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Streszczenie Niespalona substancja organiczna w popiołach lotnych występuje najczęściej w formie ziaren masywnych lub porowatych, niekiedy przyjmujących postać cenosfer. W badanych popiołach lotnych ze spalania węgli brunatnych i kamiennych pochodzących z elektrowni cieplnych stwierdzono występowanie mikrocząstek należących do następujących grup: glinokrzemiany (kwarc, mulit), tlenki żelaza, węglany oraz niespalona substancja organiczna. Substancja organiczna w badanych próbkach występuje w ilości 3,6–9,5%. Cząstki węglowe wykazują duże zróżnicowanie zarówno pod względem wielkości jak i morfologii. Ich wielkość waha się w przedziale od kilku μm do około 1 mm. Można wyróżnić kilka form ich występowania. Są to formy sferyczne porowate cienkościenne i grubościenne. Ponadto niespalona substancja organiczna tworzy nieregularne ziarna porowate, których ścianki są o zmiennej grubości. W badanych próbkach występuje również substancja organiczna inertynitowa w formie fuzynitu wykazującego strukturę komórkową lub niekiedy są to formy masywne lub zwarte. Częstą formą występowania substancji organicznej w badanych popiołach lotnych są cząstki detrytyczne o wymiarach poniżej 10 μm. Występują również cząstki węglowe zawierające domieszki mineralne. W przypadku, gdy ilość substancji mineralnej przekracza 50%, cząstki te klasyfikowane są jako mineralne. W celach dokumentacyjnych oraz do określenia porowatości wykonano zdjęcia mikroskopowe obserwowanych cząstek węglowych. Porowatość określono stosując komputerową analizę obrazu poprzez binaryzację i progowanie odcieni szarości. Dla struktur porowatych obliczono współczynnik porowatości jako iloraz wartości powierzchni zajmowanej przez pory do powierzchni substancji węglowej, w obrębie której występują pory. Wielkość ta jest największa dla ziaren cienkościennych o kształcie nieregularnym oraz cenosfer i osiąga wartości powyżej 80%, maksymalnie 87%. Współczynnik porowatości dla cząstek o podobnym kształcie ale grubościennych osiąga wartości od powyżej 50 do 79%, co jest pomierzoną wartością maksymalną. Dla struktur typu fusinoid/solid porowatość wynosi od kilku do 80%.

In coal seams, depending on the composition of coal macerals, rank of coal, burial history, and migration of thermogenic and/or biogenic gas. In one ton of coal 1 to 25 m3 of methane can be accumulated. Accumulation of this gas is included in unconventional deposits. Exploitation of methane from coal seams is carried out with wells from mining excavations (during mining operations), wells drilled to abandoned coal mines, and wells from the surface to unexploited coal seams. Due to the low permeability of the coal matrix, hydraulic fracturing is also commonly used. Operations related to exploration (drilling works) and exploitation of methane from coal seams were analyzed. The preliminary analysis of the environmental threats associated with the exploration and exploitation of coalbed methane has made it possible to identify types of risks that affect the environment in various ways. The environmental risks were estimated as the product of the probability weightings of adverse events occurring and weightings of consequences. Drilling operations and coalbed methane (CBM) exploitation leads to environmental risks, for which the risk category falls within the controlled and accepted range.

In this paper, we discuss the impact of the rank of coal, petrographic composition, and physico-chemical coal properties on the release and composition of syngas during coal gasification in a CO2 atmosphere. This study used humic coals (parabituminous to anthracite) and lithotypes (bright coal and dull coal). Gasification was performed at temperatures between 600 and 1100 °C. It was found that the gas release depends on the temperature and rank of coal, and the reactivity increases with the increasing rank of coal. It was shown that the coal lithotype does not affect the gas composition or the process. Until 900 °C, the most intense processes were observed for higher rank coals. Above 1000 °C, the most reactive coals had a vitrinite reflectance of 0.5–0.6%. It was confirmed that the gasification of low-rank coal should be performed at temperatures above 1000 °C, and the reactivity of coal depends on the petrographic composition and physico-chemical features. It was shown that inertinite has a negative impact on the H2 content; at 950 °C, the increase in H2 depends on the rank of coal and vitrinite content. The physicochemical properties of coal rely on the content of maceral groups and the rank of coal. An improved understanding these relationships will allow the optimal selection of coal for gasification.

Samples of coal from the eastern part of the Upper Silesian Coal Basin, between Jaworzno and Libiąż, were collected from test boreholes and underground excavations in the Janina Coal Mine, southwest Poland. The No. 111-119 hard coal seams are in the upper part of the Cracow Sandstone Series (the Libiąż Beds, Westphalian D). Macroscopically, iron sulfides (pyrite and marcasite) found in hard coal seams are usually in vein and impregnation forms. On the basis of microscopic observations, the following forms of iron sulfides occurrence in the studied coal were observed: framboidal pyrite, euhedral crystals, skeletal and massive vein forms, or pocket-like (impregnation) forms. On the basis of SEM-EDS analysis and X-ray diffraction it can be stated that the iron sulfides observed in coal are a mixture of pyrite and marcasite. WDS analysis in the micro area revealed the chemical composition of sulfides. The iron sulfides contain admixtures of Pb, Hg, Zn, Cu, Au, Ag, Sb, Co, and Ni. There was no As and Cd found in the examined minerals. It has been shown that the tested iron sulfides do not include significant admixtures. There is only a slight enrichment in lead in the vein forms of sulfides. In addition to the iron sulfides, individual inclusions of galena and sphalerite within the pyrite and marcasite have been observed. When it comes to iron sulfides in the vicinity of the crystallized galena, no lead (Pb) in the pyrites can be observed.

Bituminous coal samples were collected from mine excavations of six mines in the Upper Silesian Coal Basin. I n the mentioned mining excavations, the stratighaphic sections, in the form of spot samples, were measured. Based on the macroscopic and microscopic observation, an attempt was made to determine the different lithotypes of coal. Vitrain coal is made of tellinite and collotelinite; the thickness of the layers varies from very thin, thin, medium, to coarse. Durain, which is dominated by macerals from the vitrinite group, is characterized by a darker, almost black color, genetically linked to heavily flooded peat areas, where the deposited phytogenic material is subjected to humification and gelification processes. A brighter durain, with a dark gray color, is dominated by macerals from the inertinite group that originated in the shallower areas of peat bogs where the water level was periodically lowered, which has led to the oxidation of the material deposited in the peat bog. Fusain is another coal component or constituent; it is produced as a result of peat bog fires. It is a charred (not burned) material deposited in the form of layers, lenses, usually with a thickness of up to several millimeters (or, less commonly, several centimeters), or dispersed in the form of shreds in the durain. The petrographic composition is dominated by fusinite and inertodetrinite. Fusain occurs in two varieties: soft (empty cellular spaces) and hard, usually mineralized with carbonates (siderite) or sulphides (pyrite, marcasite). The structure of bituminous coal is, due to its origin, most often laminated and consists of alternating dull and bright layers. Occasionally, such layering can be observed in bright coal, which is the result of layering of large parts of gelified plant materials. When it comes to larger sections of dull coal (without bright coal) in the profile, a solid structure can be observed. Some of the sections in the coal seam profiles show a distorted structure; warped, sometimes shredded layers of vitrain in durain, often containing lenses or shreds of fusain, can be observed.

The concentration of critical elements, including such REE as Fe, Co, W, Zn, Cr, Ni, V, Mn, Ti, Ag, Ga, Ta, Sr, Li, and Cu, in the so-called fly ash obtained from the 9 Polish power plants and 1 thermal power station has been determined. The obtained values, compared with the global average concentration in bituminous coal ash and sedimentary rocks (Clarke values), have shown that the enrichment of fly ash in the specified elements takes place in only a few bituminous coal processing sites in Poland. The enrichment factor (EF) is only slightly higher (the same order of magnitude) than the Clarke values. The enrichment factor in relation to the Clarke value in the Earth’s crust reached values above 10 in all of the examined ashes for the following elements: Cr, Ni, V, W, and, in some ash samples, also Cu and Zn. The obtained values are low, only slightly higher than the global average concentrations in sedimentary rocks and bituminous coal ashes. The ferromagnetic grains (microspheres) found in bituminous coal fly ashes seem to be the most economically prospective in recovery of selected critical elements. The microanalysis has shown that iron cenospheres and plerospheres in fly ash contain, in addition to enamel and iron oxides (magnetite and hematite), iron spinels enriched in Co, Cr, Cu, Mn, Ni, W, and Zn.