High-Temperature and Explosion-Proof Corundum High-Strength and Wear-Resistant Castable for Kiln Lining

Corundum high-strength wear-resistant refractory castable is a wear-resistant refractory castable formed by high-strength and low-cement combination materials cemented with corundum, silicon carbide and other substances. Corundum is a trigonal crystal mineral with a melting point as high as 2050°C and a thermal expansion coefficient of 8.6*10-6K-1. It is a material with moderate to low thermal shock resistance. The hardness of corundum is 9, which is only lower than diamond and a few synthetic high-hardness minerals. Corundum products have high strength. For example, the compressive strength of alumina ceramics can reach 2000MPa, the flexural strength can reach more than 250MPa, and the hot flexural strength at 1000°C is 150MPa. Therefore, the corundum in the corundum high-strength wear-resistant refractory castable has strong resistance to wear.

Corundum high-strength wear-resistant refractory castable

Corundum high-strength and wear-resistant refractory castables are mainly used at the front end of cement kiln burners. Because this part is always washed by the air flow in the kiln, especially the lower part is washed more seriously. Moreover, this air flow contains clinker dust in the kiln, which will cause strong erosion and wear due to impact on the front end of the burner. Thereby reducing the service life of the equipment. There is also the corner of the tertiary air duct, which is relatively easy to wear under the erosion of dust airflow. Therefore, materials with good wear resistance and fire resistance should be used in these parts. In order to facilitate construction, corundum high-strength, wear-resistant and refractory castables should be used.

Corundum castable mainly refers to the corundum phase (a-AL2O3) with high-temperature main crystal phase as refractory castable. It is a high-grade refractory material. It has high refractory temperature, wear resistance and structural strength. It is a castable commonly used in high-temperature industrial kilns in contact with solutions or wear-resistant layers. Corundum refractory castable is an amorphous refractory material with ultra-high alumina clinker as the main aggregate and powder, as well as pure aluminate cement binder and various mixing components.

Types of Aggregate Raw Materials for Corundum Wear-Resistant Castables

1. Special grade high alumina clinker. It mainly refers to clinker after high-temperature calcining of bauxite raw materials, with an AL2O3 content of more than 85%, and is divided into particles of different sizes. The high-temperature main crystal phase of corundum castable is mainly corundum phase, containing a small amount of mullite crystal and glass phase.

2. Fusion of white corundum. It is made from industrial alumina or calcined alumina as raw material and melted at high temperature in an electric arc furnace. The content of Al2O3 is more than 98.5%, it is white, the crystals are huge, porous, and the porosity is 6%-10%. The main crystal phase is α-Al2O3, and the crystals are elongated or rhombus-shaped.

3. Dense corundum. It uses industrial alumina as raw material, adds additives and melts it in an electric arc furnace. The appearance is gray, gray black or gray white, the Al2O3 content is greater than 98%, the apparent porosity is less than 4%, and the bulk density is 3.8g/cm3. It is a new type of high-grade refractory raw material, resistant to acid, alkali and high temperature, with dense particles and low porosity.

4. Molten white fused alumina. When the light combustion special grade or first grade bauxite clinker is melted in an electric arc furnace under a photoreducing atmosphere and controlled conditions, it is a reducing agent (carbon), a settling agent (iron filings) and a decarburizing agent (iron phosphorus). Impurities such as SIO2\FE2O3\ and TIO2 are removed, and corundum material is obtained after smelting. The content of Al 2 O 3 is about 98% and it is gray, gray black or gray white. The apparent porosity is less than 4%, and the bulk density is greater than 3.8g/cm3.

5. Brown corundum. It is a brown corundum material, which is obtained by adding a small amount of iron filings to an electric arc furnace at about 2000℃ to melt natural high-alumina light combustion materials and carbon materials to remove impurities. The AL2O3 content is 94.5% to 97%, and the bulk density is greater than 3.9g/cm3.

No matter which primary material is used as aggregate, it needs to be broken down into particles of different sizes. Mix coarse and medium-fine powders in a certain proportion, add binders and various mixtures (microsilica powder, water reducing agent, explosion-proof fiber), etc. Can be configured as a pourable material. After the castables are configured, the cast samples should be tested under various equipment for various tests. Such as high temperature resistance, strength, bending strength, etc. Only after testing meets the usage requirements of high-temperature industrial furnaces can mass production be carried out.