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
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.
The alkali-resistant brick for cement kiln has the characteristics of strong alkali erosion resistance, good thermal shock resistance and high cost performance.
Brown corundum is made of natural bauxite as raw material, carbon (mainly coke) is used as reducing agent, and iron filings are added as sedimentation agent (clarifier) to form ferrosilicon deposited on the bottom of electric furnace.
The high-alumina bricks are mainly used in the regenerator of the hot blast stove. The lattice bricks with a certain structure are arranged in an orderly manner, and the upper and lower through holes of the lattice bricks can allow the gas to pass through.
Silicon carbide used in industry is a synthetic material, commonly known as emery. Silicon carbide is one of the most commonly used non-oxide refractory raw materials in the field of refractories.
Brown corundum refractory brick is made of fused corundum as the main raw material. It is formed by high pressure and fired at high temperature. It has high thermal shock stability, low porosity, low expansion, good resistance to melt vapor and gas erosion, and excellent oxidation resistance. Dimensionally accurate advantages.
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.
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.

