A study of bubble coalescence in flotation froths

This paper is concerned with changes in bubble size and bubble size distribution in the froth phase of a flotation column. A continuous flotation cell of special design is used in which deep froths can be formed. The effect of parameters such as degree of hydrophobicity, gangue concentration (entrained solids), initial bubble size (pulp bubble size) and froth height has been investigated. Special attention has been given to the use of particles of well-defined hydrophobicities so that their effect on the behaviour of the froth phase could be assessed more accurately. Glass particles of different hydrophobicities (as reflected in the contact angle) are prepared using controlled silanation. Contact angles chosen are 50degrees, 66degrees and 82degrees. The results suggest that the size of the bubbles strongly depends on the degree of hydrophobicity of particles. In the presence of entrained solids, the bubble coalescence rate substantially decreases mainly due to reduced liquid drainage in the bubble films. (C) 2003 Elsevier B.V. All rights reserved.