Abstract: The middlings product of the heavy-medium separation system of Xinyu Coal Preparation Plant,Shanxi Province,is used as the object of study.Comparative test is carried out using 2 kinds of flotation columns which differ in air inlet structure—one swirl type and one non-swirl type,with the middlings as the feed after liberation of organic matters through first crushing and then fine grinding.Test result indicates that: when the swirl-type column works with a larger aeration quantity,the recovery rate of combustible matter is up to 66.67%; and when the non-swirl version works with a smaller aeration volume,the ash of the flotation concentrate can be reduced to 10.31%.Based on the test result and in the light of the characteristics of the coking coal middlings,it is proposed to treat the middlings with heavymedium separation + rougher flotation + cleaner flotation process.