What are the characteristics of commonly used refractory materials for glass furnaces?

Silica brick for glass furnace

Silica bricks are used more in glass melting furnaces, and the main component is silicon dioxide (SiO2). Silica bricks used in glass melting furnaces require a SiO2 content of more than 94%, a maximum operating temperature of about 1600~1650℃, and a density of 1.8~1.95g/cm3. The apparent porosity is required to be less than 22%. The larger the porosity, the worse the quality of the silica brick. The appearance of silica bricks is mostly white crystals, and the microscopic composition is tridymite crystals. Because silica bricks undergo crystal transformation and volume expansion at high temperatures, especially at 180-270 °C and 573 °C, the crystal transformation is more difficult. It is intense, so in the process of baking kiln and cold repairing, it is necessary to adapt to the crystallization transformation of silica bricks and take appropriate measures such as elastic ties. Silica brick masonry should have expansion joints.

The working temperature of silica brick is about 200 ℃ higher than clay brick, but it has poor corrosion resistance to glass liquid and alkaline fly material, so it is used to build structures such as large arches, breast walls and small furnaces. When masonry, high-silicon refractory mud or silica brick powder should be used as cementing materials, which are close to the composition of silica bricks.

Clay bricks for glass furnace

The main components of clay bricks are Al2O3 and SiO2, Al2O3 content is between 30%~45%, SiO2 is between 51%~66%, density is 1.7~2.4g/cm3, apparent porosity is 12%~21%, the highest operating temperature is 1350~1500℃. In the glass industry, clay bricks are used to build the bottom of kilns,the pool wall of the working part and the passage, the wall of the regenerator, the arch, the lower checker brick and the flue. As the temperature increases, the volume of clay bricks also expands. When the temperature exceeds 1450°C, the volume shrinks again.

 

High alumina brick

The main components of high alumina bricks are also SiO2 and Al2O3, but Al2O3 should be greater than 46%. It is made of corundum, high alumina bauxite or sillimanite minerals (Al2O3-SiO2) as raw materials. The density is 2.3~3.0g/cm3, the apparent porosity is about 18%~23%, and the maximum operating temperature is 1500~1650℃. When the porosity of the high alumina brick is low, the corrosion resistance is better. High-alumina bricks can be used to build the pool wall of the cooling section, the regenerator, and the regenerator wall.

 

Mullite brick

The main component of mullite brick is Al2O3, and its content is about 75%. Because it is mainly mullite crystal, it is called mullite brick. The density is 2.7-3 2g/cm3, the open porosity is 1%-12%, and the maximum operating temperature is 1500~1700℃. Sintered mullite is mainly used to build regenerator walls.

Fused mullite brick is mainly used for building pool walls, observation holes, wall stacks, etc.

Fused zirconium corundum brick

Fused zirconium corundum bricks are also called white iron bricks. Generally, fused zirconium corundum bricks are divided into 3 grades of 33%, 36% and 41% according to the content of zirconium. The zirconium corundum bricks used in the glass industry contain 50%~70% Al2O3 and 20%~40% ZrO2. The density is 3.4~4.0g/cm3, the apparent porosity is 1%~10%, and the maximum operating temperature is about 1700 ℃. Fused zirconium corundum bricks with zirconium content of 33% and 36% are used to build kiln pool walls, flame space parapets, small furnace craters, small furnace flats, small furnace stacks, tongues, etc. The zirconium content is 41% fused corundum bricks are used to build the corners of the pool wall, liquid holes and other parts where the glass liquid has the most severe erosion on the refractory material. This material is the most widely used fused cast refractory in the glass industry.

Fused alumina brick

It mainly refers to fused α, β corundum and fused β corundum fused cast refractory bricks. The operating temperature is around 1700°C.Fused alumina brick has excellent resistance to glass dialysis and hardly pollutes the glass liquid. It is widely used in the working part pool wall, pool bottom, flow channel, working part forehearth pool wall, forehearth pool bottom and other parts of glass melting furnace that are in contact with glass liquid and require no refractory pollution.

 

Quartz brick

The main component of quartz brick is SiO2, its content is more than 99%, the density is 1.9~2g/cm3, the refractoriness is 1650℃, the working temperature is about 1600℃, and it is resistant to acid erosion.It is used to build the pool wall of acid boron glass, the flame space thermocouple hole brick, etc.

 

Alkaline refractory

Alkaline refractories mainly refer to magnesia bricks, alumina magnesia bricks, magnesia chrome bricks, and forsterite bricks. Its performance is resistant to the erosion of alkaline materials, and the refractoriness is 1900-2000 °C. It is widely used in the upper wall of the regenerator of the glass melting furnace, the checker of the regenerator, the body of the regenerator, and the partial structure of the small furnace, etc.

 

Insulation brick for glass kiln

The heat dissipation area of the glass melting furnace is large and the thermal efficiency is low. In order to save energy and reduce consumption, it is necessary to use a large number of thermal insulation materials for comprehensive thermal insulation. Especially in the regenerator, melting part, working part and other parts of the pool wall, pool bottom, arches, walls should be insulated to reduce heat dissipation. The porosity of thermal insulation bricks is very large, the weight is very light, and the density does not exceed 1.3g/cm3. Due to the poor heat transfer performance of air, thermal insulation bricks with large porosity have a thermal insulation effect. Its thermal conductivity is 2 to 3 times lower than that of general refractory materials, so the larger the porosity, the better the thermal insulation effect. There are many different types of thermal insulation bricks, including clay thermal insulation bricks, silica thermal insulation bricks, high alumina thermal insulation bricks, etc.

Zhengzhou Shennan Refractory Company (SNR) as a professinal refractory materials manufacturer is founded in 1986 and located in Zhengzhou China. We are dedicated to the development, manufacture, management and service in the field of refractory materials for glass industry,iron and steel industry and other industries.At the same time, we have a professinal team to provide the solution and service of glass furnace design,furnace construction,and furnace renovation and upgrading.Any demands ,please don't hesitate contact with us. 

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