Effect of temperature on the synthesis of sodalite by crystal transition process

Abstract In the study, sodalite was synthesized with the kaolinite as the raw material in the steam and air atmosphere by crystal transition method. It was found that the content of sodalite in products decreased first and then increased as the temperature increased from 200 °C to 800 °C. The difference of the reaction paths at different temperatures was the main reason for the decreasing sodalite. At 200–300 °C, kaolinite would directly transform into sodalite. At 400–800 °C, kaolinite would first transform into nepheline and then transform into sodalite. At relatively low temperatures (400–600 °C), the reaction rates were both lower, which resulted in the lower content of sodalite. The reaction temperature was suggested above 600 °C to ensure the high yield of sodalite for the treatment of radioactive wastes.