent was substantially independent of the zeta potential. It is clear that double layer effects on the surfaces of particles and bubbles have significant roles in flotation of particles as small as those studied here.