Magnesium Oxide

Magnesium oxide is produced by the calcination of magnesium carbonate or magnesium hydroxide. Magnesium hydroxide is obtained by the treatment of magnesium chloride solutions, typically seawater, with lime.


Mg2+ + Ca(OH)2 → Mg(OH)2 + Ca2+


Calcining at different temperatures produces magnesium oxide of different reactivity. High temperatures (1500 – 2000 °C) diminish the available surface area and produces dead-burned (often called dead burnt) magnesia, an unreactive form used as a refractory. Calcining temperatures (1000 – 1500 °C) produces hard-burned magnesia, which has limited reactivity and calcining at lower temperature, (700 – 1000 °C) produces light-burned magnesia, a reactive form, also known as caustic calcined magnesia. Although some decomposition of the carbonate to oxide occurs at temperatures below 700 °C, the resulting material appears to reabsorb carbon dioxide from the air.


Minteq utilizes magnesium oxide as aggregate and matrix in a variety of products in the steelmaking industry as well as non-ferrous product, petrochemical, cement, and power generation industries.  Its primary function is to provide thermal insulation and chemical stability.