High-temperature-resistant inorganic adhesives have been widely used in the heat-resistant bonding of metals, ceramics, graphite, oxides, and other materials. Easy to use, used for direct bonding of high-temperature resistant materials. The coating can be sprayed directly on the surface of a high-temperature substrate of 400-1000°C. When the water evaporates, the coating will instantly adhere to the surface of the substrate, forming a uniform and dense high-temperature resistant protective coating with good thermal shock resistance.
High-Temperature Gunning Refractory Material for Lining Repair
It also has good strength at high temperatures, with an average compressive strength of 90Mpa and a tensile strength of 8Mpa at 1300°C. After applying high-temperature inorganic adhesive on the kiln windshield, hanging parts, and cracks, the bond will be firm and will not cause any damage to the kiln lining. Adhesives are easy to use and play a very important role in the normal operation of the furnace. It has been successfully used in rotary kilns, drying furnaces, and combustion chambers in the cement industry. Heating furnaces and smelting furnaces in the machinery industry. Electric furnaces, roasters, and blast furnaces in the metallurgical and chemical industries. Tunnel kilns in the ceramic industry, boilers in the thermal power industry, and other types of kilns.
The high-temperature-resistant expansion glue uses a high-temperature inorganic silicate modified solution as the film-forming material, and is composed of rare earth oxides, re-expanded mullite, and vaporized SiO2 powder as fillers. The cured coating film has a temperature resistance of up to 2200°C and can maintain good thermal stability, bonding performance, wear resistance, and corrosion resistance in high-temperature environments. The coating has a high linear expansion coefficient, and the coating expansion rate can reach 15% under high-temperature conditions.
The kiln lining protective coating uses the company’s special high-temperature resistant inorganic silicate modified solution as the film-forming substance and is composed of nano-scale alumina, silicon carbide, rare earth oxides, ceramic fibers, etc. The cured coating film has high-temperature resistance, which can reach 1800°C, thermal shock resistance, high adhesion, good heat insulation, strong aging resistance, and convenient construction. It can be sprayed directly on the surface of various materials lining the kiln, including insulation bricks, castables, metals, ceramics, refractory fibers, quartz sand, silicon carbide, quartz glass, etc.
High-aluminum poly-light brick is a high-performance lightweight thermal insulation material with excellent performance and wide application prospects. Rongsheng Refractory Materials Manufacturer has an in-depth understanding of the characteristics, application fields, and preparation processes of high-alumina poly-light bricks. It can provide high-performance lightweight insulation materials for high-temperature industrial furnaces, including high-aluminum poly-light bricks, mullite insulation bricks, micro-nano insulation series, etc.
High-Alumina Poly Light Insulation Brick
Characteristics of High Alumina Poly Light Bricks
High-aluminum poly light brick is a kind of lightweight brick made of high-aluminum clinker as the main raw material, adding an appropriate amount of polymer and additives, and sintering at high temperatures. It has the following characteristics:
Lightweight and high strength. High-aluminum poly-light bricks are lightweight and high-strength. Its density is only 0.6-1.0g/cm3, but its strength is as high as 5-20MPa.
High fire resistance. The fire resistance of high-alumina poly light bricks is as high as 1300°C, which can meet the protection needs of high-rise buildings and high-temperature equipment.
Heat insulation. High alumina poly-light bricks have excellent thermal insulation properties. Its thermal conductivity is only 0.2-0.4W/(m·K), which can reduce the energy consumption of buildings.
Strong corrosion resistance. High alumina poly light bricks can resist the erosion of various chemical substances, such as acids, alkalis, salts, etc. Therefore, it is widely used in the chemical industry and other fields.
Convenient construction. High alumina poly-light bricks have standard sizes and are easy to install and construct. At the same time, its lightweight also facilitates transportation and installation.
Application Fields of High Alumina Poly Light Bricks
High alumina poly light bricks are used in kiln linings in metallurgy, machinery, ceramics, chemical, and other industries. It is not corroded by solutions and is used in insulation layers. It is an ideal energy-saving product.
RS High-Alumina Poly Light Insulation Brick
Application Advantages of High Alumina Poly Light Bricks
Lightweight. Compared with traditional refractory bricks, high-alumina poly-light bricks are lighter in weight and are easier to transport and construct. It reduces the overall load of the furnace body and reduces the requirements for the furnace body support structure.
Reduce energy consumption. High-alumina poly-light bricks have good thermal insulation properties and can effectively reduce heat transmission and thermal radiation losses. By using high-aluminum polylight bricks, fuel consumption can be reduced and energy efficiency improved.
Extended service life. High-alumina polylight bricks have excellent fire resistance and corrosion resistance, which can extend the service life of the furnace body. It can reduce ablation and wear inside the furnace and ensure the stability and safety of the furnace structure.
The technology is widely used. Due to the characteristics and advantages of high-alumina poly-light bricks, it has been widely used in various industrial fields. Such as steel, metallurgy, chemical industry, building materials, and other industries, especially suitable for kilns and furnaces in high-temperature environments.
Preparation Technology of High Alumina Poly Light Bricks
The preparation process of high-alumina poly light bricks mainly includes the following steps:
Ingredients. Mix high-aluminum clinker, polymers, additives, and other raw materials evenly according to a certain proportion.
Forming. Put the mixed raw materials into the mold and press it into shape.
Dry. The molded green body is dried to remove moisture from the green body.
High-temperature sintering. The dried green body is put into a high-temperature kiln for sintering, turning it into a lightweight brick with excellent properties.
Finished product inspection. Conduct quality inspection on high-alumina poly-light bricks, and qualified products can be shipped out of the factory.
Rongsheng High Alumina Poly Light Brick Manufacturer
As a high-performance lightweight thermal insulation material, high-aluminum polylight bricks have broad application prospects and important practical value. This article introduces the characteristics, application fields, and preparation process of high-aluminum poly-light bricks, providing a reference for readers to understand high-aluminum poly-light bricks. With the continuous development of science and technology, it is believed that high-alumina poly-light bricks will be more widely used in the future. To purchase high-quality lightweight insulation products, please contact us.
The main purpose of the carbon fiber graphitization treatment furnace is to induce the graphitization crystal orientation of the fiber to increase the elastic modulus of the carbon fiber. The production of carbon fiber is carried out in a high-temperature sealed graphitization furnace. Both ends of the furnace are sealed with high-purity argon gas. The heating element is made of graphite material, and the graphite tube is both the furnace tube and the heating element of the high-temperature furnace. The heating temperature is generally between 2500°C and 2800°C.
The life of the graphitization furnace depends on the properties of the refractory material. The furnace shell of the graphitization furnace is rolled from ordinary carbon steel plates. Special refractory materials are used as insulation materials in the shell, which are generally composed of heat-resistant layer, heat insulation layer and protective layer. In order to ensure the airtightness of the furnace, the inner surface of the refractory lining must be round and smooth. Otherwise, the air tightness of the lining will be affected and it will not be resistant to airflow erosion. In addition, there are temperature measuring holes and pressure measuring holes on the furnace.
Graphitization Furnace Corundum Material
When using the graphitization furnace, great attention must be paid to temperature changes caused by rapid cooling and rapid heating. When production is stopped for maintenance, if the furnace cannot be kept warm by gas or other heat sources, the front and rear of the furnace must be tightly blocked to prevent the furnace from bursting due to rapid cooling. Prevent metal objects from entering the furnace and contacting the corundum lining, because metal and corundum materials generate a low melting point eutectic, which reduces the refractoriness and causes partial melting of the furnace body. The cooling water jacket must be designed reasonably to prevent burnout due to local overheating and to prevent water from entering the furnace and causing the furnace body to explode. In addition, carbon black fillers must not be affected by moisture. The graphitization furnace must be covered, and the flue gas must be treated to meet standards before it can be discharged.
Special insulation materials are selected as insulation materials for high-temperature graphitization furnaces, which refer to single materials such as high-purity oxides, non-oxides and carbon with melting points above 1800°C. Or they are made of various composite materials and produced using traditional production techniques or special production techniques. Its products are new refractory materials with special properties and special uses. The main function of high-temperature graphitization furnace insulation materials is to reduce heat energy loss and save energy. Ensure the needs of production process and improve equipment capabilities. Improve working conditions, achieve safe production, and extend the operation period of equipment.
Graphitization furnace insulation materials play the dual roles of heat preservation and electrical insulation in the graphitization furnace. Insulation materials have a very important influence on the temperature rise of graphitization furnace. The quality and thickness of the insulation material determine to a large extent the thermal energy utilization efficiency of the graphitization furnace and the temperature difference in various parts of the furnace, and determine the energy consumption during graphitization of carbon fiber. Insulation materials are also related to the safety and performance of refractory masonry and furnace building structures. The electrical insulation of the insulation material is key to ensuring that electric current acts effectively on the furnace tube. It requires low thermal conductivity and good thermal insulation performance. It has high resistivity and good electrical insulation properties. Does not hinder the discharge of gas in the furnace. Does not react with products in the furnace at high temperatures. Cheap and easy to purchase in large quantities.
Corundum (α-AL2O3) is produced by electrofusion or sintering of industrial alumina or bauxite ore. The mineral composition of corundum is a-AL2O3, its density is about 3. 85 ~ 4. 01g/cm3, its melting point is 2050°C, and its deformation temperature is 1750°C. It has good thermal conductivity, good electrical insulation and chemical stability, and can resist the erosion of NaOH, Na2CO3, etc. And it has the ability to resist the action of reducing agents (such as hydrocarbon chemicals, hydrogen and free metals, etc.) below 1800°C. It has the characteristics of high mechanical strength under high temperature, good thermal shock resistance, strong corrosion resistance, and small thermal expansion coefficient. It is the best lining material for various high temperature furnaces.
[Tips]Carbon fiber is a fibrous carbon material. Its biggest feature is its high elastic modulus and light weight. The deformation resistance of high elastic modulus carbon fiber is more than 2 times greater than that of steel and 5 to 6 times greater than that of aluminum alloy. The specific gravity of carbon fiber is less than 1/4 of steel and 1/2 of aluminum. Carbon fiber is a fiber with a carbon content of more than 90%, which is made from polyacrylonitrile fiber, pitch fiber, viscose fiber or phenolic fiber through oxidation, carbonization and other processes. Those with a carbon content higher than 99% are called graphite fibers.
Lightweight mullite insulation brick is a kind of insulation brick, which is an insulating refractory brick made of mullite as aggregate. Mullite insulation bricks are white, can be directly exposed to flames, and have high refractoriness. Mainly used in hot blast furnace tops, blast furnace shafts, and bottoms, glass melting furnace regenerators, ceramic sintering kilns, dead-end furnace linings in petroleum cracking systems, etc.
Lightweight mullite insulation bricks
The dimensions of conventional lightweight mullite insulation bricks are 230 x 114 x 65mm. Common models of lightweight mullite insulation bricks include JM23, JM26, JM28, and JM30. The main difference between them is the content of aluminum oxide and iron oxide. Different contents can withstand different refractory temperatures, thermal conductivity, and thermal expansion rates.
Low Iron JM23 JM26 JM28 Mullite Insulation Bricks
Characteristics of low-iron JM23 lightweight mullite insulation bricks
Low thermal conductivity and good thermal insulation effect.
Low thermal melt. Due to low thermal conductivity, mullite series lightweight insulation bricks store very little heat energy. The energy-saving effect is obvious in intermittent operation.
Low impurity content and very low oxide content such as iron metal. Therefore, the fire resistance is high. The higher aluminum content allows it to maintain good performance under a reduced atmosphere.
High hot compressive strength.
The appearance dimensions are precise, speeding up the masonry work and reducing the usage of refractory mud. The strength and stability of the masonry are ensured, thereby extending the life of the lining.
It can be processed into special shapes to reduce the number of bricks and joints.
RS refractory material manufacturer can provide lightweight mullite insulation bricks, with standard sizes and customized sizes. Low iron JM model, contact us for a free quote and sample.
Rongsheng Mullite Insulation Brick
Lightweight mullite insulation bricks for industrial kilns
Lightweight mullite insulation bricks for industrial kilns are a widely used energy-saving material. Has the following characteristics. Lightweight. The density of mullite insulation bricks is less than or equal to 1000 kg/cubic meter. It is much lighter than traditional stone or metal thermal insulation materials, which can reduce the burden and weight of the kiln. Insulating properties. Mullite insulation bricks have high porosity and large porosity, which can effectively improve thermal insulation performance and reduce heat loss and transmission. Durability. Mullite insulation bricks have very good durability due to their porous structure. Its stability and durability can be guaranteed even in high-temperature environments. Easy to process. Mullite insulation bricks can be mechanically crushed or pressed into different shapes and sizes for easy use and processing. In industrial kilns, mullite insulation bricks are often used for thermal insulation and preventing heat loss. This material can effectively reduce the energy consumption and cost of the kiln, and improve production efficiency and safety.
Low-iron JM23 lightweight mullite insulation brick manufacturer and RS refractory insulation brick manufacturer produce mullite lightweight insulation bricks with industrial Al₂O₃ powder, clay, well-sintered bauxite, and kyanite as the main raw materials. Add wood chips (1mm screen) and polystyrene balls (diameter 0.2~0.5mm) to prepare lightweight bricks. It has the characteristics of high-temperature strength, low porosity, and corrosion resistance. Widely used in high-temperature industrial kiln linings.
Mullite insulation brick is a new type of thermal insulation refractory material, low iron JM23 lightweight mullite insulation brick. According to the difference in density, it can be divided into lightweight mullite insulation bricks and corundum mullite bricks (also called heavy mullite insulation bricks). Mullite insulation bricks are divided into JM23, JM26, JM28, and JM30 according to their grades. Mullite insulation bricks are divided into 1350 mullite insulation bricks, 1450 mullite insulation bricks, 1550 mullite insulation bricks, etc. according to different use temperatures. Moreover, 1550 mullite bricks can be directly exposed to flames and have the characteristics of high-temperature resistance, small thermal conductivity, and significant energy-saving effects.
Mullite insulation brick product price
The price of mullite insulation brick JM23 is 2,600 yuan/ton, and the use temperature is 1,350°C.
The price of mullite insulation brick JM26 is 3,200 yuan/ton, and the use temperature is 1,450°C.
The price of mullite insulation brick JM28 is 4200 yuan/ton, and the use temperature is 1550℃.
The price of mullite insulation brick JM30 is 4,800 yuan/ton, and the use temperature is 1,600°C.
JM23 lightweight mullite insulation bricks, the body density of lightweight mullite insulation bricks is 0.6, 0.8, 1.0, 1.2g/cm3. Mullite lightweight thermal insulation bricks are suitable for high air temperature metallurgical hot blast furnaces, molten steel impactors, slag lines, the roof of steelmaking electric arc furnaces, the forehearth of glass melting furnaces, regenerator arches, and superstructures. The lining of ceramic sintering kilns, ceramic roller kilns, tunnel kilns, electric porcelain drawer kilns, dead-end furnaces of petroleum cracking systems, glass crucible kilns and various electric furnaces. The walls of the clarifier can be in direct contact with flames.
To learn more about RS low-iron JM23 lightweight mullite insulation bricks, please contact us.
The selection of refractory materials for hot blast stoves is mainly determined by the temperature of the hot blast. When the wind temperature is lower than 900°C, clay bricks are generally used, and their service life can reach about 20 years. When the air temperature is between 900 and 1100°C, high-alumina bricks, mullite bricks, or sillimanite bricks are used for the furnace lining and checker bricks in the high-temperature part. When the air temperature is higher than 1100°C, high alumina bricks, mullite bricks, and silica bricks are generally used as furnace lining or checker bricks.
In recent years, newly built or renovated blast furnace hot blast stoves in various countries mainly adopted external combustion type. The supply air temperature is 1200~1350℃, and the vault temperature is generally 1500~1550℃, even close to 1600℃. Therefore, the high-temperature parts of the furnace lining and the upper layer of checker bricks are generally constructed with silica bricks, which has better results.
Low Creep High-Alumina Bricks for Hot Blast Stoves
What is the Alumina Content of High-Alumina Refractory Bricks Used in Hot Blast Stoves?
Regarding the high alumina refractory bricks with alumina content used in a new hot blast stove, it is generally recommended to choose high alumina refractory bricks with higher alumina content. High-alumina refractory bricks usually have an alumina content between 48% and 80%, which can provide better fire resistance and corrosion resistance.
The use of high alumina bricks in the medium temperature zone and high and low temperature alternating zones of hot blast furnaces.
The medium temperature area of the hot blast stove (600~1150℃) refers to the middle part of the flame in the combustion chamber, and in the regenerative type it refers to the middle part of the checker bricks, the transition section from high temperature to low temperature. In this area, low creep high alumina bricks or high-grade andalusite bricks are generally selected. For internal combustion and external combustion hot blast stoves, the area from the top of the burner to the vicinity of the hot blast outlet. As well as the top-fired hot blast stove, the space enclosed by the inner wall of the burner – the pre-combustion chamber, is a high and low temperature alternating area (35~1100℃). The temperature changes in this area are mainly caused by the mutual conversion of the “combustion-air supply” cycle of the hot blast stove. It is advisable to choose andalusite or cordierite bricks with good thermal shock resistance.
The hot air ducts of hot air stoves are also traditionally made of andalusite bricks. In recent years, with the increase in wind temperature, refractory bricks using andalusite-mullite composite have also appeared.
Kinds of Low-Creep High-Alumina Bricks for Hot Blast Furnace
There are many types of high alumina bricks, and their properties vary greatly depending on the Al2O3 content and crystal form.
Low creep high alumina bricks
The main characteristic of low creep high alumina bricks is their good creep resistance. Domestic production of low creep high alumina bricks generally uses bauxite as the main raw material. The “three stone” minerals (andalusite, sillimanite, and kyanite) are additives. Among the “three stone” minerals, the addition of andalusite is more common.
Adding tristone to solve the creep resistance problem of high-alumina products lies in the final mulliteization of tristone. During the firing process of high alumina bricks, the three stones will undergo mullite formation, and the reaction will directly generate mullite. The accompanying SiO2 will react with high-alumina materials again, causing secondary mulliteization. After the final firing is completed, the three stones in the crystal phase will be completely converted into mullite, and n(Al2O3)/n(SiO2) is close to 3:2, forming a stable columnar mullite crystal phase structure. This structure determines that high alumina bricks have good creep resistance.
Andalusite bricks
Andalusite bricks have good high-temperature properties, and their high-temperature creep resistance is better than high-alumina bricks and most mullite bricks. Moreover, the volume expansion associated with high-temperature mullite formation is small, and it has good thermal shock resistance. It is an ideal low-creep refractory material.
The main raw material used in the production of andalusite bricks is andalusite, and the proportion is generally higher than 40%. If it is made into andalusite-mullite composite brick, a part of mullite or corundum should also be added. If the mullite raw material is synthetic mullite. The crystals should be thicker to reduce the number of grain boundaries, weaken the slip of the crystals at high temperatures, and enhance the creep resistance of the bricks.
Cordierite bricks
The linear expansion coefficient of cordierite bricks is small. The linear expansion coefficient at 20~900℃ is (1.25~1.92)×10-6℃-1, and it has good thermal shock resistance. However, the refractoriness of cordierite is low, only 1370℃. When the firing temperature is too high, a glass phase is easily produced. Pure cordierite bricks cannot be well used in high and low-temperature alternating areas due to their low operating temperature range. In actual production applications, cordierite is often added as an auxiliary raw material, which has a significant effect on improving the thermal shock resistance of bricks.
In the glass manufacturing industry, the same glass products and the same glass kiln have different maintenance times, repair parts, and kiln service life. What are the causes of corrosion of fused AZS refractory brick pool walls in glass furnaces? Normal material erosion is within the designed use time range of the material, while abnormal material erosion is a malignant condition that occurs in a location that is not necessarily fixed and within the designed service life of the material. The hidden negative effects of these situations are huge, affecting not only the economic interests of glass companies. To a certain extent, it also affects and restricts the healthy development of the entire glass industry.
Fused Cast AZS Brick #36
Harmful Components and Corrosion Mechanisms in Fused AZS Refractory Bricks
Glass phase
The phase composition of fused cast azs refractory products is baddeleyite, corundum, a small amount of mullite, glass phase, and pores. In the manufacturing process of fused cast azs refractory bricks, in order to reduce and eliminate residual thermal stress, a certain amount of glass phase is required in the product as an absorbent to buffer thermal stress. However, the existence of the glass phase also brings some disadvantages. In terms of the resistance of refractory materials to the erosion of glass liquid, the glass phase is the weak link. During the erosion process, the glass phase first precipitates and is replaced with the high-temperature glass melt, thereby accelerating the erosion of the crystal. Under high-temperature use conditions, the glass phase will also ooze out and release bubbles, thereby contaminating the glass melt.
Carburizing
Generally, zirconium corundum fused cast refractories brick products produced by the reduction method have serious carburization. According to literature reports, the corresponding carbon content can be judged according to the color of the cross-section of the refractory material: light gray 0.03%~0.06%, off-white <0.03%, gray 0.08%~0.18%, dark gray 0.15%~0.19%. Even products produced by advanced oxidation methods (long arc and oxygen blowing) contain some carbon (<0.01%). Carburizing exists in the form of carbides, mixed nitrogen compounds, sulfides, solid carbon, and residual reducing gases. When used under oxidizing conditions, gas is released, causing the glass phase to seep out and the temperature to decrease. When the AZS refractory brick contains a large amount of glass phase (#33 is generally about 20%), it will soften and ooze out at temperatures above 1100°C. And as the temperature increases, the loss intensifies. The exudation of the glass phase is related to the carbon, carbide, low-priced iron and titanium, and other impurities present in the brick. When there is an oxidizing atmosphere in the kiln, oxygen diffuses to the bricks and reacts with these impurities to release CO2, SO2, and other gases. These gases squeeze out the molten glass phase and form nucleation bubbles on the surface. The crystalline phase is lost due to the loss of the combination of the glass phase. This is the cause of the erosion of AZS refractory bricks.
fused AZS refractory bricks for glass furnaces
The entry of harmful components in the production process of fused AZS refractory bricks
Sand inclusion and other foreign matter enter the product
For the casting model produced by adding quartz sand and water glass, the sand inclusion phenomenon refers to the high-temperature molten liquid gradually rising in the model during pouring, similar to that of pool wall bricks. The part not covered by the melt undergoes high temperature, and the sand on the surface breaks away in lumps and falls into the melt, forming a sand inclusion phenomenon. Due to the high temperature of 1750℃, the added sand skin exists in the glass state inside the product. In addition, there is a flat material program during the melting process. The flat material tool is a cast steel drill. If the steel drill is exposed to high-temperature molten liquid for a long time, its texture will soften. When prying the unmelted material block, the steel drill may break. The broken steel drill may be completely melted in the melt, increasing the iron content in the product. It is also possible that it is not completely melted and enters the product during pouring.
Oxidation uniformity of fused AZS refractory bricks
The degree of oxidation or uniformity of oxidation of fused AZS refractory bricks is one of the key indicators of whether the quality of the product is excellent. Each manufacturer has complete system requirements in formulating the oxygen-blowing process, but most of them have defects in setting the position of the oxygen lance. It is an inevitable phenomenon that the oxygen lance hole is blocked during oxygen blowing. Oxygen guns generally have seven oxygen outlets distributed around or at the bottom of the ball head. When one or several oxygen outlets are blocked, uneven oxidation of the product will occur. It can be seen if it is serious, but it is difficult to judge intuitively if it is not serious. Even on a single brick, there will be color inconsistency. Dark color indicates a large amount of carburization, and light color indicates a small amount of carburization. The clogging of the oxygen lance hole directly leads to poor oxidation effect of the product and increased carburization of the product. When the glass furnace is operating, the glass phase is precipitated along with bubbles, mostly carbon dioxide gas.
The formation of gaps in glass furnaces
1 Grinding or masonry kiln
When the product is processed and ground, the flatness of the machine tool surface cannot meet the requirements after aging, causing the product to be convex or recessed in the middle. During pre-assembly, the gap is evened up and down, making it seem that the gap is not large. During the kiln masonry construction, due to foundation flatness errors or defects in the bottom of the product, the builder’s negligence caused the bottom of the product to be elevated. When the final kiln is baked, the expansion of the product may not be shaped according to the uniform gap, which may cause the gap at the bottom or upper part of the pool wall brick to be significantly enlarged.
2 Kiln sill specification design
In a glass kiln, improper arrangement of kiln sill bricks will also cause the kiln sill to be deformed due to the impact of glass liquid. Since the kiln ridge bricks must withstand the impact of the molten glass turning over, the kiln ridge must have sufficient thickness and support. The height of the supporting bricks needs to exceed 1/2 of the height of the kiln sill bricks for more effective support. When the kiln sill bricks are deformed by the impact of glass liquid, the gap between the bricks will become wider.
3 kiln deformation
In the temperature range of the kiln, the zirconium component in the fused AZS refractory brick transforms from the monoclinic phase to the tetragonal phase at 1100°C. Some volume changes will occur at this time. The temperature decrease when the temperature is unstable will cause some volume changes in the opposite direction. This temperature fluctuation causes the reverse volume change of the zirconium component, which is the fundamental reason for the explosion of the product. When baking the kiln, a heat preservation stage is usually set at 1100°C to fully convert the volume of the fused AZS refractory bricks.
To sum up,
the reasons for the erosion of the fused AZS refractory brick pool wall in glass furnaces are as follows. Listed here for reference by refractory material manufacturers and glass production companies to choose a suitable solution for their own glass furnace refractory lining. Reduce maintenance costs, increase production capacity, and create more economic benefits.
(1) The glass liquid is seamless. The gaps between the products will cause mechanical erosion of the glass liquid backflow. When glass precipitates in the gaps, it is accompanied by the precipitation of bubbles, which intensifies the erosion of the gaps in the product. When accepting the entire kiln, the stricter the requirements for gaps, the better.
(2) When constructing the kiln, ensure that the foundation is stable and there must be no overhead products. The expansion joints should be reserved reasonably or the masonry personnel should strictly control their work.
(3) The height and width specifications of the inner protective bricks of the kiln sill bricks should be appropriately increased. The protective bricks must effectively play a supporting role.
(4) The production process of fused AZS refractory bricks requires effective system management to determine whether the oxygen lance outlet holes are blocked. The position of the oxygen lance should be set to facilitate observation of the status of the oxygen lance outlet hole.
(5) For sand molds made of quartz sand and water glass, the proportion of water glass should not be less than 8%. A small amount of water glass will cause the surface sand to fall off during pouring, which will bring inherent hidden dangers to the product. It is best to choose fused AZS refractory bricks made from resin sand models.
The hazards of magnesia-chrome waste bricks. Cr in magnesia chrome bricks has many beneficial effects. However, under high temperatures, and alkaline and oxidizing atmospheres, some chromium will be converted into water-soluble hexavalent chromium, causing serious harm. Cr+ is highly harmful to human skin and mucous membranes. It can cause papules, ulcers, nasal septum perforation, and respiratory inflammation. It can also cause skin cancer and lung cancer. For example, the risk of lung cancer among workers working with chromic acid and chromium-containing pigments is 10 to 30 times higher than that of the general population.
Magnesia Chrome Bricks
In cement rotary kilns, the areas where refractory materials corrode the fastest are mainly the fire point at 9.5~16m and the location without kiln skin at 27~33m. However, the waste bricks dismantled from 3~9.5m and 16~25m are the ones that emit the most Cr+. The Cr+ carried by these two parts of waste bricks accounts for 92% of the total discharged hexavalent chromium, while the Cr+ discharged from other parts only accounts for 8%.
A 4000t/d cement kiln dismantles 181t of magnesia-chrome bricks at one time, and the waste bricks carry an average of Cr+183kg. The average Cr6+ content is about 1kg/t or 1000mg/kg, which is 20,000 times higher than the Cr6+ content of 0.05 mg/L allowed by national environmental standards for Level IV. Therefore, a single discharge of magnesia-chromium bricks can harm 3.6 million tons of pure water. In other words, 2.5 tons of water will be harmed for every 1 ton of clinker produced! It can be seen that the harm of magnesia-chrome waste bricks to the environment and the threat to human health are very alarming.
It is very unreasonable to use magnesia chrome bricks in the 3~9m and 27~33m sections in the cement rotary kiln. At a position 3 to 9 meters inside the kiln, close to the kiln entrance, the oxygen partial pressure is high. The chromium in the magnesia-chromium bricks is easily oxidized, causing the fire bricks to contain high hexavalent chromium, which seriously harms the environment. At 27~33m in the kiln, the hot end temperature and alkali content in the transition zone are very high. Cr in magnesia-chrome bricks is easily converted into K2CrO4 and volatilizes, causing the magnesia-chrome bricks to corrode quickly. Therefore, magnesia-chrome bricks are only used in the most severely corroded parts 9.5 to 16 meters inside the kiln, and chromium-free alkaline bricks can be used in other parts. In this way, it does not affect the life of the kiln lining and reduces the harm of waste bricks.
Suppression of the Hazards of Magnesia-Chrome Waste Bricks
After suppression treatment, the hexavalent chromium in the magnesia-chrome waste bricks can be destroyed, so that the waste bricks can meet the requirements for safe discharge. The most economical known inhibition method is thermal reduction inhibition – the waste bricks are buried in carbon and heat treated at 900~1000℃, and CO gas is used to reduce hexavalent chromium into non-toxic substances.
When treated at around 900°C, hexavalent chromium in waste bricks can be removed. Make the Cr6+ content of the immersion liquid <0.05mg/L, meeting the requirements of Class IV water stipulated in the national environmental standards. In the same way, firing in a weak reducing atmosphere before stopping the kiln will also help reduce the Cr6+ content in magnesia-chrome waste bricks.
Refractory repair methods for blast furnace hearth-side walls. When high temperature occurs on the side wall of the blast furnace hearth, it needs to be solved by pressing in the side wall of the hearth. For high-temperature conditions on the side walls of the blast furnace hearth, it is first necessary to determine whether the cause is thinning of the lining or wind channeling from the back of the brick lining. Only when it is determined that there is back-channeling wind, it is necessary to press in. The pressed parts generally need to be determined by detecting the temperature changes of each part.
Repairing Blast Furnace Hearth Side Walls with Refractory Materials
Refractory Repair of Blast Furnace Hearth-Side Wall
Generally, the pressed material is carbonaceous mud similar to the hearth brick lining material, or other non-hydraulic materials. For the press-fitting of the furnace side wall, there are three main forms depending on the structure of the furnace lining.
The first is the furnace lining structure using large carbon bricks. Because of this structure, there is usually a layer of carbonaceous ramming material between the large carbon bricks and the furnace shell or cooling stave. High temperatures in the hearth are often caused by gaps in the carbon ramming material layer, allowing high-temperature gas to pass through. Therefore, the key point of press-in grouting is to fill and seal these gaps with press-in material. At this time, the grouting position should be to use the reserved holes on the furnace shell or drill holes in the parts where the cooling wall can penetrate, and send the pressed material to the carbon ramming material layer.
The second is for the furnace lining structure using small carbon bricks. However, during design and construction, the carbon bricks are built close to the furnace shell or cooling stave. But in fact, due to various reasons such as manufacturing and installation accuracy, there is inevitably a gap between the carbon bricks and the furnace shell or cooling stave. At this time, the grouting method is the same as the first one.
The third type refers specifically to the furnace side wall having a cooling stave structure. When the surface temperatures of the furnace lining and the furnace shell rise simultaneously, it indicates that the gap between the cooling stave and the furnace shell has become a hot coal gas flow channel. At this time, it is necessary to grout the lining of the furnace while also grouting the space between the cooling stave and the furnace shell. The key to this grouting is to find the gas channel to determine the location of the drill hole. The depth of the drill hole must ensure that it penetrates the furnace shell without damaging the cooling wall. In this case, the pressed material can be selected from carbonaceous mud or other non-aqueous pressed materials based on actual conditions such as temperature and historical records.
For the press-in of the furnace side wall, the press-in point is generally determined by arrangement and blocking.
Repair of refractory lining materials, and design of refractory materials for high-temperature industrial furnace insulation layers. Rongsheng Refractory Materials Manufacturer is a refractory material manufacturer with rich experience in the production and sales of refractory materials. The quality of our refractory products is guaranteed and ready for shipment at any time. And our comprehensive customer service also protects the rights and interests of our customers.
Both corundum bricks and corundum mullite bricks are high-grade refractory materials with high-temperature compressive strength and excellent wear resistance. There are differences between the two in terms of composition and physical properties. Rongsheng Refractory Material Manufacturer is a refractory material manufacturer with rich production and sales experience. We provide refractory services globally. Product quality is reliable, after-sales service is guaranteed.
Corundum Brick and Corundum Mullite Brick
Corundum brick. Corundum bricks are mainly made of high-purity raw materials such as alumina and corundum and usually do not contain impurities such as free silicates. Among them, corundum is a mineral with high hardness and high density, which can form a hard crystal structure in the sintering process. As a result, the corundum brick has high compressive strength, wear resistance, and other properties.
Rongsheng Corundum Bricks
Corundum mullite bricks. Corundum mullite bricks are mainly composed of corundum, mullite, alumina, and other raw materials. Among them, the functions of corundum and alumina are similar to those of corundum bricks, while mullite has a high melting point and refractory performance, and is a common component of high-quality refractory materials. The production process of corundum mullite bricks is more complicated than that of corundum bricks and requires multiple processes. From raw material preparation, and mixing to molding, sintering, etc. The whole process needs to control factors such as temperature, time, and pressure.
Physical properties of corundum bricks and corundum mullite bricks
density. The density of corundum bricks is usually between 3.6-3.8g/cm³, while the density of corundum-mullite bricks is between 2.9-3.2g/cm³. Therefore, under the same volume, the corundum brick is heavier than the corundum mullite brick.
compressive strength. In high-temperature environments, both corundum brick and corundum mullite brick have high compressive strength. But in general, the compressive strength of corundum bricks is higher than that of corundum mullite bricks. Specifically, at a temperature of 1600°C, the compressive strength of corundum bricks can reach more than 120MPa, while the compressive strength of corundum-mullite bricks is around 80-90MPa.
Corundum Mullite Brick
abrasion resistance. Since the corundum brick contains a large amount of corundum crystals, its wear resistance is relatively excellent. Corundum bricks are widely used in the manufacture of wear-resistant lining boards, ceramic tiles, and other products. The corundum mullite brick also has high wear resistance, and due to the participation of mullite. Making it more corrosion-resistant, it can be used to make products such as acid and alkali-resistant bricks.
fire resistance. Corundum bricks and corundum mullite bricks have excellent refractory properties and are not prone to structural changes and shrinkage in high-temperature environments. The operating temperature range of the two is also very wide and can be used for a long time in a high-temperature environment of 1400°C-1800°C. Has extremely high stability and mechanical strength.
Thermal expansion coefficient. The coefficient of thermal expansion of corundum bricks and corundum mullite bricks is relatively small, especially at high temperatures. The thermal expansion coefficient of corundum bricks at 900°C is about 6.0×10^-6/°C, while that of corundum mullite bricks is about 7.0×10^-6/°C. Therefore, on some occasions that need to withstand high-temperature expansion stress, corundum bricks, and corundum mullite bricks are more suitable for use.
Application field of corundum brick and corundum mullite brick
Application fields of corundum bricks. Corundum bricks are widely used in various high-temperature industrial fields, such as metallurgy, building materials, chemicals, electric power, medicine, and other industries. Corundum bricks can be used to manufacture high-temperature furnaces, refractory linings, casting molds, electrolytic cell linings, etc. Its excellent properties make it an ideal refractory material.
Application fields of corundum mullite bricks. Corundum mullite bricks are widely used in the chemical industry, metallurgy, ceramics, and other fields. Among them, corundum mullite bricks have better acid corrosion resistance, especially in the steelmaking process, corundum mullite bricks can be used to make acid-resistant reactors. At the same time, corundum mullite bricks can also be used in high-temperature occasions such as making aluminum electrolytic cells.
RS Global Refractory Manufacturer
Both corundum bricks and corundum mullite bricks are high-grade refractory materials with excellent physical properties, but there are differences in their composition and physical properties. Corundum bricks are mainly composed of alumina and corundum and have high compressive strength and wear resistance. The corundum mullite brick is composed of corundum, mullite, alumina, and other raw materials, and its acid corrosion resistance is better. Both materials have a wide range of application fields, and it is necessary to choose the appropriate material according to specific production needs and environmental requirements. To purchase high-quality refractory brick products, please contact us. Get free samples, solutions, and quotes.
Mullite refractory castable is generally a kind of medium and low-temperature thermal insulation refractory material configured by using mullite aggregate as raw material. It is generally used in petrochemical industry tubular heating furnaces, light diesel oil, ethane cracking furnace linings, atmospheric and vacuum furnaces, sulfur recovery units, and steam boilers. Tortoiseshell net heat insulation layer, two tanks, and pipe heat insulation single layer. Other industrial furnace doors, fire viewing holes, the lining of observation hole doors, etc.
Mullite castable is a refractory castable made of high-quality porous mullite aggregate as raw material, plus fine powder and additives. The critical particle size of mullite aggregate is 12mm, and the long-term use temperature is 1350 degrees. The advantage of mullite refractory castable is that its refractory temperature is higher than other thermal insulation castables, and it can directly contact the flame and be directly used as the lining of the kiln.
Rongsheng Mullite Refractory Castable
The Formula of Mullite Refractory Castable
The type and quality of aggregate have a significant impact on a series of properties of lightweight castables, such as bulk density, strength, heat insulation, maximum service temperature, etc. The aggregate is artificially synthesized from selected natural raw materials at a high temperature of 1680°C. The mullite reaction of the aggregate is good, the main crystal phase reaches more than 70%, and the composition is uniform and stable. The mullite crystals are needle-like interlaced to form a network structure, which is very beneficial to the strength and high-temperature index of lightweight castables.
In order to meet the high-temperature environment, the cement adopts pure calcium aluminate cement with Al2O3 content greater than 75%, and the micro powder is mainly mullite micro powder and aluminum micro powder. Adding a proper amount of silicon micro powder and dispersant can reduce the amount of castable water and improve fluidity. A variety of micro-powder composite addition methods can ensure the construction and use performance of lightweight castables.
In view of the high water absorption rate of the lightweight aggregate itself, the line shrinkage after burning is relatively large, which is likely to cause shrinkage cracks in the entire masonry. While selecting a variety of fine powders to improve the performance, a part of aluminum-containing fine powder and high-quality kyanite imported from the United States are appropriately added. Promote the continuous expansion of castables in high-temperature use, and ensure the volume stability of lightweight castables at different temperatures.
Mullite Refractory Castable in Rongsheng
Lightweight Mullite Castable’s Performance
①Applicable to the working lining or thermal insulation lining of various flame furnaces and other industrial kilns to achieve high temperature and energy saving.
② High strength, small unit density. Used as industrial kiln roof, wall, door, and other parts. Compared with ordinary low-cement castables, the structural weight is reduced by more than 30%. Eliminate hidden dangers such as broken bricks and collapses.
③Using high-quality porous mullite as aggregate, combined with various micro-powders and dispersants, it has low thermal conductivity and a good heat preservation effect. Compared with ordinary castables, the heat loss of the kiln can be reduced by 25% to 35%, and the fuel can be saved by about 10%.
④The construction is simple, and it can be poured as a whole on-site. It can also be combined and installed with prefabricated parts of any shape.
There is also a corundum mullite refractory castable. The corundum mullite castable is a refractory castable made of corundum as aggregate and powder plus some binders. It has higher mechanical strength and abrasion resistance than high alumina refractory castables and mullite refractory castables, but its thermal shock resistance is slightly worse. It is mainly used as the lining material of boilers, blast furnaces hot blast stoves, heating furnaces, ceramic kilns, and other kilns.
The difference between corundum mullite refractory castable and mullite refractory castable is that. One is refractory and wear-resistant (corundum mullite refractory castable). One is thermal insulation (mullite insulation castable). And their prices are also different. The price of corundum mullite refractory castable is generally around 4000~6000 per ton. The price of mullite refractory castable is much lower, about 3000~4000 per ton.
Rongsheng Global Refractory Factory is a refractory castable manufacturer with rich experience in the production and sales of refractory castables. Our fully automatic, environmentally friendly monolithic refractory castable production line has an annual output of tons. Provide high-quality refractory and wear-resistant linings and thermal insulation refractory linings for various high-temperature industrial furnaces. We can customize refractory lining solutions for you according to your production needs. Contact us for a free quote.
