Abstract: In order to improve the problems of long settling time，low filtration rate，severe wear leakage phenomenon，low content in filter cake during thickening and dehydration for fine grained hematite concentrate.Effects of types and dosage of flocculants，slurry pH，temperature，and degree of mixedness on the sedimentation behavior were studied，using an iron concentrate from Brazil as research object.The results indicated that：there were significant influence on sedimentation of hematite concentrate by adjusting flocculants addition，for too low addition have no obvious improvement on the sedimentation rate，with excessive addition could initiate colloid protecting，and the sedimentation velocity will not increase with dosage increase of flocculants.Sodium polyacrylate flocculants have good settling performance in alkaline conditions，while polyacrylamide flocculants have good settling performance in acidic condition.Hypothermia have disadvantage in improving the sedimentation rate，hyperthermia would lead to degradation of flocculants.Sufficient reversal and mixing was conducive to sedimentation，excessive mixing will worsen sedimentation effects.The results have important implications for suitable flocculant selection in iron concentrate settling and improve the concentrate sedimentation.

Key words: Ultrafine hematite, Flocculants, Sedimentation rate