A modified Solvay process with low‐temperature calcination of NaHCO₃ using monoethanolamine: Solubility determination and thermodynamic modeling

An energy‐saving, modified Solvay process for dense soda ash production was proposed to replace the high‐temperature, calcination step of NaHCO 3 . We found NaHCO 3 completely decomposed into anhydrous, Na 2 CO 3 at 353 K in a mixed‐solvent containing at least 65 wt% of monoethanolamine (MEA), which is an amine‐absorbent prevalently used for CO 2 capture. A chemical model was built after the determination of solubilities and through data regression for the solid–liquid system: Na‐Cl‐NH 4 ‐CO 3 ‐HCO 3 ‐MEA‐H 2 O. Reparameterization for paired‐ion interactions were performed via the mixed‐solvent electrolyte model. Thermodynamic analysis elucidated the shift in ion dominance from HCO 3 − to CO 3 2+ , thereby providing the phase transition mechanisms. An exploratory, fed‐batch experiment was implemented to verify the accuracy of the model, for which the obtained solids were in the form of saleable, dense soda ash products; bulk densities up to 1.01 g/cm 3 were achieved in the laboratory.