Abstract: In order to make full use of the primary coking coal resource and improve economic performance of Huaibei Coal Preparation Plant, an experimental study is conducted by the plant on middling rewashing feasibility with the middling product of the plant′s heavy medium separation system as the object of study.Given the property and liberation characteristics of the middling product, the middling product is first crushed down to a size of＜0.5mm and then treated separately with flotation process, gravity separation process and slime H.M.cyclone.Test result shows that the separation result obtained by using the latter two methods is better than that of flotation process.When the enhanced gravity separation process is used for treating a predeslimed feed with a feed concentration of 15%, a backflush water pressure of 0.04 MPa and a centrifuge turning frequency of 40 Hz, the yield and ash of clean coal are 42.46% and 13.37% respectively.With the use of H.M.cyclone, an up to standard clean coal product with a yield of 27.90% and an ash of 11.83% can be obtained.