Magnesia-chrome brick is a refractory product composed of magnesia and chromium trioxide as the main components, and periclase and spinel as the main minerals. This type of brick has high refractoriness, high temperature strength, strong corrosion resistance to alkaline slag, excellent thermal stability, and certain adaptability to acidic slag.
The main raw materials for the manufacture of magnesia-chrome bricks are sintered magnesia and chromite. The purity of magnesia raw materials should be as high as possible. The chemical composition of chromite should be Cr2O330%~45%, and CaO should not be more than 1.0%~1.5%. The production process of magnesia-chrome bricks is roughly similar to that of magnesia bricks. In order to eliminate the loosening effect caused by the expansion of spinel due to the reaction of MgO and Cr2O3, Al2O3 or iron oxides during the firing process of the brick, the synthetic co-sintering material can also be used to make magnesia-chrome bricks.
In addition, there are unburned magnesia chrome bricks, for example, unburned magnesia chrome bricks combined with inorganic magnesium salt solutions. The production process of unburned magnesia-chrome bricks is simple, the cost is low, and the thermal stability is good, but the high temperature strength is far less than that of fired bricks.
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In the late 1950s, a so-called "direct-bonded" magnesia-chrome brick was developed. This brick is characterized by pure raw materials, high firing temperature, direct bonding between high-temperature phases such as periclase and spinel, and silicic acid. Low-melting phases such as salt are distributed in islands, so the high-temperature strength and slag resistance of bricks are significantly improved.
The method of co-grinding and calcining the compacts with chrome ore and magnesia and making bricks with the coarse particles of magnesia is an effective measure to eliminate the loosening effect. Compared with ordinary magnesia-chrome bricks, the magnesia-chrome bricks made by this method have lower porosity and higher compressive strength, softening temperature under load and flexural strength. The magnesia-chrome bricks made of chrome ore-magnesite powder compact and synthetic magnesia-chrome sand calcined at high temperature have better slag resistance and high-temperature strength than other magnesia-chrome bricks.
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In addition, there are also fused-cast magnesia-chrome bricks obtained by direct casting of magnesia-chromium materials in an electric arc furnace.
Magnesia-chrome bricks are mainly used in the metallurgical industry, such as the construction of open hearth furnace tops, electric furnace tops, out-of-furnace finishing furnaces and various non-ferrous metal smelting furnaces. The high-temperature parts of the furnace wall of the ultra-high power electric furnace 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 magnesia chrome bricks. In addition, magnesia-chrome bricks are also used in the firing zone of cement rotary kilns and the regenerators of glass kilns.
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Zhengzhou Shennan Refractory Co.,Ltd are professional in producing high quality magnesia chrome bricks ,any demands ,please don't hesitate contact with me.
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