Production and characterisation of sodium and potassium carbonate salts from carbonation alkaline aluminate liquor

ABSTRACT The polythermal crystallization method has been used to extract sodium and potassium carbonate salts as valuable by-products. The salt production was carried out using an alkaline carbonate solution from the Azarshar nepheline syenite pilot plant in Iran. The optimum conditions were obtained by comparison between the results of thermodynamic modelling and experiments. To better understand the properties of the carbonate salts, thermal analysis, chemical analysis, and X-ray diffraction methods were also utilised. The optimum density and temperature for sodium carbonate crystallization were found to be 1.50 g/cm3 and 115–120°C, respectively, and for hydrated potassium carbonate crystallization to be 1.68 g/cm3 and 130°C at the first stage, and 1.70 g/cm3 and 135°C at the second stage, respectively. The thermodynamic modelling showed good agreement with experimental data for the carbonate salts.