Impact of carbon addition method on extent of nitridation reaction of fly ash

The carbon addition methods to fly ash are discussed here, on their impact on the extent of the nitridation reaction. These methods are mechanical shaking, ultrasonic mixing, and high-energy ball milling. The extent of nitridation is evaluated by the nitrogen content determined by a LECO Nitrogen/Oxygen determinator. Ultimately, dry high energy ball milling is proposed for CRN reaction of fly ash and carbon black mixture. The nitrogen content introduced into the fly ash can reach 23.1% after the CRN reactions, as compared with 0.3% before the nitridation reaction. Moreover, the reducing activity of intrinsic carbon in untreated fly ash is between that of a mechanically mixed fly ash/carbon and that of a ball-milled fly ash/carbon mixture. Equipment analysis was carried out to characterize the samples, including BET surface area measurement, scanning electronic microscopy, and energy dispersive x-ray diffraction.