What is magnesia?

Magnesia is a term used to describe various products derived from magnesium-rich sources. Magnesite is the most common source of magnesia and serves many important industrial applications.  Magnesia is produced from magnesite ore or extracted from seawater or brines as magnesium hydroxide.

The two most commercially important magnesia products are dead-burned magnesia and caustic-calcined magnesia.

Dead-burned magnesia, also known as refractory magnesia, is produced from the heating of magnesite or magnesium hydroxide and is the primary component in refractory materials. The steel industry is the largest user of refractory magnesia, a non-metallic substance with extreme heat resistant properties widely used for linings in furnaces, kilns and reactors.

Caustic-calcined magnesia (or light-burned magnesia) retains its reactivity and is an essential component in a number of agricultural, environmental, construction and industrial applications.

Industrial applications

In agricultural applications, magnesium is vital for photosynthesis.  In animals, magnesium is required to prevent an often-fatal disorder known as hypomagnesia, or grass tetany.

Magnesia also plays a vital role in environmental protection.  It is used to treat industrial wastewater by removing silica and precipitating heavy metals and to reduce air pollution by stripping sulphur dioxide from industrial air emissions.  Its absorbent properties are used to clean-up hazardous chemical spills.  And it often is used to render metal-bearing wastes non-hazardous.

In construction, the caustic-calcined product is used to make magnesium-based cements. These cements are widely used in the flooring industry.

More recently, its heat resistant properties have seen magnesia used for the flame-resistant building products.

Other industrial applications include use by the oil drilling industry in drilling muds, and by the rubber industry as a vulcanizing agent.

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