Research Progress and Prospects of Land Reclamation and Ecological Restoration Technologies in Coal Mining Subsidence Areas of Arid and Semi-Arid Northwestern China

The ecologically fragile areas in the arid and semi-arid regions of Northwest China highly overlap with coal-rich regions. While intensive coal mining ensures national energy supply, it also causes large-scale surface subsidence and associated ecological problems. Existing single remediation technologies have significant limitations in their application in Northwest mining areas: physical restoration cannot fundamentally restore soil fertility, chemical restoration carries secondary pollution risks, and microbial restoration is constrained by harsh environmental conditions. This paper systematically analyzed existing key technologies for land reclamation and ecological restoration, and summarized their applicability and application effects in coal mining subsidence areas of the arid and semi-arid regions in Northwest China. The comprehensive analysis indicates that: (1) Land reclamation and ecological restoration technologies have evolved from pure engineering reclamation to biological reclamation, and then to multi-technology synergistic restoration, with the restoration concept shifting from land leveling and vegetation coverage to holistic recovery and enhancement of ecosystem functions. (2) Under the complex ecological conditions of Northwest coal mining subsidence areas, existing single restoration technologies struggle to achieve multiple objectives including soil reconstruction, nutrient recovery, vegetation rebuilding, and moisture regulation, necessitating the development of comprehensive restoration models integrating multiple technologies. (3) Chemical–microbial synergistic restoration technology achieves a coupling effect whereby chemical amendments improve the soil physicochemical environment, and microbial communities activate soil nutrients and promote plant growth, demonstrating good applicability advantages and technical potential in the restoration of subsidence lands in arid and semi-arid mining areas. In-depth research and engineering application of chemical–microbial synergistic restoration technology will provide important technical support for the ecological recovery and sustainable utilization of coal mining subsidence lands in Northwest China.