The Research On The Critical Gas Content Of The Outburst Zone Prediction Of The Ⅱ₂Coal Seam In Juji Colliery

With the increase of mining depth, the coal seam gas content increased rapidly inthe Juji mine. Mine gas emission increased significantly since2009. In the27th miningarea of the mine south wing and the26th mining area of the north wing,coal walloverall relocation and coal guns and other phenomena happened in the productionprocess. The dynamic phenomenon of gas outburst was obvious. The coal miningactivities had reached into the coal seam highlight the danger zone, which posed apotential threat to the safe coal mining. According to this phenomenon, increasing theeffective prediction and prevention of coal and gas outburst and accurately investigatinggas content parameter threshold is the key technology of the coal outburst danger zoneforecast, the test of the regional integrated control measure effect and the establishmentof gas extraction standards. It is also the necessary requirement for efficient and safecoal mining and has important practical significance to reduce production costs and easethe mining succession tension. Taking the juji coal mine as a research base, according tothe historical data collection, the actual measurement of field parameters, laboratoryexperiments and on-site track inspection and so on, the beginning of sudden gas contentthreshold of primary mining coal bed layer II2seam were investigated and determined.The research focused on the following four aspects: according to collect and organizethe gas content measured during the mine’s geological exploration, the original gascontent of coal seams during gas production and gas pressure projection to make acomprehensive analysis of the mine gas occurrence law and the major factor whichaffect the gas occurrence; by collecting, sorting, keeping track of the inspectionefficiency indicator data and its gas emission data, and according to actual needs, thesupplemental test of the gas content was made to examine the beginning of outburst gascontent; under the constant temperature, the adsorption and desorption experiments ofcoal samples was made to study the relations of the gas pressure, gas content and gasdesorption indicators, and to further examine the beginning of sudden gas content; dueto the certain similarity in the coal rank, adsorption capacity, and gas elutioncharacteristic in Jincheng, Jiaozuo, Anyang, Hebi coal mining area, a lot of scientificresearch about the critical value of the gas content had been done. And after a long-term verification of production, it can provide a reference for the research of critical value ofcoal gas content in Juji mine. By the deep and subtle study of these four areas, thecritical value of gas content in Juji mine were finally determined as9m~3/t. and theon-site industrial test proved that the results were reliable.Gas plays an important role in the coal and gas outburst, accurate determination ofcoal seam gas content and the critical value of the gas content has crucial significance tothe prevention of outburst. Based on the field and laboratory measured data, bycombining theory with practice, the affecting factors of coal seam gas content thresholdwere analyzed and researched systematically.