Influence of auxiliary ventilation devices on a distribution of methane concentration at the crossing of longwall and ventilation roadway

One of the commonly present gas hazard in hard coal mines methane hazard. The most endangered region by this hazard, during ventilation of longwall in „U from boundaries” system is the crossing with ventilation roadway (so called “upper corner of longwall”). Accumulation of methane in this place results from its release from goaf. Therefore, in order to decrease methane concentration in this region, auxiliary ventilation devices are used. They are aimed to supply to this place such an amount of fresh air, as to dilute the dangerous concentration of methane. This process is called reblowing, and is aimed to ventilate top corner of the wall. In the paper results of numerical studies of distribution of methane concentration in hazardous zone (upper corner of longwall) are presented. Modeling studies were carried out basing on the real data from mined hard coal seam. Within the scope of performed analysis three ventilation cases were considered and compared. First case, in which auxiliary ventilation device was not used. Second one, in which only auxiliary device was used, and third case in which auxiliary ventilation device and ventilation baffle were used. The obtained results clearly show that numerical methods, combined with the results of tests in real conditions can be successfully used for the analysis of variants of processes related to ventilation of underground mining, and also in the analysis of emergency states.