High alumina refractory bricks are classified according to their mineral composition: low mullite, mullite, mullite-corundum, corundum-mullite and corundum. Their mineral compositions are mainly corundum, mullite and glass phases
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High-alumina refractory bricks are a type of refractory material. They use high-alumina bauxite clinker as the main raw material, soft clay and waste pulp paper liquid as the binding agent. The mud is made of multi-level particle proportions, which are formed by high pressure and dried. , fired at high temperature. The main component of this refractory brick is Al2O3. If the Al2O3 content is higher than 90%, it is called corundum brick. Due to different resources, national standards are not completely consistent. For example, European countries stipulate that the lower limit of Al2O3 content for high-aluminum refractory materials is 42%. In China, high alumina bricks are usually divided into three grades according to the Al2O3 content: Grade I - Al2O3 content >75%; Grade II - Al2O3 content is 60-75%; Grade III - Al2O3 content is 48-60%. The production process of high alumina bricks and multi-clinker clay bricks is similar. The difference is that the proportion of clinker in the ingredients is higher, which can be as high as 90-95%. The clinker needs to be sorted and screened to remove iron before crushing. The firing temperature Higher, for example, when high alumina refractory bricks such as I and II are fired in a tunnel kiln, the temperature is generally 1500 to 1600°C.
Characteristics of high alumina refractory bricks:
(1) Fire resistance. The refractory resistance of high alumina bricks is higher than that of clay bricks and semi-silica bricks, reaching 1750-1790 degrees, and it is an advanced refractory material.
(2) Load softening temperature. Because high-aluminum products have high Al₂O₃, low impurities, and less fusible glass, the load-softening temperature is higher than that of clay bricks. The load-softening temperature of high-aluminum products is generally above 1420-1550 degrees. However, because the mullite crystal does not form a network structure, the load softening temperature is still not as high as that of silica brick.
(3) Slag resistance. High alumina refractory bricks contain more Al₂O₃, which is close to neutral refractory materials and can resist the erosion of acidic slag and alkaline slag. Because it contains SiO₂, its ability to resist alkaline slag is weaker than that of acidic slag.
(4) Chemical resistance. High-aluminum refractory products are very resistant to corrosion and oxidation and reduction reactions of acidic or alkaline slag and molten metal, and are enhanced as the Al₂O₃ content increases and the harmful impurity content decreases.
Customizable High alumina refractory bricks | ||||
Item | Grade I High Alumina Brick | Grade II High Alumina Brick | Grade III High Alumina Brick | Special High Alumina Brick |
LZ-75 | LZ-65 | LZ-55 | LZ-80 | |
AI2O3 | 75 | 65 | 55 | 85 |
Fe2O3 | 2.5 | 2.5 | 2.6 | 2.0 |
Volume density g/cm³ | 2.5 | 2.4 | 2.3 | 2.6 |
Normal temperature compressive strength Mpa> | 70 | 60 | 50 | 80 |
Load softening temperature℃ | 1510 | 1460 | 1420 | 1550 |
Refractoriness degree℃> | 1790 | 1770 | 1770 | 1790 |
Apparent porosity%< | 22 | 23 | 24 | 21 |
Line change rate % | -0.3 | -0.4 | -0.4 | -0.2 |
Mainly used for lining blast furnaces, hot blast furnaces, electric furnace roofs, blast furnaces, reverberatory furnaces, and rotary kilns. In addition, high alumina bricks are also widely used as open-hearth regenerative checker bricks, plugs for pouring systems, nozzle bricks, etc.
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