Fused magnesia important raw materials castable Refractory Materials Iron and steel smelting
Fused magnesia is a general term for the products of magnesite and other magnesian raw materials that are sintered at high temperature. Magnesia calcined with natural magnesite as raw material is called sintered magnesia by one-time calcination or two-step calcination process with high-temperature equipment such as shaft kiln and rotary kiln; Using magnesite as raw material, fused magnesia is formed after melting in electric arc furnace and cooling; Magnesium oxide extracted from seawater is called seawater magnesia. Magnesia is one of the most important raw materials for refractories. It is used to manufacture all kinds of magnesia bricks, magnesia aluminum bricks, ramming materials, furnace mending materials, etc. Those containing more impurities are used to pave the bottom of steelmaking furnace, etc.
High purity magnesia is made by flotation purification of natural super grade magnesite ore, light burning, fine grinding, ball pressing and ultra-high temperature oil shaft kiln calcination. It is a high-quality raw material for brick making and refractory materials.
Medium grade magnesia is produced from light burned magnesia with MgO content of 97% by ball pressing, high temperature shaft kiln calcination and other processes. The product has good sintering degree and dense crystallization. It is a high-quality raw material for the production of medium-grade magnesium refractory products.
Fused magnesia is prepared by melting selected super-a natural magnesite or high-purity light burned magnesium particles in an electric arc furnace. The product has high purity, large crystalline particles, compact structure, strong slag resistance and good thermal shock stability. It is not only an excellent high-temperature electrical insulation material, but also an important raw material for making high-grade magnesia brick, magnesia carbon brick and amorphous refractory.,
The melting point of the main crystalline phase periclase is 2800 ℃, sublimation begins at 1600 ℃ in vacuum, and sublimation begins above 2000 ℃ in reducing atmosphere. The density is greater than 3.40g/cm, the porosity is 0% ~ 10%, the Mohs hardness is 5.5, and the corrosion resistance of alkaline slag is very strong. Periclase is often cubic, octahedral or irregular granular, and the cube cleavage is complete; Coefficient of linear expansion α=( 14～15) × 10 / ℃ (0 ~ 1500 ℃) and increases with the increase of temperature.