Natural brine valorisation: Application of the system K+, Mg2+/Cl−, SO42−//H2O at 25°C observations on kinetics formation of K2SO4 and K2SO4.MgSO4.6H2O

Abstract The crystallization of K 2 S0 4 in the system K + , Mg 2+ /Cl − , SO 4 2 /H 2 O involving the reaction 2KCl + MgSO 4 K 2 SO 4 + 2KCl was studied. Independently of the experimental procedure applied, it was confirmed that schoenite (K 2 SO 4 .MgSO 4 .6H 2 O) is an inevitable intermediate product of the considered transformation. The double decom position reaction kinetics depend on formation and dissolution rates of intermediate salt and potassium sulphate, respectively. The formation of schoenite outside of its crystallization field might indicate a metastable space extension of this domain to cover the K 2 SO 4 one. The formation kinetics rate of MgSO 4 .K 2 SO 4 .6H 2 0 is quicker than the K 2 S0 4 one.