Ventilation mode transformation and gas control practice of goaf in fully mechanized working face of Chengzhuang Coal Mine

In order to make 4312 fully mechanized working face of Chengzhuang Coal Mine safely transformed from the partial Y-type ventilation to the multi-lane U-type ventilation, a new extraction system in upper corner was proposed, the gas extraction in caving zone of goaf was strengthened by closed wall buried pipe in the ventilation connection lane at rear of working face, in this way, a gas control mode was formed in the mining face, which is composed of main gas extraction in high drilling roof fault zone, main gas extraction in closed wall buried pipe in the ventilation connection lane, and wind exhausting goaf. The stoping process in the working face was divided into four stages for analysis, it is found that after the multi-lane U-type ventilation in the working face is stabilized, the gas mixture of the upper corner extraction system is about 420 m³/min and the gas concentration of the extraction system is about 2.00%; the gas extraction rate in goaf of the mining face is 57.65%, and the gas concentration in the upper corner is about 0.60%; it is concluded that with the existing extraction capacity, the ventilation connection lane spacing can be expanded to 80 m.