White electrocorundum refractory material properties and usage
White electrocorundum is one of the most important refractory raw materials. There are several properties of WFA:
1. High strength and wear resistance.
2. Corrosion and penetration of acid-resistant slag.
The main crystal phase of various types of white electrocorundum is alpha-Al2O3. It has good corrosion and penetration resistance of acid resistant slag. The slag generated in metallurgy is generally acidic, with a higher SiO2 content and a lower CaO content. White electrocorundum can resist the penetration of those slags.
The steel making industry generally uses Al2O3 based refractory materials as lining, such as high alumina bricks for the blast furnace body, Al2O3-SiC-C refractory materials (castable and ramming materials) for the iron ditch, Al2O3-SiO2-SiC-C refractory materials (castable and refractory bricks) for gun mud (Al2O3-SiO2-SiC-C), hot metal ladle and torpedo tank, etc.
3. Excellent thermal properties.
The main crystal phase of corundum is α-Al2O3. It can work with many oxide and non oxide phases. In that way, the mixed refractory can improving thermal properties such as thermal shock resistance, slag (acidic or alkaline) corrosion resistance, etc. The white electrocorundum can mix with SiO2 to form corundum mullite refractory. It can also combine with MgO to form corundum spinel refractory. Work with zircon sand (ZrO2 and SiO2), it can make Al2O3-SiO2-ZrO2 refractory materials. White electrocorundum mixed with silicon carbide and carbon to form Al2O3-SiC-C refractory, etc.
4. The diversity of bonding methods.
White electrocorundum refractory material is compatible with various binders. And it is suitable for multiple bonding methods. With high-temperature sintering, low-temperature bonding, and other bond methods can get different characteristics of fire bricks.
Corundum is mainly divided into two categories in refractory materials: Shaped refractories and Un-shaped refractory products.
The Usage of white electrocorundum refractory mainly include:
1. Corundum refractory material products.
Self bonded solid-phase sintered high-purity corundum products, mainly composed of corundum and a small amount of mullite. It is mainly used in petrochemical industry gasifiers, carbon black reaction furnaces, gas making furnaces, ammonia decomposition furnaces, secondary conversion furnaces, high-temperature and ultra-high temperature kilns in refractory ceramic industry, and blast furnaces in metallurgical industry.
2. Modified high alumina refractory bricks:
a. Low creep high alumina fire bricks. For high alumina bricks with a creep temperature of 1500 ℃ -1550 ℃, adding some fused corundum and silica raw materials can produce low creep rate high alumina bricks.
b. Phosphate bonded high alumina fire brick. A chemically bonded refractory product made from special or first grade high alumina bauxite clinker as the main raw material. In the meantime, adopt phosphoric acid or aluminum phosphate solution as the binder. Then add an amount of white electrocorundum, mullite to strengthen the matrix. At last, heat the matrix at 400-600 ℃. The high alumina fire bricks are maily used in ironmaking hot blast furnaces, cement kilns, electric furnace roofs, steel ladles, etc.
3. Corundum mullite shaped refractory.
The raw materials are white fused corundum aggregate, tabular corundum, and fused mullite. The get the shaped refractory products by batching, mixing, high-pressure forming, and firing in a high-temperature kiln. The main crystal phase of the product is corundum, and the binding phase is mullite. Those shaped refractory used in high-temperature firing kilns and kiln furniture such as push plates and bearing plates in the ceramic industry.
