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Is the Złoczew lignite deposit geologically suitable for the first underground gasification installation in Poland?

Urbański Paweł, Widera Marek

Geologos

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2020

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Vol. 26, No. 2

113--125

EN

The present study focuses on alternative methods of exploiting lignite in comparison to conventional opencast mining and combustion in power plants for the generation of electricity. In Poland, opencast lignite pits cover large areas, creating social and environmental conflicts. In order to stabilise the production level of electricity and reduce the negative effects of opencast mining, alternative ways of exploiting lignite are suggested, one of these being underground gasification in situ. The Złoczew lignite deposit, which will most likely be exploited in the near future, provides an opportunity to discuss the unconventional method of underground coal gasification (UCG). On the basis of technological and geological criteria that have been established to determine the suitability of Polish lignite for underground gasification, resources to be used this way have been estimated. Through gasification, over 15 million tonnes of lignite can be utilised, which is about 2.5 per cent of resources of the Złoczew deposit intended for opencast mining. With this in mind, we suggest to take action by starting a pilot installation, to be followed by a commercial one for underground gasification after completion of superficial mining. Naturally, any future application of this method will be preceded by assessment of geological conditions at the Złoczew opencast pit.

2

Characteristics and origin of deformation structures within lignite seams : a case study from Polish opencast mines

Widera M.

Geological Quarterly

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2016

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Vol. 60, No. 1

181--191

EN

The present paper discusses the genesis of some deformation structures within Miocene lignite seams in Poland. These meso- to macro-scale deformation structures are the best developed in areas where the thickest lignite seams are exploited, that is, in the Bełchatów, Turów and Lubstów lignite opencast mines. They show a wide variety of structures such as high-angle inclined strata, normal and reverse faults and folds, fractures and clastic dikes. These deformation structures were not analysed in terms of the structural development of the lignite-bearing areas, but rather in the context of their origin. The high-angle inclination of clastic sedimentary strata clearly formed mainly as a result of vertical tectonic movements in the sub-Cenozoic basement, their currently measured dip angle being significantly higher than their natural angle of repose. All the observed normal and reverse faults cutting the Miocene strata are a clear example of syn- and/or post-depositional tectonics. The normal faults clearly indicate tensional tectonics while the reverse faults reflect compressional tectonics. In turn, the majority of folds occurring within the lignite seams are a result of peat/lignite compaction. However, one of the folds studied is predominantly the result of vertical displacements in the sub-Cenozoic basement. The en echelon fracture pattern may additionally indicate the horizontal component of these displacements. Finally, the most spectacular and debatable structures are clastic dikes. In this study the genesis of some of them is linked with the evolution of the graben’s marginal fault.

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What are cleats? Preliminary studies from the Konin lignite mine, Miocene of central Poland

Widera M.

Geologos

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2014

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Vol. 20, No. 1

3--12

EN

Cleats (fractures, joints) are discontinuities in coals, including lignites. They are important in mining activity because of their gas and water permeability in hard coal, and mainly because of their water permeability in lignites. As opposed to hard-coal cleats, lignite cleats have not been studied in detail before. The present contribution does so, using as an example the 1st Middle-Polish Lignite Seam (MPLS-1) in the Jóźwin IIB opencast mine in central Poland. It should be mentioned here that any remarks in the present contribution concerning MPLS-1 refer exclusively to this lignite seam in the Jóźwin IIB opencast mine. The investigated discontinuities consist of two sets, i.e. the face and butt cleats, which are roughly oriented NW–SE and NE–SW, respectively. The mean spacing of the face cleats is ~12.4 cm, while the mean spacing of the butt cleats is ~12.8 cm. The maximum average aperture is ~4.9 mm for the face cleats and ~4.1 mm for the butt cleats. The cleat spacing and aperture do not depend on the lignite thickness, but the cleat spacing increases with increasing mineral-matter and xylite content, whereas the aperture increases when the contents decrease. The regional folding and local salt diapirism tentatively explain the formation of the orthogonal system of the lignite cleats, partly because of the parallelism of the face cleats and the major tectonic directions in central Poland.