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Abstract

The research was aimed at examining the impact of the petrographic composition of coal from the Janina mine on the gasification process and petrographic composition of the resulting char. The coal was subjected to fluidized bed gasification at a temperature below 1000°C in oxygen and CO2 atmosphere. The rank of coal is borderline subbituminous to bituminous coal. The petrographic composition is as follows: macerals from the vitrinite (61.0% vol.); liptinite (4.8% vol.) and inertinite groups (29.0% vol.). The petrofactor in coal from the Janina deposit is 6.9. The high content of macerals of the inertinite group, which can be considered inert during the gasification, naturally affects the process. The content of non-reactive macerals is around 27% vol. The petrographic analysis of char was carried out based on the classification of International Committee for Coal and Organic Petrology. Both inertoid (34.7% vol.) and crassinetwork (25.1% vol.) have a dominant share in chars resulting from the above-mentioned process. In addition, the examined char contained 3.1% vol. of mineroids and 4.3% vol. of fusinoids and solids. The calculated aromaticity factor increases from 0.75 in coal to 0.98 in char. The carbon conversion is 30.3%. Approximately 40% vol. of the low porosity components in the residues after the gasification process indicate a low degree of carbon conversion. The ash content in coal amounted to 13.8% and increased to 24.10% in char. Based on the petrographic composition of the starting coal and the degree of conversion of macerals in the char, it can be stated that the coal from the Janina deposit is moderately suitable for the gasification process.
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Abstract

The Bogdanka coal mine, the only currently operating mine in the Lublin Coal Basin (LCB), extracts coal from the Upper Carboniferous formations of the LCB. The average sulfur content in the No. 385/2 seam is 0.98%, while in the case of the No. 391 seam it is slightly higher and amounts to 1.15%. The iron sulfides (pyrite and marcasite) in bituminous coal seams form macroscopically visible massive, vein, and dispersed forms. A microscopic examination has confirmed their complex structure. Massive forms contain euhedral crystals and framboids. The sulfide aggregations are often associated with a halo of dispersed veins and framboids. Pyrite and marcasite often fill the fusinite cells. Framboids are highly variable when it comes to their size and the degree of compaction within the carbonaceous matter. Their large aggregations form polyframboids. The cracks are often filled with crystalline accumulations of iron sulfides (octaedric crystals). The Wavelenth Dispersive Spectrometry (WDS) microanalysis allowed the chemical composition of sulfides in coal samples from the examined depoists to be analyzed. It has been shown that they are dominated by iron sulfides FeS2 – pyrite and marcasite. The examined sulfides contain small admixtures of Pb, Hg, Zn, Cu, Ag, Sb, Co, Ni, As, and Cd. When it comes to the examined admixtures, the highest concentration of up to 0.24%, is observed for As. In addition, small amounts of galena, siderite, and barite have also been found in the examined coal samples. The amounts of the critical elements in the examined samples do not allow for their economically justified exploitation. Higher concentrations of these elements can be found in the ashes resulting from the combustion process.
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