Research On Gas Desorption Characteristics Of Powering Coal Sample From 7# Coal Seam Of 86 Mining Area Of Haizi Coal Mine

In this thesis, through the study of Haizi coal 7# multiple physical parameters, desorption and index, obtained a series of experimental or theoretical conclusions which are used to analysis and explain the unexpected abnormal index, pointing out the limitations of traditional outburst index system and the measure equipment for the specificity of coal like 7# coal seam in Haizi coal mine. The main conclusion are as follows:Result of multiple physical parameters experiment of different particle size of coal sample are as follows. The result of industry analysis shows: The proportions of water are roughly the same, The proportions trend of ash and volatile are not monotonous. The SEM shows, 7# coal seam has a significant layered structure, there are a lot of coal slag attached to the surface under a high magnification. The study of pore structure shows that coal macroporous pore volume proportion increases with decreasing particle size. It can be explained from three aspects: intergranular pore, coal surface area and inkwell effect. The basic physical parameters of coal sample show that the difference of adsorption constants a, b and f between 3 coal samples are little. With the increase of the particle size, the initial velocity of gas emission decreases exponentially.According to the desorption characteristics and index research of different grain size of 1# coal sample, cumulative desorption increases as pressure increases and grain size decreases. The higher the pressure is and the smaller the grain size is, the faster initial desorption rate and decay are. Desorption fitting results of logarithmic and Sun are good, but for Barrel is bad. Combined with dual porosity medium model, from the perspective of the matrix, intergranular four holes, surface area and inkwell effect analyzed theoretically the reason of desorption law. Theoretical analysis derived error of index 1K is larger, but still has a reference resistance, the index 2Dh are more reliable. Experimental results, when the particle size is 0.5-1mm, the measured index is maximum. For each grain size of coal samples, there are apparent exponential relationship between index 1K and 2Dh. At the same pressure, logarithmic relationship between index 1K, 2Dh and grain size is significant. Theoretical analysis and experimental data fit both demonstrated a significant linear relationship between 1K and 2Dh. According desorption data, obtained the cumulative desorption equations by fitting, and verified its accuracy.Return to the site, analyzed the reason of anomalously large index with the conclusion above. From the experimental point of view, validated the conclusion that index 2Dh are more reliable again. With cumulative desorption equations, demonstrated the unreality of the sample grain size, and calculated that the actual equivalent diameter is 1.677. From the aspect of nature of structure of the coal, concluded that index 1K and 2Dh can’t be the outburst prediction index for 7# coal seam in Haizi coal mine with the critical value given by the provision.