Carbonation of FBC ash by sonochemical treatment

This work explores the sonochemical-enhanced carbonation of FBC ash for direct disposal in landfills. Tests have been conducted using four ashes originating from three commercial CFBC boilers. Experiments with additives such as NaCl and seawater have also been carried out. Tests were performed at low (20°, 40 °C) and high (60°, 80 °C) temperatures. Sonicated samples were analyzed using TGA, TGA–FTIR and XRD techniques to determine the influence of other calcium compounds (OCC). The particle size reduction brought about by sonication was quantified using wet sieving. The ash reactivity displays a strong temperature dependency with almost complete carbonation achieved in minutes at higher temperatures. Additives were found to increase the level of hydration of the ashes, in line with previous work; however, carbonation levels were unaffected. TGA, TGA–FTIR and XRD analysis of the samples indicated participation of OCC, which were also formed during hydration.