Chemical Changes of Australian Coking Coals from Different Basins with Various Ranks and Maceral Compositions: Linking to Both Physical and Thermal Changes

Chemical changes of eight Australian coking coal samples from six different basins with various ranks (RvMax from 0.87 to 1.52) and maceral constituents (vitrinite from 48.2 to 76.5%) were dynamically investigated to explore the mechanism of coal coking linking to the synchronized physical and thermal changes. Volatile release during coal pyrolysis was monitored using a novel technique of dynamic elemental thermal analysis (DETA) that is able to differentiate tar and gas evolution in terms of carbon and hydrogen compositions. Condensed coal tars were characterized both chemically and thermally using the DETA and laser desorption ionization–time of flight–mass spectrometry (LDI–TOF–MS) techniques. Coal pyrolysis experiments were conducted at a heating rate of 5 °C/min from room temperature (25 °C) to 1000 °C with a top coal particle size of 212 μm, which kept the same experimental conditions as the physical and thermal measurements. The results indicated that, overall, the volatile evolution rates decrease...