97 fused magnesia

nature

The main crystal phase periclase has a melting point of 2800°C, and it starts to sublime at 1600°C in a vacuum. It begins to sublime at 2000°C in a reducing atmosphere. The density is greater than 3.40g/cm, the porosity is 0%-10%, the Mohs hardness is 5.5, and the Alkaline slag is very corrosive. The periclase is often cubic, octahedral or irregular granular. The cubic cleavage is complete; the linear expansion coefficient α=(14～15)×10/℃(0～1500℃), and increases with the temperature. 97 fused magnesia

The thermal conductivity λ=123.5W/(m·K) (at 100°C), which decreases as the temperature rises. The modulus of elasticity is 1.96 MPa. It is chemically stable and does not react or weakly react with various refractory materials except silica bricks at a high temperature of 1500°C. The grain size of periclase increases with the increase of the calcination temperature and the extension of the holding time, and the corresponding slag resistance is also improved.

Production Process

The production process of fused magnesia is short and simple, but the equipment investment and resource consumption are large. The fused magnesia industry in my country mostly uses electric arc furnaces to melt natural magnesite ore to prepare fused magnesia. The production technology and equipment are backward, with low power, small capacity, low efficiency, and low automation. The grades of fused magnesia produced are not high. High, leading to low utilization rate of magnesium resources and serious environmental pollution.

The main raw material for the production of fused magnesia in my country is magnesite ore. The current production process is divided into two forms: one-step melting method and two-step calcining melting method. The one-step melting method is made by melting natural magnesite ore or purified magnesite concentrate powder at a high temperature above 2800℃ in an electric arc furnace; the two-step calcination melting method is to melt magnesite ore or purified magnesite Concentrate powder is lightly burned in a shaft kiln or rotary kiln at about 1000°C to obtain light burnt magnesia powder, then finely ground, compacted, and finally melted in an electric arc furnace to obtain fused magnesia.

Manufacturing materials

More pure magnesite, light burned magnesia (containing natural magnesite or sea (brine) water) or sintered magnesia are used to melt in the electric arc furnace, and the melt is naturally cooled. Make periclase crystals crystallize and grow from the melt. Due to the use of high-purity raw materials and low silicate impurity content, the direct bonding degree of periclase crystals is relatively high, and the good performance of periclase can be fully displayed. From the use of fused magnesia and sintered magnesia for magnesia-carbon bricks, it has been found that since the erosion of slag starts from the periclase crystal interface, the large crystals of fused calcite are better than those of sintered magnesia The corrosion resistance of crystal is much stronger. Fused magnesia is mostly used as a raw material for higher grade magnesia-carbon refractory products.