The dehydration of MgCl2·6H2O in MgCl2·6H2O–KCl–NH4Cl system

The dehydration of MgCl2·6H2O in MgCl2·6H2O–NH4Cl–KCl system was investigated. The dehydration process was characterized by X-ray diffraction and chemical analysis. The dehydration effects of MgCl2·6H2O in different systems were compared. The dehydration mechanism of MgCl2·6H2O in MgCl2·6H2O–NH4Cl–KCl system was proposed and discussed. The formation of NH4Cl·MgCl2·nH2O (6 > n ≥ 0) below 300 °C can effectively suppress hydrolysis. The anhydrous KMgCl3 formed above 400 °C is more stable than anhydrous MgCl2 at elevated temperature, which can effectively protect the dehydration product from hydrolyzing at high temperature. The content of MgO in anhydrous MgCl2 was 0.02 wt.% when dehydrating MgCl2·6H2O in MgCl2·6H2O–KCl–NH4Cl system with the molar ratio of MgCl2·6H2O:KCl:NH4Cl was 1:2.87:1.