Chronostratigraphic and Depth Variability of Porosity and Strength of Hard Coals in the Upper Silesian Basin / Chronostratygraficzna I Głębokościowa Zmienność Porowatości I Wytrzymałości Węgli W Górnośląskim Zagłębiu Węglowym

Abstract

In the article, values of porosity and compression strength of hard coals from the area of the Upper Silesian Coal Basin are presented. Change of the stage of carbonification, which results from conversion of coal substance in the process of coalification, is a source of many changes in the structure of coal. These changes exert influence on values of physical parameters, including value of porosity and strength. Porosity and compression strength change with the degree of carbonification which is a result of the depth of deposition. Presented in the article, values of effective porosity of coals and their strength have been determined considering age chronology of coal seams and depth of their occurrence. Coals of the Cracow Sandstone Series, the Mudstone Series, the Upper Silesian Sandstone Series and the Paralic Series, from depth ranging from about 350 m to about 1200 m, were examined. The authors have shown that effective porosity of the Upper Silesian coals changes for particular stratigraphic groups and assumes values from a few to a dozen or so per cent, while compression strength from several to several dozen megapascals. It has been observed, from chronostratigraphic perspective, there is a shifting of the upper and lower limit of intervals of porosity variations towards higher values for younger coals. With the increase of compression strength, value of porosity in particular stratigraphic groups generally decreases. However, no regular changes were observed of mean uniaxial compressive strength with the increase of age of subsequent stratigraphic groups. On the other hand, for bright coal and semi-bright coal, visible decrease of compression strength with the depth of deposition of strata was observed.

The manometric sorptomat—an innovative volumetric instrument for sorption measurements performed under isobaric conditions

“…Since bituminous coal is a porous medium distinguished by good sorption properties (Bukowska et al 2012), (Baran et al 2015) fifteen granular coal samples were used in the comparative sorption studies. The samples were obtained from various mines of the Upper Silesian Coal Basin in Poland: ˗ the 'Borynia-Zofiówka' hard coal mine, ˗ the 'Brzeszcze' hard coal mine, ˗ the 'Pniówek' hard coal mine, ˗ the 'Budryk' hard coal mine.…”

Analysis of the Influence of Coal Petrography on the Proper Application of the Unipore and Bidisperse Models of Methane Diffusion

“…The literature survey conducted shows that there is a significant correlation between coal petrography and gas diffusion kinetics [21][22][23][24][25][26]. The change in porous structure is closely related to the change in the degree of coalification, and pores vary in shape and size [27]. The diffusivity of coal was found to decrease degree of coalification increased due to an increase in the proportion of micropores in its structure [28].…”