Groups Of Different Coal Lithofacies Study On Pore Structure And Adsorption Property

The microstructure of coal is complex and diverse.Different macerals have different material composition,pore structure and adsorption properties.The pore evolution and adsorption and desorption law of coal can be evaluated from maceral level.Paper meander in Shanxi Province,Rong tai,Zhao Zhuang three three different kinds of coal in coal mine of low rank coal coal as the research object,based on the different density of liquid gravity flotation,isolated from different microscopic group of coal sample,to carry out pulverized coal maceral are made of light and the microscopic observation quantitative,industry analysis,liquid nitrogen adsorption at low temperature,carbon dioxide,methane adsorption isothermal adsorption experiment,The evolution process of pore structure of different coal maceral groups with coal rank change was determined,and the adsorption,desorption and diffusion properties of methane in different coal maceral groups were determined.The relationships among component content,pore structure and adsorption and diffusion properties of different maceral groups were further discussed.The main research results are as follows:(1)Based on the density difference of vitrinite and inertinite,pulverized coal with different contents of maceral groups was separated: samples with particle size of 60-80 mesh were conducive to the enrichment of vitrinite,while the difference in wettability of vitrinite and inertinite led to the disadvantageous separation flotation of pulverized coal with particle size of over 200 mesh.(2)The pore morphology,pore size distribution and fractal characteristics of different separated samples were studied by low temperature liquid nitrogen adsorption and low temperature carbon dioxide adsorption experiments.The pore morphology of the separated coal samples is similar to that of the raw coal samples.With the increase of inertinite content,the total pore volume of BJH increases and the BET ratio of the surface increases.With the increase of coalification,the surface roughness of coal samples decreases at first and then increases.The fractal dimension of vitrinite enrichment in the same coal samples is generally smaller than that of inertinite enrichment.(3)Based on the two-hole diffusion model,the effects of metamorphic degree,pressure,particle size and maceral groups content on methane diffusion law were discussed.The increase of pressure and inertinite content were conducive to methane diffusion.(4)The relationship between inertinite and vitrinite content and adsorption capacity is revealed.The inertinite has larger pore volume and specific surface at the middle and low coal rank stage,which leads to the phenomenon that inertinite adsorption capacity is stronger than vitrinite.With the increasing of evolution degree,idler of stable properties,structural change is not big,vitrinite of hydrocarbon generation to generate many new superfine hole(diameter 0 to 2nm),inert mass groups increased the content of no longer produces a larger specific surface and pore volume,because the inert mass adsorption ability weak in vitrinite group itself,a high coal rank stage inert mass groups of weak adsorption ability in the phenomenon of vitrinite.