Authors: A.N. Zaostrovsky

Title of the article: Dependence of the free swelling index on the petrographic composition of coals

Year: 2022, Issue: 4, Pages: 52-58

Branch of knowledge: 05.17.07 Chemical technology of fuel and high-energy substances

Index UDK: 662.741.3.022.001.5

DOI: 10.26730/1999-4125-2022-4-52-58

Abstract: The relevance of the study is dictated by the fact that tens of thousand tons of coals are supplied to modern coke production every day, for which it is necessary to determine their technological value by express methods. One of such methods is the free swelling index SI (“swelling index”) as an indicator of coal sintering, which is related to expansion pressure, having a great influence on the quality of coke and on the coal behavior during coking. The SI index for coal grades: DG, G, GZh, Zh, K, KO, KS, OS, SS varied from 1.0 to 9.0 according to the scale of standard profiles with a maximum for fat and coke coals. The straight-line relationship between swelling and the thickness of the plastic layer (Y, mm) of coals is very approximate and covers only the part of the coals with a plastic layer of more than 13 mm (and in many cases even more). Swelling is determined mainly by the viscosity and gas permeability of the plastic mass and, like viscosity, is not an additive property, since the viscosity and thickness of the plastic layer characterize different aspects of the plastic state. If the viscosity index determines the degree of coal softening, i.e. the quality of the plastic mass, then the thickness of the primary plastic layer gives an indication of its quantity, due to the temperature interval (time) of softening at a given heating rate. The thickness of the measured plastic layers more than Y = 12 mm is exaggerated by swelling. The difference in the role of viscosity and the thickness of the plastic layer is clearly manifested when the heating rate changes. The performed study shows the dependence of the index of free swelling (SI) on genetic factors in the series of metamorphism of Kuzbass coals, which are characterized by petrographic composition. The SI is proportional to the fluidity of coal and decreases with an increase in the content of inertinite and liptinite. The highest values of the SI index are characteristic of reduced coals.

Key words: Coal swelling index petrographic composition thinning components plastic layer sinterability

Receiving date: 03.08.2022

Approval date: 30.08.2022

Publication date: 06.10.2022

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