Abstract: To maximize the utilization of coking coal as a scarce resource, this paper conducts a feasibility study on the retreatment of middlings from heavy medium (HM) separation, taking the Wobei Coal Preparation Plant as a case study. Crushing, screening and float sink tests were performed on the plant’s HM middlings. By analyzing the float sink results in detail, the feasibility of crushing, liberation and secondary separation was explored. Key technologies involving crushing liberation, separation and recovery were analyzed. Based on different investment environments and the existing plant layout, two optimization schemes were proposed. Furthermore, an in-depth analysis was conducted on the process flows, equipment layout and key machinery, followed by a forecast of project investment and economic benefits.The results indicate that the retreatment of HM middlings after crushing and liberation can effectively recover a significant amount of qualified coking clean coal. Both optimization schemes demonstrate technical feasibility and substantial economic benefits. Scheme 1 (crushing to lower than 3 mm and returning to the original system for separation) requires an investment of 1.9 million yuan, yielding an annual profit increase of 31.58 million yuan with a payback period of 0.7 months. Scheme 2 (crushing to lower than 1mm with a newly added separation system) requires an investment of 19.8 million yuan, yielding an annual profit increase of 43.08 million yuan with a payback period of 5.5 months. This study provides a practical technical path for coking coal preparation plants to improve recovery rates and economic returns, holding significant practical importance for the efficient utilization of scarce coking coal resources.