Pacification of FBC ash in a pressurized TGA

The high CaO content of FBC ashes causes difficulties with their management. The use of CO2 to recarbonate or pacify the ashes was suggested in order to increase the concentration of CaCO3 in the ashes and decrease the amount of free lime. Work was performed using a Cahn 1100 pressurized TGA on coal and petroleum coke FBC residues at 0.1 and 1.1 MPa. Both hydrated and nonhydrated ashes were tested. Conversion of the CaO to CaCO3 in nonhydrated ashes ranged from 9 to 27.4% while hydrated ashes showed conversion levels of 51.7–60%.