Study On Gas Emission Law Of Coal Wall In Coal Mining Face Based On Monitoring Data Of Gas Concentration

As the coal seam is deeply buried and its geologic construction conditions is complicated in our country,underground mining is adopted in most regions.However,it is difficult to mine and prone to gas accident.Coal mining face is one of the main sources of mine gas emission.The gas emission sources of coal mining face include gas in mining layer,gas in adjacent seams and goaf gas,the gas in the mining layer mainly consists of the gas of coal wall and the gas of coal falling.As an effective means of ensuring security,mine safety monitoring and control system plays an increasingly important role in routine safety management.For example,such a system can help obtain some hidden information in the monitoring data of gas concentration thoroughly and find out change rules of the amount of gas emission from the coal wall of coal mining face.Based on the analysis of gas emission sources in stoping face,this paper reveals the characteristics and rules of the amount of gas emission from coal walls in coal mining face basedon the monitoring data of gas consistency.The main work of this paper is as follows:Taking the 14171 working face of Guhanshan Coal Mine as an example,the author analyzed the features of the historical monitoring data.More concretely,the author pre-treated raw data by Matlab to obtain the monitoring data of gas concentration under regular production,drawn one fluctuation curve of the changed gas concentration for further determination of the characteristics and main influencing factors of the change in gas concentration of coal mining face under different time sequences,and put forward a method for analyzing the variation trend of the gas emission volume from coal walls of the mining face based on the individual and combined morphological characteristics of the curve.Moreover,the numerical model of the gas emission change of coal walls was optimized as well,that is:C=c _w+c₀*e^-t/? and Q=Q _w+Q₀*e^-t/?.Typically,in the course of the study on 14171 working face of Guhanshan Coal Mine,the optimized numerical model of the gas emission change of coal walls was tested before good results had been obtained during research operated on 16021 working face of Guhanshan Coal Mine.These findings show that the change curve of gas concentration monitored by methane sensor in coal mining face is mainly affected by production processes,and most of daily monitoring curves of the gas concentration in mining face are characterized by"two peaks and one valley",when it is under regular conditions for coal mining.And the amount of gas emission of coal walls in mining face decreases in a larger negative exponential order with the length of exposure time of coal walls till it levels off to a non-zero value in the working face.The value is the sum of gas emission from goaf and coal lost.To sum up,these statistics show a high correlation between the gas concentration and gas emission volume.Therefore,the attenuation coefficient of gas emission from coal wall and the gas emission of coal wall can be obtained directly by monitoring data.Furthermore,such results will greatly help people make full use of the monitoring data of gas concentration to exploit coal mines,strengthen information management,and prevent gas disasters such as gas concentration overrun.