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How to use castable construction

Nov 27, 2023

Refractory castables are widely used in high-temperature fields mainly for their convenient construction performance and usability. Compared with refractory bricks of the same material, they greatly shorten the construction period, improve the construction site environment, increase maintenance efficiency, and reduce costs.

The uses and construction methods of refractory castables made of different materials are different. insulating castables Give an example of the use of refractory castables: In parts that are corroded by molten iron, molten steel and slag and have high operating temperatures, such as tap troughs, steel ladles, blast furnace shafts, tap troughs, etc., low calcium and Refractory castables made of high-quality granular and powdery materials with high alumina content and good sintering, combined with pure high-alumina cement. Another example is that phosphate refractory castables can be widely used in heating furnaces and soaking furnaces for heating metals, and can also be used in coke ovens and cement kilns in parts that are in direct contact with materials. The use of high-quality phosphate refractory castables for repairing some parts of metallurgical furnaces and other containers that are in direct contact with slag and molten metal also has good results. In some areas where the working temperature is not very high and high wear resistance is required, it is more appropriate to use phosphate refractory castables. low cement castables If corundum refractory materials are used to make refractory castables, they generally have better results when used in a reducing atmosphere. No matter what kind of castable is used to cast the lining, it should be baked before first use so that the physical water and crystal water in it are gradually eliminated and a certain degree of sintering is achieved, so that its volume and certain properties reach a stable state during use. . The baking regime has a great influence on the service life. The basic principle of the baking system should be that the temperature rise rate should be consistent with possible dehydration and other phase changes and deformations. During certain temperature stages where the above changes occur rapidly, the temperature should be raised slowly or even kept warm for a considerable time. If it is baked improperly or is quickly heated up and put into use without baking, it is easy to cause serious cracks or even looseness and collapse. Especially in thicker parts, explosions may occur.

The construction methods of refractory castables are as follows:

① Add water and pour directly into the overall lining, such as high-aluminum castables and low-cement castables. Mold support is required.

② Depending on the complexity of the pouring parts, self-flow molding can be used for parts that cannot be constructed by pouring. Commonly used low-cement self-flow castables do not require mold support;

③Using the smearing method for construction, no kiln mold is needed, and a thin lining is applied, which saves time and effort. Such as refractory coating;

④ Use the ramming method for construction, fill the material into the furnace shell, and use ramming tools to vibrate vigorously to obtain a strong density, which can be directly put into production to form a ceramic structure at high temperature;

⑤ If the gunning method is used for construction, it is necessary to use spraying equipment to directly spray the mixed materials into the construction site.

⑥Inject materials directly into the parts to be constructed, also known as refractory injection materials, such as foam mud for blast furnace tapholes;

⑦ Prefabricated parts are poured directly at the manufacturer and constructed at the construction site, which are called castable prefabricated parts or refractory prefabricated parts.

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