Burned magnesia call magnesium oxide, its connection with oxygen. Magnesia is used in medicine, food and electronic industry and also for production of rubber and oil products.
Oxide of magnesium can be met in the nature in the form of small correct cubes and octahedrons, they form mineral a periclase. The color of a periclase varies from dark green to gray-green, depending on content of iron in it. Because of property of refractoriness oxide of magnesium is actively used during creation of devices. It is applied to production of magnesian cement and xylolite and also as filler by production of rubber. Burned magnesia is nutritional supplement, in medicine it is used as means from the increased acidity of gastric juice.
Receiving
Oxide of magnesium (MgO) is formed when burning magnesium on air or when calcinating its oxygen-containing salts, nitrate and hydroxide of a carbonate. Then MgO sublimates in the electric furnace and is besieged in the form of crystals. The easiest to receive it calcinating together with a mineralizer, for example about calcium boravolume. For technical needs use the burned magnesia received by calcinating of hydroxide of the magnesium which is formed in brines which remain by production of potash salts. To besiege iron in the form of hydroxide, add a small amount of limy milk to brines. Its further addition causes magnesium oxide sedimentation. One more method of receiving MgO consists in magnesium chloride processing by means of water vapor, a by-product of this reaction is hydrochloric acid. This way demands big expenses of fuel as magnesium chloride completely decays only at a temperature about 500 wasps.
Chemical and physical properties
Crystal MgO is almost not subject to effect of water. Acids react c to them hardly while magnesium oxide in a powdery look easily in them is dissolved, and water gradually turns it into hydroxide. Oxide of magnesium represents colourless crystals of a cubic form, its chemical properties depend on receiving temperature. At a temperature 500-700os light magnesia which then can react with water and acids is formed, it absorbs carbon dioxide from air therefore the magnesium carbonate turns out. Temperature increase leads to reduction of reactionary ability of oxide of magnesium when it reaches 1200-1600os heavy magnesia is formed, it is called still metallurgical powder. It represents large crystals of a periclase which are resistant to influence of water and acids.