Magnesium Oxide, Magnesia (MgO)

Formula: MgO

Melting point: 2825ºC

Density: 3.6 g/cc

Commonly known as magnesia, this oxide is produced from the calcination of magnesium carbonate or dolomite and has been used since ancient times, initially as a pigment and refractory material. During the 19th century, its industrial importance was recognized, and in the 20th century, its widespread use in cement, refractory bricks, and high-heat-resistant ceramic products became established.

In its pure state, MgO appears as a milky-white solid of medium hardness, although it is rarely used without combining it with other oxides. It has excellent mechanical and thermal properties, notable for its hardness, toughness, and high heat resistance. These characteristics make it an excellent refractory material, capable of maintaining its structural integrity even at temperatures close to its melting point.

Magnesia is chemically inert under normal conditions and only reacts appreciably with strong acids and reducers when subjected to very high temperatures. Its stability makes it an essential component in advanced structural and ceramic materials.

Magnesium oxide plays a fundamental role in various industries. Its main application is the manufacture of refractory parts used in high-temperature furnaces, such as those used in the steel industry and non-ferrous metal production. Secondly, it is used as a basic component of cement, especially Portland cement, where it contributes to improving the mechanical strength and chemical stability of the hardened material.

A third highly relevant application is its use as an additive in most commercial glasses, including soda-lime and borosilicate glasses, where it acts as a stabilizer and structural modifier, improving durability and resistance to thermal shock.

Interestingly, the same compound found in refractory bricks and industrial cements is used in medicine under the same name, magnesia, for the treatment of digestive disorders, although in much lower doses and in purified forms.

MgO remains a strategic material due to its unique combination of thermal resistance, chemical stability, and industrial versatility. Its role as a refractory material, a glass additive, and an essential component in cements ensures its presence in sectors as diverse as construction, metallurgy, chemical engineering, and medicine.