Study of the thermal decomposition of carbonate groups in sedimentary apatites by thermogravimetric analysis

Abstract Many groups can substitute phosphate sites in sedimentary rock apatites. The main properties of these apatites (solubility, thermal behaviour, ...) are affected by the degree of substitution by carbonates. Thermogravimetric analysis of these compounds show secondary reactions occurring simultaneously with decomposition reactions of carbonate groups. Properties of carbonate groups decomposition are deduced from experimental factors study as processing gases, heating rate and grinding. Secondary reactions are due to high calcium content of sedimentary rocks and the presence of minerals associated. Several kinds of carbonate groups with different thermal stabilities occur in mechanically activated apatites. The presence of these types in sedimentary rock apatites, more or less substituted, is discussed.