Meikuang Anquan (Jul 2022)
Study on pore structure of coking coal based on low-temperature nitrogen adsorption and mercury intrusion method
Abstract
In order to clarify the pore structure characteristics of deep coking coal in Pingdingshan No.12 Coal Mine, low-temperature nitrogen adsorption method and mercury intrusion method were used to conduct experimental research on its soft and hard coal. The pore structure fractal was carried out on the parameters measured by mercury intrusion method using the Menger sponge model. The results show that the low-temperature nitrogen adsorption isotherms of soft and hard coal in Pingdingshan coking coal are close to the IV isotherm, the development of soft and hard coal is relatively consistent, and there is a small hysteresis loop. The types of micropore and small pore are mainly the impermeable pore and closed pore with one end closed, and the pores above the middle pore are mainly open and permeable; the pore area of soft coal measured by mercury intrusion method is 5.058 m2/g, the pore volume is 0.037 5 cm3/g, the pore area of hard coal is 4.641 m2/g, and the pore volume is 0.036 8 cm3/g. The pore size distribution of soft and hard coal is relatively consistent, the adsorption space is concentrated in micropores and small pores, and a higher proportion of micropores is conducive to gas storage; the pore characteristics of coking coal samples show a “polarization” distribution, and the macropores, visible pores and cracks are compared. It is conducive to the flow and drainage of coal seam gas in Pingdingshan No.12 Coal Mine, but a small proportion of mesoporous pores may result in poor gas production and migration channels; soft and hard coal seepage pores have obvious fractal characteristics, the fractal dimension of adsorption pores is generally higher than that of seepage pores, indicating that the pore structure of micro-pores is more complex and irregular.
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