Abstract: College of Resources and Civil Engineering，Northeastern University，Shenyang 110819，China To solve the problems of flotation index decrease resulted from fine siderite particles adhere and cover on coarse hematite particles and coarse quartz particles surface in the mixed magnetic separation concentrate from Donganshan.The effects of dispersant added in the first step flotation of step-by-step flotation on direct flotation of siderite were researched specially to find suitable dispersant to facilitate pulp dispersion and improve flotation index.Results indicated that，adding dispersant is beneficial for pulp dispersion，increase flotation index.Using citric acid as dispersant in siderite direct flotation，tailings of direct flotation via one roughing-one cleaning-three scavenges closed-circuit process，iron concentrate with iron grade of 67.89% and recovery of 69.35% was obtained.

Key words: Siderite, Dispersant, Covering, Agglomerate, Step-by-step flotation