Magnesite is a natural mineral resource that often appears in alkaline refractory materials. After burning natural magnesite, the content of magnesium can be further increased. Magnesite is a magnesium carbonate mineral and it is the main source of industrial magnesium refining. According to the degree of calcining and producing technology, it can be divided into light-burnt magnesia and dead-burnt magnesia.
Light-burnt magnesia is produced by calcining magnesium carbonate or magnesium hydroxide at relatively lower temperatures, usually ranging from 750 to 1100 °C. This moderate heating process preserves a significant portion of the original crystal structure, resulting in a product with lower density and increased reactivity. Since the burning loss of magnesite is generally about 50%, the magnesium oxide content in the ore can be almost doubled through light burning. Therefore, light burning is the most effective means of enriching MgO. Light-burnt magnesia has high activity; it is an ideal raw material for producing high-density magnesia.
Dead-burned magnesia belongs to burned magnesia, and its main component is magnesium oxide. It is the main raw material for the production of ordinary magnesia-fired bricks and amorphous refractory materials. Dead-burned magnesia is a product of hydrogen extracted from magnesite, brucite, or seawater, which escapes completely under high pressure when it is calcined in a high-temperature shaft kiln at 1800°C. Magnesium oxide forms dense blocks of periclase with a high MgO content, usually between 90%-93%, it is the raw material for the production of ordinary magnesia bricks and aMonolithic refractory materials.
Light burnt magnesia tends to retain more of its original crystalline structure, imparting a higher surface area and porosity. This characteristic leads the product more reactive and suitable for applications that demand quick hydration or dissolution. Due to its porous nature, it has increased surface activity, making it as an excellent choice for agricultural, environmental, and some industrial applications.
Dead burnt magnesia loses much of its initial crystalline structure due to the higher calcination temperatures, resulting in a denser and less porous material. This altered structure leads to decreased reactivity and increased chemical stability, making it an ideal choice for applications that require high heat resistance and structural integrity.
Light burnt magnesia is mainly used as an intermediate product in the two-step calcination method. For example, it can be ball-pressed and calcined to produce sintered magnesia (DBM) with different grades, synthesize composite materials such as magnesia-calcium sand and magnesia-aluminum spinel sand, or produces professional products such as fused magnesite (FM) and electrical grade magnesium oxide. In addition to being an intermediate product of secondary calcining of magnesia refractory raw materials, light-burned magnesia can also be used to manufacture magnesium chemical products, magnesia cement, magnesite building materials products, heat insulation materials, feed additives, etc. In addition, light-burned magnesium after chemical treatment can be made into a variety of magnesium salts, which are raw materials for medicine, rubber, artificial fibers, papermaking and other fields. In the building materials industry, light-burned magnesia can be made into tire boards, particleboards, insulation columns, railings, artificial marble, asbestos tiles, wall panels, etc.
Dead burnt magnesia’s primary application lies in industries that demand high-temperature resistance and stability. It is mainly used in metallurgy industry. It can be also used to make magnesia bricks, chrome magnesia bricks, magnesite, metallurgical powder, fused magnesium oxide, etc. Meantime used for the lining of medium and high frequency induction furnaces for smelting special alloy steel, non-ferrous metals and precious metals. In addition, it can also be used as high temperature electrical insulation material.
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