Research on spatial distribution pattern of coal spontaneous combustion hazardous zone under condition of regenerated roof
In order to avoid the spontaneous combustion of residual coal from the regenerated roof during coal mining,the characteristics of interior fluid field were clarified,and the dynamic law of coal spontaneous combustion hazardous zone was explored.Taking the spontaneous combustion features of residual coal from the regenerated roof of a mine in Shandong province as an example,the numerical simulation method was used to simulate and compare the air leakage characteristics of goaf and regenerated roof under different air volume.Subsequently,based on the structural characteristics of the regenerated roof,the scope of coal spontaneous combustion hazardous zone was determined by adopting a new method of projection superposition judgment with oxygen concentration and air leakage speed as comprehensive indexes.The results of the study show that the oxygen mass fraction of goaf decreases gradually when the depth is smaller than 60 m,while it's no longer affected by the air volume when the depth exceeds 60 m.The oxidation zone is asymmetrically distributed,forming a"triangle"hollow area at the end of the return airway.The air leakage and backflow occurs in the range of 20-40 m in dip direction of goaf,whereas the air leakage velocity of regenerated roof presents a U-shaped symmetrical distribution.The change features of coal spontaneous combustion hazardous zone in the goaf resemble those of the oxidation zone.In contrast,the coal spontaneous combustion hazardous zone in the regenerated roof is mainly distributed near the middle of the intake airway and the inner part of the front middle of the return airway,and the area of coal spontaneous combustion hazardous zone gradually expands and extends towards the tail with the increase in air volume.
regenerated roofcoal spontaneous combustionhazardous zonegoafoxidation zone
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