Calcined alumina is a product obtained by calcining aluminum hydroxide at high temperature to partially or almost completely convert it into aAl2O2.
Calcined alumina powder for refractory material
Calcined alumina powder is a product obtained by calcining aluminum hydroxide at high temperature to partially or almost completely convert it into aAl2O2. Calcined alumina can be classified into many grades according to calcination (crystal size, specific surface area) and Na2O content (0.01%~0.5%). The so-called industrial alumina (or industrial alumina) in our country is a kind of calcined alumina, but its general calcination degree is poor.
The production methods of calcined alumina mainly include Bayer method, soda lime sintering method, and Bayer-sintering combined method.
The smaller the particle size of a-alumina micropowder, the higher the activity, the better the dispersibility, and the better the water reducing effect and dispersibility in the castable. In the case of the same ratio and the same amount of addition, the addition of alumina fine powder with small particle size improves the construction performance of the castable, the bulk density is large, and the flexural strength and compressive strength at room temperature and high temperature are higher than those with large particle size. Alumina micropowder castable. For the alumina powder with large particle size, the fluidity of the castable decays faster, and the working time of the castable becomes shorter.
The greater the amount of alumina powder added, the better the fluidity of the castable. This is because the alumina micropowder has a small particle size and can be filled into the gaps and flocculation structures between particles.
The higher the amount of alumina added, the higher the high temperature cold flexural strength of the castable, because a large number of staggered CA2 and CA6 crystals are formed in the matrix, forming a network-like structure in the matrix.
type |
Project |
Al2O3% |
SiO2% |
Fe2O3% |
Na2O3% |
burn |
true density(g/cm3) |
α-Al2O3 |
low sodium |
AN-03 |
99.5 |
0.06 |
0.03 |
0.03 |
0.10 |
3.97 |
95 |
AN-05 |
99.5 |
0.06 |
0.03 |
0.05 |
0.10 |
3.97 |
95 |
|
AN-10 |
99.3 |
0.08 |
0.04 |
0.10 |
0.10 |
3.96 |
95 |
|
AN-20 |
99.0 |
0.10 |
0.05 |
0.20 |
0.20 |
3.95 |
93 |
|
medium sodium |
AN-30 |
99.5 |
0.04 |
0.04 |
0.30 |
0.20 |
3.93 |
90 |
AN-40 |
99.0 |
0.10 |
0.05 |
0.40 |
0.20 |
3.90 |
85 |
|
AN-50 |
97.0 |
0.15 |
0.10 |
0.50 |
0.40 |
3.85 |
80 |
Advantages of a-alumina powder:
smaller particle size
higher activity
better dispersion
The better the water-reducing effect and dispersibility in the castable
The refractory ramming material is prepared from a high proportion of granular and powdery materials and a very low proportion of binders and other components, even all of which are composed of granules and powders, and are subject to strong ramming. Bulk materials for construction.
White corundum is made from industrial alumina powder, which is smelted in an arc at a high temperature above 2000 ℃ and then cooled. After crushing and shaping, magnetic separation to remove iron, it is divided into various particle sizes.
Corundum self flowing castable is a high-tech product developed according to the theory of solid fluid and combined with the application characteristics of refractory materials, which is the first in China. The corundum self-flowing material can be degassed and leveled without vibration with the help of its own gravity, so as to achieve densification.
Corundum bricks are mainly used in iron-making blast furnaces and blast furnace hot blast furnaces, refining furnaces outside steel-making furnaces, sliding water heaters, glass melting furnaces and petrochemical industrial furnaces, etc.
High alumina brick is mainly used for lining of blast furnace, hot blast furnace, electric furnace roof, reverberatory furnace and rotary kiln. In addition, high alumina brick also widely used as open hearth regenerative lattice brick, pouring system with plug,such as nozzle brick.
Coke furnace silicon bricks are mainly used in the heat storage room, oblique road, charcoal room, combustion room, top of the furnace, and bottom of the furnace.
The refractoriness of clay bricks is comparable to that of silica bricks, up to 1690~1730℃, but the softening temperature under load is more than 200℃ lower than that of silica bricks. Because in addition to the high refractory mullite crystal, the clay brick also contains nearly half of the low melting point amorphous glass phase.
Castables Refractory for cement kiln Castables for cement kilns are special refractory castables for cement kilns. In my country, the new dry-process cement technology is developing rapidly, and the design and brick shape of PC and SP kilns are also very complicated. In order to adapt to this situation, our factory has developed a series of new refractory castables to replace the traditional refractory materials. Practice has proved that it is more suitable to use castables in parts with complex structure and kiln body deformation. Castables are also suitable for coolers, preheaters, precalciners, kiln door covers, tertiary air ducts and other parts that require thermal insulation. Its varieties include alkali-resistant castables, high-alumina and corundum castables, heat-insulating castables, and steel fiber reinforced refractory castables. Gongyi Yuying Refractory Co., Ltd. operates: castables for cement kilns, prefabricated blocks, low cement castables, refractory mud, refractory ramming materials, corundum castables, refractory castables, steel fiber castables, steel jade castables, Refractory plastics, high alumina castables, wear-resistant castables, plastics, castables, clay castables, refractory castables manufacturers, the company has 160 employees, including 12 senior professional and technical personnel, with an annual production capacity of 60,000 tons , has light and heavy material production lines, various production, testing and testing equipment, including 10 sets of 400-ton to 1,000-ton series forming presses, two (148 meters long and 118 meters long) high temperature tunnel kiln . Castables are also suitable for use in some parts of coolers, preheaters, precalciners, kiln door covers and tertiary phoenixes. Suitable thermal insulation castables can be used in preheaters of cement kilns and other parts that require thermal insulation. The main castables used in cement kilns are: index Alkali resistant castable High alumina castable High Alumina Steel Fiber Castable High strength mullite castable Silicon carbide anti-skin castable GT-13NL G-16 GF-16 G-20G GC-13H Al2O3%≥ 35 65 65 65 55 SiO2+SiC%≥ - - - - 35 Bulk densityg/cm3≥ 2.10 2.5 2.5 2.60 2.5 Cold pressed strengthMpa≥ 110℃×24h 60 80 80 80 80 1100℃×3h 60 80 80 90 100 Flexural strengthMpa≥ 110℃×24h 6 8 9 8 8 1100℃×3h 6 8 9 9 10 Rate of change of line after burning 1100℃×3h ±0.5 ±0.3 ±0.3 ±0.3 ±0.3 1. Alkali resistant castable Experiments show that the alkali pouring material has excellent alkali resistance much better than ordinary clay or high alumina pouring material. Ordinary and low-cement alkali-resistant castables have been successfully used in double-layer structural linings for preheater roofs, cones, tertiary air ducts, etc., where shaped bricks are not suitable. The low-cement alkali-resistant pouring material can also be used in the rear kiln mouth, cooler and kiln door cover. 2. High alumina and corundum castables High alumina and corundum castables for cement kilns include low cement and ultra-low cement castables, high strength corundum castables, etc. Calcined bauxite and cut jade are used as aggregates in the castable. Low cement and ultra-low cement type high alumina castables can be used in front and rear kiln mouths, chain belts, kiln door covers and cooler side walls. 3. Insulation casting section The heat-insulating castables for cement kilns include ordinary heat-insulating castables, high-strength heat-insulating castables, and ordinary and low-cement alkali-resistant heat-insulating castables. Usually high alumina cement is used as a binder in the castable. Ordinary heat-insulating castables use expanded perlite, expanded vermiculite and waste light bricks as aggregates. High-strength heat-insulating castables use refractory clay ceramsite, fly ash ceramsite, shale ceramsite, etc. as aggregates. Alkali-resistant and heat-insulating castables use alkali-resistant lightweight aggregates. Ordinary heat-insulating castables and their prefabricated blocks can be used as heat-insulating villages in double-layer structural linings of coolers, preheaters, calciners, kiln door covers and tertiary air ducts; high-strength heat-insulating castables and their prefabricated Blocks are available as single-layer linings in the neck and disintegration zones of conventional kilns. Ordinary and low-cement alkali-resistant and heat-insulating castables can be used in preheaters in small and medium-sized kilns and other parts that require alkali-resistant heat insulation. 4. Steel fiber reinforced refractory castables Adding steel fiber can improve the dismantling strength of the castable, and greatly improve the thermal shock resistance, impact resistance and wear resistance of the castable. Our company has carried out a lot of systematic research on steel fiber reinforced refractory castables, and developed a series of steel fiber reinforced refractory castables.