Abstract: Semi-coke produced from coal slime by low temperature pyrolysis is characterized by small particle size and high ash content.The flotation method is adopted to decrease the ash.The optimum reagent system determined for flotation is kerosene 1 200 g/t, triton X-100 200 g/t, and octanol 100 g/t.The clean coal with ash content 21.08%, productivity 75.67%, combustible recovery 82.93% is obtained.After analyzing by SEM and EDS, it is found that the semi-coke grain is of low density and high ash content.On its surface, there are many fine gangue mineral compositions and complex surface structures.The semi-coke grains are concentrated with -1.0 g/cm³ products mixing in the froth product in the process of flotation.