There are many different kinds of magnesia

Re-sintered magnesia can be divided into natural magnesia and seawater magnesia or synthetic magnesia. Natural magnesia mainly comes from natural magnesite, but it is difficult to obtain high purity and high quality products due to the quality restriction of the original ore. Up to now, seawater magnesia has become the main source of magnesia used in industrial developed countries. Magnesite in MgO style theory content is 47.3%, the rest of the classification of CaO, SiO2, iron impurities, magnesite heated to 700 ℃ ~ 800 ℃ in air decomposition, known as the "light burned magnesia, further becomes inactive when it is heated to above 1530 ℃ periclase become hard burned magnesia, referred to as the" dead burned magnesite ". The synthetic magnesia used in industrial production is made from sea water and digestive dolomite. The precipitated Mg(OH)2 was calcined to obtain MgO, and the ratio of calcium to silicon in the synthetic magnesium sand used for non-sintering bricks was 0.3 to 0.5, while the ratio of calcium to silicon in the high-purity seawater magnesium sand was more than 1.7, and its high temperature intensity was the highest.

The impurities in magnesite come from dolomite, talc, diorite, quartz and so on in magnesite, so that magnesite contains impurities such as SiO2, Al2O3, Fe2O3, CaO, etc. These impurities reduce the high temperature strength of magnesia, and their influence degree is 1:3:11:70 if Fe2O3 is taken as 1 and compared with Cr2O3, Al2O3 and B2O3. In addition to magnesite, a variety of silicate minerals can be formed according to CaO/SiO2 ratio, which have different effects on the properties of magnesia products.

According to the chemical composition of sintered magnesite products can be predicted and phase composition, the quality of the, when calculating the phase composition, only when the uniformity of sinter raw material and material calcining temperature enough to make the phase equilibrium, then calculate the phase composition will be consistent with the experimental results, and the higher the purity is more consistent with the material.

Decomposition discharge CO2, magnesite calcination at 700 ℃ to 1000 ℃ or so calcined into light burning magnesium stone (caustic magnesium oxide), commonly known as magnesia powder, the quality of a material is loose, large chemical activity. Continue to raise the temperature to 1700 ~ 1800 ℃ above, periclase grains grew older, volume shrinkage, density, chemical activity greatly reduced, the calcined be sintered magnesia.

magnesia