Research On Movement Law Of CO Gas In Gob Of Caving Workface In Easily Spontaneous Combustion Coal Seam O Lingwu Mining Area

The coal seam belongs to easily spontaneous combustion coal seam in Lingwu mining area Ningxia Hui Autonomous Region. In the mining process, CO gas comes out from the upper corners of fully mechanized and caved working faces in some coal mines, therefore the level of CO gas is often over the limit. It is necessary to research the concentration distribution and migration law of CO in the gob also has a very significant meaning of early predicting the degree to coal spontaneous combustion in gob and efficiently managing CO transfinite at the upper corners of working face.In this article,the NO. 12207 working face is researched in Zaoquan coal mine of Lingwu mining area, Ningxia Hui Autonomous Region. First of all, the characteristics temperature of coal's spontaneous combustion and the quantity and rate of CO gas produced from coal samples at different temperatures condition, is carried out through the spontaneous combustion temperature-programmed experiment of samples from Zaoquan 2# coal seam at the experimental condition. The rules of CO generating from coal sample is obtained also; Secondly ,The distribution of CO gas concentration changes with depth in gob is acquired by means of buried pipe in the gob. The distribution of rock pressure, porosity, leakage channels and permeability of the gob are studied through theoretical analysis and field observation. Then a mathematical model of seepage and air species concentration is built and simplified by coordinately using the theory of heat and mass transfer in porous media. After that, distribution of CO concentration and the velocity of air flow in the gob are calculated by simulating the flow field using Fluent software numerically. Furthermore the migration law of CO in the gob is also obtained. Finally, the analysis of the intensity to spontaneous combustion of floating coal in the gob of the NO.12207 working face in Zaoquan coal mine is achieved through experimental and numerical simulation data. According to the monitoring data of CO concentration at the upper corner of working face, the degree to spontaneous combustion of floating coal in the gob is revealed: the maximum temperature of floating coal in the gob is close to its critical temperature of spontaneous combustion at 65℃,then it is successful to predict the degree to spontaneous combustion of floating coal in the gob and Provide scientific basis for managing CO transfinite at the upper corners of working face.