General knowledge of magnesia

Magnesia can be divided into natural magnesia and seawater magnesia or synthetic magnesia. Natural magnesite mainly comes from natural magnesite, but it is difficult to obtain high-purity and high-quality products due to the quality constraints of raw ore. So far, seawater magnesite has become the main source of magnesite used in industrial developed countries. The theoretical content of MgO in magnesite is 47.3%. The other impurities are CaO, SiO 2 and iron. Magnesite is decomposed at 700 ~800 ~C in air, which is called "light burnt magnesia". When further heated to 1530 ~above, it becomes inactive periclase and becomes hard burnt magnesia, which is called "dead burnt magnesia". The synthetic seawater magnesia used in industrial production is made from seawater and digestive dolomite. MgO was obtained by calcining precipitated Mg(OH)2. The ratio of calcium to silicon in synthetic magnesia for unburned bricks was 0.3-0.5, and that of high purity seawater magnesia was over 1.7. The high temperature strength of magnesia was the highest.