A factorial design was used to study effects, and their interactions, of the main parameters affecting column efficiency to recover phosphates from their wastes. Three-phase experiments were performed using a mixture of fatty acid and fuel oil as a collector for phosphate while pine oil was used as a frother. Meanwhile, 2-phase experiments were conducted to correlate the results of 3-phase experiments with that of bubble diameter and air holdup. The results show that application of statistical design reveals very interesting information about the interaction between the studied parameters. For example, it is shown that the interaction (X₁X₂) between superficial gas velocity (X₁) and frother concentration (X₁) has a beneficial effect on grade but aversely affect recovery.