Magnesium-aluminum spinel brick for cement rotary kiln

Performance index and application of magnesia alumina spinel brick

The magnesia alumina spinel brick is a magnesia-made brick with magnesia alumina spinel as the main mineral produced by adding alumina to the ingredients in order to improve the thermal stability of the magnesia brick. The advantage of magnesia-alumina spinel brick is good thermal stability, it will react with clinker during use, and then form a thin calcium aluminate protective layer on the surface of the brick, so that the liquid is not easy to penetrate, and its resistance to The peeling performance is better than that of directly bonded magnesia-chrome bricks. The service life of the cooling zone and transition zone of the kiln can be doubled compared with the direct combination of magnesia-chrome bricks. However, in terms of corrosion resistance, it is slightly inferior to directly bonded magnesia-chrome bricks. At the same time, sintered spinel bricks are easy to hydrate, resulting in a larger coefficient, and the temperature of the kiln body is higher than that of directly bonded magnesia-chrome bricks. Pay attention to these issues when using them.

The magnesia-alumina spinel brick has a high melting point, small thermal expansion, low thermal stress, good thermal shock stability, and also has stable chemical properties and strong resistance to alkaline slag.

The application of magnesia-aluminum spinel brick is mainly reflected in the following two aspects:

One is to replace magnesia-chromium sand to manufacture magnesia-alumina spinel bricks for cement rotary kiln, which not only avoids chromium pollution, but also has good spalling resistance;

Second, it is used to make ladle castables, which greatly improves the corrosion resistance of steel plate linings. It is widely used in refractory materials for steel making. The preparation of high-quality pre-synthetic spinel provides new raw materials for the production of amorphous and shaped high-purity refractories;

Seven advantages of magnesia-aluminum spinel bricks

① The elastic modulus is small, magnesia alumina brick is (0.12~0.228)×105MPa, while magnesia brick is (0.6~5)×105MPa;

② MA can transfer MF from periclase and sweep FeO, and the reaction is as follows:

FeO+MgO • AI2O3→MgO+FeAl2O4

FeO+MgO→(Mg • Fe)O

MA absorbs Fe2O3 and undergoes minor expansion

③ high melting point. The melting point of spinel is 2135 ℃, and the initial melting temperature of periclase is 1995 ℃ higher. The combination of the two will improve the bonding performance of magnesia bricks.

④ The softening temperature under load is high, but the spinel formation is accompanied by volume expansion, and the ability to aggregate and recrystallize is weak, so a higher sintering temperature is required.

⑤ Excellent thermal shock resistance.

⑥ High strength.

⑦ Strong corrosion resistance.

Technology

Application of Magnesia Alumina spinel brick

Mainly used in the upper and lower transition zones of cement rotary kilns and thermal kilns that require high temperature resistance and thermal shock.