caracterisation of the kaolinite clay minerals (nador-north morocco) using infrared spectroscopy and calorimetry of dissolution

The enthalpies of dissolution in hydrofluoric acid of metakaolinites, obtained by thermal dehydroxylation of kaolinite (NADOR-MOROCCO) in the temperature range 450-950°C, have been measured calorimetrically. They are minimum dehydroxylation at 720-800°C. The optimal calcinations parameters, for which complete dehydroxylation of the material, are temperature 650 °C and heating time of 6 H. The conversion of the kaolinite to metakaolinite was confirmed by IR analyses of the starting and thermally treated kaolin samples. The result confirms previous observations about obtaining metakaolinite with optimum reactivity when hydrated with calcium hydroxide as chemical activator.