Effects of chemistry and mineral on structural evolution and chemical reactivity of coal gangue during calcination: towards efficient utilization

The utilization of coal gangue is usually subjected to calcination to achieve high chemical reactivity and exclude carbon. The correlation between the composition and properties of coal gangue during calcination is essential for its applications. In this paper, the effect of chemistry and minerals of coal gangues on the thermal behavior, structural evolution and chemical states of silicon and aluminum during the calcination process were systematically investigated. The results show that high alumina (Al-H) containing coal gangue consists primarily of kaolinite, while in medium and low alumina containing (Al-M and Al-L) groups, the major mineral phases are quartz, kaolinite, illite with minor impurities. The chemical reactivity of coal gangue mainly contributes to the transformation of kaolinite to metakaolinite, while illite plays a minor role and quartz is inert. The combustion of carbon may promote the dehydroxylation of clay minerals and further affects the structure evolution of coal gangue. The optimal calcination temperature to exclude carbon and achieve high chemical reactivity is therefore suggested as 700 A degrees C. Based on the findings the utilization of coal gangue is discussed in light of composition and structure.Common Development Fund of Beijing; National Natural Science Foundation of China [51172003, 51074009]; National High Technology Research and Development Program of China (863 Program) [2012AA06A114]; China National Key Technology RD Program [2011BAB03B02, 2013BAC14B07]SCI(E)EIARTICLEzuotaizhang@pku.edu.cn92779-27934