Flow behavior of liquid and multicomponent mixtures of solid particles in fluidizing columns with an external conduit was investigated for a self-circulating operation by an airlift effect. Experimental and analytical results are presented for circulating rates of liquid and particles and for axial changes in holdups of gas and solid in the column. From good agreement between both results, it was found that a one-dimensional sedimentation-dispersion model and mechanical energy balance equation were successfully applied to predict the axial change in gas and solid holdups as well as the circulating rates of liquid and solid particles in the columns.