Phase transformation of coal gangue by aluminothermic reduction nitridation: Influence of sintering temperature and aluminum content

The effect of sintering temperature and aluminum content on the phase transformation of coal gangue by aluminothermic reduction nitridation (ARN) was investigated. The process was carried out in flowing N2 within the temperature range of 1400–1500 °C and holding time of 4 h. The results showed that temperature and Al content were two essential factors determining the nitridation of coal gangue and the phase yields of nitrided products. Kaolinite, the main mineralogical phase of coal gangue, was transformed into high-temperature composites containing β-SiAlON, corundum and Al6O3N4 by ARN at 1400–1500 °C. The products consisted of globular β-SiAlON/corundum particles and continuous SiAlON fibers. The transformation provided a feasible mean of dealing with coal gangue for high-temperature utilization.