Publish Time: 2024-04-19 Origin: Site
At present, the application of andalusite in refractory materials is mainly based on the mullitization of andalusite at high temperature. It is mainly reflected in the following aspects:
1. The volume expansion of andalusite in the process of generating mullite at high temperature can effectively offset the sintering shrinkage at high temperature, so that the volume of the product is stable. Using the expansion effect of andalusite at high temperature to adjust the firing shrinkage is very effective to ensure the dimensional accuracy of the product and improve the yield.
2, improve the thermal shock stability of refractory products. It is generally believed that there are two reasons: First, the added andalusite is converted to mullite at high temperature, which increases the mullite content, and the interwoven structure formed by the needle column mullite is beneficial to thermal shock stability; Second, the andalusite is not completely mullite, forming a composite structure, which is conducive to the mismatch of the expansion coefficient of each mineral and improve the thermal shock stability. Andalusite is widely used in the production of mullite and mullite cordierite kiln wares to improve their thermal shock stability.
3. Add andalusite to the matrix, and after the andalusite mullite is fossilized at high temperature, the matrix forms a knitted mullite interwoven network microstructure, which improves the mineral composition and microstructure of the matrix, and can improve the load softening temperature and creep resistance of the product.
In summary, the application of andalusite in refractory materials, its role is mainly to improve the performance of refractory materials. At present, the main refractory product categories for the application of andalusite are: synthetic mullite, for low creep bricks, ceramic kiln and amorphous materials.
Adding andalusite to improve the performance of refractory materials, should pay attention to the following points: first, try to choose high purity, low impurity content of concentrate; Second, it is necessary to select and control the particle size and addition amount of concentrate reasonably; The third is to determine the reasonable product firing temperature and holding time.
1, andalusite for amorphous refractories At present, the application of andalusite in refractories is mainly the use of andalusite at high temperature mullitization. It is mainly reflected in the following aspects:
1. The volume expansion of andalusite in the process of generating mullite at high temperature can effectively offset the sintering shrinkage at high temperature, so that the volume of the product is stable. Using the expansion effect of andalusite at high temperature to adjust the firing shrinkage is very effective to ensure the dimensional accuracy of the product and improve the yield.
2, improve the thermal shock stability of refractory products. It is generally believed that there are two reasons: First, the added andalusite is converted to mullite at high temperature, which increases the mullite content, and the interwoven structure formed by the needle column mullite is beneficial to thermal shock stability; Second, the andalusite is not completely mullite, forming a composite structure, which is conducive to the mismatch of the expansion coefficient of each mineral and improve the thermal shock stability. Andalusite is widely used in the production of mullite and mullite cordierite kiln wares to improve their thermal shock stability.
3. Add andalusite to the matrix, and after the andalusite mullite is fossilized at high temperature, the matrix forms a knitted mullite interwoven network microstructure, which improves the mineral composition and microstructure of the matrix, and can improve the load softening temperature and creep resistance of the product.
In summary, the application of andalusite in refractory materials, its role is mainly to improve the performance of refractory materials. At present, the main refractory product categories for the application of andalusite are: synthetic mullite, for low creep bricks, ceramic kiln and amorphous materials.
Adding andalusite to improve the performance of refractory materials, should pay attention to the following points: first, try to choose high purity, low impurity content of concentrate; Second, it is necessary to select and control the particle size and addition amount of concentrate reasonably; The third is to determine the reasonable product firing temperature and holding time.
Andalusite is used for amorphous refractory materials
At present, andalusite is widely used in amorphous refractors-its purpose is to use the volume expansion of andalusite at high temperature due to its mollitization to compensate for the shrinkage of amorphous refractors-at high temperature to prevent structural spalling. It can extend the service life of amorphous refractory materials. In the application of amorphous refractory materials, andalusite can be used either as an aggregate (such as andalusite) or as a matrix powder (such as andalusite concentrate).
2, used to synthesize mullite
There are two ways to synthesize mullite from andalusite: one is to calcinate andalusite directly to form chalco mullite clinker; The second is to add bauxite, industrial alumina, zircon and so on with andalusite concentrate. Mullite or zirconium mullite clinker is formed by calcination at high temperature, which is of practical significance for the utilization of large quantities of fine powder concentrates in andalusite concentrators, and is also a way to further process andalusite raw materials.
3, manufacture shaped refractory materials
After calcination, andalusite is made into profiles, which can be used in key parts such as hot blast furnaces and hot air towers, and can also be used in various auxiliary pouring and operating equipment, and can also be made of kiln facilities, high temperature alumino-silicate insulators, foundry mold fabrics. The use of refractory fiber made of andalusite as furnace lining can save 30 ~ 50% energy compared with refractory soil or light brick lining. The use of andalusite firebrick can not only reduce fuel consumption and increase stability, but also save more than 40% of the consumption of general refractory materials.
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2024-04-19