A two-stage reaction sequence for C3S formation

Abstract Reaction mechanism and kinetics were investigated for the formation of C 3 S from C 2 S obtained as a byproduct from the Ames Lime-Soda Sinter Process for the recovery of Al 2 O 3 from the mixed oxides found in power plant fly ash. A change in the rate of reaction was found to occur after about 25 minutes at burning temperatures of 1300 to 1500 C. The change was attributed to a two-stage reaction sequence in which the reaction rate for the first stage is phase boundary controlled and for the second phase diffusion controlled. A modified version of the Ginstling-Brounshtein solid-state reaction rate equation was found to describe the diffusion-controlled portion of the process. Apparent activation energies determined for this part of the process agreed with reported activation energies for Ca diffusion in clinker melt and for the self-diffusion of Ca in CaO.