Study On Comprehensive Control Technology For Fire In The Sealed Working Face Of Steep-inclined And Extra-thick Coal Seam

As the demand for coal surges, the proportion of steep-inclined coal seam mining gradually increases. And the application of horizontal slice full-mechanized caving mining method has achieved highyield and efficiency in steep-inclined and extra-thick coal seam. But the technology also leads to large amount of coal left in goaf, serious and repetitive surface collapse as well as abundant air leakage crack, so coal spontaneous combustion arises extremely easy in goaf, and it is difficult to eliminate the fire as the area is large and the deep and upper fire sources are hidden. Besides, the working faces were frequently sealed due to fire, causing huge economic losses.This paper aims at the treatment of the fire in sealed full-mechanized caving face of Urumchi mining area. By analyzing the influence factors of the goaf coal spontaneous combustion in horizontal slice full-mechanized caving face of steep-inclined and extra-thick coal seam, we know that the spontaneous combustion of goaf coal mainly results from coupling effect of the three-dimensional spatial distribution of coal and air leakage from surface crack. And the flammable area is mainly at the side of the roof of goaf.Based on the analysis of fire prevention and extinguishing mechanism as well as the rule and control difficulties of coal spontaneous combustion in steep-inclined and extra-thick coal seam with horizontal slice full-mechanized caving mining method, the overall governance idea was formed, which is "delineating fire area range, plugging the wind, inerting fire area, eliminating the high temperature, preventing recrudescence, checking effect". A comprehensive fire control technology system was proposed which adopted rapid construction of fire-control drillings and spatial injection of efficient three-phase inhibitive foam as main method to cool fire area and prevent recrudescence, assisted by surface backfill, wind plugging by anchoring and shotcreting, inert gas and liquid injection as well as detection of fire area.The effect of fire area management was tested by selecting suitable index gases based on coal spontaneous combustion index gases experiment and by combining the comprehensive judgement indexes of combustion state in sealed fire areas, which have been successfully applied in the scene of sealed fire area governance projects in Tunbao coal, Hongda coal, Luxin coal by author, to test the effect of fire area, ensuring the safely unsealing of sealed fire area.Finally, the comprehensive fire control technology system proposed in this paper was applied to field practice, and effective governance and safely unsealing of sealed fire area were achieved, which provided a reference for similar fire area management.