Effect of flotation froth properties on froth rheology

Abstract

Froth flotation is a widely used process of particle separation exploiting differences in surface properties. The froth performance in a flotation cell is expected to be affected by the froth rheology, as it affects the froth residence time that determines the probability of recovery of valuable minerals in the froth phase. Flotation froths have a similar structure to the gas–liquid foams whose rheology has been widely studied. However, to date, very little work has been done in the rheology of flotation froths owing to their instability and the presence of solid particles (on bubble surfaces and in the plateau borders) that are believed to influence froth rheology and complicate any investigation. In this paper, the effects of froth properties on froth rheology were studied by examining the results of 33 flotation tests performed under various conditions that resulted in changes in the froth properties and, consequently, the froth rheology. The experiments were performed in a 20L continuous flotation cell. It was found that the bubble size and the fraction of lamellae covered by solids defined the froth rheology, while the presence of particles in the plateau borders contributed very little to the froth rheology. A model structure was developed by taking into account froth properties to predict froth viscosity.