Magnesia-chrome bricks have almost replaced magnesia bricks in the iron and steel smelting and non-ferrous metal smelting industries. Since the chromium oxide (Cr2O3) contained in them can continue to diffuse, magnesia-chrome bricks can be easily attached to the kiln skin, so in the past 30 years, it has been Cement kiln firing zone recommended refractories.
Magnesia-chrome bricks are mainly used in the metallurgical industry, such as building open hearth furnace tops, electric furnace tops, refining furnaces outside the furnace and various non-ferrous metal smelting furnaces. The high-temperature parts of the ultra-high-power electric furnace wall are made of fused-cast magnesia-chrome bricks, the high-erosion area of the refining furnace outside the furnace is made of magnesia-chrome bricks made of synthetic materials, and the high-erosion areas of non-ferrous metal flash smelting furnaces are made of fused-cast magnesia-chrome bricks and synthetic materials. Made of chrome magnesite brickss. In addition, magnesia-chrome bricks are also used in the firing zone of cement rotary kilns and the regenerators of glass kilns.
Direct bonded chrome magnesite bricks is a product made of high-purity or sub-high-purity sintered or fused magnesia and chrome concentrate. The product has few impurities. After high temperature and ultra-high temperature firing, the glass phase is concentrated in the triangular area of the crystal phase, and the crystal phase and the crystal phase are directly combined. It has low porosity, high compressive strength, strong wear resistance, corrosion resistance, thermal shock resistance and good spalling resistance.
Directly bonded magnesia-chrome bricks are made of high-purity sintered magnesia and chromite with SiO2 less than 2% by high temperature sintering. Between the magnesia-chromium grains is the direct combination of periclase periclase or periclase spinel, and a small amount of silicate is isolated between the grains. During the firing process of the direct bonded brick, the silicates in the gaps of the chrome ore particles gradually move into the matrix as the temperature increases, so that the chrome ore particles come into contact with the periclase, and diffuse and dissolve into the periclase crystal. At high temperature, the periclase and chrome ore in the matrix part are dissolved in silicate, and when cooled, they precipitate as desolubilized particles secondary spinel or secondary periclase in the periclase crystal and grain boundary, making it A direct combination of periclase to periclase and periclase spinel is formed, and a small amount of silicate phase is isolated between the grains. As the sintering temperature increases, the dissolution at high temperature and the precipitation during cooling increase, and the degree of direct intergranular bonding increases.
Directly bonded bricks are widely used in open hearth furnace tops, electric arc furnaces, copper smelting converters, flash furnaces, RH, DH vacuum treatment devices, out-of-furnace refining VOD furnaces, AOD furnaces, cement rotary kilns, etc.
Wechat Us 
