河南Use of magnesium oxide

Magnesia can be divided into natural magnesia and seawater magnesia or synthetic magnesia. The natural magnesia of magnesia manufacturers mainly comes from natural magnesite, but it is difficult to obtain high-purity and high-quality products due to the restriction of raw ore quality. So far, seawater magnesia has become the main source of magnesia used in industrial developed countries. The theoretical content of MgO in magnesite is 47.3%, and the remaining impurities are CaO, SiO2, iron, etc. The magnesite is decomposed when heated to 700 ℃~800 ℃ in air, which is called "light burned magnesia". When further heated to above 1530 ℃, it becomes inactive periclase and becomes hard burned magnesia, which is called "dead burned magnesia". Synthetic seawater magnesia for industrial production is made from seawater and digested dolomite. The precipitated Mg (OH) 2 is calcined to obtain MgO. The calcium silica ratio of synthetic magnesia used for unfired bricks is 0.3~0.5. The calcium silica ratio of high-purity seawater magnesia is above 1.7, and its high temperature strength is the highest.