Thermodynamics of the Na-Al-silicate formation system containing CO3(2-) and SO4(2-)

The concentrations of aluminum (A1), and silicon (Si) ions in equilibrium with Al-Si complexes were measured in laboratory synthesized green and white liquors. The effect of hydroxyl, sulfate, and carbonate ions were investigated. The structure of the precipitates was elucidated by X-ray diffraction and chemical analysis. The green liquor precipitates were found to be a mixture of sodalite and hydroxysodalite. The white liquor precipitates have only the structure of hydroxysodalite. Precipitates containing either carbonate and/or sulfate were not observed.