Abstract: Through analytical methods such as contact angle measurement, infrared spectroscopy, and X-ray fluorescence spectroscopy, the surface properties and chemical composition of coal slime from the Qinglongsi Coal Preparation Plant were systematically studied. It was found that the coal slime belongs to low-rank, high-ash coal slime, containing a large number of oxygen-containing functional groups that readily form hydrogen bonds with water, leading to reduced hydrophobicity and poor initial floatability. By optimizing the flotation process and adopting a two-stage flotation process consisting of roughing and scavenging, the yield of flotation concentrate reached 66.30%, with the ash content reduced to 9.97%, while the tailings ash content reached 79.38%, allowing the tailings to be directly mixed with gangue for reuse. After process optimization, the flotation concentrate was blended into mixed coal, increasing the calorific value of the mixed coal by approximately 200 kcal/kg, significantly improving the utilization efficiency of coal resources and bringing substantial economic benefits to the enterprise. This study provides technical reference for enhancing the quality and efficiency of coal slime treatment in thermal coal preparation plants, with significant environmental and economic implications.