What's the use of light burned magnesium?

Light burned magnesium is widely used in building materials, chemical industry, metallurgy, medicine and other fields. It is an ideal material for the production of fireproof board, light partition board, magnesium sulfate, papermaking, sulfur removal process, slag splashing in steel plant.


Magnesite, brucite and magnesium hydroxide extracted from sea water or brine are calcined at about 800 ~ 1000 ℃ to decompose and discharge CO2 or H2O to obtain calcined magnesia, also known as light burned magnesia, caustic magnesia or light burned magnesium, commonly known as bitter earth powder. Light burned magnesia powder has loose texture and high chemical activity. It can be used not only to manufacture magnesium cement, magnesite building materials, heat insulation materials, but also to produce high quality magnesia by two-step calcination method.


When the magnesite is heated, equiaxed periclase appears at about 600 ℃; at 650 ℃, equiaxed periclase disappears with non equiaxed periclase; at 850 ℃, equiaxed periclase disappears completely. These periclase lattices have higher surface energy due to the presence of point defects and dislocations. The lattice of MgO is not much water than that of MgCO3 lattice group, so the inter lattice pores increase, the porosity is high, the specific surface area is large, and the activity is high.


Light burned magnesia powder is light yellow and light brown, with particle size below - 100 mesh. Periclase crystal is very small (< 3 μ m), true specific gravity is 3.07 ~ 3.22, bulk density is 0.8 ~ 1.2g/cm3, refractive index is 1.68 ~ 1.70, lattice constant is large (α = 0.4212), lattice defect is many, texture is brittle, pore structure, reaction activity is high, it is easy to carry out solid-state reaction or sintering, react with water to produce Mg (OH) 2 and harden Bond ability. The volume shrinkage of light burned magnesia powder calcined from magnesite is about 5%, and 3% ~ 5% CO2 is usually remained due to incomplete decomposition.


The light burning temperature and time of magnesite have certain influence on the activity of light burned magnesite powder. The magnesite was calcined at 600, 650, 700, 750, 800, 850 and 900 ℃ respectively, and the calcination temperature of 700, 750 and 800 ℃ had no obvious effect on the activity of light burned magnesia powder within 15 ~ 90 minutes; the influence of 600, 650, 850, 900 ℃ on the activity of magnesite powder was particularly significant, and the activity increased significantly with the extension of time when calcined at 600 and 650 ℃, and the activity extended with the burning time of hydrocarbon at 850 and 900 ℃ It is long and obviously decreased.