摘要：Flotation indexes gradually decrease with the increase of cycle time of the backwater in bauxite floatation,and discharge of backwater brings environmental *** this study,methods such as Fenton-oxidation,adsorption and coagulation were used in the treatment of backwater,the flotation indexes were checked after backwater treatments,and Box-Behnken design(BBD)was used in the optimization of the main operating *** results reveal that flotation indexes are effectively improved after coagulation treatment by polyaluminum ferric chloride(PAFC).The optimum parameters predicted by BBD are pH 7.55,1.09 g/L PAFC dosage and temperature of 25℃.Under these optimum conditions,a maximum recovery of Al2O3 of 82.83%and a minimum A/S of 1.30 of tailings are gained,while the deviations are less than 3%from the predicted *** findings encourage the application of BBD for the optimization of critical parameters in backwater treatment.