What are the preparation methods of magnesium chloride?

Preparation method of magnesium chloride:

1. A by-product brine obtained from seawater salt is concentrated into a carnallite (KCl·MgCI·6H2O) solution, cooled to remove potassium chloride, concentrated, filtered, cooled, and crystallized. Magnesium oxide or magnesium carbonate is obtained by dissolving and substituting hydrochloric acid. Anhydrous magnesium chloride is obtained by deamination by heating with ammonium magnesium chloride.

2. Anhydrous magnesium chloride can be prepared by dehydrating a mixture of ammonium chloride and food grade magnesium chloride or a double salt of ammonium chloride or magnesium chloride hexahydrate in a hydrogen chloride stream. Equimolar amounts of MgCl2·6H2O and NH4Cl were dissolved in water, and crystallized as a double salt in an aqueous solution having a temperature slightly higher than 50 ° C to keep the original temperature separate from the mother liquid. Recrystallization is carried out once more.

Slightly dry and hot into a quartz boat, the boat is placed in a quartz tube for dehydration operation, dry hydrogen chloride gas is introduced, and the temperature is raised to 100 ° C for 3 h, then heated to 250 ° C for 1 h, and then heated to 400 ° C. 1h, finally melted in a short time, and passed through CO2 gas to expel HCl gas, and the obtained anhydrous magnesium chloride can be stored in a phosphorus pentoxide protector. The double salt NH4Cl·MgCl2·6H2O can also be placed in a vacuum furnace and heated to 200 ° C for dehydration under reduced pressure, so that the amount of hydrogen chloride gas can be reduced. The by-product brine in seawater salt is concentrated to form a solution of carnallite (KCl·MgCl 2 ·5H 2 O), cooled to remove potassium chloride, concentrated, filtered, cooled and crystallized. Magnesium oxide or magnesium carbonate is obtained by dissolving and substituting hydrochloric acid. Anhydrous magnesium chloride is obtained by deamination by heating with ammonium magnesium chloride.

Whether it is anhydrous magnesium chloride or magnesium chloride hexahydrate, they all have a generality: easy to absorb moisture, easy to enter into water. Therefore, we should pay attention to storage in a dry and cool place when storing.