In China, backfill mining has been selected as an effective approach to realize the green mining of underground coal resources, where backfill materials are the major factor in the development of backfill mining. In order to provide a better reference for further research and development of backfill mining, the experience and research achievements are reviewed in this paper. Firstly, the backfill materials that have been successfully applied in Chinese underground backfill coal mining are divided into two categories according to whether water is used during the backfill mining operation. Then, the primary considerations of each backfill material during its preparation, transportation and activation stages are discussed and evaluated. Finally, suggestions for backfill material exploration are proposed in terms of the future backfill mining of coal resources in Western China, where there is serious surface desertification.

Coal mine backfilling can effectively prevent large-scale movement of rock formations, not only improving the overall production capacity of the mine but also protecting the surface from destruction and maintaining the original ecological environment. Backfilling extent and backfills compactness are two factors determining the supporting effect on the overburdens in underground coal mines. To make full use of the aeolian sand as the backfill materials in underground coal mines in the desertification areas, Northwest China. Then, vibratory compaction was proposed to enlarge the compactness of these sand-gabion backfills by considering the limited working space. After that, the movement law of the sand particles during vibratory compaction, the influencing law of the vibratory parameters, and the gabion constraint on the ultimate compactness of the sand-gabion backfills were studied using the discrete element software PFC3D from the microscopic point of view. It was found that the aeolian sand particles are more likely to inter-squeeze under vibration than under static load. Furthermore, there are a series of optimal vibratory compaction parameters to the inner aeolian sand for each external gabion constraint strength. The optimal vibration parameters were frequency 50 HZ, excitation force 0.3 MPa, amplitude 40 KPa, and vibration time 4 s. Conclusions of this study can provide references for enlarging the compactness of the sand-gabion backfills in the underground goaf in the desertification area of Northwest China.

The aeolian sand-box backfilling method proves effective for environmentally friendly coal extraction in northwestern regions, including Xinjiang. This study investigated the geomechanical characteristics of aeolian sand-box backfill material and its control effects on overlying strata through indoor experiments, mechanical analysis, and numerical simulations. Uniaxial compression tests on models with varying mesh sizes, wire diameters, and dimensions revealed that larger mesh sizes and wire diameters increased the bearing capacity of the aeolian sand-box backfill material, while increasing dimensions had the opposite effect. A mechanical analysis of the metal mesh box deformation produced equations describing its restraining force. Subsequent experiments and simulations on models of different dimensions consistently demonstrated the material’s mechanical properties, with stress-displacement curves closely aligned. 3DEC5.2 software simulations highlighted the effectiveness of aeolian sand-box backfill material in controlling displacement and stress variations in goaf areas. Notably, smaller-sized backfill material exhibited a more pronounced impact on controlling overlying strata displacement and stress development.