Gas control technology for coal mining with short distance to upward protected seam

A discovery practice on coal mining with short distance to the protected seam was conducted in No. 5 Mine of Pingdingshan Tian'an Coal Mining Corporation Ltd. The practices results showed that during the heading period in the gateway with a short distance to the protected seam, using the 3D gas drainage method combined with the short borehole gas drainage, adjacent strata gas drainage and floor gas drainage, a safety and rapid excavation was made for the heading in the gateway with a short distance to the protected seam. Dur- ing the coal mining period, an U type ventilation was adopted, the gas drainage operation conducted at the two upward corners, one ex- haust ventilator applied for the gas drainage and a short borehole gas drainage operation conducted in the coal mining face. Under the con- dition of the gas content frequently over the limits, the ventilation system was changed to the"two air income and one air return"Y + L ventilation system. The average day production increased from the previous 800 ton to 1700 ton and the problem of gas content over limits was completely solved during the coal mining period in the seam with a short distance to the protected seam.