Abstract: The iron grade of the comprehensive iron tailings in Yanshan mine is 9.14%， in which the ratio of magnetic iron ore is 20.13% and the ratio of hematite and limonite is 55.91%. The iron ore is mainly enriched in micro-size fraction，followed by coarse fraction. The original iron reverse-flotation idle system was adopted to recover the iron from the comprehensive tailings. The results showed that under the conditions of induced magnetic field intensity of 0.72 T in high magnetic separation， grinding fineness with -74 μm 90%， magnetic field intensity of 238 kA/m in low intensity magnetic separation， NaOH as pH regulator of 1 300 g/t （pH=11.5）， caustic starch as inhibitor of 840 g/t， CaO as activator of 687.5 g/t and GK68 as collector of 1800 g/t in roughing separation （900 g/t in cleaning separation)， a high-quality iron concentrate with grade of 69.84% and recovery rate of 4.13% was obtained by the process of pre-concentration in the high intensity magnetic separation， grinding， low intensity magnetic separation and reverse flotation of one roughing-one cleaning-one scavenging. The improved production practices showed that by adopting the process of pre-concentration by the disk magnetic separator， stage-one closed-circuit grinding， concentrated magnetic separation， stage-two closed-circuit grinding， low intensity magnetic separation and closed circuit flotation of containing one roughing-one cleaning-three scavenging to treat the combined tailings， about 55， 000 tons of iron concentrate of over 69% grade can be output annually， with annual profit of 17.50 million Yuan gained.

Key words: Comprehensive tailings, Idle system, High intensity magnetic separation, Low intensity magnetic separation, Reverse flotation