A review of entrainment: Mechanisms, contributing factors and modelling in flotation

• The mechanism of entrainment and its effects in flotation are discussed.
• Methods for the quantification of entrainment are reviewed.
• Current entrainment models lack predictive capacity.
• An entrainment model incorporating the effect of major contributing factors is desirable.

This paper reviews the recovery by entrainment in froth flotation. In flotation, entrainment is a mechanical mass transfer process by which particles suspended in the water between bubbles enter the flotation froth from the top pulp region and are transferred to the concentrate. Both hydrophobic and hydrophilic mineral particles suspended in water can experience entrainment. In this paper, the mechanisms of entrainment are reviewed. The essential factors affecting entrainment are also discussed. The methods for the quantification of entrainment are identified. Entrainment models presented in the literature are reviewed with the aim of identifying their significance and usefulness in industrial applications. There is a need to develop a more general model of entrainment since the current models available cannot be used to predict entrainment at a changed operating or feed condition.