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Hot Air Furnace Refractory Bricks

Hot Air Furnace Refractory Bricks

The supply air temperature of the hot blast stove has been continuously increasing, typically ranging from 1200°C to 1250°C, while the upper part of the hot blast stove and the heat storage chamber is elevated by 200 to 300°C. Under such high thermal loads, the upper part of the hot blast stove generally uses low-creep series, high-alumina thermal insulation bricks, silicon bricks or low-creep high-alumina bricks with a temperature resistance of 1400 to 1500°C.

What Kind of refractory Bricks for Hot Air Furnace?

TypesRefractory MaterialsIntroduction
Type 1Clay BrickThe technical properties of hot blast stove fireclay bricks are as follows: Al2O3 42%44%; refractoriness 1730-1750°C; softening temperature under load 13501400°C; linear change on reheating (1350°C, 2h 0~0.4%; apparent porosity 24%; ambient temperature compressive strength 24.5~29.4MPa.
Type 2High Alumina BrickFor hot blast stoves, high-alumina bricks are classified by purpose into two types: ordinary high-alumina bricks and low-creep high-alumina bricks.
Type 3Low Creep Clay BrickThe hot blast stove fireclay brick is made from refractory clay and is used for constructing the hot blast stove in a blast furnace. This brick exhibits excellent resistance to thermal shock and a relatively high softening temperature under load.
Type 4Low Creep High Alumina BrickThe low-creep high-alumina grid brick for hot blast stoves is mainly used in the middle and upper parts of the heat storage chamber.
Type 5Fireball for RegeneratorsThe characteristics of refractory balls include high strength, good thermal shock stability, a large surface area for heat storage, and low resistance.
Type 6Mullite BrickThe use and development of refractory linings for hot blast stoves are primarily determined by the temperature of the hot blast.
Type 7Sillimanite BrickMainly used in glass kiln, non-alkali fiber kiln, blast furnace hot blast furnace, refractory tunnel kiln and other key parts of the kiln

Type 1:fireclay brick for hot blaststove

Hot blast stove fireclay brick refers to clay bricks made from refractory clay, specifically designed for constructing the hot blast stove in a blast furnace. These bricks exhibit excellent resistance to thermal shock and have a relatively high softening temperature under load.

ITEMUNITRN-42RN-40RN-36
Chemical Components AI2O3424036
Bulk densityg/cm32-2.22-2.22-2.2
refractoriness under load°C141013501300
linear change on reheating1400°C×2h-0.4~01350°C×2h-0.5~01350°C×2h-0.5~0
Apparent porosity22(24)22(24)22(24)
Cold Crushing StrengthMpa353025
Thermal shock(1100°C water-cycle)Verify the measured data in the quality certificate

Type 2:High Alumina Brick

For hot blast stoves, high-alumina bricks are classified by purpose into two types: ordinary high-alumina bricks and low-creep high-alumina bricks. These bricks typically have an alumina content of 48% or more, featuring high heat capacity, excellent resistance to creep, high softening temperature under load, elevated temperature strength, and outstanding resistance to thermal shock. They are well-suited for applications in the furnace lining, combustion chamber, and heat storage chamber of hot blast stoves, with an emphasized usage lifespan

ITEMUNITRL-65RL-55RL-48
Chemical Components AI2O3655548
refractorinessg/cm3178017601740
0.2Mpa refractoriness under load°C150014701420
linear change on reheating1500°C×2h+0.1~-0.41500°C×2h+0.1~-0.41450°C×2h+0.1~-0.4
Apparent porosity242424
Cold Crushing StrengthMpa4944.139.2

Type 3:Low Creep Clay Brick

The Iron Ladle Mouth Feed Castable is designed for the mouth or feeding zone of iron ladles. This castable is engineered to withstand the challenges associated with the intake and pouring of molten iron. It exhibits properties that make it suitable for withstanding high temperatures, thermal shocks, and the corrosive effects of molten iron.

ITEMUNITDRN-125DRN-120DRN-115DRN-110
Chemical Components AI2O345424036
Bulk densityg/cm32.15~2.352.00~2.202.00~2.202.00~2.20
Apparent porosity22(24)22(24)22(24)22(24)
Cold Crushing StrengthMpa40353025
Creep Rate(0.2Mpa)1250°C×0-50h1200°C×0-50h1150°C×0-50h1100°C×0-50h
   0.80.80.80.8
Heating permanent line change1400°C×2h-0.3~0.1
 1350°C×2h -0.3~0.1
 1300°C×2h -0.4~0.1-0.4~0.1
Thermal shock stability(1100°C water-cycle)timeProvide date

Type 4:Low Creep High Alumina Brick

The low-creep high-alumina grid brick for hot blast stoves is mainly used in the middle and upper parts of the heat storage chamber. To achieve a long and sustainable operation of blast furnaces and hot blast stoves, the use of high-quality low-creep high-alumina grid bricks is crucial. These products can be categorized based on their physical and chemical properties into six grades: DRL-155, DRL-150, DRL-145, DRL-140, DRL-135, and DRL-130. The low-creep high-alumina brick is manufactured using high-quality high-alumina bauxite, along with premium refractory materials such as spinel, corundum, and sillimanite. These high-end components undergo two phases of mullite crystallization during the firing process, ultimately forming a stable mullite phase, which imparts excellent resistance to creep deformation.

ITEMUNITDRL-155DRL-150DRL-145DRL-140DRL-135DRL-130DRL-127
Chemical Components AI2O375756565656050
Apparent porosity20212122222223
Bulk densityg/cm32.65-2.852.65-2.852.50-2.702.40-2.602.35-2.552.30-2.502.30-2.50
Cold Crushing StrengthMpa60606055555550
Creep rate(0.2Mpa,50h)1500°C1500°C1450°C1400°C1350°C1300°C1270°C
   0.80.80.80.80.80.80.8
linear change on reheating1500°C×2h-0.2~0.1-0.2~0.1-0.2~0.1
 1450°C×2h -0.2~0.1-0.4~0.1-0.4~0.1-0.4~0.1
Thermal shock stability(1100°C,water-cycle)(top, wall tiles) provide data

Type 5:Fireball for Regenerators

The characteristics of refractory balls include high strength, good thermal shock stability, a large surface area for heat storage, and low resistance. They can be used multiple times, and their usage cycle is long.

The highest usage rates for refractory balls are for those with diameters of 50 and 60, primarily used for constructing the heat storage body in hot blast stoves. Balls with diameters of 20 and 30 are used specifically for filling. Additionally, refractory balls with a diameter of 80 or corundum balls are used in the upper part of the heat storage body in hot blast stoves, although the usage rate of corundum refractory balls is relatively low.

Generally, refractory balls with a 65% alumina content are widely used, mainly because of the large quantity required for the heat storage body in hot blast stoves. However, for furnaces exceeding 550 cubic meters, porous bricks are predominantly used, while those below 450 cubic meters utilize refractory balls more frequently. In China, large furnaces using balls for heat storage are found in places such as the Liugang Steel Company.

ITEMUNITMullite fireballMgO-AI2O3 fireballHigh-strength and density alumina fire ballAI2O3-65 low creeping fire ballAI2O3-75 low creeping fire ballMgO-AI2O3-Cr2O3 fire ballMgO-Cr2O3 fireball
Chemical Components AI2O3755~107565755~10
 Fe2O3 1.51.51.5
 MgO 855580
 Cr2O3 22
Apparent porosity22182322212020
Bulk densityg/cm32.42.852.552.62.652.82.6
compressive strengthN/ball16000180002000015000150001500020000
refractoriness°C1790179017901790179017901790
linear change on reheating0.1~0.40.1~0.40.1~0.4
refractoriness under load°C1550148014801500152015201520
Thermal shock resistancesTime401515151515
Creep rate(1450°C×50h×0.2Mpa) <1.0<1.0

Type 6:Mullite Brick

The use and development of refractory linings for hot blast stoves are primarily determined by the temperature of the hot blast. When the blast temperature is below 900°C, clay bricks are generally selected, with a service life of around 20 years. For blast temperatures ranging from 900 to 1100°C, high-alumina bricks, mullite bricks, or sillimanite bricks are used for the refractory lining and checker bricks in the high-temperature zone. When the blast temperature exceeds 1100°C, high-alumina bricks, mullite bricks, and silicon bricks are commonly chosen for the furnace lining or checker bricks.

ITEMUNIT75Mullite Brick70Mullite Brick
  LSM-75LSM-70
Chemical Components AI2O37570
 SiO2 2325
 Fe2O3 0.40.4
Bulk densityg/cm32.72.6
Apparent porosity1818
Cold Crushing StrengthMpa100100
refractoriness under load(0.2Mpa,0.6%)°C16801680

Type 7:Sillimanite Brick

Mainly used in glass kiln, non-alkali fiber kiln, blast furnace hot blast furnace, refractory tunnel kiln and other key parts of the kiln

ITEMUNIT65Sillimanite Brick60Sillimanite Brick
  LS-65LS-60
Chemical Components AI2O36560
 SiO2 3237
 Fe2O3 0.51
Bulk densityg/cm32.52.3
Apparent porosity1819
Cold Crushing StrengthMpa8080
refractoriness under load (0.2Mpa,0.6%)°C16501600
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