Abstarct: Measurements of bubble size distributions are very important in flotation. Although numerous authors determined bubble size distributions (BSD-s) in gas-liquid systems, BSD-s have been rarely determined in gas-liquid-solid systems. Therefore, one the purposes of this work is focused on measurements of bubble size distributions by changing surfactant dosage, solid percentage, air velocity and particle size as well as establishing the relationships between bubble size distribution properties and flotation performances. Furthermore, Hydrodynamic variables in flotation columns can also affect flotation conditions, thus the relationships between bubble size distributions, gas holdups, interfacial area of bubbles and flotation kinetics, will be discussed. On the other hand, the knowledge about bubble–particle attachments during flotation is essential for understanding flotation. It was found that the experimental bubble size distributions are successfully fitted by using the log-normal distribution model in which the two model parameters (µ and σ) are used. The results showed that the most important factors affecting the Sauter mean diameter (d32), the model parameters and the flotation recoveries are the surfactant dosage and the solid percentage. The results show that d32 and the model parameters represent the true BSD-s. However, a thorough understanding of bubble size distributions is needed to better understand flotation performances. Although The results demonstrated that the gas holdups were particularly affected by the pulp density. The increase in the pulp density resulted in higher bubble loadings, making air bubbles more stable and thus increasing gas holdups. The results showed that the gas holdups were directly proportional to the interfacial areas of bubbles. The bubble sizes were reduced predominantly in the case of the highest pulp densities. Thus, there were significant collisions between bubbles and particles, leading to high flotation rate constants. These results showed that the knowledge about bubble size distributions and gas holdups are required to explain the flotation kinetics at different flotation conditions. The results indicated that air bubbles are mobile rather than immobile. The reason is that in the case of mobile bubbles, the decrease in particle size resulted in a lower bubble–particle attachment efficiency probably because a small particle follows liquid streamlines and thus the small particle may not collide with the bubble. The higher the induction time, the lower the flotation rate constant. This study demonstrated the importance of using mobile air bubbles in fundamental flotation models.