Devolatilization and kinetics study of Australian metallurgical coals: correlations of TGA and kinetic derived parameters with coal properties
摘要
Coke, produced mainly from metallurgical coals because of their thermoplastic properties, is in high demand by the iron and steel industries. This study simultaneously investigates the kinetics and devolatilization of Australian metallurgical coals, as well as the effects of coal rank and other coal properties on kinetic and TGA-derived parameters, highlighting temperature-phase transitions and devolatilization profiles during pyrolysis. Findings show that correlations between MMR, Rmax, and Tmax are stronger during secondary than primary devolatilization. As coal rank increases, aromatic ring condensation and cross-linking intensify, resulting in greater structural ordering and higher vibrational frequencies required for pyrolysis. For the primary devolatilization stage (300–680 °C), activation energies range from 55 to 59 kJ mol−1, and pre-exponential factors from 6.17E + 09 to 8.39E + 09 s−1. In the secondary stage (630–850 °C), activation energies range from 43 to 50 kJ mol−1, with pre-exponential factors between 5.50E + 09 and 9.14E + 09 s−1. To our knowledge, the kinetics and devolatilization of Australian coking coals, along with the effects of coal rank and other properties on the derived TGA and kinetic parameters, have not been investigated simultaneously in prior research, highlighting unique temperature-phase transitions and devolatilization profiles during pyrolysis. The results of this study will help coal experts and marketers select suitable coals for blending and produce the high-premium coke required by the iron and steel industries. More samples will be investigated in future research.