Colorless crystals, which, when in the atmosphere, quickly begin to disintegrate, are magnesium chloride, whose formula is MgCI2. If they are dissolved in water, then the solution thus obtained is widely used for the production of a variety of building materials of artificial origin, for example, magnesia cement. Storage of this substance should be done in a sealed container, since it is very hygroscopic.
Being a highly soluble substance in water, magnesium chloride is found in ordinary sea water, and it is also found in deposits of potassium salts, where it is in the form of hexahydrate. Therefore, this substance is not extracted by any laboratory-industrial method, but natural compounds are used to produce it, which are purified and the crystals obtained are crushed. As a starting material, MgCl2 is used in the preparation of magnesium and its oxide for the production of fire-resistant impregnations for wood. In addition, magnesium chloride is used to prepare the so-called Sorel cement. During this production, calcined magnesium oxide is added to a concentrated solution of magnesium chloride.
The property of the obtained substance — rapid solidification at ordinary atmospheric temperature — allows it to be used as xylolite, a sealing and cementitious building material. The astringent properties make it possible to use MgCl2 for pressing sawdust and producing fiberboard. Fiberboard is used as soundproofing material. The hardening effect is ensured by the hydrolysis process and the production of the Mg2OCl2 salt, which does not dissolve in water.
Due to its high hygroscopicity, the substance magnesium chloride is able to participate in the formation of hydrates with different numbers of water molecules. The level of this hygroscopicity is so great that if the humidity of the surrounding air is below 50%, then magnesium chloride, as well as calcium and lithium chlorides, initiates the destruction of metals. One of these hydrates is hexahydrate, which is a needle-shaped crystal that melts at 106 ° C. In the interaction of magnesium chloride with ammonium, rhomboid crystals are formed, which are salty-bitter in taste and are readily soluble in aqueous solutions and alcohols.
The magnesium chloride compound, due to its properties, forms abundantly basic salts, which have a protective effect. The relative stability of these salts in a certain temperature range leads to their widespread use, but at the same time it creates enough problems associated with environmental pollution. In particular, potassium salts of magnesium chloride are used in the destruction of ice on roads in the winter. The effect of this application is extremely doubtful, since this creates a threat of contamination of effluents and causes damage in the form of corrosion.
Magnesium chloride is also used for the electrolytic production of magnesium in the form of a metal; the preparation of this compound using this technology can also be found for medical purposes.
In nature, this substance, in addition to the already mentioned sea water, is found in the form of carnallite. The most important sources of this mineral are in the Solikamsk region. The most common area where magnesium chloride is used is the utility sector, where this substance is used to activate the snow melting process. In food production, this compound is known as the food supplement E511. This supplement, as a food component, is most often used by residents of Japan. They call it "nigari" - bitter juice. Nigari is obtained naturally from seawater by evaporation. This product contains many useful elements - iron, sodium, potassium, zinc and others. Nigari is used mainly as a means of curdling soy milk and for cooking Japanese national tofu dishes.