Investigation and application of novel advancing fully-mechanized mining method with dense backfilling

To overcome a series of technical challenges in China mining industry, which include the difficulty of extracting three-under (buildings, railways, and water) coal resources, coal-waste disposal, roadway-development intensity, mining-filling coordination, and mining-development continuity, a novel advancing fully mechanized mining method with dense backfilling is proposed. The technical principle, process workflow, method advantages, complete equipment system, and key technologies of the proposed method are systematically elucidated. A coordinated operating system integrating advancing mining, paste backfilling, and gob-side entry retaining is established. The system layout, including the mining, backfilling, and entry-retaining equipment, is designed, and the key structural parameters and functions of each piece of equipment are clarified. Key technologies, including advance detection, parallel mining-filling operations, gob-side entry formation, and stability control, are proposed, and the method is finally demonstrated at the E3_lower01 working face of Daizhuang Coal Mine, Shandong Energy Group. The field industrial practice results indicate that the proposed method requires only a small amount of roadway excavation to rapidly establish the production system, significantly shortening the commissioning period of the working face, substantially reducing the roadway-development demand, and effectively alleviating mining-development continuity issues. The gob-side retained entry exhibits a well-formed cross-section, and the surrounding rock deformation satisfies the requirements for safe production. Significant surface subsidence control is achieved without causing damage to surface buildings, while large-scale underground disposal of coal-based solid wastes can also be realized. The technical system for coal mine backfill mining in China is further improved, providing reliable technical support and engineering guidance for safe, efficient, and green extraction of three-under coal resources and underground resource utilization of coal-based solid wastes in China.