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What are the commonly used lightweight insulation bricks for glass melting furnaces?
Jan 08, 2019

The interior of the lightweight refractory brick is a shaped block-shaped insulating refractory product having a porous structure and a heat insulating property, which is also called a lightweight heat-insulating refractory brick. According to the raw materials used, lightweight refractory bricks can be divided into lightweight bricks such as clay, siliceous, high alumina and magnesia.

Light bricks have low compressive strength, poor slag resistance, poor wear resistance, poor thermal shock resistance, and cannot be in direct contact with glass or flame.

1. Lightweight clay brick

Lightweight clay bricks are often added to sawdust and shaped by plastics. The clay is composed of clay (30%~40%), clinker (15%~25%), hardwood chips (30%~45%), and a certain amount of syrup and sulfite pulp waste liquid is added, and the mixture is mixed. Stirring, drying after forming (residual moisture should be less than 10%), and then firing (sintering temperature 1250~1350 °C), heat preservation for 4h. It is also possible to mix clay with porous or hollow objects (such as fly ash float beads, diatomaceous earth) to make lightweight bricks. The bricks are greatly deformed during drying and firing, and the products need to be shaped after burning. The lightweight clay brick has a bulk density of 0.4 to 1.3 g/cm3.

Light clay brick

2, lightweight silica brick

Lightweight silicon bricks are manufactured in a similar manner to lightweight clay bricks. Grinding ordinary silica to less than 1mm, adding anthracite with less than 10% ash (particle size less than 0.2~1mm) or coal char 30%~45%, adding a small amount of lime or gypsum and pulp waste liquid, forming and drying after 1270 It is fired at ~1300 ° C. The bulk density of the lightweight silica brick is 0.9 to 1.1 g/cm 3 . The thermal conductivity is only half that of ordinary silica bricks. Thermal shock resistance is also good. Its load softening start temperature can reach 1600 ° C, much higher than light clay bricks. Therefore, the maximum use temperature of lightweight silica bricks can reach 1550 °C. Does not shrink at high temperatures, and even a little expansion.

3, lightweight high alumina brick

Lightweight high alumina bricks are commonly produced by foaming. Use high aluminum clinker, clay, a small amount of sawdust (to thicken the billet) to make a slurry, and also add a certain amount of dielectric [such as Al2 (SO4) 3] to stabilize the mud. A foaming agent having a small surface tension (such as rosin soap) is added to the slurry in proportion to make it foam. A foam slurry was made in a blender and poured into the mold. The molded green body is first dried at a low temperature (about 40 ° C), and then dried at 80 to 95 ° C after demolding. The residual moisture after drying should be between 3% and 5%. Then, it is fired at 1300 to 1350 ° C and kept for 4 to 6 hours. The lightweight high alumina brick has a bulk density of 0.4 to 1.0 g/cm 3 and a porosity of 66% to 67%.

High aluminum poly light brick

Light bricks can be insulated because the bricks contain a lot of pores (closed pores and open pores). The method of producing the pores, that is, the production method of the lightweight bricks is:

1 Add the combustible method. Add appropriate amount of burnt-in additions to the mud, such as sawdust, charcoal powder, lignite or peat coke, petroleum coke, walnut shells, etc. The filler is burned off when the brick is fired to form pores. When the additive is burned out, the ash is less.

2 foam method. A foaming agent is added to the mud to cause bubbles in the slurry. A fixative is added to stabilize the formed bubbles.

3 chemical methods. Carbonate and acid, caustic and aluminum or metals and acids are added to the slurry. The gas is generated by a chemical reaction to obtain pores in the product.

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