Lightweight castable is a refractory material with many excellent properties such as light weight, high strength, corrosion resistance, fire resistance, thermal insulation, etc. It is widely used in high-temperature industrial kilns in metallurgy, building materials, nonferrous metals, chemical power and other industries. Its volume density is usually between 400-800kg/m³, and its thermal conductivity is less than 0.1W/(m·K). Because of this, lightweight castable has excellent thermal insulation performance. At the same time, compared with other castables, after pouring and hardening, its overall weight is reduced by more than 40%, which has significant advantages in reducing the load on the kiln structure.
However, lightweight castables also have certain limitations, such as their relatively low refractory temperature, generally around 1350℃-1500℃. The compressive strength is usually in the range of 0.5-5MPa. The compressive strength and refractoriness are relatively low, so they are more suitable for those parts that do not require high temperature and pressure.
Lightweight castables have certain properties of acid and alkali corrosion resistance, and have certain resistance to acidic and alkaline media. At the same time, they have good thermal shock resistance. Currently, common lightweight castables mainly include lightweight acid-resistant castables, lightweight alkali-resistant castables, and lightweight mullite castables. The selection is usually based on the properties of the medium.
Lightweight castables are usually used for the thermal insulation (heat preservation) layer of kilns. They are not in direct contact with the flames and can slow down the temperature drop of the kiln, ensure the working environment of the kiln, and reduce the load on the kiln. Therefore, they are a good choice for the lining of kilns, thermal equipment, flues and smoke windows, especially in furnace doors, furnace roofs, flues and other parts, which can significantly reduce the structural load and extend the service life.
When choosing lightweight castables, we must choose according to the working medium, working environment, refractory temperature and other performance indicators, so that we can choose the appropriate lightweight castables. In short, lightweight castables are a good refractory material for insulation.