Caustic calcined magnesia

Lightly burned magnesium (causticized magnesium) Calcined magnesite, brucite and magnesium hydroxide extracted from seawater or brine at about 800~1000℃, and decomposed to discharge CO2 or H2O, so as to obtain Caustic calcined magnesia, also known as magnesia, caustic magnesia or magnesia. Lightly burned magnesium powder has loose texture and high chemical activity, which can be used to manufacture magnesium cement, magnesite building materials, thermal insulation materials, etc. It is also an intermediate product of producing high-quality magnesia by two-step calcination method [1-2]. When magnesite is heated, equiaxed periclase appears at about 600℃. When the temperature reaches 650℃, the equiaxed periclase disappears and the non-equiaxed periclase is produced. The equiaxed periclase disappears completely at 850℃. These periclase lattices have higher surface energy due to the appearance of point defects and dislocations. The lattice of MgO is less water than that of MgCO3 lattice group, so the pores between lattices are enlarged, the porosity is high, the specific surface area is large, and it has high activity. Lightly burned magnesium powder is light yellow and light brown powder, the particle size is mostly below -100 mesh, periclase crystal is very small (< 3μm), the true specific gravity is 3.07~3.22, the bulk density is 0.8~1.2g/cm3, the refractive index is 1.68~1.70, the lattice constant is large (α=0.4212), and there are many lattice defects and crisp texture The volume shrinkage of light burned magnesia powder calcined from magnesite is about 5%; Usually, 3%~5% CO2 remains due to incomplete decomposition. The light burning temperature and time of magnesite have certain influence on the activity of light burning magnesium powder. Magnesite was calcined at 600, 650, 700, 750, 800, 850 and 900℃, respectively, and the calcination temperatures of 700, 750 and 800℃ had no obvious effect on the activity of light burned magnesia powder in 15~90 minutes. The effects of 600, 650, 850 and 900℃ on the activity are particularly significant. When calcined at 600 and 650℃, the activity increases obviously with time. When calcined at 850℃ and 900℃, the activity decreased obviously with the increase of hydrocarbon calcination time.