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ArticleName Effects of low-temperature treatment on the coals mechanical properties microscale and airborne dust formation
DOI 10.17580/gzh.2022.04.11
ArticleAuthor Agarkov K. V., Epstein S. A., Kossovich E. L., Dobryakova N. N.

National University of Science and Technology ‘MISIS’, Moscow, Russian Federation:

K. V. Agarkov, PhD student
S. A. Epstein, Head of Scientific and Educational Testing Laboratory of Physics and Chemistry of Coals, D.Sci. (Engineering),
E. L. Kossovich, Senior Researcher, Scientific and Educational Testing Laboratory of Physics and Chemistry of Coals, Ph.D. (Physics and Mathematics)
N. N. Dobryakova, Researcher, Scientific and Educational Testing Laboratory of Physics and Chemistry of Coals, Ph.D. (Engineering)


The effect of freezing-thawing on the mechanical properties of coals at the microscale, the character of their destruction during cyclic nanoindentation, and the release of airborne dust have been studied. For these purposes, three hard coals from the Apsatsky deposit, two hard coals from the Pechora coal basin, and two lignites from the Kangalassky deposit were studied. It has been established that low-temperature impacts lead to a decrease in the content of airborne dust for all the coals. It was revealed that after freezingthawing of coals, their strength decreases, however, the character of destruction under mechanical impacts do not change. The exception is the coal of the middle stage of metamorphism of the Pechora basin, selected from a pack potentially prone to coal and gas outbursts. For this coal, low-temperature effects lead to a change in the character of its destruction during cyclic nanoindentation. Namely, there was a switch from the local (in the zone of contact with the indenter) character of destruction of the initial coal to the bulk one (outside the zone of contact with the indenter) for coal after low-temperature treatment. To assess the coals propensity to form fine dust particles, an index characterizing the degree of compaction of coal matter during cyclic nanoindentation with increasing load was introduced. It has been established that this index is proportionally connected with the content of airborne dust in coals (with sizes of less than 10 microns). It is shown that the coals proneness to form airborne dust under low-temperature impacts does not depend on the stage of coal metamorphism. For bituminous coals of the Apsatsky deposit with similar metamorphism degree the propensity to form dust is different. Variations in the propensity to form dust in coals of the Pechora basin, which also have a similar metamorphism degree, are apparently due to the peculiarities of the vitrinite structure of these coals.
This work was carried out with the financial support of the Russian Science Foundation (Grant No. 18-77-10052).

keywords Сoal, airborne dust, low temperature impacts, mechanical properties, crushing, nanoindentation, cyclic nanoindentation

1. Coal base of Russia. Vol. 1–6. Ed. by A. A. Timofeev et al. Moscow : Geoinformtsentr, 2001.
2. Lei Qin, Cheng Zhai, Shimin Liu, Jizhao Xu. Factors controlling the mechanical properties degradation and permeability of coal subjected to liquid nitrogen freeze-thaw. Scientific Reports. 2017. Vol. 7, No. 1. DOI: 10.1038/s41598–017–04019–7.
3. Chengzheng Cai, Gensheng Li, Zhongwei Huang, Shouceng Tian, Zhonghou Shen et al. Experiment of coal damage due to super-cooling with liquid nitrogen. Journal of Natural Gas Science and Engineering. 2015. Vol. 22. pp. 42–48. DOI: 10.1016/j.jngse.2014.11.016.
4. Chengzheng Cai, Feng Gao, Gensheng Li, Zhongwei Huang, Peng Hou. Evaluation of coal damage and cracking characteristics due to liquid nitrogen cooling on the basis of the energy evolution laws. Journal of Natural Gas Science and Engineering. 2016. Vol. 29. pp. 30–36. DOI: 10.1016/j.jngse.2015.12.041
5. Lei Qin, Cheng Zhai, Shimin Liu, Jizhao Xu, Guoqing Yu et al. Changes in the petrophysical properties of coal subjected to liquid nitrogen freeze-thaw – A nuclear magnetic resonance investigation. Fuel. 2017. Vol. 194. pp. 102–114. DOI: 10.1016/j.fuel.2017.01.005.
6. Agarkov K. V., Epshtein S. A., Kossovich E. L., Dobryakova N. N. Freeze-thaw conditions effects on coals grain size composition and resistance to breakage. GIAB. 2021. No. 6. pp. 72–83. DOI: 10.25018/0236_1493_2021_6_0_72.
7. Cheng Zhai, Shiliang Wu, Shimin Liu, Lei Qin, Jizhao Xu. Experimental study on coal pore structure deterioration under freeze–thaw cycles. Environmental Earth Sciences. 2017. Vol. 76, No. 15. 507. DOI: 10.1007/s12665-017-6829-9
8. Shi-Qi Liu, Shu-Xun Sang, Hui-Hu Liu, Qi-Peng Zhu. Growth characteristics and genetic types of pores and fractures in a high-rank coal reservoir of the southern Qinshui basin. Ore Geology Reviews. 2015. Vol. 64. pp. 140–151. DOI: 10.1016/j.oregeorev.2014.06.018
9. Yanmei Yu, Weiguo Liang, Yaoqing Hu, Qiaorong Meng. Study of micro-pores development in lean coal with temperature. International Journal of Rock Mechanics and Mining Sciences. 2012. Vol. 51. pp. 91–96. DOI: 10.1016/j.ijrmms.2012.01.010
10. Nikolenko P. V., Epshtein S. A., Shkuratnik V. L., Anufrenkova P. S. Experimental study of coal fracture dynamics under the influence of cyclic freezing–thawing using shear elastic waves. International Journal of Coal Science & Technology. 2021. Vol. 8, Iss. 4. pp. 562–574. DOI: 10.1007/s40789-020-00352-x
11. Hu Wen, Zhenbao Li, Jun Deng, Chi-Min Shu, Bin Laiwang et al. Influence on coal pore structure during liquid CO2-ECBM process for CO2 utilization. Journal of CO2 Utilization. 2017. Vol. 21. pp. 543–552. DOI: 10.1016/j.jcou.2017.09.002
12. Smirnov V. G., Manakov A. Yu., Dyrdin V. V., Ismagilov Z. R. Formation of methane hydrates in natural carbon. Vestnik nauchnogo tsentra po bezopasnosti rabot v ugolnoy promyshlennosti. 2017. No. 1. pp. 13–25.
13. Jizhao Xu, Cheng Zhai, Shimin Liu, Lei Qin, Shangjian Wu. Pore variation of three different metamorphic coals by multiple freezing-thawing cycles of liquid CO2 injection for coalbed methane recovery. Fuel. 2017. Vol. 208. pp. 41–51. DOI: 10.1016/j.fuel.2017.07.006
14. Peng Jia, Nadimi S., Jinzhang Jia. Quantitative micro mechanical and pore structural characterisation of coal before and after freezing. Fuel. 2022. Vol. 316. 123421. DOI: 10.1016/j.fuel.2022.123421
15. Kossovich E. L., Dobryakova N. N., Epshtein S. A., Belov D. S. Mechanical Properties of Coal Microcomponents under Continuous Indentation. Journal of Mining Science. 2016. Vol. 52, No. 5. pp. 906–912. DOI: 10.1134/S1062739116041382
16. Epshtein S. A., Kossovich E. L., Vishnevskaya E. P., Agarkov K. V., Koliukh A. V. Determination of total and fine airborne dust in coals. GIAB. 2020. No. 6. pp. 5–14. DOI: 10.25018/0236-1493-2020-6-0-5-14
17. Kossovich E. L., Epshtein S. A., Golubeva M. D., Krasilova V. A. On using cyclic nanoindentation technique to assess coals propensity to fine dust formation. GIAB. 2021. No. 5. pp. 112–121. DOI: 10.25018/0236_1493_2021_5_0_112.
18. Bulychev S. I., Alekhin V. P., Shorshorov M. K., Ternovskij A. P., Shnyrev G. D. Determination of Young modulus by the hardness indentation diagram. Zavodskaya Laboratoriya. 1975. Vol. 41, No. 9. pp. 1137–1140.
19. Oliver W. C., Pharr G. M. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. Journal of Materials Research. 1992. Vol. 7, No. 6. pp. 1564–1583. DOI: 10.1557/JMR.1992.1564
20. Kossovich E. L., Epshtein S. A., Dobryakova N. N., Minin M. G. Structural features and mechanical properties of anthracite, metaanthracite and graphite. Gornyi Zhurnal. 2020. No. 4. pp. 25–29. DOI: 10.17580/gzh.2020.04.05
21. Epshtein S. A., Kossovich E. L., Prosina V. A., Dobryakova N. N. Features of sorption-induced strength degradation of coals originated from potentially prone to outburst and non-hazardous packs. Gornyi Zhurnal. 2018. No. 12. pp. 18–22. DOI: 10.17580/gzh.2018.12.04

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