MEASURING THE REACTIVITY OF LOW-VOLATILE COALS BY DIFFERENTIAL THERMAL GRAVIMETRY

The reactivities of a suite of low-volatile Australian coals were measured by the standard burning profile test, modified to use closely sized particle fractions. It was found that particle shrinkage during burnout was a function of the content of volatile matter. From the change in particle surface area with burnout, the activation energies were found to be constant from 5 to 85% burnout. Burning occurred in Regime II with activation energies that fell with increasing content of volatile matter. The measured reactivities were consistent with values reported elsewhere for the same coals burned in entrainment flow at much higher temperatures, but extrapolation of differential thermal gravimetry (DTG) kinetic values above 900-degrees-C is not recommended.