Abstract: The paper described the cause of loss of coarse coal slime in the flotation,analyzed the applicability of coarse coal slime flotation,provided theoretical explanations from aspects of structure and separation mechanism that the cyclone micro-bubble flotation column can separate coarse coal slime. Then data analysis of pilot-plant test results show that the separation slime containing particle size great than 0. 25 mm by cyclone micro-bubble flotation column are satisfactory,meanwhile,several measures which can improve the flotation effects of coarse particles by cyclone micro-bubble flotation column were suggested.