Lightweight insulation floating bead bricks are mainly made of floating beads. A high-strength lightweight insulation refractory brick with micropores is made by using a binder as the binding material, modifying it with additives and mixing it with water in a certain proportion, and then mixing, plasticizing, molding, drying, and baking it.
Lightweight insulation floating bead bricks have lower density, lower thermal conductivity, and better insulation performance compared to ordinary refractory bricks. They can be directly used for working layers in kilns below 1300 ℃; Used as insulation layer above 1300 ℃; This has created favorable conditions for promoting the lightweight and energy-saving of thermal equipment in kilns; The floating beads floating on the water in the fly ash account for about 0.2%~1% of the total amount of fly ash, while the other part of the hollow sunk beads sinking in the water account for about 50%. The floating beads and hollow sunk beads can both produce light insulation bricks, but the process is different. The former is usually pressed by semi dry method, while the latter is often formed by pouring method (foam method).
Due to its advantages such as low density, good high-temperature performance, low thermal conductivity, and low cost, thermal insulation bricks have become one of the rapidly developing lightweight thermal insulation bricks in China, benefiting ash discharge, processing, and application units. This also indicates that lightweight thermal insulation bricks are an effective way to utilize fly ash.
The composition materials of floating bead insulation refractory bricks include floating beads, binders, and additives.
1. Floating beads
Floating beads are the main body of refractory bricks. In order to achieve purity, some floating beads must be rinsed or selected several times before application.
2. Adhesive
The bonding agent plays a role in adhesion and reinforcement. The requirements are as follows:
At room temperature: it can make floating beads stick together into a solid body, forming a certain geometric shape and producing a certain strength.
Medium temperature: In addition to maintaining the original bonding performance and geometric shape, it also prevents a decrease in strength.
High temperature: In addition to maintaining external stability, it also improves its strength and other technical performance.
The commonly used bonding materials include refractory clay, CMC (carboxymethyl cellulose, commonly known as chemical paste), alumina cement and alumina (which can play a dual role in fire resistance and bonding), phosphoric acid and phosphate, sodium silicate (i.e. water glass), etc.
3. Admixtures
Admixtures are mainly used to increase the internal micropores of refractory bricks, reduce their own weight, and enhance their insulation and fire resistance performance.
Common additives include:
Wood chips (sawdust) - pores are generated after roasting, so it is also known as loss on ignition agent, but its fineness (<3mm) must be considered;
Mature sand - made by crushing waste refractory bricks and other materials, which can be used as waste and increase the refractoriness;
Aluminum sulfate - This material begins to decompose at 590 ℃ and completes decomposition at 639 ℃.
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