The great advantage of lightweight castable refractory working layer

The great advantage of lightweight castable refractory working layer

Castables can be divided into heavy castables or light castables according to their bulk density. Since there is no uniform regulation, the division boundary is not clear. According to the classification, it is usually divided by the bulk density of 2.1g/cm3. The bulk density of s2.1g/cm3 is regarded as light castable, and the bulk density of 22.1/cm3 is regarded as heavy castable.
Since heavy castables have the advantages of wide range of raw materials, simple production process, convenient construction, low price, and high castable strength, heavy castables are increasingly used in refractory working layers. Heavy flow injection materials also have problems such as high bulk density and high thermal conductivity. These problems lead to large construction consumption and high investment once added, especially resulting in relatively high long-term energy consumption of thermal equipment. Usually heavy castables with a volume density greater than 2.3g/cm3 have poor thermal insulation effects, so thermal equipment adopts a multi-layer structure design to improve thermal insulation performance. It consists of the insulation layer of bricks and the working layer of refractory castables. The above-mentioned structure can realize a lower temperature of the outer wall of the furnace and reduce energy consumption of the equipment, but due to the complex structure, the construction period and investment for construction and maintenance are relatively large.
However, light castables generally have insufficient compressive strength and low fire resistance, making it difficult to use them in load-bearing parts for a long time. As a result, only heavy castables can be used in furnace wall parts with load-bearing requirements. In addition, other measures to solve the insufficient refractory performance of light materials include the use of higher-grade raw materials for preparation, and at the same time increase the firing temperature
The reason for the insufficient compressive strength of lightweight materials is that there are too many defective pores in lightweight aggregates. The pores supporting the lightweight aggregate structure come from the sintering of the refractory skeleton remaining after the organic matter is burned off. This needle-like and granular skeleton is naturally accumulated according to the formula, and there are many unsatisfactory defect holes in the process of burning out
gaps, resulting in insufficient strength of lightweight aggregate. Lightweight mullite aggregate, the maximum long-term service temperature can reach above 1500°C, the bulk density range of lightweight mullite aggregate is 0.6-1.1g/cm3, and the lightweight castable made of light mullite can replace Traditional heavy castables are used in the working layer of heating furnaces and aluminum melting furnaces, especially the furnace door and furnace roof. When used on the furnace roof, the load of the furnace roof’s mis-fixed bricks is greatly reduced, and the service life can reach 5-8 years. Lightweight Mullite flow injection is usually only used for non-load-bearing working layers of heating furnaces, aluminum melting furnaces and other equipment. Now new reinforced lightweight mullite aggregate can be used instead of traditional lightweight aggregate to prepare castables. Compared with heavy materials, it has the same compressive strength, and at the same time, the bulk density can be reduced by 20%-40%. This new type of lightweight mullite castable can be applied to furnace walls and other parts, and because of its low thermal conductivity
Points can greatly reduce the energy consumption under the operation of thermal equipment. The use of lightweight mullite castables is basically the same as that of ordinary castables, and it has great advantages in baking. The baking of traditional heating furnaces takes 10-30 days, and the baking time of light mullite castables According to the construction quantity and construction thickness, it can be reduced to 1-5 days, greatly saving the construction period, especially suitable for maintenance projects