Studies on the quality of bituminous coal are mainly focused on physico-chemical analysis, examining the ash content, sulphur content, volatile matter content, moisture content, and the Net Calorific Value of coal. Until now, the above mentioned parameters form the basis of the Polish Standard PN-82/87002, on the basis of which individual types of bituminous coal are determined. In addition, an elemental analysis, providing information about the content of primary elements in the organic matter of solids, i.e. coal, hydrogen, nitrogen, oxygen, and sulphur, is carried out for the selected samples. This issue has been studied by many authors, which undoubtedly provide invaluable knowledge due to the huge amount of data, but, as the authors themselves indicate, the knowledge of the petrography of coal, coking properties (Probierz et al. 2012) and finally the coke obtained from individual coal types (based on tests carried out using the Karbotest installation or the so-called „box tests” performed in the coke oven battery) is still very limited. The article discusses the impact of petrographic composition on the quality of metallurgical coke. The analysis was performed using samples of coking coal from the following mines: Pniówek, Zofiówka, Borynia, and Krupiński. The mentioned coal types are used to produce coke mixtures used for the production of coke in the Przyjaźń and Radlin coking plants. Based on the rank of coal and physicochemical parameters, the mentioned coal types were classified according to the Polish classification and the UN/ECE International Classification of In-Seam Coals (UN/ECE 1995). The prediction of thermomechanical properties of coke (CSR and CRI) performed according to the original CCP method were compared with the results obtained using the classical method of Nippon Steel Corporation.

The paper presents the correlation between the CRI (Coke Reactivity Index), CSR (Coke Strength after Reaction) and the remaining 36 quality parameters of coking coal from the Pniówek deposit (SW part of the USCB). The test results were obtained for a region of fundamental importance to the Polish reserves of coking coal, characterized by highly variable coalification and quality parameters. The tests related to the determination of relationships of the CRI and CSR indices to other parameters were based on 25 channel samples acquired from active workings. The characteristics of the variability of the CRI and CSR indices were analyzed using statistical methods. The dependencies between the CRI and CSR indices and the parameters having an impact on their values were determined using linear correlation. An attempt was also made to determine the correlations between the concerned parameters using the multiple correlation method. The obtained results have been presented and compared to the results of globally conducted experiments in the form of charts presented by (North et al. 2018b). No clear dependence of the CRI and CSR indices was exhibited in case of most of the analyzed quality parameters, which is supported by low correlation coefficients of r < 0.5. The statistical analysis exhibited only 9 cases of correlation between CRI and CSR with other quality parameters, where the correlation coefficient was r ≥ 0.5, that is: Ht a, Na2O, Al2O3 and SiO2, Mn3O4, da a and dr a. This confirms the different characteristics of coal from the studied area, exhibited multiple times, that should be related to the specific coalification process, especially the occurrence of thermal metamorphism.