Relationship between the content of hazardous trace elements in coal lithotypes and their ashes (405 coal seam, U.S.C.B.)

This study analyzed the variability in the content of selected hazardous trace elements (Ba, Cd, Co, Cr, Cu, Ni, Pb, Zn, Mn, Be, Li, V, As, Ga) from the 405 (Załe{ogonek}że beds) coal seams' coal lithotypes and their ashes. The significant variability in the content of the trace elements from the examined samples depends partly on the type of lithotype, and mainly on the ash content. Within all distinguished lithotypes, the highest concentrations were of the elements Ba and Mn. Other evaluated elements could be categorized by average content in the lithotypes in following order: Zn < Pb < V < Cu < Ni < Cr < Ga < Co < Be < Li < As < Cd. A similar trend in elemental content has been observed in the ashes from the lithotypes. The enrichment coefficient (W) values have been calculated for the ashes of the lithotypes as a ratio of an element's content in the ash to its content in the lithotype. The assumption was that coefficient W values increase with increasing content of an element related to the organic matter of the coal. The highest values of these coefficients (from 5 to 7) were shown by Cr, Be, Cd, and Cu. The other elements exhibited lower values (from about 2 to about 3), and the lowest values of the enrichment coefficient were most frequently observed in the case of Co, Li, and Mn. On the basis of the calculated enrichment coefficient values in the ashes, it has been found that elements such as Ba, Mn, Li, As, Co, Ga, Ni, Pb, and Zn demonstrated high correlation with to the mineral substance (low enrichment coefficient in the ash). Their maximum concentrations decreased for the strongly mineralised lithotypes - dull coal or semi-vitreous coal. However, a small number of elements such as Cr, Be, Cd, and Cu demonstrated high correlation with the organic matter of coal (high enrichment coefficient in the ash) and tended to be most heavily concentrated in vitreous lithotype. The trace elements' content in the lithotypes is connected with their affinity toward organic matter or mineral matter. This was determined based on the value of the coefficient of enrichment in the ashes of these elements. On the basis of the volume of the coefficient of correlation, a significant correlation was established between trace elements in lithotypes and content of ash and mineral matter in coal.