Lightweight Refractory Castable

Lightweight castables are made of ceramsite, lightweight perlite, vermiculite, lightweight mullite, porous clay aggregates, fine powder, and refractory cement that can form initial strength. They are resistant to high temperatures and can be used at temperatures between 800 and 1200 degrees Celsius. Lightweight castables have high porosity and can be used for heat insulation. They are also called lightweight insulating castables. Lightweight castables have low bulk density, which can reach 0.6-1.3g/cm3. Lightweight castables are used in the heat insulation layer of kilns to isolate high temperatures and achieve heat preservation and energy-saving effects. The preparation and molding of lightweight castables are basically the same as those of heavy refractory castables. The difference is that lightweight aggregates have a small bulk density and are easy to absorb water. Therefore, when mixing, the weighed lightweight aggregates should be poured into a forced mixer, and half of the water should be added first. After wet mixing, refractory powder and cement should be added, and the remaining water should be added for mixing. During molding, lightweight aggregates tend to float up and cause stratification, so the vibration time should be shorter and should be controlled.

 

When preparing lightweight castables with lightweight bricks as aggregates, lightweight insulation bricks with a bulk density of 0.8~1.2g/cm3 are generally used to crush refractory aggregates. Their bulk density is small and the particle strength is large. When using thermal insulation bricks with a bulk density greater than 1.2g/cm3 or less than 0.8g/cm3 to crush aggregates, the former has high particle strength but high bulk density; the latter has a low bulk density but low particle strength, and even in the crushing process, most of them become brick powder, making it difficult to obtain granular materials. In order to reduce its bulk density, it is generally used to add light aggregates such as expanded perlite, ceramsite and vermiculite, with a dosage of 2%~10%. The cement, refractory powder and light aggregate used have different types and dosages, and their performance is also different. The castables added with water reducers have obvious water consumption reduction and strength improvement; adding additives with low bulk density can reduce the bulk density of the castable and improve its thermal insulation performance, but the strength decreases exponentially, and the more it is used, the more obvious it is. Therefore, according to the use conditions of thermal kilns and the use parts of the castables, lightweight brick sand refractory castables should be reasonably prepared and selected to achieve the purpose of longevity and energy saving of the kiln.

A castable mixture made of lightweight refractory aggregate, powder, binder and admixture is called lightweight castable. Since lightweight castable has a small volume density and low thermal conductivity, it is also called lightweight insulating refractory castable and lightweight heat-insulating refractory castable.

Lightweight castables are widely used in the lining of kilns, thermal equipment, chimneys, flues and smoke windows in industrial sectors such as metallurgy, machinery, petrochemicals, electricity and building materials. Lightweight castables are generally used as thermal insulation layers. However, with the improvement of lightweight castable materials and the advancement of preparation technology, there are also many occasions where they are directly used as working linings for atmosphere furnaces. Generally, low-temperature and medium-temperature lightweight castables are mainly used as thermal insulation linings and do not directly contact flames. A large part of high-temperature lightweight castables are directly used as working linings that do not contact the melt or solid medium in the furnace, especially for various heating furnaces and heat treatment furnaces. It can greatly save energy consumption. Lightweight castables are widely used, generally as insulation layers, working layers or load-bearing components, and all achieve good results.

1. Product description: It is made of natural lightweight aggregate and synthetic lightweight aggregate as the main body, and is formulated with a composite binder as a carrier.

2. Product features: low volume density and good heat resistance and thermal insulation performance.

3. Use location: Suitable for thermal insulation layers of the bottom, top and wall of high-temperature kilns.

4. Construction method: vibration pouring, coating, spraying, etc.

Main physical and chemical indicators of lightweight castables (I)

Main physical and chemical indicators of lightweight castables (II)

Main physical and chemical indicators of lightweight castables (III)

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