For the masonry of glass kiln, should the insulating layer be light high alumina brick or light silica brick?

Light fire-resistant insulating brick is a shaped block heat-insulating refractory product with porous structure and heat insulation performance, also known as light heat-insulating refractory brick. According to the raw materials used, light refractory bricks can be divided into clay, silica, high alumina, magnesium and other light bricks.

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

  1. Light clay brick

Light clay bricks are often formed by plastic method by adding sawdust. The blank is composed of clay (30% – 40%), clinker (15% – 25%), hardwood chips (30% – 45%), etc. add a certain amount of syrup and sulfite pulp waste liquid, dry after mixing, trapping and forming (the residual moisture shall be less than 10%), and then burn (firing temperature 1250-1350 ℃) and keep warm for 4H. Light bricks can also be prepared by mixing clay with porous or hollow objects (such as fly ash floating beads and diatomite). Bricks are deformed greatly during drying and firing, and the products after firing need to be shaped and processed. The bulk density of light clay brick is 0.4 ~ 1.3g/cm3.

For the masonry of glass kiln, should the insulating layer be light high alumina brick or light silica brick?

Kerui refractory light insulation brick series products

  1. Light silica brick

The manufacturing method of light silica brick is similar to that of light clay brick. Grind ordinary silica to less than 1mm, add anthracite with ash content less than 10% (particle size less than 0.2 ~ 1mm) or coal coke 30% ~ 45%, then add a small amount of lime or gypsum and pulp waste liquid, and burn it at 1270 ~ 1300 ℃ after forming and drying The bulk density of light silica brick is 0.9 ~ 1.1g/cm3. The thermal conductivity is only half that of ordinary silica brick. Thermal shock resistance is also good. The starting temperature of load softening can reach 1600 ℃, which is much higher than that of light clay brick. Therefore, the maximum service temperature of light silica brick can reach 1550 ℃. It does not shrink at high temperature and even expands a little.

  1. Light high alumina brick

Light high alumina bricks are usually produced by foam process. The slurry is made of high alumina 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 foam agent (such as rosin soap) with small surface tension in proportion to the mud to make it foam. Make foam slurry in the mixer and pour it into the model. The green body with mold shall be dried at low temperature (about 40 ℃), and then dried at 80 ~ 95 ℃ after demoulding. The residual moisture after drying shall be 3% – 5%. Then it is fired at 1300 ~ 1350 ℃ and kept warm for 4 ~ 6h. The bulk density of light high alumina brick is 0.4 ~ 1.0g/cm3, and the porosity is 66% ~ 67%.

The reason why light bricks can be insulated is that there are a large number of pores (closed pores and open pores) in the brick body. The methods to cause air holes, i.e. the production methods of light bricks, include:

① Combustible addition method. Add an appropriate amount of burnt additives to the mud, such as sawdust, charcoal powder, lignite or mud coal coke powder, petroleum coke powder, walnut shell, etc. The additive is burned off when the brick is fired to form pores. The ash content shall be less when the additives are burned out.

② Foam method. Add foaming agent into the mud to make the mud bubble. And add fixing agent to stabilize the formed bubbles.

③ Chemical method. Add carbonate and acid, caustic and aluminum or metal and acid to the mud. Gas is produced by chemical reaction to make the product obtain pores.