Transformation behavior of mineral composition and trace elements during coal gangue combustion

The transformation behavior of mineral and trace elements during combustion of Chinese coal gangue at varies temperatures were studied. The coal gangue sample was placed at muffle roaster and heated up to 8-desired temperature points, from 500 °C to 1200 °C with 100 °C for each interval. The mineral compositions of coal gangue and its combustion ash were determined by X-ray powder diffraction techniques (XRD). FTIR spectroscopy analysis was taken to determine coal gangue and combustion ash functional group, phase transition characteristics and the variation in combustion. The concentration of trace element in coal gangue and combustion ash was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Results show that the transformation behavior of mineral phase of coal gangue mainly relies on the combustion temperature. The volatilize ratios of selected trace elements increase with increasing combustion temperature. Besides, 10 trace elements studied in the current study can be classified into two categories according to their volatilize tendencies: (a) Ni, Cu, Zn, Cd, Sn, Pb and As were vaporized at intermediate temperature and have high volatilize ratio; (b) V, Cr, and Co were relative non-volatile.