Flash calcines of kaolinite: kinetics of isothermal dehydroxylation of partially dehydroxylated flash calcines and of flash calcination itself

Abstract

Kaolinite has been flash calcined to produce calcines kinetically frozen at different levels of dehydroxylation. The kinetics of subsequent isothermal dehydroxylation of the calcines were consistent with a three-dimensional diffusion model. Activation energies and rate constants generally decrease as dehydroxylation of the calcine increases. A decrease in reaction rate at high levels of dehydroxylation is consistent with collapse of the interlamellar space, restricting diffusion of water out of the particles. The kinetics of flash calcination were shown to obey the same principles as isothermal dehydroxylation.