Light weight high alumina brick is an ideal insulating refractory, with advantages of high strength, low thermal conductivity, good insulation property and low price. For various industrial kilns & furnaces, it is a kind of essential refractory for energy saving and temperature preservation.

Light weight high alumina brick is also called high alumina insulating brick. It contains more than 48% Ai2O3 and mainly consists of mullite and glass phase or corundum. It is usually made of high bauxite and a small amount of clay. After the raw materials are grounded, it is made into mud. Then it is cast and molded and fired at 1300～1500℃. Sometimes industrial alumimum is used to replace bauxite. Inorganic matter is added as ignition loss substance in order to increase the porosity of the refractory.

It has such advantages as high porosity, good insulation effect, high mechanical intensity, small thermal conductivity and long service life. It has high cold crushing strengh,size precision and holds the most stable and lowest thermal conductivity of all insulating refractory bricks at present. Its maximum service temperature is 1350℃. Thermal efficiency and working condition can be improved, energy consumption can be lowered, productivity and significant economic results can be achieved.

It is characterized by low bulk density. The total weight of the furnace body and walls thickness can be reduced effectively.

It has found a wide application in ceramics tunnel kiln, roller kiln, shuttle kiln, coking furnaces of iron and steel industry and other thermal equipment. It is mainly used in lining and insulating layer of areas without strong erosion by high temperature melts. When in direct contact with flame, the surface contact temperature can not be higher than 1350℃.

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The key to production of silica bricks is to select the raw materials and the firing process in which the degree of quartz transformation is suitable for the intended application.

The raw material for silica brick is quartz which must meet certain requirements. If refractoriness or thermal expansion are the main requirements, a quartz of high chemical purity must be selected. If volume stability is the main requirement, raw materials should have good transformation properties.

The chemical composition of quartz is important in its evaluation as a raw material, in particular the content of alumina and alkali, as these lower the melting point and considerably reduce the possibilities of application. In addition the firing behavior of the quartz must be taken into account.

After the raw materials have been crushed, ground and screened to the various grain fractions, they are mixed in predetermined proportions according to the required application properties. In most cases, mixers are used for mixing and special bonding agents. Generally around 2% lime water and some sulphite solution as a temporary binder, are added at the same time. The mixture is then processed on friction presses or hydraulic presses. Complicated shapes or those where short runs are required, are still rammed by hand.

After drying, silica bricks are fired at temperature of about 1450-1500℃. Because the transformation of the silica takes place suddenly, cooling must be carried out slowly, or the brick will crack. It is necessary to maintain a carefully planned time temperature cycle during firing. A strong, well bonded high quality silica brick can be obtained only after passing through critical temperature ranges. During firing, silica brick will have about 4% linear growth.

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Silica brick is one of the most widely used high temperature refractory materials. Silica brick is a light yellow refractory product made from silica rock that contain at least 90 percent SiO2. It is used primarily in coke ovens and glass furnaces. It is also used in other applications, such as glass tank walls, acid practice electric furnaces, tunnel kilns, and regenerators.

Silica is the main component of silica brick. It occurs in a variety of crystalline modifications, e.g. quartz, tridymite, and cristobalite and also as an under-cooled melt called quartz glass. The crystalline modifications each have a high and low temperature forms which can transform reversibly. The crystal structure of the individual SiO2 modifications can differ widely, so that distinct density changes occur during transformation. This is of great importance during heating and cooling because of the change in the volume.

Quartz requires the smallest volume and the quartz glass the largest. During firing above approximately 900 ℃, quartz transforms into the other modifications and melt completely at 1725℃. During slow cooling , reversible volume decreases take place which are a result of the spontaneous transformation of the crystal structure from the high to the low temperature modification. The reversible and irreversible volume effects can cause considerable stress within the refractory brick structure.

Any common silica brick having large non-transformed silica content is undesirable because it exhibits extraordinary expansion so as to impair stability of industrial furnace which employs such brick as the refractory. Therefore, the extent of transformation of silica is one of very important factors which have to be considered in designing an industrial furnace in regard to selection of material and evaluation of adequateness of the use of the selected material.

Silica brick provides a high temperature resistant and non-reactive lining. It is characterized with its good resistance to spalling at high temperatures. It also retains their rigidity, are lightweight, have a good resistance to most fluxes present in coke ovens, and offer high resistance to abrasion. It has a relatively long lifespan. It is also nonreactive with the melted glass whereas other refractories, such as magnesia brick, could discolor the final product.

Silica brick is used as a refractory in building and repairing industrial furnaces, such as coke ovens, hot blast stoves and glass furnaces. Silica brick crowns have been successfully used in glass furnaces for producing container, float glass, table-ware and TV panel glass. They have the attributes of a relatively long life, excellent insulation at a low cost, and limited defects as silica is the dominant oxide.

Refractories are the main materials used in the glass furnaces and have big influence on the service life of glass furnaces, the quality of glass, the energy consumption and the cost. The development of the manufacturing technology of glass greatly depends on the the development of refractory technology and improvement of the quality of refractories.

Glass is melt at more than 1600℃, so the refractories will suffer from corrosion during the manufacturing process. The corrosion resistance performance and corrosion rate of refractories determines the service life of glass furnaces. The larger the scale of glass furnaces is, the bigger the production capacity is. The quality and accuracy of refractories has direct influence on the scale of glass furnaces. The application of the oxygen-fuel technology and reduced pressure technology depends on the performance of refractories, since those technologies increase the concentration of alkali vapor and water vapor, make the refractories more serious and have more demanding performance on the performance of refractories. Since the corrosion of refractories can also cause glass defects such as stones, bubbles and stripes, the corrosion resistance performance has a big influence on the quality of glass.

According to the types of glass produced, the size and structure of furnaces, the quality of glass required and the production capacity, different refractories are selected. So far, refractories for the glass industry, especially the float glass furnaces, include fused cast refractories, silica bricks and magnesia refractories.

Fused Cast Refractories

Fused cast refractories are refractories made by melting the raw materials and then casting the melt into a mold. Fused cast refractories for glass furnaces mainly include fused cast AZS, fused cast alumina block and fused cast high zirconia block. Fused cast AZS and fused cast alumina block are the main refractories used in float glass furnaces, Electronic glass furnaces, household glass furnaces, and pharmaceutical glass furnaces. Besides glass contact areas, they are also used in demanding areas such as the beast wall and the crown.

Silica brick

Silica brick is a traditional refractory used in glass furnaces, especially in the crown and superstructure. The quality of glass furnaces will affect the normal operation and service life of glass furnaces.

Magnesia refractories

Magnesia refractories are alkali refractories, including fused cast magnesia brick, high pure magnesia brick, direct bonded magnesia chrome brick and magnesia zircon brick. Magnesia refractories are mainly used in the regenerator.

Zhengzhou Sunrise is a refractory material supplier from China, offering high quality refractory materials for glass furnaces, including fused cast AZS block, fused cast alumina block, fused cast high zirconia block, mullite brick, zircon brick, alumina bubble brick, magnesia brick, sillimanite brick, corundum brick, low porosity fireclay brick, high alumina brick, all kinds of glass furnace ramming masses, etc..