Abstract: In order to fully recover clean coal from coking middlings, taking the product of middings of heavy separation sedimentation centrifuge as the study objec t, the possibility of re-preparation of middings was analyzed by carrying out a series of tests, including screening, comminution, float-and-sink separation, and progressi ve released flotation experiment.The mineral dissemination characteristics before and after crushing were observed by the polarized microscopy.The experimental resul ts show that the optimum comminution size is 0.3mm, in this case, the organic matters are liberated well with the inorganic matters, such as pyrite and quartz. However, the clay minerals are not liberated well from organic matters, which may cause a higher ash content for the concentrate during the floatation.The float-and-sink test sho Ws that the theoretical yield of the concentrate is 50.00% corresponding to the ash content of 11.00% The rougher-cleaning flotation experiment show that when the dos age of diesel oil is 1 kg/t and the dosage of 2-Octanol is 0.1 kg/t, the ash content of the concentrate is 10.57% and the yield is 46.47%.