Refractory materials are the main components of glass melting furnaces, which have a decisive influence on glass quality, energy consumption and product costs. The future of glass melting technology depends to a certain extent on the advancement of refractory manufacturing technology and the improvement of product quality.
For large float lines, the glass furnace is usually composed of an L-shaped suspended wall (usually using silica bricks), a melting part (the area directly in contact with the molten glass should use electric fused bricks, and the top part uses silica bricks or electric Melting bricks), necks (usually using silica bricks), cooling parts including ear pools (corundum materials are usually used where they are in direct contact with molten glass, and silica bricks or corundum are used where they are not in direct contact with molten glass), annealing kilns, Regenerator (consisting of high-alumina bricks, clay bricks, directly combined with magnesia-chrome bricks) and other parts, the commonly used insulation materials are as follows.
Silica brick for glass kiln:
Silica bricks are widely used in glass melting furnaces, and the main component is silicon dioxide (SiO2). The silica brick used in the glass melting furnace requires a SiO2 content of 94% or more, the maximum operating temperature is about 1600~1650℃, and the density is 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 silicon bricks is mostly white crystals, and the microscopic composition is tridymite crystals. Because silicon bricks will undergo crystallization conversion and volume expansion at high temperatures, especially at 180-270℃ and 573℃, the crystallization conversion will be more severe. Because it is fierce, it is necessary to adapt to the crystal transformation of silica bricks and take appropriate measures such as elastic strips during the baking and cold repair process. The silicon brick masonry should be left with expansion joints. The working temperature of silica brick is about 200℃ higher than that of clay brick, but its resistance to corrosion of molten glass and alkaline flying materials is poor. Therefore, it is used for masonry structures such as masonry, parapets and small furnaces. When building, use high-silicon refractory mud or silica brick powder and other materials close to the composition of silica bricks as the cementing material.
Zircon bricks for glass kiln:
Zircon refractory brick is made of natural zircon sand (ZrSiO2) as raw material. The zircon silicate brick is fired in 1600℃ furnace with the zircon content more than 60%. The Zircon bricks have compact crystal structure, high density and high mechanical strength. Since it has good thermal shock stability, low re-fire shrinkage and high temperature creep, and has extremely high chemical stability and resistance to alkaline media, it is widely used in important position of glass furnace
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 cooling pool walls, regenerator walls, and regenerator walls.
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 2.2-3 2g/cm3, the open porosity is 1%-12%, and the maximum operating temperature is 1500~1700℃. Sintered mullite is mainly used for masonry walls of regenerators. Fused mullite is mainly used to build pool walls, observation holes, wall stacks, etc.
Fused cast AZS Blocks:
Fused cast AZS blocks are also called fused cast ziconium corundum blocks. Generally, fused zirconium corundum blocks 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 use temperature is about 1700℃. The fused zirconium corundum bricks with 33% and 36% zirconium content are used for masonry of kiln pool walls, flame space breast walls, small furnace vents, small furnace flats, small furnace stacks, tongue hangings, etc., with a zirconium content of 41 % Of the fused corundum bricks are used to build the corners of pool walls, liquid holes and other parts where the refractory materials are eroded most severely by glass liquid. This material is the most widely used fused cast refractory material in the glass industry.
Fused alumina brick:
It mainly refers to fused α, β corundum and fused β corundum fused cast refractory bricks, which are mainly composed of 92%~94% Al2O3 corundum crystal phase, density 2.9~3.05g/cm3, apparent porosity 1%~10%, the highest The operating temperature is about 1700°C. Fused alumina has excellent resistance to glass dialysis and hardly pollutes molten glass. It is widely used in the working part pool wall, pool bottom, runner, working part channel wall, and channel bottom of the glass melting furnace that contact glass liquid and require no refractory pollution.
Magnesia Refractory Bricks:
Magnesia Refractory Bricks mainly refer to magnesia bricks, aluminum magnesia bricks, magnesia chrome bricks, and forsterite bricks. Its performance is corrosion resistance to alkaline materials, and its refractoriness is more than 1700 ℃. It is widely used in the upper wall of the regenerator of the glass melting furnace, the regenerator trellis, the grid body, and the partial structure of the small furnace.
Fused quartz Bricks:
Fused quartz bricks also called fused silica bricks are mainly composed of SiO2, with a maximum content of over 99%, a density of 1.9~2g/cm3, a refractoriness of 1650°C, a working temperature of about 1600°C, and resistance to acid corrosion. It is used to build the pool wall of acid boron glass. Flame space thermocouple hole bricks, etc.
Insulation bricks for glass furnace:
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, a large amount of insulation materials are required for comprehensive insulation. In particular, the pool wall, pool bottom, chute and wall in the regenerator, melting part, working part, etc. must be insulated to reduce heat dissipation. The thermal insulation brick has a large porosity, a very light weight, and a density not exceeding 1.3g/cm3. Because the heat transfer performance of air is very poor, the thermal insulation brick with a large porosity has a thermal insulation effect. Its thermal conductivity is 2 to 3 times lower than that of general refractory materials, so the greater the porosity, the better the insulation effect. There are many different types of thermal insulation bricks, including clay thermal insulation bricks, silicon thermal insulation bricks, high alumina thermal insulation bricks and so on.
Fireclay bricks
The main components of fireclay bricks are Al2O3 and SiO2. The content of Al2O3 is between 30% and 45%, the content of SiO3 is between 51% and 66%, the density is between 1.7 and 2.4g/cm3, and the apparent porosity is between 12% and 21%, the highest The operating temperature is 1350~1500℃. In the glass industry, clay bricks are used to build the bottom of the kiln. The pool wall of the working part and the passage, the wall of the regenerator, the trellis, the lower checker brick and the flue. As the temperature rises, the volume of clay bricks will also expand. When the temperature exceeds 1450℃, the volume will shrink again.
As a professinal manufacturer of refractory material for glass furnace, Zhengzhou SNR refractory Co.,ltd will always keep improving to provide the customers with better products and service. If any question or demand of refractory material, please feel free to contact us: info@snrefractory.com
