High Alumina Poly Light Ball Insulation Brick

High-alumina poly light insulation bricks, also known as high-alumina insulating refractory bricks, are insulating refractory products made of bauxite as the main raw material with an Al2O3 content of not less than 48%. High-alumina poly light insulation bricks mainly use bauxite clinker, combined with clay as raw materials, mixed with binders and sawdust. In order to improve product performance, fine powders of industrial alumina, corundum, sillimanite, kyanite, and silica are added to produce products with a volume density of more than 0.4g/cm3. The maximum operating temperature varies with the Al2O3 content and volume density, usually between 1250~1350℃, and some can reach 1550℃.

 

The high-alumina poly-lightweight insulating brick process includes five parts: preparation of foaming agent, modulation of foam slurry, molding, drying and firing.

1.Preparation of foaming agent. Foaming agent is essentially a surfactant. Foam is a dispersion system of air in a liquid phase. In this system, air is the dispersed phase and liquid is the dispersion medium for bubble separation. An adsorption layer is formed at the gas-liquid interface. The greater the surface activity, the stronger the adsorption layer is and the stronger the ability to adsorb solid fine particles is. The stability of the adsorption layer is related to the concentration of the foaming agent. The pH value of the colloidal solution generated by gas and liquid also affects the stability. The pH value of the foaming agent used by most factories in China is between 8 and 9. When the arrangement of surfactant molecules in the surface layer is unsaturated, the foam is most stable. At this time, the foaming agent can be fully hydrated and firmly combined with water. The quality of the foaming agent is generally identified by three performance indicators: foam toughness, water exudation, and foaming multiple. Rosin soap is commonly used as a foaming agent. Its preparation method is: put a mixture of rosin (31%), NaOH (6.1%) and water (62.9%) into an alkali-resistant heater and heat it to 70~90℃ until the rosin is completely dissolved and saponified. After cooling, wash with salt water 3-4 times on a 0.147mm screen, and then rinse with clean water 1-2 times to make the pH value reach 8-9 to obtain a light yellow paste of rosin soap. Add rosin soap to hot glue water and stir evenly to form a rosin soap foamer. Alum or aluminum sulfate is often used as a foam stabilizer. The water glue solution is mixed with the emulsion of rosin soap in a hot state, and the mixture is diluted with water to a liquid with a rosin content of 10%, and then stored in this state. The foamer entering production also needs to be diluted with water to a density of 1.0-1.10g/cm. When it contains 0.5% rosin soap (calculated as rosin), 0.5% water glue (calculated as dry weight of water glue) and 99% water, it is put into a foaming machine and foamed to produce small and uniform white foam with a volume density of 0.04-0.05g/cm3.

2.Preparation of foam mud. Finely crushed binding clay, high-alumina clinker and screened sawdust are mixed with water in proportion to make mud. Then they are mixed with the prepared foam in a mixer in proportion to make foam mud. The ratio of foam to mud depends on the volume density of the product. Foam mud with a volume density of 0.51~1.26g/cm3 can be made into high-alumina polylight insulation bricks with a volume density of 0.4~1.0g/cm3.

3.High-aluminum poly light insulation brick molding. The brick mold can be a wooden mold or a metal mold. The working surface of the brick mold should be smooth and lubricated. The brick mold is placed on a dry board with pad paper and foam mud is injected. In order to prevent the product from generating large bubbles and affecting the organizational structure, the grouting should be carried out slowly and the mud should be stirred or vibrated in the mold to exhaust air, and then the remaining slurry should be scraped off with a wooden board.

4.Drying of high-aluminum poly light insulation bricks. After pouring, dry the mold at about 40℃ for 18~20h, and demould when a gap of 3~5mm is opened around the brick mold. Continue drying. At this time, the temperature can be raised to 80~90℃; if dried in a tunnel dryer, the inlet temperature should not exceed 40℃, and the outlet temperature should not exceed 150℃. Residual moisture in the brick: standard bricks are not more than 3%, and large bricks are not more than 1%. Drying is a key process. If it is not properly controlled, cracks, bottom crispness, concave core, sticky molds, and falling edges and corners will appear.

5.Firing of high-alumina polylight insulation bricks. Use side-loading kiln, build a frame with silica bricks, and stack the bricks in the frame. The height of the stacking frame should not exceed 1.6m.

High-alumina poly-lightweight insulating bricks are made of special-grade high-alumina as the main raw material, supplemented with appropriate additives and produced by poly-lightweight burning loss method. The products have the advantages of high strength, good thermal shock stability, small re-firing line change, and small thermal conductivity. They can be widely used in various industrial kiln linings (not corroded by molten liquid) and insulation layers in metallurgy, machinery, ceramics, chemical industry and other industries. It is an ideal energy-saving product with an operating temperature below 1400℃.

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