Collaborative Optimization Of Alkali-fixing Sulfur And Gas Drainage In High-sulfur Coal Mines

In the process of coal mining, it has often been encountered much of poisonous and harmful gases, such as gas, hydrogen sulfide, carbon monoxide, sulfur dioxide, nitrogen dioxide and hydrogen, etc. After decades of coal exploitation in China, with the deepening of mining depth, the problem of hydrogen sulfide in some coal mine is becoming more and more serious, especially in the process of coal mining in high sulfur. With gas and mine water outburst, there is always been a large amount of hydrogen sulfide (H2S) in the working face, threating the safe production in coal mining. Now the effective method of removing hydrogen sulfide is pre-injecting alkali inside the coal seam before extraction, and the alkali reacts with hydrogen sulfide in the coal seam so as to achieve the purpose of solid sulfur, at the same time the internal drilling to gas extraction has become an important means of governance on gas disasters in coal seam. Therefore, the main purpose of the article is to study the seepage law of injecting alkali liquid and gas, to explore the optimization of well drilling location, and the ultimate goal is to provide certain theoretical support and practical reference for safe production and economic production in coal mining.This article is mainly based on the background of geological conditions, occurrence conditions of hydrogen sulfide and gas. By establishing the coupling migration model of gas-liquid two phase flow in chemistry-seepage field, the transport law of alkali injection and gas extraction were studied. It has obtained relatively economic and efficient plan of well location by optimizing the well of alkali injection and extraction in coal seam.Finally the data of field investigation in the coal seam of Shanxi was compaired with the results of numerical simulation, verifying the correctness and reliability of numerical model applied, the main conclusions are:(1) Approximately the penetration radius of alkali grows linearly with the alkali injection pressure in different pressure conditions. The natural penetration radius grows linearly with time approximately, and the effective penetration radius grows nonlinearly with time.(2) The seepage velocity gradient of alkali is larger near the well, while is smaller far from the the well, which all meet the Darcy’s law. The velocity vector is larger when the injection time is short. With the increase of time, the velocity vector became smaller, and eventually tending to be a relatively small stable value.(3) The penetration radius-time curves are in the same trend no matter whether considering the sulfur deposition or not, the damage effects of sulfur deposition increases with time and gradually stabilized.(4) By optimizing drilling arrangement, the time of sulfur removal can be greatly reduced. By comparing and analyzing the plane optimization scheme, it can be concluded that the optimized scheme 2 can reduce 90% time of alkali injection. By analyzing the optimal placement of drilling in space, it can be concluded that it should adopt different space drilling hole arrangement according to different construction conditions and gas occurrence in coal seam.(5) The effective penetration radius of alkali is 6 m to 8 m according to the alkali injection tests, and the effective penetration radius of alkali is 6.1 m. It is showed that the numerical simulation and the result of alkali injection test is basically consistent, verifying the correctness and reliability of numerical model applied, which can provide certain reference for safe production and economic production in Longtan mine.