Species characteristics and application of spalling resistant high alumina bricks

High alumina bricks are aluminum silicate refractories with Al2O3 above 48%. Because of the high alumina content, it is called high alumina refractory. It can also be classified according to the content of Al2O3, such as: Al2O3>75% for first-grade high-alumina bricks; Al2O3 for second-grade high-alumina bricks is 65%~70%, and Al2O3 for third-grade high-alumina bricks is 55%~60%.

Properties of high alumina bricks

①High refractoriness Because the refractoriness is generally 1750~1790℃.

②The softening temperature under load is high, generally 1400-1520℃. Due to the low content of impurities, the softening point under load is high; the high-temperature performance of high-alumina bricks is related to the microstructure of the material. The high temperature resistance of the matrix part is much lower than that of the particle part, and the slag first erodes the matrix part during use. Therefore, it is possible to improve the high temperature service performance of the material by improving the matrix portion and structure of the adjustment material.

③ Good slag resistance; Al2O3 content in high alumina brick is high, which is close to neutral material. The slag resistance of high-alumina materials increases with the increase of Al2O3 content, but its corrosion resistance to basic slag is lower than that of basic refractory materials, and the reduction of impurity content is beneficial to improve slag resistance. At the same time, increasing the density of the material and reducing the porosity are also effective measures to improve its slag resistance.

④Good thermal stability; small expansion coefficient of bricks. The thermal shock resistance of high alumina bricks is worse than that of clay bricks, which is closely related to the mineral composition of the material. The first and second grade high alumina bricks are worse than the third grade high alumina bricks. In production, the thermal shock resistance of the material is often improved by improving the particle structure characteristics of the material or adding a certain amount of synthetic cordierite (2MgO·2Al2O3·SiO2) and other minerals to the ingredients.

Development of High Alumina Bricks

In recent years, many refractory research and production units have done a lot of work on the development of high-alumina bricks, improving the performance of high-alumina bricks by adding other minerals or chemical components; using synthesis or electrofusion to improve the high-temperature crystal phase of high-alumina bricks The composition and high temperature properties of high-alumina bricks have achieved effects, thereby expanding the application field of high-alumina bricks.

spalling resistant high alumina bricks

Spalling resistant high alumina bricks use high alumina bauxite as the main raw material, introduce a small amount of ZrO2, add a certain amount of composite binders and additives, and control the particle gradation of the mud. It is called anti-stripping high alumina brick. The traditional high alumina brick is a kind of refractory material, and the main component of this refractory brick is Al2O3.

The physical and chemical indicators of spalling resistant high alumina bricks mainly involve the content of aluminum oxide, bulk density, apparent porosity, compressive strength at room temperature, softening temperature under load, thermal shock stability and other indicators. ZrO2 spalling resistant high alumina bricks; another type is spalling resistant high alumina bricks without ZrO2.

Product features: (1) High refractory temperature; (2) 0.2MPA load softening temperature greater than 1500 degrees; (3) Excellent thermal shock resistance, more than 25 times of water cooling at 1100 degrees; (4) High compressive strength at room temperature, greater than 60MPA; (5) Low apparent porosity, stable volume at high temperature; (6) Excellent anti-stripping performance; (7) Good resistance to chemical attack.

Applications

spalling resistant high alumina bricks have strong anti-shedding ability, high refractoriness, good chipping resistance and strong corrosion resistance, as well as corrosion resistance of potassium, sodium, sulfur, chlorine and alkaline salts, low thermal conductivity and other properties. Ideal material for transition zone and decomposition zone of cement kiln, and can also be used for kiln door cover, cooler and other parts of cement kiln. For now, spalling resistant high alumina bricks are mainly used in cement kilns.

Low creep high alumina brick

Low-creep high-alumina brick is a kind of high-alumina refractory brick. Because of its low creep rate, it is also called low-creep high-alumina brick.

The characteristics of low creep high alumina bricks are:

1. Low creep rate and good volume stability at high temperature. Under the action of constant temperature and constant load, the interior of high-alumina bricks changes slightly with time, and the volume is stable under high temperature environment, and there is no danger of lining falling off.

2. Good resistance to gas erosion and erosion. In the high temperature environment, the low creep high alumina brick not only does not change in volume, but also has good resistance to gas erosion and long service life.

3. High compressive strength and good wear resistance. Low-creep high-alumina bricks can withstand greater gas pressure and resist the impact of dust in the gas.

Low-creep high-alumina bricks are an improvement on the basis of commonly used high-alumina refractory bricks. In the production formula of the original high-alumina bricks, refractory raw materials with low creep rate are added, and the forming and firing are reasonably controlled to make high-alumina bricks. Bricks have a certain low creep rate.

Low creep high alumina brick application:

Common low-creep high-alumina bricks can be used in blast furnace hot blast stoves, as well as other industrial kilns, and can also be made into low-creep high-alumina bricks of different sizes according to specific construction requirements, such as lattice bricks, special-shaped bricks, anchor bricks, etc. , mainly used in industrial kilns in long-term high temperature environments.