Kinetics of carbon oxidation from fly ash

Thermal gravimetric analysis (TGA) and evolved gas mass spectroscopy were used to study the kinetics of carbon oxidation from a Class-F fly ash. A multi-process ignition loss schema is presented wherein carbon combustion is modeled as a series or discrete independent reactions. These processes were studied at temperatures up to 1000 °C (1832 °F), for oxygen partial pressures between 0.05 and 0.50 and for heating rates between 5 and 40 °C/min (9–72 °F/min). The results show that carbon combustion can be modeled by a series of at least three processes; the weights (fractions) of which are a function of temperature and not a function of oxygen partial pressure. Such detailed combustion kinetics are relevant for the post processing of fly ash to produce materials suitable for use as concrete admixtures or in the manufacture of sintered artificial aggregate or similar densified structures based on fly ash. Such are low temperature, low heating rate processes relative to coal combustion power generation applications.