A simple empirical dimensionless model to calculate the mineral gangue recovered per size class (R-G,R-i) by entrainment, in terms of the water recovery (R-w), in an industrial flotation cell is presented. For modeling purposes, a dimensionless entrainment factor EFi, corresponding to the ratio (R-G,R-i/R-w), was defined for each particle size class. From experimental data measured in an industrial 130 m(3) flotation cell, it was found that EFi was well correlated with the dimensionless ratio (d(P,i)/delta) by EFi = exp(-0.693(d(P,i/)delta)(Phi)) where d(P,i) is the particle size class "i", and delta parameter corresponds to the mean particle size for EFi = 0.5, Phi is a drainage parameter, which depends on the mineral characteristics and cell operating conditions (i.e. cell design and water recovery). The gangue recovery model was evaluated in a large industrial flotation cell, where the entrainment factorwas calculated by direct measurement of the bubble load grade for non-selective froths (high water recovery), and by measuring the top of froth grade for selective froths (low water recovery). The model was also successfully tested using two different sets of industrial flotation data, taken from literature (Engelbrecht and Woodburn, 1975; Zheng et al., 2006). The particle entrainment model is a powerful tool for flotation process modeling and simulation, to explore the impact the water recovery has on the final concentrate grade. (C) 2009 Elsevier B.V. All rights reserved.