Magnesium chloride anhydrous is one of the varieties of magnesium chloride, with the molecular formula MgCl₂and a relative molecular mass of 95.21. It shares the same applications as magnesium chloride hexahydrate and is produced by gradually dehydrating magnesium chloride hexahydrate to form magnesium chloride dihydrate, which is then further processed to obtain magnesium chloride anhydrous. By weight, magnesium chloride anhydrous consists of 74.54% chlorine and 25.48% magnesium. When dehydrated in air, it typically loses only four molecules of water without significant side reactions. However, removing the remaining two molecules of water causes pronounced hydrolysis of magnesium chloride, resulting in the formation of magnesium hydroxychloride, magnesium oxide, hydrogen chloride, and other compounds. This means that dehydrating magnesium chloride hydrates in air cannot yield magnesium chloride anhydrous.
1.Properties and Uses
Magnesium chloride anhydrous appears as white, shiny hexagonal crystals with a melting point of 714°C and a boiling point of 1412°C. It exhibits extremely strong hygroscopicity, even more so than hexahydrate and dihydrate magnesium chloride. Its physical and chemical properties are largely similar to those of hexahydrate magnesium chloride. In addition to its use as a cementitious material in magnesite products, anhydrous magnesium chloride is primarily employed in the production of metallic magnesium and finds applications in chemical, light industry, coal, construction, and other sectors.
2.Production Methods
The current methods for producing magnesium chloride anhydrous include:
(1) Hydrogen chloride dehydration method;
(2) Complex salt dehydration method;
(3) Complex compound dehydration method.
Currently, magnesium chloride anhydrous on the market is mainly a by-product of sponge titanium production. If possible, it is advisable to purchase magnesium chloride anhydrous in whole ton blocks. If purchasing crushed forms, care must be taken to ensure that flake-like hexahydrate magnesium chloride has not been mixed in, as this could cause deviations in the preparation of brine solution during production.
3.Advantages and Disadvantages in Magnesite Production
The main advantages of using magnesium chloride anhydrous in the magnesite industry include reduced transportation costs, high purity with low impurity levels, and suitability for production in low-temperature winter environments. Since adding water to magnesium chloride anhydrous during brine preparation generates significant heat, it aids in maintaining the temperature and fluidity of the slurry. However, this same property becomes a disadvantage during summer production.
4.Usage in Magnesite Production
The method of using magnesium chloride anhydrous in magnesite material production is the same as that for hexahydrate magnesium chloride. Due to its strong hygroscopicity, magnesium chloride anhydrous readily absorbs moisture and converts back to hexahydrate magnesium chloride. Therefore, it is typically directly mixed with water to prepare a brine solution of a specific Baumé degree. However, since adding water to magnesium chloride anhydrous generates substantial heat, protective measures must be taken during the process to prevent burns.
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Post time: Aug-26-2025