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
Magnesia alumina bricks use periclase as the main crystal phase and magnesia-alumina spinel as the matrix. They are better in thermal shock resistance than magnesia bricks. In order to improve the thermal shock resistance of magnesia bricks, alumina or alumina is introduced into the ingredients. Bauxite clinker fine powder to form a magnesia-alumina sharp stone matrix, thereby making magnesia-alumina bricks
Common low-creep high-alumina bricks can be used in blast furnace hot blast stoves, as well as other industrial kilns, and can also be made into low-creep high-alumina bricks of different sizes according to specific construction requirements, such as lattice bricks, special-shaped bricks, anchor bricks, etc. , mainly used in industrial kilns in long-term high temperature environments
Silica brick: an acidic refractory mainly composed of tridymite, cristobalite and a small amount of residual quartz and glass phases. Its silica content is more than 94%, it has anti-acid slag erosion performance, high high temperature strength, high load softening temperature, long-term use in high temperature flower wells without deformation, but low thermal shock stability (heat exchange in water is 1-4 Second-rate).
Refractory castable is a kind of refractory material that does not need to be formed and has good fluidity after being fired and stirred with water.
Refractory wet mud used to block the iron outlet can be divided into two categories: water cannon mud and waterless gun mud. On large and medium -sized blast furnaces on high top pressure and high degree of smelting.
The refractory pre -production is the category of irregular refractory materials, also known as the prefabricated block of the pouring materials, and the irregular refractory prefabricated block.
Corundum refractory castable has the characteristics of high strength and good fluidity, which is convenient for construction. It is mainly used for the parts that are easy to be washed and worn, such as the combustion chamber, separator and flue of circulating fluidized bed boiler.
Silicon carbide castables mainly use 98 silicon carbide as the main raw material, add water reducing agent and micropowder, and use pure calcium aluminate cement as binder to make amorphous refractory materials. Cupola and other high temperature materials to be recorded.