CFD modeling of a tailgate ventilation condition in a longwall bleeder system
Face ignitions at the longwall are a serious hazard in underground coal operations and can lead to a major mine explosion. Despite having methane monitoring systems mounted on the shearer and at various locations on the longwall face, undetected methane accumulations can still occur and result in face ignitions. With the use of Computational Fluid Dynamics (CFD), the interaction between the air flow at the longwall face and factors that contribute to accumulations around the face can be modeled and visualized in great detail. The results confirm that the tailgate corner of the longwall face is a critical area prone to face ignitions and thus needs to be properly monitored. Roof falls at the tailgate entry inby the face and/or poor caving conditions behind the shields can both pose a safety risk at any longwall operation. Poor gob caving can lead to insufficient face air quantity with which to dilute methane at the tailgate corner, while a blocking of the tailgate by a roof fall can carry methane-contaminated air from behind the shields back into the face near the tailgate corner and pull the explosive gas zones (EGZs) inside the gob and closer to the face. Additional monitoring locations are deemed necessary to provide early indicators for such events.
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Colorado School of Mines. Arthur Lakes Library