Thermogravimetric characterisation of maceral concentrates of Russian coking coals

The most significant constituents which control the properties of coking coals are vitrinite and fusinite. For better understanding of the devolatilisation characteristics of coking coals, vitrinite-rich and fusinite-rich concentrates were produced from Russian coking coals of rank (Ro) varying from 0.80 to 1.54. The generation of the maceral concentrates was carried out by repeated cycles of float–sink separation under centrifugal force. The devolatilisation characteristics of these concentrates were studied using thermogravimetric analysers coupled with gas chromatography. Differences in the thermal behaviour of these concentrates could be observed in many aspects. Vitrinite-rich concentrates were characterised by the higher content of volatiles, higher values of maximum rate of weight loss, higher weight loss for tar formation and lower weight loss for gas formation. The effects of rank on the thermal properties of vitrinite and fusinite were also studied. Significant factors were identified and regression equations were developed for prediction of various devolatilisation characteristics. The relationship between the DTG curve and the Gieseler fluidity curve was also examined.