Aluminum silicate refractory fiber products are made of high-quality calcined coke as raw materials. They are melted and sprayed in an electric furnace to form fiber cotton. After removing the slag balls, the surface is processed into fiber products (felt, blanket, block, etc.). Because of its light bulk density, which is 1/5-1/6 or lower than that of general lightweight insulation bricks, it has low heat capacity and good insulation performance. It is a high-quality insulation material. It is widely used in the insulation layer of various thermal equipment in metallurgy, machinery, chemical industry, power and other industries.
(1) Recrystallization of aluminum silicate fiber Aluminum silicate fiber manufactured by the melting method adopts gas blowing or spinning process to disperse the molten liquid stream and rapidly cool it into fiber.
When aluminum silicate fiber and its products are used as lining materials or thermal insulation materials of kilns, the crystallization phenomenon first occurs on the heating surface side. With the increase of heating temperature or heating time, this phenomenon gradually develops to its inner layer.
The high-purity aluminum silicate fiber made of high-purity raw materials has a higher crystallization temperature than ordinary aluminum silicate fiber. Therefore, high-purity aluminum silicate fiber has excellent heat resistance and stability in reducing atmosphere.
(2) Manufacture of high-purity aluminum silicate fiber High-purity aluminum silicate fiber, also known as "standard" aluminum silicate fiber, is made of high-purity industrial alumina powder and silica sand or quartz sand as raw materials, and some also add a small amount of B2O3 or ZrO2 additives. It is melted in an arc furnace or resistance furnace to form a stable stream, and is made by blowing or spinning. The total content of A12O3+Si02 in the industrial alumina powder and silica sand used should be greater than 99%.
Industrial alumina powder and silica sand are mixed in a weight ratio of 1:1 and dry mixed for 4 to 5 hours. A certain amount of water and a suitable binder are added to the mixture, and then mixed and pressed into blocks using a brick press. The agglomerates are calcined at high temperature and then broken into blocks with a particle size of 20 to 60 mm. The broken blocks are melted in an electric arc furnace and fiberized to obtain high-purity aluminum silicate fibers.
The obtained high-purity aluminum silicate fibers can also be further processed into various forms of secondary products.
The process of making fiber blankets by needle punching of aluminum silicate refractory fiber products is based on the needle punching method of non-woven fabrics in the textile industry. The characteristic of this method is that the barbs on the needle punching machine are used. When the needle punches the fiber blanket, the fibers are brought down, and when the needle is pulled up, the fibers are brought up, so that the fibers between layers are intertwined. Thus, the strength of the fiber blanket is improved. However, since refractory fibers are not as soft as organic fibers and are more brittle, the fibers are easily broken during needle punching, so lubricants need to be added to make the fibers and the fibers and the needles slide well for needle punching. However, due to the presence of lubricants, the tensile strength of the blanket after needle punching is low, so the lubricants must be removed.
The chemical composition shall comply with the following table:
|
Ingredients |
index |
|
|
AL2O3+SiO2 % |
≥ |
96 |
|
AL2O3 % |
45 |
|
|
Fe2O3 % |
≤ |
12 |
|
K2O+Na2O % |
0.5 |
The physical properties meet the requirements of the following table:
|
project |
index |
||
|
Capacity (kg/m3 ) |
130 |
±15 |
|
|
160 |
|||
|
190 |
|||
|
220 |
|||
|
Slag ball content %(＞ 0.25mm) |
≤ |
5 |
|
|
Heating line shrinkage % 1150℃ for six hours |
4 |
||
|
Water content% |
0.5 |
||
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