Abstract: The problem facing the plant is that the flotation concentrate is considerably high in ash due to degradation of raw coal in water. To address this issue, a technical study is made of the way to reduce the ash of the concentrate products of the rear cells of the mechanically-agitated flotation machine. Through the study, a secondary flotation process is designed. Industrial test shows that the flotation performance is greatly improved as evidenced by the drop of concentrate ash from 10.56% to 10.17% and an increase of concentrate yield by 1.66 percentage points.