Introduce the production process of high alumina bricks!

he following is an introduction to the production process of high-alumina bricks.

Method of adding combustibles. The combustibles addition method is a common method for producing lightweight refractory bricks at present. Add combustibles that are easy to burn out, have little impact on molding, and can obtain fine and uniform pores in the mud. Commonly used combustible additives are sawdust, charcoal, hard coal, wood rope and other combustible materials with less ash content. At present, PVC hollow balls are also added. Lightweight clay bricks, lightweight high alumina bricks and lightweight silica bricks can be produced by this method. Since the combustible materials added during the firing process burn out and form pores, refractory bricks have porosity and thermal conductivity, which depend on the amount of combustible materials added.

Foam method. The brick throwing method is mainly used to produce lightweight high-aluminum bricks. First, a mixture composed of high-aluminum clinker, bonded clay or sawdust is added with water to make a mud with a moisture content of 25% to 30%. It is sent to a foaming machine to foam and mixed evenly. Then pour in the foam-saturated slurry, dry it with the mold, fire it at 1300~ 1350 ℃, and then trim it to ensure accurate size. The refractory brick has high porosity and a bulk density of generally 0.9~ 1.01g/cm3. The key to this method is the selection and preparation of the foaming agent. Any substance added to water that can form foam is called foam hanging meat. Foaming agent is a surface active substance. Foam is a colloidal system composed of liquid phase and gas phase. Among them, the gas is the dispersed phase, and the fluid is the dispersion medium for separating the bubbles. Commonly used foaming agents are soap base (or pine soap), pentanone, gelatin, protein and pectin, etc. Among them. Loose soap is widely used. Stabilizer is made of hydrogel and potassium alum.

Third, the chemical method. The chemical method is called chemical method, which is to add chemical substances to the mud, generate gas through chemical reaction, and make the refractory brick obtain pores. For example, in the production of high-alumina bricks, dolomite and an appropriate concentration of sulfuric acid solution are usually added to make the refractory brick porous through the following chemical reaction. MgCa (CO3) + 2h2so4 = mgso4 + caso4 + 2H20 + 2co2. Other carbonates, such as calcium carbonate (chalk and calcite, etc.), are not commonly used because they react quickly with acid and are difficult to control. The coagulant hemihydrate gypsum (CaSO40.5H2O) is added to the slurry containing additives, and then it is injected into the mold to create air bubbles in the mold and expand its volume. It is recommended to add a coagulant to make the slurry expand and rise to the designated position of the mold and solidify. Dry together with the mold. After demoulding, it is fired at 1240~ 1300 ℃. 4. Foam clinker method. The foam clinker method is to make light porous clinker (volume density is 0.9~ 1. Og/cm3) as an aggregate, then add some amount of binder (such as bonded clay), and fire at 1360-1410 ° C to make lightweight refractory bricks.

Add the type of combustibles in high alumina bricks.

1. Sawdust: It is a soft and loose material (bulk density is 200 grams/cubic meter). It can reduce the plasticity of the billet and make the billet more elastic and flammable; but its product strength is low and it is easy to deform during firing, so the content in the billet is limited, generally between 25% and 30%. It is easy to use the sawdust of hardwood (such as oak and pine).

2. Charcoal: Charcoal chips make the blank shape, less elastic and shrinkage, but not easy to burn out. In production, general sawdust: charcoal = 1:5 or 1:7 (mass ratio). It is required that wood chips pass through 3-4mm sieves and charcoal pass through 1.5-2.5mm mesh. With the increase of particles, the moisture content and shrinkage rate will increase, and the mechanical strength of the product will decrease.

3. Anthracite and coke powder: The characteristics are the same as above, but it is suitable for semi-dry molding. The disadvantage is that it is not easy to burn out.

4. Lignin: high volatile matter (7%), high dispersibility, no swelling after adding water, suitable for semi-dry molding, but expensive and less used. When the method of adding combustible additives is adopted, the combustible additive should have high volatility and flammability; it should be able to produce small uniform pores; it should also have less elasticity to facilitate molding.