Comprehensive mining method of group drawing and automated drawing during longwall top coal caving

Abstract To address issues such as inefficient top-coal drawing, challenges in simultaneously mining and drawing, and the need for intelligent control in extra-thick coal seams, this study examines the principles of top-coal drawing and explores automation and intelligent equipment solutions within the framework of the group coal drawing method. Numerical simulations were performed to investigate the impact of the Number of Drawing Openings (NDO) and rounds on top-coal recovery, coal drawing efficiency, and Top Coal Loss (TCL) mechanism. Subsequently, considering the recovery and coal drawing efficiency and by introducing the instantaneous gangue content and cumulative gangue content in simulations, the top-coal recovery, gangue content, and coal loss distribution when considering excessive coal drawing were analyzed. This established a foundation for determining the optimal NDO and shutdown timing. Finally, the key technical principle and automated control of a shock vibration and hyperspectral fusion recognition device were detailed, and an intelligent coal drawing control method based on this technology was developed. This technology enabled the precise control of the instantaneous gangue content (35%) during coal drawing. The top-coal recovery at the Tashan Mine 8222 working face increased by 14.78%, and the gangue content was controlled at ~ 9%, consistent with the numerical simulation results. Thus, the reliability of the numerical simulation results was confirmed to a certain extent. Meanwhile, the single-group drawing method significantly enhanced the production capacity of the 8222 working face, achieving an annual output of 15 million tons.