Distribution of magnesia chrome brick manufacturers

Direct bonded magnesia chrome brick has high temperature resistance, SiO2 corrosion resistance and anti-oxidation reduction effect, high temperature resistance, mechanical stress resistance, and better kiln skin hanging performance. It is widely used in cement kiln firing zone. Since the use of magnesia chrome brick, under the action of alkali or sulfur, the stable conversion of 3-valent chromium into 6-valent chromium with strong oxidation capacity will cause extremely serious harm to human body. Since the mid-1980s, a series of environmental protection and health standards have been formulated by countries all over the world to restrict the use of magnesium chromium bricks. In the 1990s, due to the excellent performance and low price of magnesia chrome brick, direct bonded magnesia chrome refractory brick with better performance than magnesia chrome brick is being used in large precalciner kilns with more severe working conditions in many countries and regions.

Magnesia dolomite brick

Magnesia dolomite brick is made of raw materials formed by organic binder and then fired. Magnesia dolomite brick has the following advantages: it has chemical stability and affinity to cement clinker; it has high fire resistance; it is easy to hang kiln skin; its price is relatively cheap. Therefore, it is used more abroad, but it is easy to hydration.

Price of magnesia chrome brick

When the temperature in the kiln changes rapidly, the magnesia dolomite brick is easy to produce structural spalling at the interface between the original brick layer and the reaction layer, so the use of the magnesia dolomite brick in the cement kiln with low operation rate is limited. High alumina brick is widely used in the top of electric furnace, and the content of Al2O3 is between 75% and 85%. Compared with silica brick, high alumina brick is characterized by high fire resistance, good heat resistance, slag resistance and high compressive strength. Due to its good thermal shock resistance and structural integrity, high alumina amorphous materials do not need to be made into special-shaped bricks. Generally, ramming materials are used in the center of furnace cover and around electrode holes. Due to the rich bauxite resources in China, high alumina brick has become the main refractory material for electric furnace top, and its service life is about 2-3 times of that of silica brick furnace top. With the development of large-scale ultra-high power electric furnace, the service life of high alumina brick decreases, which leads to the further use of basic bricks such as fired or unburned magnesia bricks and magnesium chromium bricks.

Due to the low high temperature strength and self weight of bricks, hanging structure is widely used to avoid the subsidence of furnace top due to deformation. Magnesium chromium bricks are also used on the top of some ultra-high-power electric furnaces. The direct bonding alkaline bricks with good high-temperature strength can overcome the serious spalling phenomenon caused by structural cracking or thermal cracking of ordinary alkaline bricks due to large expansion coefficient and absorption of slag dust, and its service life is up to 300 heats. The refractory wall for furnace wall is divided into general furnace wall, slag line area and hot spot adjacent to arc. It is not only heavily eroded and scoured by molten steel and slag, but also subjected to mechanical impact and rapid cooling when scrap is added. What's more serious is the strong thermal radiation from the arc of high temperature electrode, and the temperature of molten steel in hot spot area is as high as 2000 ℃. Therefore, local melting loss often occurs on the furnace wall. In addition, the lining is seriously damaged by the stirring and scouring of molten steel and slag and the atmosphere in different smelting periods, especially in UHP EAF.

In general, the furnace wall is mainly made of magnesia brick, tar pitch combination and asphalt impregnation firing dolomite brick and periclase brick. There are also magnesia chrome brick without iron shell and asphalt bonded magnesia and dolomite ramming materials, which have a long service life of 43dian. Magnesia chrome brick and high quality magnesia brick are used to build the furnace wall of ultra-high power or special steel smelting furnace, and the application effect is obviously improved. The slag line area and hot spot are the weak links of furnace wall. Since the life of the furnace wall mainly depends on the damage degree of the hot spot, the lining of the hot spot is paid special attention to. Before the 1970s, the cast magnesia chrome brick was widely used in this part, and the service life reached 100-250 heats. Since the 1980s, magnesia carbon bricks have been widely used in these areas, showing excellent high temperature resistance and slag resistance, and the service life has been significantly improved. China's high-power EAF has reached more than 300 heats.