Energy Sources Part A-recovery Utilization and Environmental Effects, Vol.35, No.19, 1807-1812, 2013
Analyses of Aluminum Structures in a Chinese Coal Ash and Its Slag by STMAS NMR
Double-quantum filter satellite-transition magic-angle spinning experiments were tentatively carried out by one high magnetic field solid-state nuclear magnetic resonance (800 MHz for H-1 Larmor frequency) to analyze the local Al-27 structure in minerals of coal ash and slag. A high magnetic field offered higher sensitivity and resolution; hereby, the inconspicuous resonances of satellite-transition magic-angle spinning were obtained successfully at less stringent conditions. An obvious single 6-coordinate Al-27 resonance was detected in the low-temperature ash; structures in pre-molten ashes (as prepared at 815 and 1,000 degrees C) located relatively integral and symmetric, while Al resonances in the ash prepared at 1,600 degrees C after once completely molten demonstrated discrete and asymmetric distribution. Moreover, the detailed spatial correlations among various aluminum species in rapid quenching slag exhibited dispersive T-O-T structures with lower signal-to-noise ratio of resonances.