Refractory Bricks

High alumina brick is a kind of refractory material. The main component of this refractory brick is Al2O3. If the Al2O3 content is higher than 90%, it is called corundum brick. Due to different resources, national standards are not completely consistent. For example, European countries stipulate that the lower limit of Al2O3 content for high-aluminum refractory materials is 42%. In China, high alumina bricks are usually divided into three grades according to their Al2O3 content: Grade I - Al2O3 content >75%; Grade II - Al2O3 content 60-75%; Grade III - Al2O3 content 48-60%.

Acid-resistant bricks are anti-corrosion and acid-resistant materials made of quartz, feldspar, and clay as the main raw materials and fired at high temperatures in a kiln. They have the characteristics of high acid resistance, low water absorption, and are not easily oxidized at room temperature and not easily contaminated by media.

Magnesia-alumina spinel brick refers to a synthetic spinel refractory raw material using magnesium oxide and aluminum trioxide as raw materials. This raw material is rarely found in nature, and magnesium-aluminum spinel used in industry is all artificially synthesized. Bauxite-based sintered magnesia-aluminum spinel uses high-quality alumina with an Al2O3 content of more than 76% and high-quality light-burned magnesium powder with an MgO content of more than 95%. After a multi-stage homogenization process, it is heated to 1800°C in an ultra-high temperature tunnel kiln. It is sintered at the above high temperature.

Silica brick is an acidic refractory material mainly composed of tridymite, cristobalite and a small amount of residual quartz and glass phases. Silica content is more than 94%. True density 2.35g/cm3. Resistant to acidic slag erosion. Higher high temperature strength. The load softening starting temperature is 1620~1670℃. It will not deform after long-term use at high temperatures. Thermal shock stability is low (heat exchange in water is 1 to 4 times). It uses natural silica as raw material, plus an appropriate amount of mineralizing agent to promote the transformation of quartz in the green body into tridymite. It is slowly fired at 1350~1430℃ in a reducing atmosphere. When heated to 1450°C, there will be a total volume expansion of about 1.5~2.2%. This residual expansion will make the seams close and ensure good air tightness and structural strength of the masonry.

It is mainly used in high-temperature areas such as the top of the blast furnace hot blast furnace, the upper furnace body and the upper grid body.

Silica bricks for coke ovens are siliceous refractory products with tridymite as the main crystal phase used for building coke ovens. Modern coke ovens are large-scale thermal equipment built with tens of thousands of tons of refractory materials and nearly a thousand brick types, of which silica bricks account for 60% to 70%. Coke oven silica bricks are used to build coke oven regenerator walls, ramps, combustion chambers, carbonization chambers and furnace roofs, etc.

Magnesia carbon bricks are made of high melting point alkaline oxide magnesium oxide (melting point 2800°C) and high melting point carbon materials that are difficult to be wetted by slag as raw materials, and various non-oxide additives are added. Non-burning carbon composite refractory material combined with carbon binder. Magnesia carbon bricks are mainly used for the lining of converters, AC electric arc furnaces, DC electric arc furnaces, and the slag lines of ladles. As a composite refractory material, magnesia-carbon bricks effectively utilize the strong resistance to slag erosion of magnesia and the high thermal conductivity and low expansion of carbon, compensating for the biggest shortcoming of magnesia's poor spalling resistance.

Magnesia-chrome bricks are refractory products with magnesium oxide (MgO) and chromium trioxide (Cr2O3) as the main components, and periclase and spinel as the main mineral components. This type of brick has high refractory resistance, high high-temperature strength, strong resistance to alkaline slag erosion, excellent thermal stability, and certain adaptability to acidic slag. The main raw materials for manufacturing magnesia chrome bricks are sintered magnesia and chromite

Magnesia iron spinel brick is a new generation of alkaline refractory with more technical content. It is mainly used in the firing zone of large dry process cement kiln. The microstructural characteristics of magnesia-aluminum spinel are relatively complex, mainly a combination of magnesia microstructure and iron-aluminum spinel microstructure. The interface between magnesia and iron-aluminum spinel is formed by Mg2+, Al3+, Fe2+ ions. The mutual diffusion and close combination realize the direct combination of materials.