Effects of igneous intrusions on the structure and spontaneous combustion propensity of coal: A case study of bituminous coal in Daxing Mine, China

Shi, Qi; Qin, Botao; Liang, Hongjun; Gao, Yuan; Bi, Qiang; Bao, Qu

doi:10.1016/j.fuel.2017.12.012

Cited by 93 publications

(30 citation statements)

References 33 publications

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“…18) allowing the transport of oxygen through the pores and the reaction of O 2 with pore surfaces. As altered coal always shows higher porosity than unaltered coal, it can be deduced that during alteration, the porous texture with a higher porosity and larger pore volume evolved, analogously (Shi et al 2018). The larger average pore diameter is attributed to this newly formed porous system as a main factor influencing the subsequent diffusion of oxygen into the coal structure and the consumption of oxygen during this low-temperature oxidation (Meng et al 2016).…”

Section: Temperature Of Coal Alteration As Estimated From Micropetrogmentioning

confidence: 95%

“…Therefore, in this case, the heating of coal up to * 100/113°C improved the transport capacity of the oxygen in the pores and the reaction of O 2 with active sites on the pore surfaces occurred. The works of Meng et al (2016), Su et al (2017) and Shi et al (2018) reveals that with increase of coal temperature, consumption of oxygen grew slowly at first at temperatures up to 70°C while O 2 chemisorption dominated, then, at temperatures above 80°C, it grew rapidly as O 2 reaction with active sites dominated. The actual oxygen reaction took place on the active centers of the coal structure, namely on the aliphatic and alicyclic groups associated with the aromatic rings, to form unstable peroxides and hydroperoxides (Kurková 2002); from these unstable intermediates then stable oxygen compounds with CO and COO groups are formed; and finally, retrograde humic acids are formed (Klika and Kraussová 1993;Klika 1999;Kurková 2002).…”

Section: Temperature Of Coal Alteration As Estimated From Micropetrogmentioning

confidence: 97%

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Coalification and coal alteration under mild thermal conditions

Straka

Sýkorová

2018

Int J Coal Sci Technol

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Coalification temperatures are often considered to be approximately 100-170°C for bituminous coal and 170-275°C for anthracite. However, our micropetrographic observations, solid state 27 Al magic-angle spinning nuclear magnetic resonance measurements, interpretation of d 13 C values for whewellite in pelosiderite concretions from Carboniferous sediments, and assessment of whewellite thermal stability show that coalification temperatures can be significantly lower. Also the temperatures of coal alteration may be substantially lower than is stated. Ordinarily, hightemperature alteration is reported, but microthermometric measurements of fluids temperatures and micropetrographic observations show that the coal alteration can take place at low temperatures. For this reason, coals from the Kladno-Rakovník Basin, part of Late Paleozoic continental basins of the Czech Republic, were analyzed. Regarding coalification, micropetrographic characterizations of unaltered coals, the presence of thermally unstable Al complexes in the coal organic mass documented using 27 Al MAS NMR method, and proven occurrence of whewellite in pelosiderite concretions suggest a lower coalification temperature, max.~70°C. Regarding coal alteration, micropetrographic observations revealed (a) the weaker intensity of fluorescence of liptinite, (b) mylonitic structures and microbreccia with carbonate fluid penetration, and (c) high oxygen content in coals (37-38 wt.%). These phenomena are typical for thermal and oxidative alteration of coal. As the temperature of carbonate fluids inferred from fluid inclusion analysis was evaluated as * 100-113°C, the temperature of coal alteration was suggested as * 113°C; the alteration was caused by hot hydrothermal fluids.

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Section: Temperature Of Coal Alteration As Estimated From Micropetrogmentioning

confidence: 95%

Section: Temperature Of Coal Alteration As Estimated From Micropetrogmentioning

confidence: 97%

Coalification and coal alteration under mild thermal conditions

Straka

Sýkorová

2018

Int J Coal Sci Technol

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“…The O atoms on the impurities' surfaces are represented by the two characteristic peaks for -OH and C-O, again in increasing BE order, as well as peaks for Si(OH) 4 and Al(OH) 3 species present in the admixed kaolinite ( Figure 3). Based on binding energy (BE) and peak attribute reference data for C 1s [22][23][24][25] and O 1s [26,27], the XPSPEAK4.1 program was used for C 1s and O 1s peak fitting, with the results shown in Figures 2 and 3, respectively. The C atoms on the surface of the kaolinitic carbon impurities existed mainly in the forms of C-C, C-H, C-O, CiO, and COO-structures.…”

Section: Discussionmentioning

confidence: 99%

Density Functional Theory Analysis of the Adsorption Interactions of Carbon Impurities in Coal-associated Kaolinite

Liu

Min

et al. 2019

Processes

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Kaolinite is a difficult-to-float clay existing in coal slurries which negatively impacts coal flotation. A better understanding of its adsorption behavior would improve coal-slurry processing. Carbon impurities in the kaolinite can affect this behavior. The appearance and elemental surface composition of the carbon impurities precipitated by kaolinite oxidative treatment were microscopically analyzed, and their chemical speciation and relative C and O contents were probed. The mechanisms of adsorption on the main kaolinite cleavage planes ((001) and (001) surfaces) for two carbon-impurity structural models, a phenolic hydroxyl unit (Ph–OH) and carbon hydroxyl unit (C–OH), were considered using density functional theory methods. The carbon impurities consisted mainly of C and O, with C present mostly as C–C, C–H, and C–O species, and O existing mainly in –OH and C–O structures. Both Ph–OH and C–OH units adsorbed stably on the kaolinite (001) and (001) surfaces through hydrogen bonding between the hydroxyl groups and surfaces. A strong electrostatic attraction occurred between the Ph–OH benzene ring and kaolinite surfaces, whereas the carbon ring in C–OH did not interact with either surface. Finally, for both units, adsorption on the kaolinite (001) surface was more stable than on the (001) surface.

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“…[1][2][3][4] Therefore, CSC prevention is of great significance for the safe production of coal. Coal spontaneous combustion (CSC) can not only produce lots of toxic and harmful gases, but also cause casualties.…”

Section: Introductionmentioning

confidence: 99%

“…Coal spontaneous combustion (CSC) can not only produce lots of toxic and harmful gases, but also cause casualties. [1][2][3][4] Therefore, CSC prevention is of great significance for the safe production of coal. 5 Many methods have been proposed to inhibit CSC in underground coal mines.…”

Section: Introductionmentioning

confidence: 99%

Effects of ionic liquid concentration on coal low‐temperature oxidation

Cui

Jiang

Zheng

et al. 2019

Energy Science & Engineering

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In order to find out the optimal concentration of ionic liquid to lower the cost of inhibiting coal spontaneous combustion, effects of aliphatic hydrocarbons, hydrogen bonds, and some structural parameters of coal samples treated with low‐concentration ionic liquids were analyzed through Fourier‐transform infrared spectroscopy (FTIR) and temperature‐programmed experiments. Meanwhile, the changes of index gases in the heating process were observed by the temperature‐programmed method. The results show that the contents of aliphatic hydrocarbons in the treated coal samples decrease remarkably, so does the length of aliphatic chain CH2/CH3; besides, the amount of CO produced also decreases to some extent. When the mass concentration ratio is 1:10, HB‐tc, BB‐tc, AC‐tc, and BN‐tc can reduce the spatial structure and enhance the structural stability of aromatic clusters in coal. The CO concentrations of 1:2 HB‐tc and 1:10 AC‐tc are obviously lower than that of raw coal, indicating their better inhibitory effects. The inhibitory effect of HB‐tc decreases with the decrease in concentration. With the rise of temperature, the effect of concentration on the inhibition of CO production gradually weakens at 180°C and 200°C. AC‐tc achieves the optimum inhibitory effect near 1:10 mass concentration ratio.

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Effects of igneous intrusions on the structure and spontaneous combustion propensity of coal: A case study of bituminous coal in Daxing Mine, China

Cited by 93 publications

References 33 publications

Coalification and coal alteration under mild thermal conditions

Coalification and coal alteration under mild thermal conditions

Density Functional Theory Analysis of the Adsorption Interactions of Carbon Impurities in Coal-associated Kaolinite

Effects of ionic liquid concentration on coal low‐temperature oxidation

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