1514 seam with a mining height of 10 m can be achieved stably and continuously, without the need for layered mining or top-coal caving. The longwall face maintained high advance rates and sustained production capacity, confirming that the ultra-large-height mining system was capable of supporting high-output, high-efficiency operation. The maximum mining height of the longwall face reached 9.75 m, with a stable operating height of 9.2–9.5 m. The maximum daily output was 71,800 t, and the peak monthly production exceeded 1.55 Mt. The coal recovery rate reached a maximum of 95.3%, representing an increase of approximately 10% compared with conventional top-coal caving longwall faces. For the working face 122104, this improvement resulted in an additional 2.35 Mt of raw coal recovered and a reduction of approximately 0.94 Mt of gangue. Compared with conventional mining methods for extra-thick coal seams, the single-pass 10-m longwall approach significantly simplified production organization and reduced operational complexity. 5.2 Ground Pressure Behavior and Roof Control Performance Field monitoring showed that roof behavior during 10-m mining was effectively controlled under the coordinated support–destressing strategy. The hydraulic shields operated within their designed working resistance range, and no large-scale support instability or structural damage was observed. The combined effect of strong active support and large-scale roof destressing led to reduced suspended roof span, moderated periodic weighting intensity, and improved stability of the surrounding rock structure. These results confirm that the extreme ground pressure conditions traditionally associated with ultra-large mining heights can be effectively managed through system-level control. 5.3 Coal-Wall Stability and Safety Performance Coal-wall stability is one of the most critical safety challenges in ultra-large-height mining. Field observations indicated that the double-layer telescopic canopy and multi-level coal-wall protection system provided effective and timely protection for the ultra-high coal wall. Coal-wall spalling was significantly suppressed, and no large-area coal-wall failures occurred during normal operation. This ensured a safe working environment for equipment operation and personnel, demonstrating that ultra-high coal walls can be reliably controlled under 10-m mining conditions. 6. CONCLUSION The world’s first application of 10-m fully mechanized longwall mining in an extra-thick coal seam has been successfully achieved, breaking the long-recognized upper limit of large-height longwall mining. Through coordinated surrounding-rock control and the development of ultra-large-capacity mining equipment, stable and safe single-pass extraction was realized under extreme conditions. Field results demonstrate that the 10-m longwall system enables high-efficiency, high-recovery, and reliable production, providing a new technical pathway for the development of extra-thick coal seams and establishing a new benchmark for longwall mining worldwide. ACKNOWLEDGEMENTS This work has been supported by the National Natural Science Foundation of China (grant no. 52325403). REFERENCES National Bureau of Statistics of China. (2025). Statistical Communiqué of the People’s Republic of China o n the 2024 National Economic and Social Development. Available at:https://www.stats.gov.cn/sj/z xfb/202502/t20250228_1958817.html (in Chinese)
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