Valorization of sodium sulfate waste to potassium sulfate fertilizer: experimental studies, process modeling, and optimization

Sodium sulfate is a common low-value industrial by-product but can be managed using the Glaserite process to convert it into high-value potassium sulfate. The aim of the study is to investigate the potential for implementing this process in an industrial application. Experimental studies were completed to determine the yield and purity of both glaserite and potassium sulfate. Process simulation using SysCAD was utilized to optimize a two-stage glaserite process to produce potassium sulfate. Comparison of experimental and simulated data was made to validate the simulator's results, finding the AAD in solid and liquid phase for glaserite production to be 6.9% and 5.7%, respectively, and for potassium sulfate to be 5.7% and 2.3%, respectively. For a process treating seven MT/hr of Na2SO4, a KCl feed strategy of 3.0 MT/hr to the glaserite reactor and 4.5 MT/hr to the K2SO4 reactor was found to maximize yield and minimize water demand. It was also found that ambient temperatures were preferred for the K2SO4 reactor and that K2SO4 yield suffered significantly under certain conditions when the glaserite reactor operated at 50°C or above.