Abstract: There is 37.03% Fe in a deep iron ore with depth of 1 400 m in Liaoning. Iron mainly exists in form of magnetite and hematite-limonite,with distribution rate of 72.83% and 22.52% respectively.The content of harmful elements such as sulfur,phosphorus is very low.Beneficiation experiments of low intensity magnetic separation(LIMS)-high intensity magnetic separation(HIMS)-reverse flotation on mixed magnetic iron concentrate were applied for exploitation and utilization of the ore.The results indicated that,at the grinding fineness of 75% passing 0.043 mm,via once LIMS and twice HIMS,mixed magnetic concentrate with iron grade of 47.05% and recovery of 95.01% is obtained.Iron concentrate with iron grade of 67.21% and recovery of 85.03% is obtained after ground the mixed magnetic concentrate to 95% passing 0.038 mm and then endure one roughing-one cleaning-two scavenging flotation process,using starch as depressor and RS-3 as collector.By magnetic and reverse flotation separation technology to deal with the deep iron ore can achieve relative ideal separation indexes,and can provide significant reference for the separation of similar refractory deep iron ore.

Key words: Deep iron ore, Stage grinding stage separation, Mixed magnetic concentrate, Reverse flotation