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Thermophysical Response Patterns of Pore Structures in Coals of Different Ranks.
Chen Guo1,2,3, Xinhang Yu1, Jinxiao Yang4
1College of Geology and Environment, Xi'an University of Science and Technology, Xi'an 710054, China.
ACS Omega
|June 22, 2026
Summary
Heat treatment increases coal porosity, especially in low-rank coals, by transforming smaller pores into larger ones. This enhances connectivity, crucial for developing effective coal thermal mining technologies.
Area of Science:
- Geology and Mining Engineering
- Materials Science
- Physical Chemistry
Background:
- Understanding coal pore structure evolution under heat is vital for thermal mining.
- Coal rank significantly influences thermal response and pore characteristics.
Purpose of the Study:
- To investigate the differential evolution of coal pore structures across various ranks under heat treatment.
- To analyze the impact of heat treatment on porosity, pore size distribution, and fractal dimensions.
Main Methods:
- Systematic collection of coal samples from different mines representing various ranks.
- Heat treatment at 200 °C, 300 °C, and 400 °C.
- Low-field nuclear magnetic resonance (NMR) testing and pore fractal geometry analysis.
Main Results:
- Heat treatment universally increased coal porosity, with low-rank coal showing the highest sensitivity.
- Micropores transformed into mesopores and macropores; low-rank coal saw increased mesopores, medium-rank improved connectivity, and high-rank increased macropores.
- Decreased fractal dimensions in mesopores and macropores indicated enhanced connectivity and reduced surface irregularity.
Conclusions:
- Heat treatment alters coal pore structure through expansion, increased pore number, and improved connectivity, favoring fluid extraction.
- Findings provide theoretical and parametric support for site selection and process control in coal thermal mining.
- Differential thermal evolution patterns of pores in coals of different ranks are revealed.
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