General knowledge of magnesia

Magnesia can be divided into two categories: natural magnesia and sea magnesia, or synthetic magnesia. Natural magnesite mainly comes from natural magnesite, but it is difficult to obtain high-purity and high-quality products because of 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 Fe. Magnesite is decomposed by heating to 700 ~800 C in air. It is called "light burned magnesia". When further heated to 1530 C, it becomes inactive calcined magnesia and is called "dead burned magnesia". The synthetic seawater magnesia used for industrial production is made of sea water and digestion dolomite. MgO is obtained by calcining the precipitated Mg (OH) 2. The calcium-silicon ratio of magnesia used in the synthesis of unburned bricks is 0.3~0.5. The calcium-silicon ratio of high purity seawater magnesia is above 1.7, and its high temperature strength is the highest.