Analysis Of Reasonable Fully Mechanized Caving Face Length Under The Constraints Of Spontaneous Combustion

The risk of spontaneous combustion in goaf is used as constraint condition, the reasonablelength of top-coal caving mining working face is studied by using goaf field flow method,namely.the numerical simulation of the three zones for spontaneous combustion. Borrow G3software that self-developed by professor Li Zongxiang for the analysis tool, simulate the effectson spontaneous oxidation zone in three factors, they are gas emission intensity，face ventilationand oxygen consumption intensity in goaf. Taking several different levels to each factor, andresearch the relationship between the length of face and spontaneous oxidation zone of eachlevel in case of leakage flow field spontaneous combustion in goaf. It related directly betweenthe working length the speed shearer cutting coal and the face advance. To the same workingface, the width of spontaneous combustion zone in goaf varies with the length of working faceaccording to the numerical simulation. theoretically，it seems that length of working face andthe width of spontaneous oxidation zone approximately follow the connection of increasingcurve.There is a certain restrict relationship between oxidation zone of spontaneous combustionand the length of working face in the side of advance extent to prevent spontaneous combustionin goaf, combine the two things can immediately determine the reasonable length of face. Inaddition, the safety allowance and the safety interval of spontaneous combustion are given out.On the basis of the theory, we conducted analysis of examples to Daxing mine andXiaokang mine of Tiemei Corporation, we got that Daxing mine could improve the length ofworking face in the existing production technology; Xiaokang mine could lead to spontaneouscombustion of residual coal in the existing length of working face, and gave the recommendedreasonable length of face.The study provides a useful means for the safe mining in spontaneous combustion coalseam (top-caving mining) and the determination of reasonable working face length duringmining design, which is favorable for preventing the coal’s spontaneous combustion in goafthoroughly and utmostly.