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refractories

Sintered Magnesia Alumina Spinel

The production process of magnesium aluminum series is quite similar to that of magnesia series. The only difference is that ingredients in the series contains a certain proportion of industrial alumina or super alumina clinker. The series is also be produced by pressure moulding and sintering within high temperature. The impurity content of industrial alumina is lower than that of high bauxite clinker. Adding natural bauxite clinker into ingredients is able to improve plasticity of the clay. In the same condition, volume density of raw bricks will be higher.

The amount added of industrial alumina is commonly 5% ~ 10%. It is usually fine grinded together with magnesia by a certain proportion. With adding those fine powder, it is conducive to form an uniform distribution of new phases of magnesium aluminum spinel series in products substrate. In addition, another producing method is pre-synthesis magnesium aluminum spinel and then batching to produce as blocks. In the process of batching, large critical particle size is conducive to improve thermal shock resistance of the product. However, it goes against product density and strength. Therefore, the size is usually adopted to 3 mm.
The particle size is generally 3 ~ 1mm and 1 ~ 0.088mm, and the proportion of 3 ~ 2mm coarse particles and fine powder less than 0.088mm should be controlled to improve thermal shock resistance of the series. The combustion temperature of magnesium aluminum product should be determined on the basis of purity of raw materials. More specifically, the temperature should be generally 30 ~ 50℃ higher than that of magnesium product. And combustion temperature of high-purity magnesium aluminum product is 1750 ~ 1800℃.

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Physical and Chemical Indicators

Item UnitMLJ-85AMLJ-93AMLJ-95AMLJ-85BMLJ-93BMLJ-95B
MgO858893828590
AI2O3953953
Fe2O3 0.70.70.70.80.80.8
SiO20.60.80.72.522.5
Cr2O3
Apparent Porodsity16-1816-1816-1817-1817-1817-18
Bulk Densityg/cm32.852.85-3.02.852.82.852.82
Cold Crushing StrengthMpa454545404040
Refraction Under Load (T0.2)Mpa170017001700170017001700
Thermal Shock Resistance
1100°C (water cooling)
1100°C (air cooling)
 cycles12
100
12
100
12
100
10
80
10
80
10
80
Thermal Conductivity (1000°C) W/mK2.82.93.02.82.93.0
Application

The product is widely used in top space structure of glass furnace and the lining of calcined lime and cement rotary furnace.

Characteristics   

The series has advantages of good erosion resistance, peeling resistance, high temperature resistance, low product pollution, etc.

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