Refractory bricks and matching refractory mud for hot blast furnaces are to ensure the use effect of refractory materials. Refractory bricks have a variety of materials, and the matching refractory mud is also selected from the same material, and the material content must be greater than or equal to the proportion of bricks, so as to ensure the masonry effect.
Hot blast furnace is one of the primary equipment in blast furnace ironmaking production. With the large-scale blast furnace, the improvement of raw material quality, the development of injection technology, and the improvement of blast furnace operation level, the required wind temperature is higher. The general requirement for hot blast furnaces is to achieve high wind temperature and long life. For this reason, it is necessary to select a reasonable hot blast furnace structure and refractory materials for masonry hot blast furnaces in the design.
Introduction to refractory bricks and matching refractory mud for hot blast furnaces
1. Silica bricks. The creep rate of silica bricks is low. During the use process, they should be heated or cooled slowly to avoid cracks. Therefore, they should not be used in parts with sudden temperature changes below 80C. Because of its relatively cheap price, it is widely used in the vaults, connecting pipes, combustion chambers and high-temperature areas above the regenerator of hot blast furnaces and the high-temperature areas above the checker bricks. Silica brick masonry is equipped with silica refractory mud.
2. Clay bricks. Clay bricks are cheap, but not wear-resistant and cannot touch flames. They are widely used in low-temperature areas below 1000℃ in hot blast furnaces. Clay bricks with high density and low alkali metal content can also be used as bricks for the lower part of ceramic burners. Clay refractory mud is used for clay brick masonry.
3. High-alumina bricks. High-alumina bricks are suitable for high and medium temperature areas of hot blast furnaces. If used for vaults, they require low creep rate and high volume stability; if used as checker bricks, they must have sufficient thermal stability and high volume stability; if used in the lower part of the combustion chamber, they require outstanding thermal stability. High-alumina refractory mud is used for high-alumina brick masonry.
Other refractory bricks are similar. Refractory mud of the corresponding material is selected, and the refractory mud material content must be greater than or equal to the proportion of brick material content, so as to ensure the use effect of the refractory material. Refractory mud is divided into dry powder bags and barreled clay, which is convenient and quick to use.
Selection plan of refractory bricks and insulation bricks for hot blast furnaces
In order to achieve the purpose of high wind temperature and long life of hot blast furnaces, it is necessary to reasonably select refractory materials for building hot blast furnaces. The selection of refractory materials is mainly determined by the design of hot blast temperature and the size of the hot blast furnace. In addition, the price factor of refractory bricks should also be considered. According to the design practice, the author believes that refractory bricks and insulation bricks for hot blast furnaces can be selected according to the following plan.
(1) Large hot blast furnace (diameter ≥ 8m, wind temperature 1200℃): silica bricks are used for the vault, the upper part of the combustion chamber, the upper part of the regenerator and the upper part of the checker bricks; mullite bricks are used in the vault part and the middle part of the combustion chamber (high temperature zone) next to the silica bricks; andalusite bricks or sillimanite bricks are used in the middle and high temperature zones of the regenerator and checker bricks next to the silica bricks and the lower area of the combustion chamber above the top surface of the burner; andalusite bricks or sillimanite bricks are suitable for the checker bricks above the grate; clay bricks are used in the low temperature zone below 1000℃.
(2) Large hot blast furnace (diameter ≥ 8m, wind temperature 1150℃): silica bricks are used for the vault, the upper part of the combustion chamber, the upper part of the regenerator and the upper part of the checker bricks. Andalusite bricks or sillimanite bricks are used in the vault part immediately adjacent to the silica bricks, the middle part of the combustion chamber, the medium and high temperature areas of the heat storage chamber and the checker bricks, and the lower area of the combustion chamber above the top surface of the burner; andalusite bricks or sillimanite bricks are also suitable for the 15 layers of checker bricks above the grate; clay bricks are used in the low temperature area with a temperature below 1000℃.
(3) Small and medium-sized hot blast furnaces (diameter <8m, wind temperature 1100-1150℃): kyanite bricks are used for the dome, the middle and upper parts of the combustion chamber, the heat storage chamber and the upper part of the checker bricks. The lower area of the combustion chamber above the top surface of the burner is made of andalusite bricks. Clay bricks are used for the low-temperature zone (including checker bricks) with a temperature below 100℃.
(4) Ceramic burner: cocoon bluestone bricks or andalusite bricks are used for the upper part, and fine clay bricks with low alkali metal content are used for the lower part.
(5) Selection of insulation bricks: The type of insulation bricks used for hot blast furnaces is determined by the type of refractory bricks used in the working layer. When the working layer is built with silica bricks, lightweight silica bricks should be laid on the back of the silica bricks. When the working layer is built with high-alumina refractory bricks, lightweight high-alumina bricks should be laid on the back of the refractory bricks. When the working layer is built with clay bricks, lightweight insulation bricks should be laid on the back of the clay bricks.
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