Lightweight refractory bricks are shaped refractory products with multi-pore structure. By mineral composition, lightweight refractory bricks can be divded into lightweight clay bricks, lightweight silica bricks, mullite lightweight bricks, lightweight high alumina bricks, lightweight anorthite bricks and so on.
Mullite Lightweight Insulating Brick
Mullite lightweight bricks contains 50%~85% of Al2O3, its principle crystalline phase is mullite (3 Al2O3·2SiO2). Mullite lightweight brick is high quality insulating refractory product, has excellent high temperature mechanical strength, low high temperature creep rate, small thermal expansion coefficient, strong chemical corrosion resistance and good thermal shock resistance. Due to lightweight mullite brick’s excellent high temperature performance, it can be used as the inner lining of industrial kilns and furnaces, can directly contact with fire. The max working temperature of mullite lightweight insulating bricks is between 1350℃~1700℃, based on alumina content and bulk density of mullite insulating bricks.
Silica Insulating Bricks
Silica insulating bricks contains more than 90% of SiO2, bulk density is less than 1.2g/cm3. Silica lightweight insulating bricks usually adopt crystalline quartz or silica sand as raw material, combustible materials such as coke, anthracite saw dust are added into raw material or gas foaming method is adopted to form multi pore structure. Silica insulating bricks have excellent refractory performance, refractoriness under load temperature is above 1620℃, which is close to dense silica bricks. Lightweight silica bricks only have small thermal expansion, and thermal stability is better than dense silica bricks, so it can be long term used in high temperature condition (1500~1550℃), where not contact with molten slag directly. Silica insulating bricks is especially suitable to be used as insulating layers of high temperature hot blast furnaces silica bricks inner linings and glass kilns silica bricks masonry.
Anorthite Lightweight Insulating Bricks
The molecular formula of anorthite is CaO·Al2O3·2SiO2, melting point is 1552℃. Anorthite insulating bricks have excellent insulting and thermal conservation property, high spalling resistance ability and chemical stability in reduction atmosphere.
Anorthite lightweight bricks have both mullite and anorthite’s good refractory characteristics, such as low bulk density, small thermal conductivity rate, excellent thermal shock resistance and reduction atmosphere resistance. The max working temperature of anorthite insulating bricks is between 1100℃~ 1300℃. The max working temperature of anorthite bonded lightweight mullite bricks can reach to more than 1400℃.
Item
ALB-1
ALB-2
Al2O3 %
38.9
54
SiO2 %
44.5
43
CaO %
11.7
3
Bulk Density g/cm3
0.5
0.5
Compression strength Mpa
1.1
3.5
Rupture Strength Mpa
1.0
3
Thermal Conductivity rate W·(m·K)-1 (350℃)
0.12
0.15
Max. Working Temperature ℃
1250
1400
Anorthite lightweight insulating bricks have a wide range of application, can be used as insulating linings of blast furnaces, soaking pits, heating furnaces and so on in steel industry, and insulating linings of various kinds of catalytic cracking furnaces in petrochemical industry.
