1. Brief introduction of magnesia:
Magnesia is one of the most important raw materials for refractories.
It can be divided into three categories: sintered magnesia, lightly burned magnesia, and fused magnesia.
It is made of magnesite, brucite or seawater and milk of lime to produce magnesium hydroxide, and then calcined at high temperature.
2. Details of magnesia:
With strong hydration ability, it is usually used to make magnesia bricks, magnesia-alumina bricks, ramming materials, furnace repair materials, etc., and those containing more impurities are used to pave the bottom of steelmaking furnaces, etc. Magnesia can be divided into two categories: natural magnesia and seawater magnesia or synthetic magnesia.
Natural magnesite mainly comes from natural magnesite, but due to the restriction of raw ore quality, it is difficult to obtain high-purity and high-quality products. So far, seawater magnesite has become the main source of magnesite used in industrially developed countries. The theoretical content of MgO in magnesite is 47.3%, and the remaining impurities include CaO, SiO2, iron, etc., and magnesite is decomposed when heated to 700°C~800°C in the air, called light-burned magnesia, and further heated to 1530°C Above ℃, 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-silicon ratio in the synthetic magnesia used for non-fired bricks is 0.3~0.5, and the calcium-silicon ratio of high-purity seawater magnesia is above 1.7, and its high-temperature strength is the highest. .
3. Application of magnesia:
Used in the manufacture of various magnesia bricks, magnesia-alumina bricks, ramming materials, furnace repair materials, etc.
4.The characteristics and requirements of magnesia:
1) High purity, containing more than 98% MgO;
2) Low R2O3 content;
3) High particle volume density, reaching above 3.4g/cm;
4) High CaO/SiO2 ratio, greater than 2;
5) The periclase grain size is large, above 100-200 μm;
6) The periclase crystal phase forms a direct bond.