Evaluation the Value of Some Petrographic, Physico-Chemical and Geochemical Indicators of Quality of Coal in Paralic Series of the Upper Silesian Coal Basin and Attempt to Find a Correlation Between Them

Abstract

Abstract A total of 56 coal seam samples (from active and closed coal mines) representing USCB Paralic Series, were tested. It was determined that the tested coal has low content of mineral matter (especially in Hruśov Beds) as well as of Ag, As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Rb, Sb, Sn, Sr, V and Zn. Only Mn and Pb content in coal is higher than in coal from other deposits around the world. There are differences in the values of physical and chemical, petrographic and geochemical indices of coal quality, between the northern and the south-western part of the USCB and in the profile of the Paralic Series. Thanks to the revealed correlations between the indices of coal quality, significant differences in the role mineral and organic substance play in concentrating some of the trace elements in the tested coal, were determined. Moreover, it was observed that an increase in the rank of coal (expressed with an increase in the value of R0 or/and Qsdaf or/and Cdaf), accompanies a decrease in the content of oxides of main elements in coal ash as well as sulfur and other trace elements in coal. The dependence was observed both in lateral and stratigraphic differences in the rank of coal. Mutual dependences between the indices of the rank of coal (R0, Cdaf, Qsdaf, Vdaf) in the northern and south-western area of the research and in Poruba Beds and Jaklovec Beds, were confirmed. It was determined that an increase in the value of Roga Index (RI) is accompanied by an increase in P2O5 content in ash of coal from the south-western part of the research area. It is probably a result of concurrence of a regional positive anomaly in the rank of coal and high P2O5 content in coal seams in the south-western part of the USCB. The observed increase in the value of RI, accompanying a decrease in the content of sulfate minerals, Cr and Ni in coal and Na2O in coal ash; results from the role the carbonisation process plays in distributing main and trace elements in the mineral matter of coal.