The Raman spectroscopic analysis for eleven different rank coals (57.58% to 94.01% of Cdaf, %) indicated that two distinct bands, i.e., D band (1340-1380 cm(-1)) and G band (1580-1600 cm(-1)), exist in the first order of Raman spectra, with the former being broader and the latter rather sharp. As the two bands were overlapped each other, each spectrum was fitted with two Lorentz peaks and the Raman information about position, intensity and FWHM of each band was thus obtained. The relation of these Raman parameters with Cdaf% showed that with the increase in C%, the position of D band and G band shifts to lower and higher frequency, respectively; the separation of the two band positions increases with the increase in C%; FWHM-D, FWHM-G and I(D)/I(G) have linear relationship with Cdaf% in the range of Cdaf% 75%-94%. The coal structural parameters, d002 and Lc from XRD are related with the position and FWHM of G band; the comparison of La from XRD and both from the Cancado and the KW equation indicated that the values from Cancado and the KW equation are unreasonable.
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J Mol Model
January 2025
School of Chemical and Environmental Engineering, China University of Mining and Technology-Beijing, Haidian District, Ding No.11 Xueyuan Road, Beijing, 100083, People's Republic of China.
Context: Understanding the structural characteristics of coal at the molecular level is fundamental for its effective utilization. To explore the molecular structure characteristic, the long-flame coal from Daliuta (DLT), coking coal from Yaoqiao (YQ), and anthracite from Taixi (TX) were investigated using various techniques such as elemental analysis, Fourier transform infrared spectroscopy, solid-state C nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy. Based on the structural parameters, the coal molecular model was constructed and optimized.
View Article and Find Full Text PDFLangmuir
January 2025
College of Mining Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China.
Flotation is an interfacial process involving gas, liquid, and solid phases, where polar ionic promoters significantly influence both gas-liquid and solid-liquid interfaces during low-rank coal (LRC) flotation. This study examines how the structures of hydrophilic groups in cation-anion mixed promoters affect the interfacial flotation performance of LRC pulp using flotation tests, surface tension tests, wetting heat tests, and molecular dynamics simulations. Results indicate that cation-anion mixed promoters enhance the LRC floatability to varying degrees.
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January 2025
School of Safety and Management Engineering, Hunan Institute of Technology, Hengyang, 421002, China.
The extraction of coal seams with high gas content and low permeability presents significant challenges, particularly due to the extended period required for gas extraction to meet safety standards and the inherently low extraction efficiency. Hydraulic fracturing technology, widely employed in the permeability enhancement of soft and low-permeability coal seams, serves as a key intervention. This study focuses on the high-rank raw coal from the No.
View Article and Find Full Text PDFPakistani lignite (PLC) was thermally dissolved at 300 °C using isopropanol (IPA) to obtain a soluble portion (SP) and insoluble portion (ISP). Proximate analysis, ultimate analysis, Fourier transform infrared spectrometry (FTIR), thermogravimetric analysis (TG-DTG) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) results were compared to explore the influence of the thermal dissolution process on the pyrolysis for PLC and ISP. Results showed that the thermal dissolution process mainly dissolved some light components of low-rank coal, and more phenols, aldehydes, esters and ethers were found in the SP, indicating that low-carbon alcohols can break the ether bridge bond in coal and generate oxygen-containing organic compounds (OCOCs).
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December 2024
Key Laboratory of Coalbed Methane Resource and Reservoir Formation Process, Ministry of Education, China University of Mining and Technology, Xuzhou, China.
This analysis revealed the alterations in the pore structure of large organic molecules in coal during the process of coal pyrolysis. Nine models of macromolecular structures in coals, representing distinct coal ranks, have been built. The research results show that along with the increasing coal rank, the average microporous volume of medium rank coal is 0.
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