In order to solve the dual problems of "acid mine drainage (AMD)" leakage and secondary pollution from waste residue in abandoned pyrite mine adits of pyrite, in this paper, Baihe County area in Shaanxi Province is studied to systematically explore the application effect of the KEP material in "treating waste with waste" technology for sealing mine adits. Through the method of combining engineering practice with long-term monitoring, the optimal ratio of KEP material to waste residue (3:7) and the grouting process parameters (pressure of 0.8 ~ 1.2 MPa) are determined. The technology is implemented in 213 abandoned mine adits in Baihe County as typical cases. The results show that the technology has achieved four core effects: 1) significantly increased sealing performance of the mine adits, with zero leakage and a permeability of the sealing body ≤ 0.01 Lu after two hydrological years of observation; 2) greatly improved watershed water quality, with the water quality of Baihe River's inflow section into the Han River and the Han River's exit section from Shaanxi consistently meeting the national Class II surface water quality standard, and the mileage affected by AMD reduced by approximately 40 km; 3) Prominent "treating waste with waste" efficiency, cumulatively utilizing 130,000 cubic meters of waste residue and reducing costs by 31.8% compared to traditional concrete technology; 4) Synergistic enhancement of geological safety and ecological benefits, with the sealing body achieving a compressive strength of 25 MPa and the vegetation coverage in the treated area increasing to 72%. The study indicates that the KEP material in "treating waste with waste" technology represents an ecologically sound and economically viable solution for pyrite mine adit remediation, providing a technical reference for ecological restoration in similar mining areas nationwide.