Abstract: In order to explore fine cleaning of sized coal and optimize coal cleaning system, a study is made of the small coal heavy medium cyclone and the coarse slime vibrating sieve bend currently applied at the plant.It is found that through the adoption of such measures as application of large-diameter fine slime H.M.cyclone, change of operating parameters and improvement of water spraying system of sieve bend, and stabilization of overflow of inclined-tube thickener, the heavy medium separation system is made possible to effect fine cleaning of the > 0.25 mm coal, further extend the system's lower size limit of separation, effectively control the ash and moisture of coarse slime, and reduce the size, ash and volume of flotation feed for easing the workload of flotation circuit.Furthermore, application of the 2-stage flotation+2-stage dewatering process can lead to reduction of ash of flotation concentrate, elimination of the need to reduce the clean coal product of the H.M.separation system to excessively low ash level, and maximization of yield of flotation concentrate.