Finely crushed and sized quartz particles were floatated in a supporting electrolyte, KNO3, both continuously and countercurrently by using a bench scale flotation column. This work is a continuation of previous work. Quartz particles were flotated by making them hydrophobic through using a cationic surfactant, a collector, and n-dodecyltrimethyl ammonium bromide. To reexamine the continuous and dispersed phase concentration profiles and removabilities, this work employs the traditional free settling and sedimentation model equations which involve a collision and attachment probability constant between a bubble and the particles. Here, in view of previous work, eddy diffusion of the particles is not taken into consideration in the model equations.Experimentally, it could be deduced that a fraction of the particles lifted by the bubbles up to the froth/slurry (pulp) interface return to the slurry phase to be flotated again.Incorporating this fraction, newly defined in this work, and the above probability constant into the model equations, they were solved numerically to reexamine the observed particle concentration profiles and the particle removabilities. As a result, the removabilities are supported by the model equations with a mean error of -18.4% and a maximum error of -35% even though data scattering was in part large.A series of the experiments were conducted to investigate how gas flow rate and collector concentration affect the apparent rate constant. As a result variations of the rate constant do not contradict these concluded by a number of previous studies of column floatation.