The parameters controlling column flotation have been investigated using laboratory and pilot-scale flotation cells. It was determined that column recovery is a function of flotation rate constant, axial dispersion, retention time and fractional air hold-up within the cell. Mathematical expressions have been developed which describe each of these parameters and the manner in which they respond to changing column geometry and flow conditions. Based on the data and mathematical expressions developed in the laboratory and pilot-scale testing, a scale-up procedure has been developed for column flotation. Unlike other column scale-up approaches, this procedure incorporates the four primary parameters governing column recovery (i.e., axial dispersion, flotation rate constant, retention time and air fraction) along with carrying capacity limitations to provide a complete scale-up of the entire column. Based on test work conducted in a 2-inch laboratory column, scale-up predictions were made and validated for 30-inch and 8-foot diameter columns. The scale-up procedure has been incorporated into a computer package for making predictions from laboratory data. / Ph. D.