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Investigation of Pore Structure and Adsorption/Desorption Properties of Coal in the Non-uniform Stress Zone: Implications for Coal and Gas Outburst.
- Source :
- Natural Resources Research; Jun2024, Vol. 33 Issue 3, p1247-1268, 22p
- Publication Year :
- 2024
-
Abstract
- The haulage roadway of the F<subscript>15</subscript>-22080 working face, No.8 mine is situated within a special non-uniform stress zone. In this area, the extraction-boreholes drilling process frequently triggers coal and gas outburst. Against this background, this study systematically conducted high-pressure gas adsorption experiments and high-pressure gas desorption experiments on coal samples collected from different stress zones and obtained their adsorption/desorption characteristics. Subsequently, coal pore structure characteristics at various scales were investigated by employing scanning electron microscopy, low-pressure N<subscript>2</subscript> adsorption and low-pressure CO<subscript>2</subscript> adsorption techniques and fractal analysis to assess the impact of varying stress levels. On this basis, a comprehensive analysis was carried out to explore the connections between stress, pore structure, adsorption/desorption traits, and the risk of outburst. The results indicate that, with increasing stress, the Protodyakonov coefficient f and the Langmuir pressure P<subscript>L</subscript> decrease, while the index of diffusion initial velocity of coal gas Δp and the Langmuir volume V<subscript>L</subscript> increase. The desorption amount and rate of gas also increase significantly. The total pore volume and specific surface area of micropores increase, while those of mesopores and macropores show an overall decreasing trend. The surface fractal dimension D<subscript>F1</subscript> increases by 9%, the spatial fractal dimension D<subscript>F2</subscript> decreases by 5.2%, and the volume fractal dimension D<subscript>SIE</subscript> increases by 1%. The induced stress leads to a decrease in the abundance of macropores and mesopores, with concurrent increase in micropores. The V<subscript>L</subscript> exhibits a linear increase with the D<subscript>SIE</subscript>, whereas the P<subscript>L</subscript> demonstrates a linear decrease with it. The initial desorption rate rises with the reduction of the D<subscript>F2</subscript> and the increase of the D<subscript>SIE</subscript>. The influence of superimposed-stress on outburst stems from alterations in pore structure and adsorption–desorption capabilities. Simultaneously, it collectively heightened the outburst risk by increasing the gas pressure gradient and weakening the strength of the coal. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 15207439
- Volume :
- 33
- Issue :
- 3
- Database :
- Complementary Index
- Journal :
- Natural Resources Research
- Publication Type :
- Academic Journal
- Accession number :
- 177371020
- Full Text :
- https://doi.org/10.1007/s11053-024-10320-w