Abstract: Effects of the content of fine fractions (< 18μm) on hematite flotation were studied by using flotation tests， extended DLVO (EDLVO) theoretical calculations and kinetics of particle aggregation. The flotation results indicate that hematite recovery is related with the size of coarse particle (> 18μm) and particle size distribution. When the size of coarse particle is relatively large， the recovery of hematite is high. EDLVO theoretical calculations confirm that the fine particles could interface with the coarse particles and the attraction energy increases with the coarse particle size increasing. The flotation recovery increases with the particle size distribution becoming balance (the fine fractions equals the coarse fractions)， and the rate of particle coagulation is relatively high in this case which is analyzed by kinetics of particle aggregation. These conclusions could explain why the recovery of hematite is influenced by particle size distribution.

Key words: fine particles, hematite, flotation, sodium oleate, particle size distribution