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Nano-scale pore distribution characterisation of coal using small angle X-ray scattering

Lookup NU author(s): Dr Sadegh NadimiORCiD

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Abstract

In the process of coal seam fracturing with liquid nitrogen (LN₂), the change of coal pore structure has an important influence on the efficiency of coalbed methane (CBM) extraction. The nano-scale pore size distribution (PSD) in coal particles before and after freezing with LN₂ are experimentally studied in this work. Coal samples are collected from four coal mines, where coal and gas outburst accidents have occurred. Small angle X-ray scattering technology (SAXS) and scanning electron microscopy (SEM) are used to study the pore structure changes of coal samples quantitatively and qualitatively. It is found that the scattering intensity of coal samples increases after freezing. The PSD of all samples significantly changes in the range of 0.8–7 nm, showing new pore spaces in 0.8–4 nm and fewer pores in the 4–7 nm range. Both the pore fractal dimension and the radius of gyration of coal samples increase after freezing and are mainly affected by the changes in pores and the anisotropy of the coal matrix. Crack expansion and pore connections are observed in the surface structure of the coal sample using SEM. This study provides a better understanding of the nano-scale mechanism of coal seam fracturing with LN₂ for the prevention of coal and gas outbursts.

Publication metadata

Author(s): Jia P, Jia J, Nadimi S

Publication type: Article

Publication status: Published

Journal: Particuology

Year: 2023

Volume: 81

Pages: 73-85

Print publication date: 01/11/2023

Online publication date: 11/01/2023

Acceptance date: 18/12/2022

ISSN (print): 1674-2001

ISSN (electronic): 2210-4291

Publisher: Elsevier BV

URL: https://doi.org/10.1016/j.partic.2022.12.014

DOI: 10.1016/j.partic.2022.12.014

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