Mullite lightweight insulation bricks are high alumina refractory materials with mullite (3Al2O3 · 2SiO2) as the main crystalline phase. The general alumina content ranges from 65% to 75%. In addition to mullite, the mineral composition also contains a small amount of glass phase and cristobalite, with lower alumina content; Those with higher levels of alumina also contain a small amount of corundum. Mullite insulation bricks can be directly used for the lining of high-temperature kilns, and are currently widely used for the lining of shuttle kilns, roller kilns, glass and petrochemical kilns.

1、 Product characteristics of mullite lightweight insulation bricks:

1. Low thermal conductivity, with excellent thermal insulation effect;

2. Low impurity content has a very low content of oxides such as iron box alkali metals, therefore, high fire resistance; The high aluminum content maintains good performance in a reducing atmosphere;

3. Mullite insulation bricks have low heat melting, and due to their low thermal conductivity, the Mullite series lightweight insulation bricks accumulate very little heat energy, resulting in significant energy-saving effects in intermittent operations;

4. The appearance size accelerates the masonry speed, reduces the use of refractory mud, ensures the strength and stability of the masonry, and thus extends the service life of the lining;

5. Mullite insulation bricks have high hot compressive strength;

6. Mullite insulation bricks can be processed into special shapes to reduce the number of bricks and joints.

2、 Classification of mullite insulation bricks:

According to its production process, there are currently two types of mullite lightweight insulation bricks: sintered mullite bricks and electric fused mullite bricks:

1. Sintered mullite bricks are made from high alumina bauxite clinker as the main raw material, with a small amount of clay or raw alumina added as a binder, and then formed and fired.

2. Electric fused mullite bricks are made from high alumina, industrial alumina, and refractory clay as raw materials, with the addition of charcoal or fine coke particles as reducing agents. After forming, they are manufactured using the reduction electric melting method.

The performance and application of mullite insulation bricks: high fire resistance, up to 1790 ℃ or above. The starting temperature for load softening is 1600~1700 ℃. The room temperature compressive strength is 70-260MPa. Good thermal shock resistance. There are two types of sintered mullite bricks and fused mullite bricks. Sintered mullite bricks are made from high alumina bauxite clinker as the main raw material, with a small amount of clay or raw alumina added as a binder, and then formed and fired. Electric fused mullite bricks are made from high alumina, industrial alumina, and refractory clay as raw materials, with the addition of charcoal or fine coke particles as reducing agents. After forming, they are manufactured using the reduction electric melting method. The crystallization of fused mullite is larger than that of sintered mullite, and its thermal shock resistance is better than that of sintered products. Their high-temperature performance mainly depends on the content of alumina and the uniformity of the distribution of mullite phase and glass. Mainly used for hot blast furnace roof, blast furnace body and bottom, glass furnace regenerator, ceramic sintering kiln, dead corner lining of petroleum cracking system, etc.