The separation of coarse particles by a moving froth bed

Abstract

The behaviour of coarse particles in a moving bed of froth was investigated as a potential flotation technique. The technique is based on the fact that coarse particles, if they are selectively rendered hydrophobic, would act as bubble film breakers if the feed is introduced onto the surface of the froth. Such particles would settle through the froth under gravity to be recovered as the underflow product, while the hydrophilic gangue would be supported by the bubble films and be recovered as a float product. The efficiency of separation is primarily dependent on the ratio of particle mass to projected area, while the contact angle has only a secondary effect on the particle trajectory. Large, high density particles and also small, low density particles cannot be separated on the basis of hydrophobicity. This means that particles to be separated on the basis of contact angle should have a mass between an upper and lower critical value. In this study both artificially coated tracer particles and a pyritic ore were used.