Abstract: In order to tackles the problems of low and inconsistent ash content in flotation tailings and high consumption of flotation reagents, based on the study and implementation of relevant national energy policies and environmental protection requirements, Huoerxinhe coal preparation plant analyzes the current status of domestic and international coal slime flotation technology and working principle of mechanical agitation flotation machine, at the same time, by comparing and analyzing the adaptability of mechanical agitation flotation machines and microbubble flotation columns to changes in feed properties, and combining with the coal quality characteristics and production reality of the plant, a technical renovation plan is proposed to replace the original three FCSMC5 500 mm × 7000 mm microbubble flotation columns with two XJM-S36 mechanical agitation flotation machines, the production effects before and after the replacement of the equipment are also compared and analyzed. The results show that the XJM-S36 mechanical agitation flotation machine has stronger adaptability to the changes in the properties of coal slime in the coal preparation plant, after replacement, the ash content of flotation tailings is stabilized at 72% ~ 73% from the previous 40% ~ 52%, with a significant increase in tailings ash content and a significant enhancement in stability; the consumption of flotation agents is decreased from 1.52 kg/t before the transformation to 1.26 kg/t, and with a significant reduction in reagent consumption.