Development System Optimization and Efficient Mining Technology Practice in the Fourth Mining Area of Hexi Coal Mine

In view of the production capacity restriction problem existing in the No.4 Mining Area of Hexi Coal Mine, including issues such as the mine's verified production capacity of 1.5 million tons per year, the main fan's efficiency at 68% falling below the specified value in AQ 1028—2006, insufficient redundancy in the ventilation system, a ventilation distance of 5.2 km from the Duhumao ventilation shaft to the working face, a ventilation resistance of approximately 3.8 N·s²/m⁸, inadequate gas control effectiveness, a gas extraction rate of about 40%, and a maximum gas concentration of 0.92% in the goaf, a technical system featuring "dual shaft zoned ventilation + three-level extraction of the current coal seam, adjacent seam, and goaf" has been proposed based on the theory of collaborative mining in deep coal seams and the zoned ventilation optimization model. Engineering practice has shown that after implementing this technical system, the mine's production capacity has increased to 3 million tons per year, the resource recovery rate has risen to 89.2%, the gas extraction effectiveness index has improved to approximately 65%, and the fatality rate per million tons has decreased from 0.045 to 0.017, significantly enhancing mine safety and production efficiency. Research findings indicate that this technical system can provide valuable technical pathways and engineering experience for the safe and efficient development of coal mines in the North China type, specifically those with Carboniferous-Permian coal seams.