6. Magnesia metallurgy

6.1 Production of magnesia from magnesite

Magnesia is produced from magnesite by calcination. Magnesium oxide activity depends on the formation of small MgO crystals 50 to 1,000 Å in length. The size of the smallest MgO crystals is therefore of the same order of magnitude as that of the periclase unit cell.

The qualities of MgO depend on the calcination conditions:

• at a temperature of 700 to 1,000°C, calcination produces caustic magnesia (CCM: Caustic Calcined Magnesia) according to the decomposition reaction: