Classification refractory temperature of magnesia

What are the properties of magnesia?

Magnesia can be divided into natural magnesia, seawater magnesia synthetic magnesia. Natural magnesia mainly comes natural magnesite, but due to the quality of raw ore, it is difficult to obtain products of purity quality. So far, seawater magnesia has become the main source of magnesia used in industrialized countries. The theoretical content of Cao, MgO 2 other impurities is 47.3%. Magnesite decomposes when heated to 700 ℃ ~ 800 ℃ in air, which is called "light burned magnesia". When further heated, it is higher than 1530 ° C, the inactive periclase turns into refractory magnesia, which is called "dead burned magnesia". Synthetic seawater magnesia for industrial production is made seawater digested dolomite. The precipitated Mg (OH) 2 was calcined to obtain MgO. The ratio of calcium to silicon in the synthetic magnesia without fired brick is 0.3-0.5, the ratio of calcium to silicon in the high-purity seawater magnesia is more than 1.7, which has high high high temperature strength.

The main chemical composition is MgO the mineral composition is pericloy crystal. The density is 3.56 ~ 3.65g/cm, the Mohs hardness is 5.5, the melting point is 2800 ℃, it volatilizes significantly at 1800 ~ 2400 ℃. Pure periclase is colorless. With the increase of Fe2O3 CaO content, the color changes light to dark, showing yellow, brown dark brown. With the increase of calcination temperature holding time, the particle size of periclase increases correspondingly, the hydration resistance slag resistance of periclase are also improved.

The impurities in magnesia come dolomite, talc, tremolite, quartz so on in magnesite. Therefore, magnesia contains SiO2, Al2O3, Fe2O3, Cao (B2O3 in seawater magnesia) other impurities. Compared with Cr2O3, Al2O3 B2O3, the influence degree of Fe2O3 is 1,3:11:70. In addition to periclase in magnesia, various silicate minerals can be formed according to Cao / SiO2 ratio, which has different effects on the properties of magnesia products.

According to the chemical composition of magnesium oxide, the quality phase composition of magnesium oxide can be predicted. When calculating the phase composition, only when the homogeneity of MgO raw material calcination temperature of the material are enough to balance the phase composition, the phase composition will be consistent with the experimental results, the higher the purity of the material, the more consistent it will be.