Preparation of Anhydrous Magnesium Chloride from Ammonium Carnallite

High-purity anhydrous magnesium chloride was prepared by using ammonium carnallite as starting material and alumina as covering agent. X-ray diffraction (XRD) analysis and thermogravimetric analysis and differential calorimetry analysis (TG-DSC) analysis were employed to characterize the process. The mechanism involved in the process was proposed and discussed. The factors affecting the purity of anhydrous magnesium chloride were investigated. The results reveal that the mass fraction of magnesia in anhydrous magnesium chloride could reach 0.08% under the optimum conditions: alumina with the thickness of 1.3 cm was put on top of dehydrated ammonium chloride (NH4Cl center dot MgCl2 center dot 1.2H(2)O), and then the sample was maintained at 450 degrees C for 1.5 h. After that, the sample was calcined at 700 degrees C for 1 h