Abstract
Thermal reactions of SO2 with natural and synthetic apatites (Aps) have been studied by thermogravimetric analysis. Experiments under dynamic and isothermal conditions were performed in the air-SO2 flow with different SO2 content (0.07%, 1%, 10%). The reactions proceeded at temperatures from 400°C to 800-850°C according to two- or three-dimensional diffusion models, the reaction rate depending on temperature, SO2 concentration and substitutions in the Aps structure (PO4↔CO3). Thermal interaction of Aps with SO2 led to decomposition of apatite. At heating during one hour at 800°C in an air-SO2 (10%) flow, 40% of fluorine from fluorapatite (FAp) and 72% from carbonateapatite (FCO 3Ap) was removed.
