Experimental Research On Adsorption Pore Characteristics And Gas Radiation Performance Of Low Rank Coal In Xinjiang Fukang Mining Area

The coal resources of Xinjiang is very rich,and it's coal seam conditions is complex.Fukang mining area is an important coal production base of Xinjiang.The resource conditions of Fukang mining area are superior,and the development prospects of it's coalbed methane is broad.The study of the adsorption pore characteristics and gas dispersion properties of low-grade coal in the Fukang mining area and the influence of the adsorption pore characteristics on the gas dispersion performance can provide favorable basis for the gas disaster prevention and coalbed methane extraction in the mine production process.In this paper,the samples of eight main coal mines in Xinjiang Fukang mining area are selected for experimental study.The macroscopic physical properties of experimental coal samples are similar.The chemical composition of the coal samples were obtained by the industrial analysis experiments,and the micro-components characteristics of the coal samples were obtained by the micro-component analysis experiments.According to the mass fraction of coal and the average reflectivity of the vitrinite,the metamorphic degree of coal samples is low.The low temperature nitrogen adsorption experiment was carried out on the coal samples.The relationship between the adsorption capacity and the relative pressure is the adsorption isotherm of the experimental coal sample.According to the adsorption isotherm shape we can see,the shape of the adsorption pores of the experimental coal samples is mainly the cylindrical pores with one end opening and the plate-shaped pores with one end closed.According to the theory of gas adsorption,using the corresponding model to calculate the parameters of pore structural characteristics,such as the average pore diameter and pore size distribution.The results show that the specific surface area of the adsorption pore is dominated by the transition pore,and the volume of the adsorption pore is dominated by the transition pore and mesopore.According to the relationship between the adsorption capacity and the relative pressure,the FHH model is used to calculate the fractal dimension of the adsorption pore surface.The results show that the fracturing characteristics of the coal sample are obvious in the study scale,the chemical composition of the coal sample and the parameters of adsorption pore structure have some influence on the fractal dimension of the adsorption pore.The initial velocity and the amount of gas dissipation of the coal sample were obtained by the experiment of the initial velocity of the gas removal of the coal sample.The Knudsen was used to judge the gas dispersion model in the adsorption pores.Through the fitting analysis we can see that,there is a linear relationship between the initial velocity of gas dissipation and the parameters of adsorption pore structure and fractal dimension.In the experimental range,there is no obvious linear relationship between the gas dispersion in the fixed space at 10 and the parameters of the adsorption pore structure and the fractal dimension of adsorption pores.The gas dispersion in the fixed space at 60 s is linearly related to the average pore diameter of the adsorption pore,and negatively with the fractal dimension of adsorption pores.There is no obvious linear relationship with the specific surface area and volume of the adsorption pore.The gas dispersion in the fixed space at 60 s has no obvious linear relationship with the specific surface area and volume of the adsorption pore.