Abstract: To address the issues of high fine coal carry-over in the underflow and high coarse coal loss in the overflow of the hydrocyclones for coarse slime classification at Jiangzhuang Coal Preparation Plant—problems that adversely affected the subsequent performance of the CSS separator and the indicators of flotation tailings—the plant collaborated with China University of Mining and Technology to conduct research on the precise classification of coarse slime. By implementing a technical solution that involved reducing the hydrocyclone diameter, introducing secondary rinse water, and developing an intelligent feed control system, the original large-diameter hydrocyclones were replaced with CC-300 high-efficiency classification hydrocyclone units. The results of industrial application showed that the fine coal carry-over in the underflow of the new hydrocyclone units decreased from 35.87% to 22.62%, while the coarse coal loss in the overflow dropped from 8.12% to 1.43%. With the ash content of clean coal remaining largely stable, the clean coal yield of the CSS coarse slime separator increased by over 2 percentage points, generating an additional annual economic benefit of approximately 3.6939 million yuan. Additionally, the ash content of flotation tailings rose to 80.97%, meeting the calorific value requirements for tailings set by Zaozhuang Mining Group. This improvement provided high-quality feed conditions for the efficient separation of coarse slime.