Abstract: Based on the investigation of middling properties,dispersion flotation of Dong'anshan middling containing iron carbonate was developed with enhanced dispersion by adding NM-3to eliminate the negative impact of iron carbonate on flotation.The optimum flotation conditions were studied systematically.The structure of Dong'anshan middling containing carbonate was discussed by means of SEM.The results show that an iron concentrate with Fe grade of 56.60% and Fe recovery of 53.89% can be obtained on optimum reagent condition through one rougher-one cleanings closed-circuit flowsheet.Adding NM-3can enhance pulp dispersion,which benefits the selective separation of middling containing carbonate.