The Research Of Methane Migration In The Fully Mechanized Caving Faces In Dahuangshan Mine

Our country is the earliest nation to mine and use coal in the world. Withthe economy developed, demand for coal is increasing day by day. In theprocess of coal mining, the exceeding gas concentration is of great harm to coalmine safety, especially in the inclined thick coal seams. Due to gas emissionamount in the mining process is large, gas amount surge in a short time in theworking face (especially in the upper corner), which increases the difficulty ofgas control. Gas delivery law of the fully mechanized caving face is the keyguiding factor for gas control and selection of gas drainage method. Systematicstudy of the gas delivery law could provide a theoretical basis for gas control inthe future.This paper takes+735working face of the Dahuangshan coal mine asstudy object, according to the characteristic of the inclined thick coal seams，in-situ gas concentration of working face and the upper corner has beenmeasured, and goaf gas has been numerical simulated by Fluent. The mainconclusions are as follows:1. Isothermal adsorption experiments with different particle sizes of45#gas coal has been conducted, Langmuir eqution curves and gas adsorption curveshave been get. Adsorption constant a were both large in the different sizes, somined coal must be tansported timely.2. Mining the735working face with the fully mechanized longwalltop-coal caving method would increase the gas emission. In-situ gasconcentration of working face and the upper corner has been measured,according to the measured results, variation law of gas concentration inworking face’s trendency direction, towards direction, vertical to coal floor andupper corner have been analysed. Results shows that the more close to returnairway, the faster gas concentration increased; gas concentration basicallyunchanged in the towards direction of intake airway; close to return airway, gasconcentration changes in the form of up direction parabolic curve; gasconcentration in upper corner reaches the maximum when caving the coal.3. Goaf gas delivery has been numerical simulated by Fluent, the verticalthree zones and horizontal three areas gas delivery law has been analysedaccording to the simulation results. We can draw the conclusion that the gasconcentration of the compaction area and the caving zone are higher.4. Through study the gas delivery law of working face, the reason that gasconcentration of the upper corner exceeds the limition has been analysed, andthe method to gas drainage with buried pipe in upper corner has been provided.The gas drainage effect is great in the in-situ application, which solved theproblems of exceeding gas concentration in upper corner. This paper studyed the gas delivery law of the+735fully mechanizedlongwall top-coal caving face, which provides a theoretical basis for gas controland selection of gas drainage method, and guarantees the advantages ofmechanized longwall top-coal caving method on the premise of coal minesafety.