A calculation procedure is proposed whereby the bubble load and interstitial concentration of different species can be estimated at different levels in the pulp phase of a pilot-scale flotation column. The model requires experimentally measured concentrations of species in the pulp (overall concentrations), the flow rates of species in the concentrate and tailings, air hold-up, the rate of aeration, the wash water rate, as well as mineralogical liberation data as input parameters. Various transport mechanisms, such as the preferential rejection of particles from bubble wakes, settling of particles, entrainment of particles, the flow of the bulk slurry and bubble transport. are incorporated in the calculation procedure. Calculated results can be used to investigate transport phenomena at the pulp-froth interface (PFI), to estimate pulp recoveries and froth recoveries, as well as to identify regions of high and low particle-bubble attachment in flotation columns. The flotation of chromite in a 15 cm diameter column serves as a case study to demonstrate the application of the calculation procedure.