Lightweight refractory bricks are shaped block-shaped heat-insulating refractory products with a porous structure inside and thermal insulation properties. They are also called lightweight heat-insulating refractory bricks. According to the raw materials used, lightweight refractory bricks can be divided into clay, silica, high alumina, magnesia and other lightweight bricks.
Lightweight bricks have low compressive strength, poor slag resistance, poor abrasion resistance, poor thermal shock resistance, and cannot be in direct contact with glass liquid or flames.
1.Lightweight clay bricks
Lightweight clay bricks are often added with sawdust and formed using a plastic method. The blank is composed of clay (30%~40%), clinker (15%~25%), hardwood chips (30%~45%), etc., and a certain amount of syrup and sulfite pulp waste liquid is added, and after mixing, The materials are trapped, dried after forming (residual moisture should be less than 10%), then fired (firing temperature 1250~1350°C), and kept warm for 4 hours. Lightweight bricks can also be made by mixing clay with porous or hollow materials (such as fly ash beads, diatomaceous earth). Bricks deform greatly during the drying and firing processes, and the fired products require shaping. The bulk density of lightweight clay bricks is 0.4~1.3g/cm3.
2.Lightweight silica bricks
The manufacturing method of lightweight silica bricks is similar to that of lightweight clay bricks. Grind ordinary silica to less than 1mm, add anthracite with an ash content of less than 10% (particle size less than 0.2~1mm) or coal char 30%~45%, then add a small amount of lime or gypsum and pulp waste liquid, form and dry at 1270 It is fired at ~1300℃. The bulk density of lightweight silica brick is 0.9~1.1g/cm3. The thermal conductivity is only half that of ordinary silica bricks. Thermal shock resistance is also better. Its load softening starting temperature can reach 1600°C, which is much higher than that of lightweight clay bricks. Therefore, the maximum operating temperature of lightweight silica bricks can reach 1550°C. It does not shrink at high temperatures and even expands slightly.
3.Lightweight high alumina bricks
Lightweight high alumina bricks are commonly produced by the foam method. A slurry is made from high-aluminum clinker, clay, and a small amount of sawdust (to thicken the blank), and a certain amount of dielectric [such as Al2(SO4)3] is added to stabilize the slurry. Add a foaming agent with a small surface tension (such as rosin soap) to the mud in proportion to make it foam. Make a foamy slurry in a mixer and pour it into the mold. The green body with the mold is first dried at low temperature (about 40°C), and then dried at 80~95°C after demoulding. The residual moisture after drying should be 3% to 5%. Then it is fired at 1300~1350℃ and kept warm for 4~6h. The volume density of lightweight high-alumina bricks is 0.4~1.0g/cm3, and the porosity reaches 66%~67%.
4. Lightweight insulation board insulation cotton
The optimized design of glass kiln insulation can save energy and extend the life of the kiln by improving the design level of the kiln. Glass furnaces are key thermal equipment that consumes energy in the glass industry. Choosing ceramic fiber boards as lightweight insulation boards for the backing of glass furnaces is beneficial to maintaining the sealing and insulation effects of the furnaces.
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