A review of entrainment: Mechanisms, contributing factors and modelling in flotation L. Wang a,⇑ , Y. Peng b,⇑ , K. Runge a , D. Bradshaw a a Julius Kruttschnitt Mineral Research Centre, University of Queensland, Australia b School of Chemical Engineering, University of Queensland, Australia article info Article history: Received 2 September 2013 Accepted 9 September 2014 Available online 29 September 2014 Keywords: Entrainment Froth flotation Modelling Gangue recovery Degree of entrainment abstract This paper reviews the recovery by entrainment in froth flotation. In flotation, entrainment is a mechan- ical 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. Ó 2014 Elsevier Ltd. All rights reserved. Contents 1. Introduction .......................................................................................................... 78 2. Entrainment mechanisms ............................................................................................... 78 3. Principal factors affecting entrainment ..................................................................................... 80 3.1. Water recovery .................................................................................................. 80 3.2. Solids percentage in the pulp ....................................................................................... 81 3.3. Particle size ..................................................................................................... 82 3.4. Impeller speed ................................................................................................... 82 3.5. Particle density .................................................................................................. 83 3.6. Gas rate ........................................................................................................ 83 3.7. Froth height ..................................................................................................... 83 3.8. Froth retention time .............................................................................................. 84 3.9. Rheology ....................................................................................................... 84 3.10. Froth structure.................................................................................................. 84 4. Entrainment measurement methods....................................................................................... 85 4.1. Method of Trahar (1981) .......................................................................................... 85 4.2. Method of Warren (1985) .......................................................................................... 85 4.3. Method of Ross (1989) ............................................................................................ 86 4.4. Entrainment tracer ............................................................................................... 86 5. Modelling of entrainment ............................................................................................... 87 5.1. Direct estimation of entrainment flow ............................................................................... 87 5.1.1. Maachar and Dobby (1992) ................................................................................. 87 5.1.2. Moys (1978) ............................................................................................. 87 5.1.3. Neethling and Cilliers (2002) ................................................................................ 87 5.2. Estimation of entrainment using classification functions and water recovery ................................................ 88 http://dx.doi.org/10.1016/j.mineng.2014.09.003 0892-6875/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding authors. Tel.: +61 7 3346 5983. E-mail addresses: l.wang12@uq.edu.au (L. Wang), yongjun.peng@uq.edu.au (Y. Peng). Minerals Engineering 70 (2015) 77–91 Contents lists available at ScienceDirect Minerals Engineering journal homepage: www.elsevier.com/locate/mineng