Production of magnesium chloride

1. The by-product brine of salt making from seawater is concentrated into carnallite (KCl. MgCI. 6H_2O) solution. After cooling, potassium chloride is removed, and then concentrated, filtered, cooled and crystallized. Magnesium Oxide or magnesium carbonate is dissolved and replaced by hydrochloric acid. Anhydrous magnesium chloride is heated by ammonium magnesium chloride to remove ammonia.


2. Anhydrous magnesium chloride can be made from the mixture of ammonium chloride and magnesium chloride hexahydrate, or from the dehydration of ammonium chloride and magnesium chloride hexahydrate in hydrogen chloride gas stream. Equimolar MgCl2.6H_2O and NH_4Cl were dissolved in water and crystallized in the form of double salts in aqueous solution at a temperature slightly higher than 50 C, keeping the original temperature separate from mother liquor. Then recrystallization is carried out again.


When slightly dried and heated, the boat is loaded into the quartz boat. The boat is put in the quartz tube for dehydration operation. The dry hydrogen chloride gas is introduced into the boat. At the same time, the temperature is raised to 100 C for 3 hours, then to 250 C for 1 h, then to 400 C for 1 h. Finally, the boat is melted in a short time, and CO2 gas is used to expel HCl gas. The anhydrous magnesium chloride obtained can be preserved. In the dryer with phosphorus pentoxide. The compound salt NH4Cl MgCl2 6H_2O 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 of salt making from seawater is concentrated into carnallite (KCl. MgCl2. 5H2O) solution. After cooling, potassium chloride is removed, and then concentrated, filtered, cooled and crystallized. Magnesium Oxide or magnesium carbonate is dissolved and replaced by hydrochloric acid. Anhydrous magnesium chloride is heated by ammonium magnesium chloride to remove ammonia.