| Taking An Yuan coal mine 378 working face under goaf as the research object,in view of the overlying mined-out area of coal spontaneous combustion danger,analyzes the factor influencing the overlying coal goaf spontaneous combustion and the impact of 378 working face mining process,and by means of numerical simulation and the experimental research and field observation method was carried out on the 378 working face of goaf coal spontaneous combustion prevention and control.First,the analysis of coal self-ignition orientation,geological structure and gas occurrence of coal seam of overlying coal goaf spontaneous combustion influence factor,the 378 working face in the process of mining roadway layout,ventilation system and other factors influencing the overlying coal goaf spontaneous combustion is analyzed,and through theoretical derivation to leak into the overlying goaf air volume and porosity,differential pressure and flow length up and down,The model was built according to the site situation of 378 working face and overlying goaf.The Fluent simulation software was used to simulate the flow field of overlying goaf during the mining process of working face.The air leakage velocity,oxygen concentration and oxidation zone distribution were analyzed to determine the coal spontaneous combustion risk area.The simulation results are verified by combining the distribution of coal residue and air leakage.Second,using scanning electron microscope(sem)and X-ray diffraction analyzer for common grouting material surface morphology and phase composition are analyzed,and the ratio of different materials for experiment to select suitable slurry material,choose loess as main material,through the experiment of suspension colloid by material of polymer and surfactant B according to the mass ratio of 2:1,at the same time,To obtain the optimal proportion,the preparation of different soil and water ratio and the concentration of suspended colloid slurry suspension characteristics experiments,8:1,when soil than for suspension colloid when the mass fraction of 0.3% slurry suspension performance is better,and by using rotating rheometer to study of the rheological properties of slurry,the test material viscosity decreases with a rise of temperature,increases with the increase of shear rate,By analyzing the rheological properties of the gelled slurry,it was determined that the slurry was a yield pseudoplastic fluid in the non-Newtonian fluid,and the rheological constitutive equation of the gelled slurry was obtained by fitting the measured data.Finally,the grouting fire prevention process system is constructed,and the pressure drop of thickened slurry pipeline is calculated,and the grouting drilling is designed and constructed according to the field conditions,and the flow direction and gas data of grout after grouting are analyzed,so as to effectively control the coal spontaneous combustion risk area and ensure the safe and smooth mining of working face. |
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