The manufacturing process of mullite thermal insulation brick mainly includes the following key steps:

I. Preparation of raw materials

The main raw materials of mullite thermal insulation brick include:

Clay.

Calcined alumina (Al₂O₃ content ≥99%, particle size 0.043~0.1mm).

Calcined mullite powder (Al₂O₃ content ≥65%, particle size 0.1~0.5mm).

Plate corundum (Al₂O₃ content ≥99.4%, particle size 0.043~0.2mm).

Kyanite and sillimanite.

Binder (such as polyvinyl alcohol, PVA).

Pore-forming agents (such as sawdust and polypropylene balls).

Foaming agent (such as sodium dodecyl sulfonate).

II. Preparation process

The preparation methods of mullite thermal insulation brick mainly include the following:

(1) Foam method

Premixing: Premixing raw materials for 4 hours according to a certain proportion.

Pulping: add 30%~35% water to mix the powder into a uniform and stable slurry.

Foaming: adding water to foaming agent and stirring at high speed to make stable foam.

Molding: Mix mud and foam evenly, inject into the mold, and slightly vibrate to remove large bubbles.

Drying and sintering: naturally drying at room temperature for 8-12 hours, demoulding, baking at 110℃ for 24 hours, and finally sintering at 1550℃ and keeping the temperature for 3 hours.

(2) Mechanical pressing method

Premixing: Premixing raw materials for 4 hours according to a certain proportion.

Stirring: after diluting the polyvinyl alcohol, add the evenly mixed powder and stir for 10-15 minutes.

Molding: extrusion into green bricks with a pressure of 5MPa.

Drying and firing: after baking at 110℃ for 24 hours, firing at 1550℃ and keeping the temperature for 3 hours.

(3) Extrusion method

Premixing: Premixing raw materials for 4 hours according to a certain proportion.

Mixing and molding: adding 10%~15% water, stirring evenly, and preparing green bricks by extrusion through process procedures such as material trapping and mud refining.

Drying and firing: after baking at 110℃ for 24 hours, firing at 1550℃ and keeping the temperature for 3 hours.

III. Quality control

In the production process, the chemical composition and particle size distribution of raw materials are strictly controlled to ensure the performance of bricks. At the same time, the performance of the product is tested by high temperature microscope, high temperature resistor, load softening instrument and other equipment to ensure the stability of product quality.

IV. Environmental protection and energy conservation

The production of modern mullite thermal insulation brick pays attention to environmental protection and energy saving, and adopts advanced gas conveying and automatic batching system to reduce energy consumption and pollutant discharge in the production process.

Through the above process, mullite thermal insulation brick can have excellent characteristics such as low thermal conductivity, high fire resistance, good thermal insulation performance and mechanical strength, and is widely used in high-temperature industrial fields.