Goaf gas distribution near the tailgate under three gateroad conditions

ABSTRACT: A collaborative project was undertaken to obtain an understanding of the goaf gas distribution profile near the tailgate area of the longwall goaf under 2 gateroad and 3 gateroad mining conditions for improved explosion risk management in gassy mines. Extensive computational fluid dynamics (CFD) modelling studies were conducted and calibrated using operational longwall goaf gas distribution data. The results of the simulations indicated that there is a significant difference in the spread of explosive fringe (or close to explosive range) gas distribution profiles near the tailgate side of the longwall goaf under 2 gateroad and 3 gateroad conditions, i.e. a significant increase in the spread of explosive fringe zone under 3 gateroad conditions. The results indicated that under 3 gateroad conditions, explosive fringe gas distribution extends into the middle roadway between the longwall panels thereby significantly increasing the area of explosive fringe distribution and likely relative increase in explosion risk. Results indicate that the explosive fringe area in the middle roadway can extend up to two pillars behind the longwall face position. The details and results of various modelling investigations including recommended strategies for gas control and minimisation of the spread of explosive fringe gas distribution in the longwall goaf are presented in this paper.