ABSTRACT
As a multiphase system, froth has distinctive properties and cannot be regarded as a simple liquid or solid. Typically, flotation froth is a dispersion of gas bubbles in a relatively smaller volume of liquid with surface-active reagents, called frothers, and fine solid particles. As described in the previous chapter, the structure of froth is complex, comprising polyhedral gas bubbles with liquid films residing between bubbles, Plateau borders where three films meet, and vertices, which are the junctions of four Plateau borders. Liquid films and Plateau borders form a network for liquid drainage out of the froth by gravity, and surface and capillary forces. The rate at which liquid and particles drain through the network varies throughout the froth: it is large at the frothpulp interface and decreases with increasing froth height. In order for the efficiency of the industrial flotation process to be properly optimized, a better understanding of the liquid drainage in froth is vitally important. This chapter presents simplified models for the froth drainage.
