Shore hardness measurements of sub-bituminous coal microlithotypes

Barbosa, Karina; Esterle, Joan; Wetering, Nikola Van de; Chen, Zhongwei

doi:10.1016/j.coal.2019.103341

Cited by 1 publication

(2 citation statements)

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“…20 The correlation between microlithotype and hardness is that the coal hardness increases with the decline of vitrinite content; carbominerite shows a ductile behavior partly, while vitrinite possesses brittle components purely. 13,21 Further, the study of Miao et al 22 shows that the organic and inorganic components have opposite effects on the coal mechanical properties (e.g., hardness and elastic modulus).…”

Section: Introductionmentioning

confidence: 99%

“…Some papers have suggested that, with the rise of coal rank, the hardness first increases gradually, then decreases slowly, and finally surges sharply; the vitrinite reflectance corresponding to the first inflection is 0.8% and the second is 1.68%. , According to the effective stress law, the coal hardness will drop as the pore gas pressure increases. − The hardness and elastic modulus are closely relevant to the coal structure and always follow this order: unaltered coal > cataclastic coal > mylonitic coal . The correlation between microlithotype and hardness is that the coal hardness increases with the decline of vitrinite content; carbominerite shows a ductile behavior partly, while vitrinite possesses brittle components purely. , Further, the study of Miao et al shows that the organic and inorganic components have opposite effects on the coal mechanical properties (e.g., hardness and elastic modulus).…”

Section: Introductionmentioning

confidence: 99%

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Control Mechanism of Macerals and Temperature on the Mechanical Properties of In Situ Coal

Hou

Jiang

et al. 2022

Energy Fuels

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The internal mechanism of how maceral and temperature control the mechanical properties of in situ coal has not been established so far. Therefore, this paper aims to discover the control mechanism of macerals and temperature on the mechanical properties of in situ coal. The improved equipment, a heatable triaxial compressor, is applied to obtain the coal hardness and elastic modulus at in situ conditions; heatable depth-sensing nanoindentation is employed to collect the hardness and elastic modulus of macerals at various temperatures. By linking the above macroscopic and microscopic mechanical properties, much information that was hitherto unknown was found, as follows. Both hardness and elastic modulus of macerals adhere to the following order: liptinite < vitrinite < inertinite. Importantly, varying temperatures would not transform the order of the above law, which is an inherent property of macerals. The content increase of liptinite would decrease the hardness and elastic modulus of the whole coal, while the content increase of vitrinite and inertinite would increase the hardness and elastic modulus of the whole coal; the effect of vitrinite is not as remarkable as that of inertinite, particularly. This characteristic could be caused by the difference in aromaticity between macerals. Temperature alters the mechanical properties of in situ coal by the intermediary, macerals, rather than its direct effect. There is a watershed in the effect of temperature on the coal mechanical properties; the effect before this temperature is more significant than that after this temperature. This work is of significant importance to understanding the inhomogeneity of mechanical properties of in situ coal.

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