In this study the dependence of the impeller speed on the particle size variation was investigated on the quartz particles using laboratory mechanical flotation cell. Maximum recovery was obtained at 1100 rpm. For either more quiescent (impeller speed <900 rpm) or more turbulent (impeller speed >1300 rpm) conditions, flotation recovery decreased steadily. Furthermore, amount of collision probabilities is calculated using various equations. According to this study, maximum collision probability was obtained around 48.35% with impeller speed of I 100 rpm, air flow rate of 15 I/h and particle size of 545 pm and minimum collision probability was obtained around 2.43% with impeller speed of 700 rpm, air flow rate of 15 I/h and particle size of 256 pm. Maximum attachment probability was obtained around 44.16% with impeller speed of 1300 rpm, air flow rate of 75 I/h and particle size of 256 pm. With using some frothers such as poly propylene glycol, M1BC and pine oil, probability of collision increased, respectively. Maximum collision probability was obtained around 65.46% with poly propylene glycol dosage of 75 g/t and particle size of 545 mu m. (C) 2008 Elsevier Ltd. All rights reserved.