Abstract: In order to improve the utilization rate of fine tailings in an iron ore concentrator，a grad⁃ ing utilization test is carried out. Through laboratory research，the cyclone classification process is deter⁃ mined. By adjusting the number of cyclones and the diameter of the grit nozzle，grit products with different concentration and particle size composition are obtained.The test results show that the coarse-grained sand can be used for underground filling. Under the same cement-sand ratio and curing conditions，the strength of the filling body is much higher than that of the full tailings filling body.The modified fine-grained over⁃ flow products can be used as admixtures for the preparation of C30，C50 concrete，M5-M2 dry powder mortar and high-performance cement-based grouting materials. The efficient comprehensive utilization of the tailings is realized，which provides a useful reference for tailless mining at home and abroad.

Key words: iron tailings, classification, filling, modification, comprehensive utilization