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Journal articles on the topic 'Low rank coals'

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Published: 4 June 2021

Last updated: 9 February 2022

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1

O. Odeh, Andrew, Samuel E Ogbeide, and Charity O Okieimen. "Elucidation of the Degradation of Poly Aromatic Hydrocarbon (PAH) in Coals During Pyrolysis." Energy and Environment Research 6, no. 2 (December 2, 2016): 27. http://dx.doi.org/10.5539/eer.v6n2p27.

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In this paper, we explore the use of high resolution transmission electron microscopy (HRTEM) in the degradation of the poly aromatic hydrocarbon (PAH) in coals of different ranks subjected to chemical plus heat treatment. The crystallite diameter on peak (10) approximations, La (10), of 37.6 Å for the high rank coal char at 700 oC fell within the HRTEM’s range of minimum-maximum length boundary of 11 x 11 aromatic aromatic fringes (28 – 44 Å). The La (10), 30.5 Å for the low rank lignite chars fell nearly on the minimum-maximum length range of 7 x 7 aromatic fringes (17 – 28 Å).The HRTEM results showed that the high rank anthracite chars at 700 oC comprised a higher distribution of larger distribution of larger aromatic fringes (11 x 11 parallelogram catenations). The mechanism for the similarity between coal chars of different ranks was the greater transition occurring in the low rank coals (lignite and sub-bituminous) to match the more resistant medium and high rank coals (bituminous – anthracite). This emphasized that the transitions in the properties of the low rank coals were more thermally accelerated than those of the high rank coals. The total PAHs detected in the coals of different ranks during pyrolysis are dominated by two- and three- ring PAHs. The amount of PAHs increase and then decrease with increase in pyrolysis temperature.

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2

Liu, Lei, Zhiqiang Gong, Zhenbo Wang, and Haoteng Zhang. "Study on combustion and emission characteristics of chars from low-temperature and fast pyrolysis of coals with TG-MS." Environmental Engineering Research 25, no. 4 (August 5, 2019): 522–28. http://dx.doi.org/10.4491/eer.2019.220.

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To achieve the clean and efficient utilization of low-rank coal, the combustion and pollutant emission characteristics of chars from low-temperature and fast pyrolysis in a horizontal tube furnace were investigated in a TG-MS analyzer. According to the results, the combustion characteristic of chars was poorer than its parent coals. The temperature range of gaseous product release had a good agreement with that of TGA weight loss. Gaseous products of samples with high content of volatile were released earlier. The NO and NO<sub>2</sub> emissions of chars were lower than their parent coals. Coals of high rank (anthracite and sub-bituminous) released more NO and NO<sub>2</sub> than low rank coals of lignite, so were chars from coals of different ranks. SO<sub>2</sub> emissions of char samples were lower than parent coals and did not show obvious relationship with coal ranks.

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3

Sun, Li Mei, and Jiang Wu. "Biological Anaerobic Treatment for Low-Rank Coal Preparation." Advanced Materials Research 361-363 (October 2011): 328–31. http://dx.doi.org/10.4028/www.scientific.net/amr.361-363.328.

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The effect of microbiological treatment of low-rank coal with an anaerobic microbial consortium on theirs characteristics and composition has been inwestigated. A large amount of pyrite sulfur is removed and coal ash is decreased with anaerobic conditions in closed flask. After biological treatment of these low-rank coals in a continuously operationg flow reactor without air blowiong and with everyday aeration, coal ash reduction is found to be more significant under conditions of reactor aeration due to activation of facultative microorganisems. In some time, some metals are removed from two kinds of low-rank coals, includiing iron, manganese, potassium, lithium, toxic and trace metals. The exchange of elements between coal and mineral culture medium depends on coal rank. Metal leaching is higher for higher rank coal.

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4

Mullins, Oliver C., Sudipa Mitra-Kirtley, Jan Van Elp, and Stephen P. Cramer. "Molecular Structure of Nitrogen in Coal from XANES Spectroscopy." Applied Spectroscopy 47, no. 8 (August 1993): 1268–75. http://dx.doi.org/10.1366/0003702934067991.

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Five major nitrogen chemical structures, present in coals of varying ranks, have been quantitatively determined with the use of nitrogen x-ray absorption near-edge spectroscopy (XANES). Similar studies of the sulfur chemical structures of coals have been performed for the last ten years; nitrogen studies on these fossil-fuel samples have only recently been realized. XANES spectra of coals exhibit several distinguishable resonances which can be correlated with characteristic resonances of particular nitrogen chemical structures, thereby facilitating analysis of these complicated systems. Many model compounds have been examined; for some, the relative peak positions are explained in terms of the orbital description of the lone pair of electrons. All features in the XANES spectra of coals have been accounted for; thus, all the major structural groups of nitrogen present in coals have been determined. A wide variety of aromatic nitrogen compounds is found in the coals; no evidence of saturated amine is found. Pyrroles, pyridines, pyridones, and aromatic amines are found in coal; of these, pyrrolic structures are the most prevalent. Pyridine nitrogen is prevalent in all except low-rank coals. The low pyridine content in low-rank (high-oxygen) coals correlates with a large pyridone content. This observation suggests that, with increasing maturation of coal, the pyridone loses its oxygen and is transformed into pyridine. Aromatic amines are present at low levels in coals of all rank. The spectral effects of aromatic amines are shown by comparing the XANES spectra of coal and petroleum asphaltenes.

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5

Olajossy, Andrzej. "The Influences of the Rank of Coal on Methane Sorption Capacity in Coals/Wpływ Rzędu Węgla Na Pojemność Sorpcyjną Metanu W Węglach." Archives of Mining Sciences 59, no. 2 (June 1, 2014): 509–16. http://dx.doi.org/10.2478/amsc-2014-0037.

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Abstract Methane sorption capacity is of significance in the issues of coalbed methane (CBM) and depends on various parameters, including mainly, on rank of coal and the maceral content in coals. However, in some of the World coals basins the influences of those parameters on methane sorption capacity is various and sometimes complicated. Usually the rank of coal is expressed by its vitrinite reflectance Ro. Moreover, in coals for which there is a high correlation between vitrinite reflectance and volatile matter Vdaf the rank of coal may also be represented by Vdaf. The influence of the rank of coal on methane sorption capacity for Polish coals is not well understood, hence the examination in the presented paper was undertaken. For the purpose of analysis there were chosen fourteen samples of hard coal originating from the Upper Silesian Basin and Lower Silesian Basin. The scope of the sorption capacity is: 15-42 cm3/g and the scope of vitrinite reflectance: 0,6-2,2%. Majority of those coals were of low rank, high volatile matter (HV), some were of middle rank, middle volatile matter (MV) and among them there was a small number of high rank, low volatile matter (LV) coals. The analysis was conducted on the basis of available from the literature results of research of petrographic composition and methane sorption isotherms. Some of those samples were in the form (shape) of grains and others - as cut out plates of coal. The high pressure isotherms previously obtained in the cited studies were analyzed here for the purpose of establishing their sorption capacity on the basis of Langmuire equation. As a result of this paper, it turned out that for low rank, HV coals the Langmuire volume VL slightly decreases with the increase of rank, reaching its minimum for the middle rank (MV) coal and then increases with the rise of the rank (LV). From the graphic illustrations presented with respect to this relation follows the similarity to the Indian coals and partially to the Australian coals.

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6

Brown, L. J., J. D. Cashion, and R. C. Ledger. "Coal ash composition of Australian low rank coals." Hyperfine Interactions 71, no. 1-4 (April 1992): 1411–14. http://dx.doi.org/10.1007/bf02397348.

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7

RAHMAN, M., A. R. HASAN, and D. N. BARIA. "LOW TEMPERATURE OXIDATION OF LOW RANK COALS." Chemical Engineering Communications 46, no. 4-6 (August 1986): 209–26. http://dx.doi.org/10.1080/00986448608911408.

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8

Zhong, Xiao Xing, Guo Lan Dou, Hai Hui Xin, and De Ming Wang. "Study on Low-Temperature Oxidation Process of Low Rank Coal by In Situ FTIR." Advanced Materials Research 652-654 (January 2013): 871–76. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.871.

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Low temperature oxidation of two different low rank coals was measured by in-situ FTIR. Curve-fitting analysis was employed to identify functional groups types of raw coals, and series technology was carried out on in-situ infrared spectrum of sample coals at low-temperature oxidation process to analyze the changes of main active functional groups with temperature. The results indicate that -CH3, -CH2, -OH, C=O, COOH are the main active functional groups in low rank coal. In the oxidation process, with temperature increasing, the methyl and methylene show the tendency of increase after decrease and then decrease, and all of hydroxyl, carboxyl and carbonyl group present the tendency of increase after decrease, there exists some differences among the main functional groups in the coal low-temperature process.

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9

Yang, Zi, Xiao Hua Pan, Sheng Qiang Yuan, and Zhi Feng Ji. "Application of NMR in Coal Reservoir Characterization." Advanced Materials Research 765-767 (September 2013): 2168–71. http://dx.doi.org/10.4028/www.scientific.net/amr.765-767.2168.

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Nuclear Magnetic Resonance (NMR) can provide information about pore and fracture structures, porosity and permeability of reservoirs. It can deep into materials without destroying samples, with advantages such as rapid, accurate and high resolution. This paper introduced the experimental principles and carried out a series of NMR experiments based on high rank coal and low rank coal samples. Results show that: the T2 spectra of high rank coal samples have an independent trimodal distribution with the main peak located at the low T2 value section, indicating that high rank coal is dominated by micropores and transition pores; while the T2 spectrum of low rank coal samples show a continuous trimodal distribution with the main peak located at the high T2 value section, demonstrating the dominance of macropores, mesopores and fractures. The pore and fracture structures of low rank coals are significantly favorable than those of high rank coals.

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10

Ding, Shang Hui, Mei Yu Gu, Ying Dong Jia, Teng Fei Chang, Ge Wang, and Chu Yang Tang. "Research Progress in Pyrolysis of Low-Rank Coals under Different Conditions." Advanced Materials Research 953-954 (June 2014): 1131–34. http://dx.doi.org/10.4028/www.scientific.net/amr.953-954.1131.

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Coal is absolute dominance in reserves-to-production ratio terms. The development of fuels derived from pyrolysis of low-rank coals is beneficial to lower fossil fuels cost and greenhouse gas emissions. The research proposal briefly summarized energy situation and sustainable development strategy as they were by 2013 at first. Then some recent process in the understanding of the pyrolysis behaviors of coal was reviewed. The influencing factors of atmospheres, additives, and catalysts during coal pyrolysis will be followed to literature. The review paper on pyrolysis characteristics will achieve the development of advanced technologies for the clean and efficient utilization of low-rank coals

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11

Machnikowska, Helena, Kamila Pawelec, and Anna Podgórska. "Microbial degradation of low rank coals." Fuel Processing Technology 77-78 (June 2002): 17–23. http://dx.doi.org/10.1016/s0378-3820(02)00064-4.

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12

Mainhood, J., and P. F. Whelan. "Flotation frothers for low-rank coals." Journal of Applied Chemistry 5, no. 3 (May 4, 2007): 133–44. http://dx.doi.org/10.1002/jctb.5010050306.

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13

Faison, Brendlyn D. "Microbial Conversions of Low Rank Coals." Bio/Technology 9, no. 10 (October 1991): 951–56. http://dx.doi.org/10.1038/nbt1091-951.

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14

Scott, D. S., J. Piskorz, and S. Fouda. "Pyrolysis of low rank Canadian coals." Fuel Processing Technology 13, no. 2 (June 1986): 157–86. http://dx.doi.org/10.1016/0378-3820(86)90057-3.

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15

Schobert, Harold H. "Structural features of low-rank coals." Resources, Conservation and Recycling 3, no. 2-3 (March 1990): 111–23. http://dx.doi.org/10.1016/0921-3449(90)90049-a.

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16

Given, P. H. "The chemistry of low-rank coals." Geochimica et Cosmochimica Acta 49, no. 3 (March 1985): 889. http://dx.doi.org/10.1016/0016-7037(85)90182-6.

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17

Zhang, Qiuli, Min Luo, Long Yan, Aiwu Yang, and Xiangrong Hui. "Kinetic Analysis of Low-Rank Coal Pyrolysis by Model-Free and Model-Fitting Methods." Journal of Chemistry 2019 (November 11, 2019): 1–7. http://dx.doi.org/10.1155/2019/9075862.

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Coal SJC, coal WJG, coal ZJM, and coal HCG were selected to investigate the pyrolysis kinetics of northern Shaanxi coals. TG and DSC experiments of four coals were carried out with a synchronous thermal analyzer at heating rates 5, 10, 15, and 20 C/min, respectively. The pyrolysis characteristics were described by thermogravimetric data, and the kinetic parameters were calculated by Flynn–Wall–Ozawa (FWO), Kissinger, general integration, and MacCallum–Tanner methods. The results show that coal SJC, coal ZJM, and coal HCG all conform to the reaction series equation, the thermal decomposition reaction rate is controlled by chemical reaction, and coal WJG conforms to Avrami–Erofeev equation. The activation energies of the four coals are 177.53 kJ/mol, 200.34 kJ/mol, 158.59 kJ/mol, and 240.47 kJ/mol, respectively.

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18

Liu, Jiajia, Jianmin Hu, Gaini Jia, Jianliang Gao, and Dan Wang. "Nuclear Magnetic Resonance Study on Microstructure and Permeability of Coals of Different Ranks." Advances in Civil Engineering 2020 (August 11, 2020): 1–10. http://dx.doi.org/10.1155/2020/7918510.

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The microscopic pore development of most coal seams in China leads to different permeability of coal seams and different gas drainage efficiency. Representative three coal rank coal samples were selected for saturation-centrifugation observation. The microscopic pore characteristics of coal samples were measured by nuclear magnetic resonance and liquid nitrogen adsorption methods. The experimental results showed that the coal samples were subjected to saturation-centrifugation and nuclear magnetic resonance (NMR) tests. It was found that the pores of the low-rank coal (XJ-1, XJ-2) were developed at various stages, and the connectivity between the pores was good and the permeability was also good. The adsorption pores of the intermediate coal (HB-1, HB-2) and high-rank coal (ZM-1, ZM-2) were relatively developed, and the connectivity between the pores was slightly poor. The parallel coal seam samples of coals of different ranks were better than the vertical bedding. The adsorption of liquid nitrogen showed that the low-order coal had more open pores and good gas permeability; the high-order coal had more openings at one end, more ink bottles, and narrow holes, and the gas permeability was not good. Studying the micropore structure and permeability of coals of different ranks has guiding significance for mastering the law of coal seam gas storage and transportation, extracting drilling arrangements, and increasing gas drainage and reducing greenhouse effect.

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19

Saleh, Muksin, and Yulianto Sulistyo Nugroho. "Thermogravimetric Study of the Effect of Particle Size on the Spontaneous Combustion of Indonesian Low Rank Coal." Applied Mechanics and Materials 330 (June 2013): 101–5. http://dx.doi.org/10.4028/www.scientific.net/amm.330.101.

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Low-temperature oxidation of two Indonesian low rank coals was characterized by Thermogravimetric analysis (TGA). The effect of particle size on the spontaneous combustion of coal was examined. Coals were classified to-599+299, -299+249, -249-150, -150+76 and-76 μm size groups and through non-isothermal method scanned from 24 to 600°C at heating rate 5°C/min with air flow rate 50 mL/min. DTA thermogram shows that the transition temperatures decrease by decreasing the particle size. Furthermore, the weight loss increases by decreasing particle size. It is indicated that the propensity of coal to spontaneous combustion increase with decreasing particle size. The moisture loss activation energy and oxidation activation energy were calculated by an integral method using the Coats-Redfern formula. The results show that the propensity for spontaneous combustion of two coal samples (judged by the activation energy) increases by decreasing particle size.

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20

Ma, Shengyue, Jie Xiong, Jing Xiao, Yueling Zhang, Ruihong Zhang, Yajun Tian, and Kechang Xie. "Reactions related with hydroxyl, carboxyl and alkyl side chain at different temperature stages and the effects on low-rank coal ignition." E3S Web of Conferences 213 (2020): 01013. http://dx.doi.org/10.1051/e3sconf/202021301013.

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Low-rank coal contains abundant hydroxyl, carboxyl and alkyl side chains, and reactions related to these groups are the main reason for the spontaneous combustion of low-rank coal. Here, two different low-rank coals (BRXL, YJL52) are selected. Firstly, the ignition temperatures of the coals are determined by thermogravimetric method. Secondly, the coals are heated at 100°C temperature intervals before the ignition temperature in the thermogravimetry, and infrared measurement is performed to explore the changes of these groups. Combining previous studies in the literatures with infrared analysis, it is found that reactions related are as follows: phenolic hydroxyl converting into alcoholic hydroxyl, alcoholic hydroxyl further oxidizing to carboxyl, and carboxyl decarboxylating into alkyl side chains. After that, the changes of phenolic hydroxyl and carboxyl on the surface of the coal at 100°C temperature intervals are determined by titration, which further reveal the main reactions occurred in every temperature interval. Additionally, the actual heat release in different temperature ranges is discussed with the reaction enthalpies of the above-mentioned main reactions. As a result, the key temperature stage that causes spontaneous combustion is found. The screening study in this paper on the reaction of low-rank coal before spontaneous combustion provides a theoretical basis for the control of spontaneous combustion of low-rank coal.

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21

Liu, Jian Zhong, Yu Jie Yu, Jun Hu Zhou, Chong Du, Lin Ye, Jun Cheng, and Ke Fa Cen. "Study on the Effects of Coal Blending on the Slurry Ability of Shenmu Coals." Advanced Materials Research 383-390 (November 2011): 3011–16. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.3011.

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Shenmu coals as low rank coal are difficult to prepare for Coal Water Slurry (CWS). The maximum slurry concentration of Shenmu CWS is lower than 60%, which is not available for practical application. Coal blending is a simple operation and low cost method to improve the slurry ability of low rank coal. Two different kinds of anthracite and bituminous coal samples were blended in Shenmu coal to study the effect on the preparation of CWS, respectively. The results showed that the maximum solid concentration of CWS increased as the proportion of high rank coal rise. And the viscosity of CWS is dropped at the same concentration. Different coals blending have different effects on the elevation of slurry ability for Shenmu coal. The raw coal with best slurry ability is not always the most suitable for blending in low rank coal. HuanNan bituminous coal is the best choice for blending in Shenmu coal. The maximum solid concentration of CWS can be increased by 6% when the proportion of HuanNan coal reached to 70%.

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22

Šlejkovec, Zdenka, and Tjaša Kanduč. "Unexpected Arsenic Compounds in Low-Rank Coals." Environmental Science & Technology 39, no. 10 (May 2005): 3450–54. http://dx.doi.org/10.1021/es0400990.

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23

Gómez-Serrano, V., M. C. Fernández-González, E. M. Cuerda-Correa, A. Macías-García, M. F. Alexandre-Franco, and M. L. Rojas-Cervantes. "Physico-chemical properties of low-rank coals." Powder Technology 148, no. 1 (October 2004): 38–42. http://dx.doi.org/10.1016/j.powtec.2004.09.018.

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24

Brockway, D. J. "Power Generation Technologies for Low-Rank Coals." Developments in Chemical Engineering and Mineral Processing 7, no. 5-6 (May 15, 2008): 483–500. http://dx.doi.org/10.1002/apj.5500070504.

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25

Šiškov, George D. "Bulgarian low rank coals: geology and petrology." Geological Society, London, Special Publications 125, no. 1 (1997): 141–48. http://dx.doi.org/10.1144/gsl.sp.1997.125.01.11.

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26

Selvi, A. V., Rintu Banerjee, L. C. Ram, and G. Singh. "Biodepolymerization studies of low rank Indian coals." World Journal of Microbiology and Biotechnology 25, no. 10 (May 24, 2009): 1713–20. http://dx.doi.org/10.1007/s11274-009-0066-7.

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27

Hou, Lei, George D. Cody, Patrick G. Hatcher, Samuel Gravina, and Mark A. Mattingly. "Imaging the microstructure of low rank coals." Fuel 73, no. 2 (February 1994): 199–203. http://dx.doi.org/10.1016/0016-2361(94)90114-7.

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28

Vasandani, A. G. M., and M. Raza Shah. "Differential thermal analysis of low-rank coals." Journal of Thermal Analysis 41, no. 5 (May 1994): 1053–61. http://dx.doi.org/10.1007/bf02547195.

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29

Walsh, D. E., P. D. Rao, H. Owens, J. R. Mokka, and O. Noirot. "Characterization of hydrothermally dried low-rank coals." Mining, Metallurgy & Exploration 16, no. 1 (February 1999): 48–56. http://dx.doi.org/10.1007/bf03402856.

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30

Quast, Keith B., and David J. Readett. "The surface chemistry of low-rank coals." Advances in Colloid and Interface Science 27, no. 3-4 (July 1987): 169–87. http://dx.doi.org/10.1016/0001-8686(87)85002-9.

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31

Purevsuren, B., Chin-Jung Lin, Y. Davaajav, A. Ariunaa, S. Batbileg, B. Avid, S. Jargalmaa, Yu Huang, and Sofia Ya-Hsuan Liou. "Adsorption isotherms and kinetics of activated carbons produced from coals of different ranks." Water Science and Technology 71, no. 8 (February 25, 2015): 1189–95. http://dx.doi.org/10.2166/wst.2015.094.

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Activated carbons (ACs) from six coals, ranging from low-rank lignite brown coal to high-rank stone coal, were utilized as adsorbents to remove basic methylene blue (MB) from an aqueous solution. The surface properties of the obtained ACs were characterized via thermal analysis, N2 isothermal sorption, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and Boehm titration. As coal rank decreased, an increase in the heterogeneity of the pore structures and abundance of oxygen-containing functional groups increased MB coverage on its surface. The equilibrium data ﬁtted well with the Langmuir model, and adsorption capacity of MB ranged from 51.8 to 344.8 mg g−1. Good correlation coefficients were obtained using the intra-particle diffusion model, indicating that the adsorption of MB onto ACs is diffusion controlled. The values of the effective diffusion coefficient ranged from 0.61 × 10−10 to 7.1 × 10−10 m2 s−1, indicating that ACs from lower-rank coals have higher effective diffusivities. Among all the ACs obtained from selected coals, the AC from low-rank lignite brown coal was the most effective in removing MB from an aqueous solution.

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32

Zhang, Yihuai, Maxim Lebedev, Gregory Smith, Yu Jing, Andreas Busch, and Stefan Iglauer. "Nano-mechanical Properties and Pore-Scale Characterization of Different Rank Coals." Natural Resources Research 29, no. 3 (October 18, 2019): 1787–800. http://dx.doi.org/10.1007/s11053-019-09572-8.

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ABSTRACT Characterization of coal micro-structure and the associated rock mechanical properties are of key importance for coal seam exploration, coal bed methane development, enhanced coal bed methane production and CO2 storage in deep coal seams. Considerable knowledge exists about coal chemical properties, but less is known about the nanoscale to the micro-scale structure of coals and how they change with coal strength across coal ranks. Thus, in this study, 3D X-ray micro-computed tomography (with a voxel size of 3.43 µm) and nano-indentation tests were conducted on coal samples of different ranks from peat to anthracite. The micro-structure of peats showed a well-developed pore system with meso- and micro-pores. The meso-pores essentially disappear with increasing rank, whereas the micro-pores persist and then increase past the bituminous rank. The micro-fracture system develops past the peat stage and by sub-bituminous ranks and changes into larger and mature fracture systems at higher ranks. The nano-indentation modulus showed the increasing trend from low- to high-rank coal with a perfect linear relationship with vitrinite reflectance and is highly correlated with carbon content as expected.

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33

Asmatulu, R., N. Acarkan, G. Onal, and M. S. Celik. "Desulphurization of low-rank coals by low-temperature carbonization." Geological Society, London, Special Publications 125, no. 1 (1997): 365–69. http://dx.doi.org/10.1144/gsl.sp.1997.125.01.33.

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34

Li, Xiangchun, Zhongbei Li, Fan Zhang, Qi Zhang, Baisheng Nie, and Yangyang Meng. "Nanopore Structure of Different Rank Coals and Its Quantitative Characterization." Journal of Nanoscience and Nanotechnology 21, no. 1 (January 1, 2021): 22–42. http://dx.doi.org/10.1166/jnn.2021.18728.

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Based on gas adsorption theory, high-pressure mercury intrusion (HPMI), low-temperature liquid nitrogen gas adsorption (LT-N2GA), CO2 adsorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and small-angle X-ray scattering (SAXS) techniques were used to analyze the pore structures of six coal samples with different metamorphisms in terms of pore volume, specific surface area (SSA), pore size distribution (PSD) and pore shape. Combined with the gas adsorption constant a, the influence and mechanism of the pore structure of different coal ranks on gas adsorption capacity were analyzed. The results show that there are obvious differences in the pore structure of coals with different ranks, which leads to different adsorption capacities. To a large extent, the pore shapes observed by SEM are consistent with the LT-N2GA isotherm analysis. The pore morphology of coal samples with different ranks is very different, indicating the heterogeneity among the coal surfaces. Adsorption analysis revealed that mesopore size distributions are multimodal and that the pore volume is mainly composed of mesopores of 2–15 nm. The adsorption capacity of the coal body micropores depends on the 0.6–0.9 nm and 1.5–2.0 nm aperture sections. The influence of coal rank on gas desorption and diffusion is mainly related to the difference in pore structure. The medium metamorphic coal sample spectra show that the number of peaks in the high-wavenumber segment is small and that it is greater in the high metamorphic coal. The absorption intensity of the C–H stretching vibration peak of naphthenic or aliphatic hydrocarbons varies significantly among the coal samples. Over a small range of angles, as the scattering angle increases, the scattering intensity of each coal sample gradually decreases, and as the degree of metamorphism increases, the scattering intensity gradually increases. That is, the degree of metamorphism of coal samples is directly proportional to the scattering intensity. The influence of coal rank on gas adsorption capacity is mainly related to the difference in pore structure. The gas adsorption capacity shows an asymmetric U-shaped relationship with coal rank. For higher rank coals (Vdaf < 15%), the gas adsorption consistently decreases significantly with increasing Vdaf. In the middle and low rank coal stages (Vdaf > 15%), it increases slowly with the increase of Vdaf. We believe that the results of this study will provide a theoretical basis and practical reference value for effectively evaluating coal-rock gas storage capacity, revealing the law of CBM enrichment and the development and utilization of CBM resources.

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35

Chakrabartty, Sujit K., and Angelo Iacchelli. "The dilemma of estimating forms of sulfur in low-sulfur low rank coals." Canadian Journal of Chemistry 64, no. 5 (May 1, 1986): 861–64. http://dx.doi.org/10.1139/v86-142.

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The analytical methods for estimating forms of sulfur in coals are reviewed on the basis of sulfur analyses of Western Canadian low sulfur subbituminous coals. The reasons for the variance in analyses are examined, and a novel method of analysis is recommended for evaluation

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36

Yuliani, Galuh, Imas Noviyana, and Agus Setiabudi. "Enrichment of Indonesian Low Rank Coal's Surface Oxygen Compounds (SOCs) Using Hydrogen Peroxide and its Adsorptive Properties." Advanced Materials Research 896 (February 2014): 159–62. http://dx.doi.org/10.4028/www.scientific.net/amr.896.159.

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Cheap and highly abundant low rank coal from Banten, West Java, Indonesia, was utilized as an adsorbent for a cationic dye. The previous reports show that raw low rank coal has low adsorption capacity when compared to activated carbon. It is also indicated that the coals surface oxygen compounds played a major role in the adsorption mechanism. This research aimed to enrich the oxygen compounds on the coals surface by a straightforward oxidation process using hydrogen peroxide and to investigate the adsorption capacities of raw and treated coals using cationic dye solutions. The oxidation process was conducted by adding the raw coal in hydrogen peroxide solutions having concentrations of 5%, 10%, and 20%, followed by stirring for 10 minutes to 60 minutes. After a serial of washing processes and air-drying, the adsorption capacities of the treated coals for a cationic dye were investigated using batch tests. The batch tests were conducted by adding 0.1 to 0.3 g of coals to 50 mL of methylene blue solutions followed by stirring the solutions for 5 hours. The experimental data were plotted using Langmuir adsorption isotherm model. The adsorption capacity of a treated coal when plotted using Langmuir isotherm was found to be 103 mg/g, significantly higher than that of the raw coal, which was only 52 mg/g. The FTIR spectra showed new absorption of carboxylates at 1700 cm-1 indicating increases in the oxygen containing groups, whilst the surface area measurement indicated an increase in surface area from 0.097 m2/g to 0.232 m2/g. It is concluded that the treatment using hydrogen peroxide solution has significantly improved the surface oxygen compounds of the low rank coal, increased its surface area and also its adsorption capacity for a cationic dye.

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Bielowicz, Barbara, and Jacek Misiak. "The Impact of Coal’s Petrographic Composition on Its Suitability for the Gasification Process: The Example of Polish Deposits." Resources 9, no. 9 (September 9, 2020): 111. http://dx.doi.org/10.3390/resources9090111.

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In this paper, we discuss the impact of the rank of coal, petrographic composition, and physico-chemical coal properties on the release and composition of syngas during coal gasification in a CO2 atmosphere. This study used humic coals (parabituminous to anthracite) and lithotypes (bright coal and dull coal). Gasification was performed at temperatures between 600 and 1100 °C. It was found that the gas release depends on the temperature and rank of coal, and the reactivity increases with the increasing rank of coal. It was shown that the coal lithotype does not affect the gas composition or the process. Until 900 °C, the most intense processes were observed for higher rank coals. Above 1000 °C, the most reactive coals had a vitrinite reflectance of 0.5–0.6%. It was confirmed that the gasification of low-rank coal should be performed at temperatures above 1000 °C, and the reactivity of coal depends on the petrographic composition and physico-chemical features. It was shown that inertinite has a negative impact on the H2 content; at 950 °C, the increase in H2 depends on the rank of coal and vitrinite content. The physicochemical properties of coal rely on the content of maceral groups and the rank of coal. An improved understanding these relationships will allow the optimal selection of coal for gasification.

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Qiu, Feng, Dameng Liu, Yidong Cai, Ning Liu, and Yongkai Qiu. "Methane Adsorption Interpreting with Adsorption Potential and Its Controlling Factors in Various Rank Coals." Processes 8, no. 4 (March 27, 2020): 390. http://dx.doi.org/10.3390/pr8040390.

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Water content, metamorphism (coal rank) particle size, and especially pore structure, strongly influence the adsorption capacity of coal to methane. To understand the mechanism of methane adsorption in different rank coals, and its controlling factors, isothermal adsorption experiments with different coal ranks, moisture contents and particle sizes at the temperature of 303.15 K were conducted. In addition, the pore structures of coals were investigated through N2 adsorption/desorption experiments at the low-temperature of 77 K for selected coals from the Junggar Basin of NW China, Qinshui Basin and Ordos Basin of north China. Moreover, the adsorption potential of methane on the surface of the coal matrix was calculated, the controlling factors of which were discussed. The obtained methane isothermal adsorption result shows that the Langmuir volume (VL) of coal is independent of the particle size, and decreases with the increase of moisture content, which decreases first and then increases when the coal rank increases. Combined with the pore structure by the N2 adsorption at 77 K, VL increases with the increase of pore surface area and pore volume of coal pores. Besides, the adsorption potential of all selected coals decreased with the increase of the methane adsorption volume, showing a negative relationship. The interesting phenomena was found that the surface adsorption potential of the coal matrix decreases with the increase of moisture content, and increases with the decrease of particle size at the same pressure. With the same adsorption amount, the adsorption potential on the surface of coal matrix decreases first, and then increases with the increase of coal rank, reaching a minimum at Ro,m of 1.38%, and enlarging with the increase of pore surface area and the pore volume of coal pores. These findings may have significant implications for discovering CBM accumulation areas and enhancing CBM recovery.

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SAEKI, TAKASHI, TAKAFUMI TATSUKAWA, and HIROMOTO USUI. "Preparation Techniques of Coal Water Mixtures with Upgraded Low Rank Coals." Coal Preparation 21, no. 1 (December 1999): 161–76. http://dx.doi.org/10.1080/07349349908945615.

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40

Larsen, John W., and Susan Shawver. "Solvent swelling studies of two low-rank coals." Energy & Fuels 4, no. 1 (January 1990): 74–77. http://dx.doi.org/10.1021/ef00019a013.

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41

Bongers, Geoffrey D., W. Roy Jackson, and Fedir Woskoboenko. "Pressurised steam drying of Australian low-rank coals." Fuel Processing Technology 57, no. 1 (August 1998): 41–54. http://dx.doi.org/10.1016/s0378-3820(98)00066-6.

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42

Bongers, Geoffrey D., W. Roy Jackson, and Fedir Woskoboenko. "Pressurised steam drying of Australian low-rank coals." Fuel Processing Technology 64, no. 1-3 (May 2000): 13–23. http://dx.doi.org/10.1016/s0378-3820(99)00070-3.

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43

Domazetis, G., P. Barilla, and B. D. James. "Lower emission plant using processed low-rank coals." Fuel Processing Technology 91, no. 3 (March 2010): 255–65. http://dx.doi.org/10.1016/j.fuproc.2009.10.006.

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Artanto, Y., W. R. Jackson, P. J. Redlich, and M. Marshall. "Liquefaction studies of some Indonesian low rank coals." Fuel 79, no. 11 (September 2000): 1333–40. http://dx.doi.org/10.1016/s0016-2361(99)00275-6.

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45

Xia, Wencheng, Guangyuan Xie, and Yaoli Peng. "Recent advances in beneficiation for low rank coals." Powder Technology 277 (June 2015): 206–21. http://dx.doi.org/10.1016/j.powtec.2015.03.003.

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RAO, P. D., DANIEL E. WALSH, and WARRACK WILLSON. "Ash Characterization for Two Alaskan Low-Rank Coals." Coal Preparation 20, no. 3-4 (September 1999): 161–78. http://dx.doi.org/10.1080/07349349908945598.

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47

Benson, Steven A., and Paul L. Holm. "Comparison of inorganics in three low-rank coals." Industrial & Engineering Chemistry Product Research and Development 24, no. 1 (March 1985): 145–49. http://dx.doi.org/10.1021/i300017a027.

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48

Bouchillon, C. W., and W. G. Steele. "ELECTROSTATIC SEPARATION OF ULTRAFINELY GROUND LOW-RANK COALS." Particulate Science and Technology 10, no. 1 (January 1, 1992): 73–89. http://dx.doi.org/10.1080/02726359208906600.

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49

Karthikeyan, Muthusamy, Joshua V. M. Kuma, Chew Soon Hoe, and David Low Yi Ngo. "Factors Affecting Quality of Dried Low-Rank Coals." Drying Technology 25, no. 10 (October 2007): 1601–11. http://dx.doi.org/10.1080/07373930701590608.

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50

Gonsalvesh, L., S. P. Marinov, M. Stefanova, R. Carleer, and J. Yperman. "Organic sulphur alterations in biodesulphurized low rank coals." Fuel 97 (July 2012): 489–503. http://dx.doi.org/10.1016/j.fuel.2012.02.015.

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