What is mullite corundum lightweight brick?

Mullite corundum lightweight brick is the crystal phase in the product containing mullite phase and corundum phase. Such products include alumina hollow spherical bricks (lightweight corundum bricks) and mullite thermal insulation bricks.

Manufacture of Mullite Corundum Brick

Using synthetic mullite and fused white corundum as raw materials and Suzhou soil as binder, mullite corundum bricks for electric furnace top can be manufactured.

Synthetic mullite was crushed to < 4mm as aggregate, fused white corundum was ground to < 0.074mm as fine powder, and the dried Suzhou soil was ground with vibration and fine < 0.5mm as binder. The proportions of ingredients range as follows: synthetic mullite 55-65%, fused white corundum 25-30%, Suzhou soil 8-10%. Mix with a wet mill. When mixing, add granular material first, mix for 1-2min, then add binder to mix for 2-3min, then add fine powder to mix for 3-5min, and the total mixing time is about 10min. The particle composition is as follows:. 2Mm 17.9~ 20.2%, 2~ 1mm 14.3%~ 18.7%, 1~ 0.5mm 3.9~ 5.8%, 0.5-0.1mm

13.1~ 15.9%, < 0.1mm41.3~ 44.7%, moisture 4.6~ 5.4%.

The embryo body is formed by a 300t friction brick press, and the density of the green body is 2.70g/cm3. The embryo body is dried in a tunnel dryer. The inlet temperature is 40~ 50 ℃, the limit high drying temperature is 130 ℃, the drying time is 48h, and the moisture of the embryo body is not more than 1.5%. The product is fired in a tunnel kiln, the firing temperature is 1550 ℃, and the holding time is 10h.

The physical and chemical indicators of the product are as follows: Al2O373.06%, SiO224.10%, apparent porosity 19.9%, bulk density 2.55g/cm3, normal temperature compressive strength 81.7MPa, 1550 ℃, 3h reburning line change rate -0.11%, load softening start temperature 1710 ℃.

Mullite corundum bricks are used as superstructure bricks, material path bricks, cover plates, lining of metallurgical and other industrial medium temperature kilns, cold sections of carbon black reactors, and lining of other industrial thermal equipment.

Lightweight mullite brick

Light mullite bricks, also known as mullite thermal insulation refractory bricks, are mainly refractory materials with aluminum silicate as the main mineral phase, and have some excellent properties, especially high temperature creep properties, which are produced from natural raw materials. Aluminum products.

However, because there are few mullite minerals, it can only be synthesized artificially. The synthesized mullite is mixed in a certain proportion to form a stable compound in the system, that is, mullite crystals, at a certain temperature. The composition of mullite is about 79% AL203 and SI02 is more suitable at 21%, but there is a certain amount of impurity components in the raw material, which will cause composition reflection at high temperature. Therefore, with the increase of impurity components, the content of vitreous and corundum will increase, and the mullite will form a coarse crystal structure, thereby increasing the porosity of the product, reducing the thermal shock stability and corrosion resistance, and prone to cracks. According to this, there are two production processes of mullite, sintering method and electrofusion method. The synthetic mullite system uses industrial alumina, aluminum hydroxide and pure clay (low-impurity kaolin) and phyllite as raw materials, and also uses high-bauxite plus clay, or high-bauxite directly synthesizes mullite for the production of mullite thermal insulation bricks and other products.

A light mullite brick with mullite as the main crystal phase. In addition to mullite, those with lower alumina content also contain a small amount of glass phase and calcite; those with higher alumina content also contain a small amount of corundum, which has higher refractoriness.

Lightweight corundum brick

Light corundum refractory materials, due to their different production methods and introduced additives, have certain differences in Al2O3 content. For general light corundum refractory bricks made by the just-burned cinder additive method, the foam method and gasification method, the Al2O3 content of Al2O3 generally does not exceed 99%. The Al2O3 content of corundum bricks made of corundum hollow spheres is high. The raw materials are ground in a silicon-lined mill, and the main residual material is SiO2. Due to the addition of sintering additive TiO2 to the rigid clinker of semi-light corundum bricks, the content of Fe2O3, Na2O, CaO, MgO, etc. that other impurities enter from raw materials and calcined additives is not large. Light corundum bricks made by casting and gasification methods are required to contain a certain amount of CaO, especially bricks added in the form of lime, gypsum or high-alumina cement, and occasionally MgO or P2O3 are added. Bricks containing P2O3 are made by gas foaming.

Lightweight corundum refractory bricks generally use polystyrene foamed beads as an additive for burning embers. Lightweight corundum bricks produced with polystyrene foamed beads are made of polystyrene foamed beads into corundum mud in a certain proportion, which are fixed in the brick by molding, and leave uniform spherical pores in the product after firing, so that the brick becomes a porous structure and the density is reduced. Since the spherical particles basically do not absorb water, the moisture content of the green body after forming is low, and the drying and deformation of the product is small, the size of the finished product is more accurate, and the product can meet the size requirements without grinding and reforming the brick.

If polystyrene foamed beads are used as an embers additive, although it does not absorb water and has small drying shrinkage, it cannot help transfer water. During the drying process, the surface of the adobe dries first, and the internal water cannot run out, which is very easy to crack. In order to solve this contradiction, composite embers additives are generally used, that is, a substance that can absorb water and burn embers is added to help transfer water and prevent the adobe from cracking. Sawdust and polystyrene foamed beads are generally used in combination. Fine wood chips should be used, which can also fill the gap between the beads and reduce the density of refractory bricks.