5 CHARACTERISTICS OF ANDALUSITE IN USE

Andalusite is a natural and high-quality energy-saving high-alumina refractory mineral raw material, which is mainly used in the production of refractory materials for iron and steel metallurgy. In order to use it reasonably, you must first get a general understanding of its performance in application. It exhibits the following characteristics during use:
(1) Low energy consumption.
Andalusite is an anhydrous silicate mineral and does not contain crystal water. Therefore, the raw material of andalusite does not need to be calcined in advance, and the raw meal can be used directly in the production. Compared with bauxite and other products, it saves the pre-calcining process, so that the energy consumption is less during production. In addition, the refractory made of it can also achieve the purpose of energy saving during use. The made high alumina bricks and unshaped refractory materials, when used in key parts such as steel and smelting blast furnace hot blast furnace and soaking furnace mixing furnace, can extend the furnace life by 150-200 furnaces or more compared with other refractory materials. , The loss rate is reduced by 43%, the energy saving is about 12%, the smelting time is shortened, and the production cost is reduced.
(2) Stable chemical properties.
Andalusite is transformed into a mixture of mullite (3Al2O3·2SiO2) and free SiO2. In the Al2O3-SiO2 binary system, only mullite is chemically stable. Therefore, refractory products made of andalusite are chemically stable. .
(3) The volume is stable.
When it is used in a high-temperature environment, it is converted into mullite with a slight volume expansion (linear expansion rate of 1% to 1.5%). Compared with other products, the volume change is relatively small, that is, the volume is relatively stable. This phenomenon can effectively fill the joints between bricks and cracks in the castable, thereby effectively blocking the penetration of liquid slag and metal, that is, good slag resistance. And this volume expansion is irreversible, so when it cools, the joint remains tight. For high-aluminum refractory castables, when it is added to the matrix, although the construction performance is reduced, the volume stability is greatly improved. If its plasticity is improved, then the high-alumina with high volume stability requirements For high-quality castables, it will be a good choice of materials. Secondly, in the application of low-creep clay bricks for blast furnace hot blast stoves, the volume effect of andalusite mullite is small, so adding it can improve the volume stability of the product.
(4) Good creep resistance.
Andalusite is transformed into mullite to form a network microstructure interwoven with needle-like alllite, so it has good creep resistance and good high-temperature mechanical properties. The high-quality low-creep clay bricks for blast furnace hot blast stoves developed with special-grade coke gemstone, andalusite and fused mullite as the main raw materials have good creep resistance, wear resistance and high-temperature volume stability.
(5) Strong thermal shock resistance.
Because most of it is converted into mullite at 1500℃, the mullite phase accounts for 80%, the glass phase accounts for 20%, and the liquid glass phase can absorb thermal stress when subjected to thermal shock, avoiding the occurrence of cracks and reducing Peeling phenomenon.