New Process for Na2CO3 Production from Na2SO4 Based on Modeling the Na2SO4–(NH4)2SO4–MEA–MEG–H2O System

Alternative means for soda ash (Na2CO3) production from sodium sulfate (Na2SO4) are needed due to the intensive consumption of energy in the conventional Mirabilite-Solvay process (MSP). We demonstrate a new process to produce soda ash using sodium sulfate as a feed material. The new process relies on the antisolvent crystallization of unreacted Na2SO4 to separate it from soluble (NH4)2SO4 in a mixed monoethanolamine (MEA) and monoethylene glycol (MEG) solution. To develop the process, the solubilities of Na2SO4 and (NH4)2SO4 solids in aqueous mixed MEA–MEG solutions were first measured and then modeled using regressed paired-ion interactions from the electrolyte nonrandom two-liquid (E-NRTL) model. Anhydrous dense soda ash with a bulk density of up to 1146 kg/m3 was obtained when the concentrated Na2SO4 brines reacted with CO2 and NH3.