In the refractory industry, water glass is mainly used to build fire mortar for magnesia refractory materials or medium and low-grade aluminum-silica refractory materials. Among them, the method of making magnesium iron refractory mortar for magnesia refractories is as follows.
Magnesium Iron Refractory Mortar for Magnesia Refractories
Raw materials. Magnesia fines <1mm; 15%~20% magnesia fine powder remaining after 0.088mm sieve. <1mm iron ore or iron scale. Iron scale is the skin peeled off from rolling steel billet, so it is named because it resembles scales. Water glass with SiO2/Na2O molar ratio 2.2~2.9 and relative density 1.41~1.44.
Proportion. Magnesia fines: Magnesia fines: Iron ore fines = 1:1:1. Dilute the water glass to a relative density of 1.30~1.32. The dosage accounts for about 25% to 30% of the dry ingredients.
The mixed cement should have a masonry time of 30 minutes and a hardening time of 4 to 8 hours. Compressive strength of 5~10MPa after drying.
The hardening of cement is affected by temperature. If it hardens too quickly, water glass can be diluted. If the hardening is too slow, 0.5% ordinary cement can be used to accelerate hardening.
If the adhesiveness of the mortar is not strong, you can increase the proportion of fine powder as appropriate. If the refractory mortar joints are very wide, the amount or particle size of magnesia fine particles can be increased.
The refractory mortar can be used as needed. Do not mix too much at one time. The newly solidified cement can be diluted with water glass, or it can be poured back immediately and mixed with new materials before use.
As we all know, refractory mortar is an accessory product used in building refractory bricks and furnace walls. It mainly includes four types: fireclay refractory mortar, high alumina refractory mortar, silica refractory mud, and magnesia refractory mortar. There is no doubt that magnesia mortar inherits the advantages and disadvantages of magnesia refractory materials and is used to build magnesia refractory bricks.
Advantages and Disadvantages of Magnesium Refractories
The melting point of MgO is as high as 2800°C, and the refractoriness of magnesia bricks is generally very high, up to more than 2000°C. Therefore, magnesia bricks have good high-temperature resistance, good stability in high-temperature vacuum, and strong resistance to alkaline slag. However, magnesia bricks have poor resistance to sulfate erosion, poor thermal shock stability, and are prone to hydration. In addition to traditional magnesia bricks, magnesia refractory materials also include forsterite refractory materials, magnesia-aluminum spinel refractory materials, magnesia-chromium refractory materials, white jade refractory materials, etc.
Advantages of Magnesia Mortar
Good plasticity and convenient construction.
High bonding strength and strong corrosion resistance.
High refractoriness, up to 1650℃±50℃.
Good resistance to slag invasion.
Good thermal peelability.
Disadvantages of Magnesia Mortar
Because magnesia refractory materials are easy to hydrate. At present, most of them have switched to the dry laying method to build magnesia refractory materials. However, for irregular parts, it is still necessary to use magnesia refractory mortar to adjust joints and pad bricks to alleviate stress concentration and increase the service life of the kiln lining.
Applications of Magnesia Refractory Mortar
Magnesia refractory mud is mainly used as a mortar filler for magnesia bricks, magnesia-alumina bricks, magnesia-chrome bricks, and other magnesia refractory bricks, and as a protective coating for magnesia masonry.
Buy high-quality magnesia refractory materials, magnesia bricks, magnesia chrome bricks, directly bonded magnesia chrome bricks, magnesia mortar, magnesia castables, and other unshaped refractory materials. Please choose Rongsheng refractory manufacturer. Rongsheng Manufacturer is a powerful manufacturer and seller of refractory materials. Our refractory products have been sold to more than 100 countries and regions around the world. The product quality is reliable, the delivery speed is fast, the customer reputation is good, and the service is guaranteed. Contact us for a free quote and solution.
Alkaline refractory bricks are a kind of refractory material mainly composed of magnesia raw materials. They have excellent slag erosion resistance, thermal shock resistance and high temperature structural stability. In industries such as metallurgy, building materials, and chemicals, alkaline refractory bricks are widely used in the lining of high-temperature equipment such as furnaces, cement rotary kilns, and glass kilns. Rongsheng Refractory Materials Manufacturer has summarized a variety of commonly used alkaline refractory bricks based on years of production and sales experience. So, do you know the magnesium oxide content of alkaline refractory bricks?
Magnesia-Chrome Brick: Magnesia-Chrome Brick is an alkaline refractory brick made of magnesia and chromite as the main raw materials and sintered at high temperatures. Magnesia chrome bricks have the advantages of high melting point, high strength, and high resistance to slag erosion. Suitable for working conditions under high temperature, high pressure, and strong alkali environment.
Magnesia-alumina brick: Magnesia-alumina brick is an alkaline refractory brick made of magnesia and alumina as the main raw materials, adding an appropriate amount of additives, and sintering at high temperature. Magnesia-alumina bricks have good thermal shock resistance, slag erosion resistance, and high-temperature structural stability. Suitable for lining of high-temperature equipment such as cement rotary kilns and glass kilns.
Magnesia-calcium brick: Magnesia-calcium brick is an alkaline refractory brick made of magnesia and lime as the main raw materials, adding an appropriate amount of additives, and sintered at high temperature. Magnesia-calcium bricks have high thermal shock resistance and slag erosion resistance. Suitable for high-temperature equipment in steel, nonferrous metals and other industries.
Magnesia dolomite brick: Magnesia dolomite brick is an alkaline refractory brick made of magnesia and dolomite as the main raw materials, adding an appropriate amount of additives, and sintering at high temperature. Magnesium dolomite bricks have good thermal shock resistance, slag erosion resistance, and high-temperature structural stability. Suitable for lining of high-temperature equipment such as cement rotary kilns and glass kilns.
Magnesia chrome bricks: The magnesium content of magnesia chrome bricks is generally between 60% and 80%, and the chromium content is between 20% and 40%. The magnesium content of magnesia-chrome bricks is high, which is beneficial to improving its resistance to slag erosion and high-temperature structural stability.
Magnesia-alumina bricks: The magnesium content of magnesia-alumina bricks is generally between 50% and 70%, and the aluminum content is between 20% and 40%. The magnesium content of magnesia-alumina bricks is moderate, which is beneficial to improving its thermal shock resistance and slag erosion resistance.
Magnesia-calcium bricks: The magnesium content of magnesia-calcium bricks is generally between 50% and 70%, and the calcium content is between 20% and 40%. The magnesium content of magnesia-calcium bricks is moderate, which is beneficial to improving its thermal shock resistance and slag erosion resistance.
Magnesium dolomite bricks: The magnesium content of magnesia dolomite bricks is generally between 50% and 70%, and the dolomite content is between 20% and 40%. The magnesium content of magnesia dolomite bricks is moderate, which is beneficial to improving its thermal shock resistance and slag erosion resistance.
Precautions
When selecting alkaline refractory bricks, the appropriate type and magnesium content should be selected based on specific working conditions and requirements.
When laying alkaline refractory bricks, attention should be paid to controlling the size of the brick joints, generally between 2-3mm. Excessive brick joints will lead to increased heat loss, while brick joints that are too small are not conducive to the expansion and contraction of the brick body.
During the masonry process, special anchors should be used to fix the refractory bricks on the base body to prevent the bricks from loosening and falling off. The selection and installation of anchors should comply with design requirements and construction specifications.
After the masonry is completed, the bricks should be trimmed and excess mortar should be removed to make the brick surface smooth and beautiful.
In short, alkaline refractory brick is a refractory material with excellent properties and is widely used in high-temperature equipment in metallurgy, building materials, chemical industry and other industries. When selecting and using alkaline refractory bricks, the appropriate type and magnesium content should be selected according to the specific working conditions and requirements to ensure the safe and stable operation of the equipment.
In the refractory industry, refractory bricks with MgO as the main component and periclase as the main crystal phase are collectively called alkaline refractory bricks. Alkaline refractory bricks are mainly used in thermal kilns used in cement, glass, ferroalloy and other industries.
In glass-melting furnaces, alkaline refractory bricks are mainly used as regenerator checker bricks. Its thermal conductivity is large, its service life is long, and its volume density is high, which increases the heat storage in the regenerator. The porosity of alkaline refractory bricks is low, and the thermal expansion coefficient increases linearly as the temperature rises. It is the largest among various refractory materials. Pay attention to leaving enough expansion joints during use.
Alkaline refractory bricks are non-insulators above 900°C and have very good electrical conductivity and cannot be used as high-temperature insulating materials.
Alkaline refractory bricks cannot be used in gas regenerators. And long-term contact with water vapor at 40~160℃ will cause hydration, which will cause the brick structure to become loose and damaged. So keep it dry during storage. Before laying the magnesite checkered bricks, the regenerator must be dried.
At present, including ordinary magnesia bricks, magnesia refractory materials also have the following types.
Ordinary magnesia bricks. It is made of sintered magnesite as raw material and sintered. The content of MgO is about 91%. It is a magnesium refractory product directly combined with silicate and is widely produced and used.
Directly bonded magnesia bricks. It is made of high-purity sintered magnesia as raw material and sintered. The content of MgO is more than 95%. It is a magnesia refractory product directly bonded between periclase grains.
Magnesia silica brick. It is made of high-silicon sintered magnesite as raw material and sintered. SiO2 content is 5%~11%, it is a magnesia refractory product combined with forsterite.
Forsterite Bricks. Forsterite refractory material is a refractory material with forsterite as the main crystal phase. It is mostly made of peridotite and pure peridotite as the main raw materials, and the formed products are called forsterite bricks.
Buy high-quality alkaline refractory bricks, magnesia bricks, magnesia checker bricks for glass kilns, metallurgical kilns, etc. Please choose Rongsheng refractory material manufacturer. Rongsheng manufacturer, product quality is reliable and delivery speed is guaranteed. Moreover, comprehensive customer service effectively guarantees the service life of the refractory furnace lining and saves production costs for customers.
Refractory spray paint is used to spray new linings and can also be used to repair furnace pipes. Spraying construction method of Rongsheng high-temp refractory coating. It is an effective unshaped refractory material that is easy to construct, extends the service life of the kiln, and reduces the consumption of refractory materials. The material composition of refractory spray paint is basically similar to that of refractory castables of the same type. The difference is that the critical particle size of refractory aggregate is smaller, generally 3~5mm, and is constructed using spraying methods. The dosage of refractory powder, ultrafine powder, and binder is relatively large, generally 35~45%.
Spraying is carried out using a spray machine or spray gun. The material obtains considerable speed with the help of compressed air and is sprayed onto the sprayed surface through the nozzle, forming a strong spray layer. The key technologies of refractory spray coatings are mainly adhesion, bonding, strength, and sintering. This is also the basic characteristic that the material should have, otherwise the service life of the spray coating will be reduced. These characteristics are not only related to the quality of the material itself, but also affected by the spraying equipment, construction technology, and the state of the sprayed body.
The particles of refractory spray paint cannot be larger than 5mm. Because when it is larger than 5mm, the spray gun will be blocked and normal construction will not be possible. During construction, the refractory spray coating is sprayed 40-50mm into the pipe, and the spray coating can be quickly formed. Generally speaking, the rebound rate of refractory spray coatings produced by refractory spray coating manufacturers is 10%.
In refractory spray coatings, medium and fine particles can greatly improve the adhesion rate, but will increase peeling during drying. Coarse particles can make the repair layer more stable, but too many coarse particles will lead to a high rebound rate and increase the amount of material used. Therefore, the particle gradation must be reasonable and cannot exceed 5mm. Because it exceeds 5mm, the spray gun cannot spray. Reasonable gradation can best improve the construction and use performance of spray coatings.
High-Temperature Refractory Coatings
Refractory spray coatings are divided into light spray coatings and heavy spray coatings. The materials selected according to different use environments include corundum, high alumina, mullite, clay, SiC, magnesium, etc. Mainly used in hot blast furnaces, heating furnaces soaking furnaces, blast furnaces, flues and chimneys, etc. However, lightweight refractory spray coatings are relatively more expensive than heavy refractory spray coatings.
The density of heavy refractory spray paint is generally 1.6-1.8g/cm3. However, there are different requirements in different furnace pipelines. Especially the sintering machine pipes must be made much better than other parts. In other words, this part needs to use refractory spray paint with a density of 2.2g/cm3. Of course, the price of refractory spray paint for sintering machines will be much higher than that of refractory spray paint for other parts.
The bulk density of heavy refractory spray coatings is generally greater than 1.8g/cm3. Refractory aggregates and powders generally use aluminum silicate materials, with a critical particle size of 5 or 10 mm. Particle composition: 3~5mm is about 30%, 1~3mm is about 30%. Less than 1mm is about 40%. The binding agent is aluminate cement and water glass, plus additives. Generally, semi-dry method or false dry method is used for construction.
Main properties of heavy refractory castables. The medium temperature strength of CA-50 cement spray coating is reduced. However, water glass and phosphate spray coatings increase with the increase of heating temperature, and their bulk density is slightly lower than the same type of refractory castables produced by vibration molding.
In recent years, medium-heavy refractory spray coatings with a bulk density of 1.8~2.1g/cm3 have been developed. That is, on the basis of heavy materials, 3% to 6% expanded perlite or 5% to 20% porous light clinker is added. It is mainly used on the heat insulation layer of kilns and has good heat preservation effect.
(2)Lightweight refractory spray coating
There are many varieties of lightweight refractory spray coatings, mainly including clay, ceramsite, perlite and other refractory spray coatings. Lightweight refractory spray paint is mainly used for the thermal insulation layer of kilns, and can also be used for the working layer of tubular heating furnaces, flues and chimneys.
The critical particle size of refractory aggregate for lightweight refractory spray paint is 5mm. The particle gradation is: 3~5mm, about 19%~30%. 0.6~3mm is about 8%~14%. 0.088~0.60mm is about 30%~40%, and less than 0.088mm is about 25%~35%.
The main properties of lightweight refractory spray coatings. During the spraying construction process of refractory spray paint, the original particle gradation will be greatly changed due to the rebound and scattering of refractory aggregates and the splashing of refractory powder. Therefore, when the aggregate size requirements of the refractory spray coating are certain, in order to make the aggregate gradation of the actual spray coating meet the requirements, the original gradation before spraying must be adjusted to meet the requirements after spraying.
refractory spray coating
Spraying construction of Rongsheng Refractory Spray Coating
Before spraying paint, test spraying should be carried out in accordance with the construction instructions provided by the manufacturer for the brand of spray paint. To determine the appropriate parameters, such as wind pressure, water pressure, etc.
Several commonly used spray coatings
(1) When spraying clay materials at room temperature, the aggregate particle size should be below 3.5mm. When the spray paint lacks viscosity, 2% clay should be added to improve its construction performance.
(2) When spraying high-aluminum materials at room temperature, additives should be added to prevent falling and increase the density of reinforced metal parts.
(3) When lightweight insulation materials are used for spraying, lightweight aggregates with higher strength should be used, and appropriate amounts of asbestos and clay should be added. Aggregates with low strength, brittle under pressure and friction, or elastic aggregates are not suitable for spraying. The volume density of lightweight thermal insulation spray paint should be between 0.7~1.3t/m3.
Reinforcement metal parts
Spraying construction must be reinforced with metal supports. Metal supports should have the characteristics of simple shape, small size, and reliable performance. Generally, it should be made of round steel.
When the thickness of the spray coating is 35~75mm, metal mesh should be used for reinforcement. The diameter of the metal mesh is Φ3.2~4.2mm, and the mesh size should be 1.5 times the thickness of the spray coating. And it is fixed on the furnace wall by welding, binding, and crimping.
When the spray thickness is more than 100mm, round steel of 4~8mm should be used to make V-shaped or Y-shaped metal parts and welded to the furnace shell.
The installation distance of metal parts: the side wall part should be 3 times the thickness of the spray coating, and the top part should be 1.5~1.8 times the thickness of the spray coating. The distance from the front end of the metal anchor to the surface of the spray coating should be 50mm for the side wall and 25~30mm for the ceiling.
spraying refractory coatings paint
Process inspection before spraying
The following process inspections should be carried out before spraying refractory spray paint:
(1) Before spraying, the installation position, spacing size, and welding quality of the metal supports should be checked and cleaned.
(2) When there is a fixed steel wire mesh on the support frame, check whether the anchoring quality of the steel wire mesh meets the requirements. The upper, lower, left, and right sides of the steel wire should overlap one grid. The overlap shall not exceed three layers and the fasteners shall be oriented toward the non-working layer.
(3) Check the sprayed surface. There should be no floating rust, dust accumulation, oil stains, or water immersion on the sprayed surface.
Spraying operations and adjustments
Refractory spray paint is sprayed onto the sprayed surface with a spray gun. Materials constructed by spraying are called refractory spray paint. Spraying is carried out using spray machines and spray guns. The refractory spray paint uses compressed air or mechanical pressure in the pipeline to obtain sufficient pressure and flow rate. Spray onto the sprayed surface through the nozzle to form a solid spray layer.
The spraying methods of refractory spray coatings are divided into three categories: wet method, dry method, and flame method. When constructing refractory spray coatings, appropriate construction plans for high-temperature coatings and refractory coatings can be specified based on actual working conditions. To extend the service life of the kiln lining.
In recent years, honeycomb regenerative furnaces have developed very rapidly. Since the regenerator can be miniaturized and integrated with the burner, and each burner maintains its independence, it becomes a regenerative burner. It truly achieves extreme waste heat recovery and ultra-low NOX emissions. The energy-saving effect brought by regenerative combustion technology is very obvious. It can absorb the heat of high-temperature flue gas to the maximum extent and avoid heat waste. Honeycomb ceramic regenerator is the key and core component of regenerative high-temperature combustion technology.
The selection of a honeycomb ceramic regenerator is very critical. Improper selection will cause blockage, burning, collapse, and other phenomena during use, causing the furnace temperature to rise slowly, failing to reach the temperature, and in serious cases causing furnace shutdown accidents. It affects production and increases gas consumption.
Therefore, when selecting a honeycomb body, in addition to considering the rapid cooling and rapid heating resistance of the honeycomb ceramic regenerator, load softening temperature, compressive strength, thermal expansion coefficient thermal shock resistance, and other indicators. The heat release characteristics of the honeycomb ceramic regenerator also need to be considered. It is necessary to select a honeycomb ceramic regenerator made of materials with a large specific surface area, large blackness, large heat capacity, and fast thermal conductivity. In this way, the honeycomb ceramic heat storage body absorbs and releases heat faster and more, and can effectively absorb the heat of the flue gas. Significantly increase the preheating temperature of gas and air, increase the combustion temperature of the heating furnace, and achieve the purpose of reducing gas consumption.
Silicon Carbide Honeycomb Ceramic Regenerator
The silicon carbide honeycomb ceramic regenerator is an improvement based on the formula of the corundum-mullite honeycomb ceramic regenerator. A certain amount of high-purity silicon carbide is added to improve the performance of the original honeycomb ceramic regenerator. Silicon carbide honeycomb ceramic regenerator combines the advantages of silicon carbide, zirconium chromium corundum, and other materials. It has the characteristics of good antioxidant, slag resistance, high-temperature resistance, high blackness, and fast thermal conductivity. Its high-temperature strength can be maintained up to 1600°C, making it the material with the best high-temperature strength among ceramic materials. Due to its fast thermal conductivity and high blackness, it has better energy-saving properties than a corundum-mullite honeycomb ceramic regenerator. According to relevant customer usage statistics, the use of silicon carbide honeycomb ceramic regenerators can significantly reduce the exhaust temperature of exhaust gas and reduce gas energy consumption by more than 5-10% compared with other honeycomb ceramic regenerators. Silicon carbide honeycomb ceramic regenerator is mainly used as the heat exchange medium for high-temperature regenerative industrial kilns above 1250°C.
Large Holes and Big Eyes Honeycomb Ceramic Regenerator
The hole shapes of honeycomb ceramic regenerators often include square holes, round holes, hexagonal holes, etc., and the hole spacing is usually between 3-6mm. Among them, the hexagonal hole surface layout is more uniform and the structure is more stable. It is currently the most commonly used hole type. In addition to matching the medium pressure, flow rate, burner combustion capacity, and other factors, the selection of hole type and aperture should also pay attention to the actual medium quality conditions. For exhaust gas with high dust content, the hole diameter and wall thickness should be appropriately increased. Choose a honeycomb ceramic regenerator with large holes and large eyes to reduce the clogging and corrosion hazards caused to the honeycomb ceramic regenerator.
The honeycomb ceramic regenerator with large holes and large eyes is mainly used to deal with the harsh working environment of some industrial furnaces and the high dust content in the flue gas. During use, the small holes of the honeycomb ceramic regenerator often become blocked. After the small holes of the honeycomb ceramic regenerator are blocked, not only will its heat storage and smoke exhaust performance be significantly reduced. It also causes smoke exhaust and uneven heating of the honeycomb ceramic heat storage body, which is prone to cracks and aggravates its damage. In regenerative industrial furnaces with harsh working environments and high dust content in flue gas, the use of honeycomb ceramic regenerators with large holes and large eyes can effectively avoid clogging the small holes of conventional honeycomb ceramic regenerators.
The honeycomb ceramic regenerator of the RTO incinerator has the characteristics of high softening temperature under load, small expansion coefficient, strong resistance to rapid cooling and rapid heating, and long service life. The basic principle of an RTO incinerator is to oxidize organic waste gas at high temperatures (>760℃) to generate CO2 and H2O. The use of honeycomb ceramic regenerators can maximize the recovery and reuse of heat energy, with a heat recovery rate greater than 95%. The geometric characteristics of the RTO honeycomb ceramic regenerator are generally made into columnar regenerators with dimensions of 150mm×150mm×150mm and 150mm×150mm×300mm and are integrated into the RTO regenerator. The number of holes in the cross-section of a piece of packing that airflow passes through is called the hole density, also expressed by the number of holes per square inch (CSI). Usually from 13×13 (number of holes 169) to 60×60 (number of holes 3600).
The greater the hole density, the larger the surface area per unit volume, which can provide a larger heat transfer area and thereby improve the heat transfer efficiency. The organic waste gas is heated to above 760°C, causing the VOC in the waste gas to oxidize and decompose into carbon dioxide and water. The high-temperature gas generated by oxidation flows through the special ceramic heat storage body, causing the ceramic body to heat up and “storage heat”. This “heat storage” is used to preheat the subsequent incoming organic waste gas. This saves fuel consumption for exhaust gas heating.
The honeycomb ceramic regenerator of the RTO incinerator should be divided into two or more zones or chambers. Each regenerator goes through the procedures of “heat storage-heat release-cleaning” in turn, starting over and over again and working continuously. After the regenerator “releases heat”, part of the clean exhaust gas that has been processed should be introduced immediately, and the regenerator should be cleaned to ensure that the VOC removal rate is above 95%. Only after cleaning is completed can the “heat storage” program be entered.
Honeycomb ceramic regenerator is the key material of regenerative industrial kilns, and it is the heat exchange medium of regenerative industrial kilns. The honeycomb ceramic regenerator absorbs and stores the heat from the waste gas in the industrial kiln, and then uses the stored heat to heat the air and fuel. This not only increases the calorific value of the fuel, lowers the emission temperature of exhaust gas, and saves energy, but also reduces the emissions of CO2 and NOX, which is helpful for environmental protection. The cross-sectional holes of honeycomb ceramic regenerators mainly have square, regular hexagonal, and circular three-hole structures. Moreover, the pores are straight channel structures that are parallel to each other. This structure greatly reduces the resistance of the pores to flow through and greatly improves the single-hole volume heat transfer efficiency of the honeycomb ceramic regenerator. The main materials of the honeycomb ceramic regenerator of the RTO incinerator are dense cordierite, high alumina, corundum mullite, chromium corundum, zirconium corundum, silicon carbide, etc. Contact us for a free quote.
Corundum castable is a high-grade castable in a series of unshaped refractory materials. It has a stable crystal structure has more stable performance in high-temperature sintering processes, and is suitable for use in high-temperature areas lined with various kilns. Corundum castable that is resistant to high temperatures and slag erosion. Refractory castables made of this material can better reflect its fire resistance and wear resistance at high temperatures. Its thermal shock resistance can also achieve better performance at high temperatures, and its performance is reliable and reliable during high-temperature operation of the kiln.
Corundum castable is used in high-temperature parts of industrial kilns between 1400℃ and 1650℃. It is produced using bauxite clinker and corundum with an aluminum content of more than 90% as aggregate, using micro-powder technology and pure calcium aluminate cement. This kind of corundum refractory castable has high strength, high volume density, and strong high-temperature stability. Used in high-temperature parts of industrial kiln linings, it has strong resistance to slag erosion, wear resistance, and high-temperature gas erosion resistance.
Performance Characteristics of Corundum Castables
Corundum castables have high-energy effects of high temperature resistance and corrosion resistance, and can still maintain stable performance under long-term use. It can be combined with silicon carbide, mullite, andalusite, sillimanite, etc. to make composite refractory castables. It can be used in high-temperature furnace lining parts in different atmospheres.
The high-temperature main crystal phase of corundum castable is corundum refractory castable. It is a refractory castable prepared with special high-alumina bauxite clinker or fused brown corundum as aggregate, adding refractory powder, pure calcium aluminate cement binder, silica powder, and admixtures. Usually, the pouring method is used for construction. It can be cast into a complete lining, or prefabricated blocks of castable materials customized by the manufacturer can be spliced on-site for use.
Corundum Castable Refractory of Slag Corrosion Resistance
(1) High compressive strength and strong lining stability at high temperatures.
(2) The volume density is high, and the overall lining has strong resistance to slag erosion and permeability.
(3) Strong resistance to erosion by solid particles, dust, and high-temperature gases.
(4) Low mechanical wear resistance.
(5) Not affected by reducing gases such as H2 and CO.
Corundum Castable Product Uses
The use temperature of corundum castable is 1600-1700℃, and it is mainly used as lining material for various high-temperature kilns and high-temperature structures. Such as the outer lining of the impregnation tube of the molten steel vacuum degassing device, the lining of the spray metallurgy, and the argon-blowing integral spray gun. The lining body of the electric furnace top triangular area and the LF furnace cover. High-temperature wear-resistant lining for catalytic cracking reactors in the petrochemical industry. High-temperature wear-resistant lining for circulating fluidized beds and power plant boilers.
How to Improve the High-Temperature Slag Corrosion Resistance of Corundum Castables?
The development trend of dense refractory castables requires the calcium aluminate cement content to be reduced as much as possible while maintaining good green strength and high-temperature mechanical properties. The key technology is to increase the packing density between particles. The above purpose can be effectively achieved by adding micron powder, submicron powder, or even nano-alumina powder. The reasons are:
1) Reduce the CaO content in the castable and reduce the low melting phase generated at high temperatures. It can significantly improve the high-temperature mechanical properties of castables.
2) Promote sintering at medium temperature and increase the medium temperature strength of castables.
3) Reduce the total amount of water added and increase the density of the castable.
In terms of comprehensive cost performance, the role of alumina micropowder cannot be ignored. Its particle morphology, size, particle size distribution and specific surface area will have a great impact on the performance of the castable. In particular, the particle size distribution plays an important role in filling the pores between aggregates and increasing the packing density. Research has found that using composite micropowders with different particle size distributions can significantly increase the packing density. Reducing water consumption is beneficial to mechanical properties such as high-temperature flexural resistance and post-thermal shock strength. Li Wenping studied the influence of alumina powder particle size on the properties of castables. It was found that as the particle size of the micropowder decreases, the flowability and setting time of the castables both show an increasing trend.
More importantly, alumina micro-powder can promote the formation reaction of the CA6 phase of calcium aluminate cement at high temperatures, thereby significantly improving the high-temperature properties of castables. Pinto et al. found that the particle size of alumina powder decreased. It can nearly double the flexural strength of castables containing 1% (mass fraction) CAC cement and promote the formation of the CA6 phase. Auvray et al. discovered the optimization of alumina micro-powder and the in-situ generation of CA6. Ceramic bonding can be formed in the castable, which significantly improves the high-temperature elastic modulus of the castable. Specifically,
1) As the alumina fine powder content increases and the corundum fine powder content decreases, the normal temperature performance and high-temperature performance of the castable samples after heat treatment at different temperatures are improved to varying degrees. After being treated at 1600°C, the normal temperature flexural strength, normal temperature elastic modulus, and elastic modulus at 1400°C can be increased by 53.9%, 47.9%, and 40.4% respectively.
2) Adding too much micro powder is detrimental to the thermal shock stability of the castable. The more the amount of alumina powder is added, the residual flexural strength retention rate of the sample after thermal shock decreases with the increase in the amount of alumina powder. After three water-cooling thermal shocks, the residual flexural strength retention rate of the material decreased from 18.45% to 11.97%.
3) As the content of aluminum oxide powder increases, the slag erosion resistance of the castable gradually increases, and the thickness of the permeable layer decreases from 2.9mm to 2.1mm. The higher content of micro-powder will make the pore diameter of the castable smaller, promote the interpenetration and bonding of plate-like CA6 in the original layer, and make the matrix bonding closer. It is beneficial to improve the slag resistance performance of castables.
As environmental protection becomes increasingly stringent, the copper metallurgical industry is facing severe challenges. Today, there are two main copper metallurgical methods: the fire method and the wet method. Among them, the fire method plays a major role, and the lining is mainly made of alkaline refractory bricks.
There are many types of pyrometallurgical furnaces. At present, the main pyrometallurgical copper smelting equipment in the world includes flash furnaces, reverberatory furnaces, blast furnaces, Noranda furnaces, and ISA furnaces (Osmet furnaces). There are more than ten kinds of smelting equipment such as Vanukov furnaces, Mitsubishi furnaces, Tenient furnaces, electric furnaces, silver furnaces, and so on. Most processes have problems such as low production capacity, high cost, high energy consumption, and serious pollution. Seriously restricting the development of the copper metallurgical industry.
Outokumpu flash smelting furnace
Legend: Outokumpu flash smelting furnace
Outokumpu Flash Smelting Furnace
Since the advent of Outokumpu in Finland in 1949, flash smelting has gradually replaced the reverberatory furnace and blast furnace through continuous improvement, improvement, and development. Today it has become a competitive smelting technology used in today’s copper metallurgy and is generally considered the standard clean copper smelting process.
Currently, more than 50% of global blister copper production is produced using this technology. Due to the mature flash smelting process, it has a high degree of automation, large production capacity, low energy consumption, and good environmental protection. At present, most of the newly built or renovated and expanded copper smelting enterprises in the world adopt the flash smelting process.
Flash Furnace Structure
Outokumpu flash smelting uses oxygen-rich air or hot air at 723~1273K as the oxidizing gas. A down-spray concentrate nozzle is installed at the top of the reaction tower. The dry concentrate and flux are sprayed into the reaction tower at high speed with oxygen-rich air or hot air and are suspended in the tower. During the downward movement of the material, an oxidation reaction occurs with the oxygen in the airflow, releasing a large amount of heat. The temperature in the reaction tower is maintained above 1673K. The material reacts rapidly (2~3s) at high temperatures, and the resulting melt settles into the sedimentation tank. Complete the matte-making and slag-making reactions, and carry out clarification and separation.
Flash Furnace Structure
Refractory Materials for Outokumpu Flash Smelting Furnace
Outokumpu flash smelting furnace consists of a reaction tower, sedimentation tank, and rising flue. The operating temperature in the tower is 1400~1500℃. Its work is subject to high temperatures, chemical erosion, and charge erosion, and is easily damaged. Generally, alkaline refractory bricks are used.
The top of the tower is suspended and built with fired magnesia-chromium hanging bricks, with a thickness of about 400mm. The lining around the spray nozzle and burner can be integrally rammed with magnesia-chromium refractory ramming material with a Cr2O3 content of 20%. First, install the finned cooling water pipe on the furnace shell. Lay a 20mm thick insulation board or refractory fiber felt, and then pound the magnesia-chromium refractory ramming material layer. Finally, the working layer is built with cast magnesia chromium bricks. The working layer of the tower wall 1m close to the top of the tower is allowed to be built with fired magnesia chrome bricks. The materials and structure used on the top of the sedimentation tank are the same as those on the top of the tower.
Water-cooled copper sleeves are installed in the slag line area of the pool wall to protect the lining body and are all built with fused magnesia-chromium bricks, while the remaining pool walls are built with fired magnesia-chromium bricks. The total thickness of the anti-arch furnace bottom of the sedimentation tank is about 1800mm. First, 20mm thick asbestos boards or insulation boards are laid against the furnace shell, and 3 layers of clay insulation bricks and 1 layer of clay bricks are laid vertically. Then pound a layer of magnesia-chromium refractory ramming material about 100mm thick. Then use fired magnesia-chromium refractory bricks to build the working layer. The rising flue is on the other side of the sedimentation tank and consists of side walls, sloping end walls, sloping tops, and flat tops. It is mainly built with ordinary fired magnesia chromium bricks.
The lining at the lower part of the inclined end wall is easily corroded, and water-cooled copper sleeves need to be buried to increase the service life. The lining body where the sedimentation tank vault meets the reaction tower and rising flue. Steel beams are used to bear the load and water-cooled copper sleeves with fins are installed, and the working layer is integrally poured with magnesia-chromium refractory castables. Its service life is much longer than that of bricks.
Under normal operating conditions, the service life of the refractory brick lining of a flash smelting furnace is generally 3 to 10 years. During this period, 1 to 3 medium and minor repairs are required.
Refractory material manufacturer’s explanation of the heat storage area per unit volume of hot blast furnace checker bricks. Modern blast furnaces use regenerative hot blast furnaces, which are huge blast furnace blast heating facilities built up of checkered bricks. As a carrier of high-temperature heat, the working principle of checker bricks is to first burn gas, use the generated high-temperature flue gas to heat the checker bricks in the regenerator, and then pass the cold air through the hot checker bricks to be heated. The hot blast furnace alternately performs combustion and air supply, so that the blast furnace continuously obtains warm air. Therefore, improving the heat transfer efficiency of hot blast furnaces is of great significance to increasing the air temperature.
Heat Storage Area Per Unit Volume of Hot Blast Furnace Checker Bricks
To improve the heat transfer efficiency of the hot blast stove, the hot blast stove checker bricks must have excellent thermal properties. Using checker bricks in the design and increasing the thermal area of the checker bricks is an important technical measure to improve the heat transfer capacity. Comparison of the heat storage areas of several typical checker bricks below.
Traditional 7-hole lattice brick. The grid hole diameter is 43mm and the heat storage area is 38.1m2/m3.
7-hole grid bricks. The diameter of the grid holes is 30mm, and the heat storage area is 47.08m2/m3.
19-hole grid brick. The grid hole diameter is 30mm and the heat storage area is 48.6m2/m3.
31-hole grid brick. The diameter of the grid holes is 25mm, and the heat storage area is 58.1m2/m3.
37-hole grid brick. The diameter of the grid holes is 20mm, and the heat storage area is 68.7 m2/m3.
The practice has proved that under basically the same conditions, the air temperature of a large blast furnace can be increased by 38°C when using 19-hole bricks with a diameter of 30mm compared with traditional 7-hole bricks with a diameter of 43mm. Using 31-hole bricks with a diameter of 25mm in small and medium-sized blast furnaces can increase the air temperature by 19°C compared with 9-hole bricks.
RS Refractory Material Manufacturer is a powerful refractory material manufacturer. The quality of our refractory products is reliable and guaranteed. And our comprehensive customer service can also provide reliable quality assurance for our refractory products. The description of the heat storage area per unit volume of hot blast furnace checker bricks can better help companies purchase suitable regenerator checker bricks.
Application and requirements of checker bricks in hot blast furnace regenerator
Choose the appropriate size and thickness of checker bricks. When choosing the shape of checker bricks and the type of checker bricks, the following conditions and requirements should be considered:
① The quality of refractory materials.
② The degree of gas cleaning.
③ Different temperature conditions between the upper and lower parts of the hot blast furnace checker bricks.
④ It has high heat transfer efficiency and can increase the hot air temperature in a guaranteed amount.
Selection of checkered bricks for hot blast furnace regenerator
The regenerator of the hot blast stove is a space filled with checker bricks. Its main function is to use the internal checker bricks to exchange heat with high-temperature flue gas and combustion air. Therefore, as a heat storage and heat transfer medium, checker bricks should have a large heating area, high thermal conductivity, and quality to facilitate heat exchange and heat storage.
The main method to increase the heating area is to increase the number of holes in the checker bricks per unit area, so the number of holes in the checker bricks in the regenerator tends to increase. To improve the thermal conductivity of the material, black silica bricks are commonly used in Europe as checker bricks inside the regenerator. Because the iron oxide content in black silica bricks is high, it has high density, high thermal conductivity, strong heat storage capacity, and high heat exchange efficiency. Therefore, the upper part of the regenerator is made of siliceous check bricks, the middle part of the regenerator is made of low-creep high alumina bricks, mullite bricks, sillimanite, andalusite bricks, etc., and the lower part of the regenerator is generally made of clay bricks.
Modern regenerative hot blast stoves can basically be divided into two major types. The hood-type check bricks have a constant cross-section throughout the entire height, and the multi-section check bricks have varying cross-sections. The latter can be divided into three types, namely checkered bricks with alternating cross-sections, core-filled bricks, and brick wall surfaces with different roughness. Checkered bricks are available in a variety of shapes, such as square, rectangular, round, hexagonal, etc.
1) Multi-section checkered bricks. It was more commonly used in the past. The checkered bricks of hot air stoves are also of this type. The points of multi-section grid bricks are as follows.
(1) When the quality of the refractory material is poor, the upper checker bricks are easily damaged due to high temperature. This difficulty can be overcome by increasing the diameter and thickness of the upper checker bricks. Increasing the checker brick diameter reduces heat transfer and therefore prevents the upper checker bricks from overheating. Increasing the thickness of the checker bricks can reduce the average temperature of the checker bricks so that the load softening point of the refractory bricks is not exceeded, which prevents the checker bricks from softening and deforming. To protect the checker bricks from having sufficient compressive strength, the thickness of the upper checker bricks should generally not be less than 50~60 mm.
By taking the above two measures, the wind temperature will not drop too much. Weakening the heat transfer effect of the upper checker bricks also means slowing down the cooling of the upper checker bricks themselves. Therefore, towards the end of the air supply stage, the outlet hot air temperature drops less. Additionally, thin bricks heat up quickly and cool down quickly. Therefore, increasing the thickness of the upper checker bricks can reduce the fluctuations in the temperature of the checker bricks themselves and the blast temperature.
(2) The temperature of the lower checkered bricks is low, the convective heat transfer effect is weakened, and the radiation heat transfer effect is also very small. Therefore, reducing the diameter of the lower checker bricks increases the airflow velocity accordingly, which can significantly improve the lower convection heat transfer effect. In addition, corrugated checker bricks and checker brick cores can also be used in the lower part. This not only increases the heating surface and reduces the diameter of the checker bricks, but also promotes turbulence in the airflow, which is conducive to convective heat transfer.
The lower checkered bricks should not be too thick. Because in the continuous alternation between the air supply period and the heating period of the hot blast stove, the temperature of the center of the lower checker brick rarely fluctuates and does not play a heat storage role. At the same time, thinning the lower checker bricks can also increase the heating area of the lower checker bricks. Therefore, the brick thickness of the lower checkered bricks is generally only 25~40 mm.
Generally speaking, when using ordinary clay bricks, multi-section checker bricks are in line with the temperature conditions and heat transfer laws in the furnace. And it can make the blast temperature drop less. However, it makes the cleaning operation of checkered bricks very difficult and prone to clogging.
2) Covered segmented checkered bricks. Recently, due to the continuous improvement of the quality of refractory materials and to avoid the difficulty of dust-cleaning operations, more and more cover-type checker bricks have been used. Although it does not comply with the rules of heat transfer, due to the use of high refractory materials, the entire checker brick can be made of smaller checker bricks and thinner brick thicknesses, which can also increase the heat transfer coefficient to make up for the shortcomings.
With the improvement of gas depressurization work, the checker bricks can be gradually reduced. At present, China generally uses 80×80 mm checkered bricks. To ensure sufficient mechanical strength, the thickness of checker bricks should not be less than 50 to 60 mm.
Construction of Checkered Bricks for Hot Blast Furnace
Before laying checkered bricks in a hot blast stove, the grates and supports must be inspected. When inspected by the wire drawing method, the surface flatness deviation of the upper surface of the grate should be 0~5mm. The allowable deviation between the center line of the grate grid holes and the designed position should be 0~3mm.
The shape and size deviation of checker bricks should be accepted according to the relevant provisions of the current industry standard “High Alumina Bricks for Hot Blast Stoves” YB/T5016. Before construction, the usage plan should be determined based on the random inspection records of the dimensions of the checker bricks. Porous lattice bricks with tongues on the upper and lower sides should be layered according to height.
The grid hole at the center point of the regenerator should be used as the benchmark for determining the horizontal cross-center line control line of the brick grid on each layer. Each layer of grid bricks should be laid according to this horizontal cross-center line, and the grid holes should be kept vertical. During brick grid construction, wooden scales can be used to control the brick grid at the same time. During construction, a central control line should be established inside the surrounding furnace walls. The misalignment between the upper and lower brick grids should not exceed 5mm.
The surface of the brick grid should be smooth. The displacement of the brick grid holes to the furnace grate grid holes should not exceed 10mm, the complete number of grid holes should be counted and concealed engineering records should be filled in.
Expansion joints should be left between the surrounding checkered bricks and the furnace wall according to design regulations and should be fixed with wooden wedges.
Anti-scaling measures should be taken during construction and the grid holes must not be blocked. After the brick lattice is laid, it should be cleaned and the lattice holes should be inspected. If the bright light of the electric lamp can pass through the grid hole, or if the inspection steel drill lowered from above with a rope can pass through the full height of the grid hole, the grid hole should be considered qualified. The number of blocked holes should not exceed 3% of the number of complete holes in the layer brick grid. When using porous lattice bricks with upper and lower groove tongues for construction, the hole-blocking rate of the brick lattice does not need to be an inspection item.
When the brick lattice uses porous lattice bricks with groove tongues on the upper and lower floors, the upper and lower floors should be built with staggered joints and expansion joints should be left between bricks according to design regulations. The surrounding checkered bricks should be pre-processed and the arrangement diagram should be drawn in sequence.
To purchase hot blast stove regenerator checker bricks, heat storage hole bricks, and high thermal conductivity bricks, please contact us. We can provide high-quality refractory lining material products for high-temperature industrial furnaces. Our perfect customer service can provide long-life refractory materials for your high-temperature industrial furnace linings to save production costs.
Stability and safety in high-temperature environments are critical to many industries. To protect equipment and personnel, fire-resistant and fireproof materials play an important role. Among them, ceramic fiber, as a multi-functional fire-resistant, and fire-proof material, has the potential to be widely used. RS refractory material manufacturer can provide ceramic fiber material products for the insulation layer of high-temperature industrial equipment, including ceramic fiber blankets, ceramic fiber wool, ceramic fiber boards, etc.
Definition of Ceramic Fiber and Finished Product Types
Ceramic fiber is a refractory material in the form of long fibers made of inorganic materials. According to different production processes and material compositions, ceramic fibers can be divided into the following types of finished products.
Ceramic fiber felt: Ceramic fiber felt is a soft material made of ceramic fibers through spinning and other processes. It has excellent thermal insulation and sound absorption properties and is widely used in construction, aerospace, home appliances, and other fields.
Ceramic fiber yarn: Ceramic fiber yarn is made from ceramic fiber through a spinning process. It has high-temperature resistance and electrical insulation properties and is commonly used as insulation material in the fields of electronics, power, and aviation.
Ceramic fiber rope:Ceramic fiber rope is a rope-like product made of high-temperature refractory materials. Mainly made of ceramic fiber and organic fiber. Mainly used for sealing and filling industrial equipment, pipes, and furnaces.
Ceramic fiber board: Ceramic fiber board is a hard board made of ceramic fibers through pressing and sintering processes. It has high mechanical strength and earthquake resistance and is widely used in high-temperature insulation equipment and hearthstone structures.
Ceramic fiber paper: Ceramic fiber paper is a thin sheet material made of ceramic fibers through a wet papermaking process. It has excellent flexibility and corrosion resistance and is widely used in chemical industry, metallurgy, shipbuilding, and other fields.
Special-shaped ceramic fiber: Special-shaped ceramic fiber refers to products in which ceramic fibers are made into different shapes through special processing methods. Compared with traditional fiber boards or fiber blankets, ceramic fiber special-shaped shapes are more flexible and moldable and can be made into various complex shapes and sizes according to actual needs.
As a fire-resistant and fireproof material, ceramic fiber has many unique advantages.
High-temperature resistance. Ceramic fiber can maintain stability at extremely high temperatures, resist damage to materials caused by high-temperature environments, and protect the safety of equipment and personnel.
Excellent thermal insulation properties. Ceramic fiber has low thermal conductivity and high thermal insulation performance, which can effectively reduce heat transfer and provide good thermal insulation protection.
Corrosion resistance. Ceramic fiber has good corrosion resistance to corrosive media such as acids and alkalis, extending its service life.
Lightweight and flexible. Compared with metal materials, ceramic fibers are lighter and more flexible, easier to process and install, and reduce the conclusion part. Next is the application of ceramic fibers on different occasions.
Application of Ceramic Fiber on Different Occasions
Due to their superior properties, ceramic fibers play an important role in many different fields.
Metallurgical industry. Ceramic fiber boards are widely used in high-temperature kilns and furnace structures in the metallurgical industry to provide effective thermal insulation protection.
Aerospace. Ceramic fiber yarn is used as electrical insulation material in the aerospace field for the insulation protection of circuit boards, cables, and sensors.
Chemical Industry. Ceramic fiber paper is often used as a lining material for acid and alkali containers in chemical plants to provide corrosion resistance and high-temperature resistance protection.
Power Industry. Ceramic fiber yarns and plates play an important role in power equipment and are used in electrical insulation materials and high-temperature insulation equipment.
Car manufacturer. Ceramic fiber felt is widely used in automobile exhaust systems to reduce heat transfer, improve engine efficiency, and reduce chassis temperature.
Fire protection field. As a fire-resistant and fire-proof material, ceramic fiber is widely used in firewalls, fire doors, and fire-proof clothing of buildings to provide reliable fire protection.
Ceramic Fiber Refractory Materials
As a multifunctional fire-resistant and fireproof material, ceramic fiber plays an important role in various fields. Different types of ceramic fiber finished products, such as yarn, felt, board, and paper, have the advantages of high-temperature resistance, excellent thermal insulation properties, corrosion resistance, and being lightweight and flexible. They are widely used in metallurgy, aerospace, chemical industry, electric power, automobile manufacturing, and fire protection fields. By providing effective thermal insulation protection, corrosion resistance, and fire protection, ceramic fiber materials provide a reliable solution for stability and safety in high-temperature environments. In the future, with the further development of technology, ceramic fiber materials will continue to play an important role in various fields, bringing greater convenience and safety to different industries.
Refractory bricks are inorganic non-metallic materials with a refractory degree of not less than 1580°C. It is a basic material for high-temperature technology, a structural material for masonry kilns and other equipment, and a functional material for manufacturing certain high-temperature containers and components or their special functions. The successful use of refractory bricks under high temperatures must have a good organizational structure, thermal properties, mechanical properties, and usability. That is to say, it has high refractoriness, load softening temperature, thermal shock resistance, and chemical erosion resistance so that it can withstand various powerful chemical changes and other effects, and meet the use requirements of thermal equipment and components. So, why can refractory bricks withstand high temperatures? RS Refractory Materials Manufacturer, a powerful refractory brick manufacturer, ensures that the refractory bricks can withstand high temperatures based on the raw materials of the refractory bricks and the characteristics of the molding and sintering process of the refractory bricks as inorganic non-metallic materials.
The raw materials used in the production of refractory bricks are generally natural ores. Refractory bricks with different properties are made by processing raw materials such as bauxite, silica, and magnesite. Such as aluminum-silicon refractory bricks, siliceous refractory bricks, and magnesia refractory bricks.
Aluminum-silicon refractory bricks are produced using bauxite as raw material. Its main component is alumina. Hydrated alumina containing impurities is an earthy mineral that is insoluble in water and soluble in sulfuric acid and sodium hydroxide solutions. It is mainly used for smelting aluminum and making refractory materials. Because the refractoriness of high-alumina clinker is as high as 1780°C, it has strong chemical stability and good physical properties. The bauxite is purified at high temperature to produce a corundum main crystal phase with an alumina content greater than 90%, which can produce ultra-high temperature refractory bricks – fused zirconium corundum bricks.
The raw material of silica refractory bricks is silica, and its main component is SiO2. The higher the content, the higher the refractory degree. The most harmful impurities are Al2O3, K2O, Na2O, etc. Silica bricks are made from natural silica as raw material, plus an appropriate amount of mineralizing agent to promote the conversion of quartz in the body into tridymite. It is slowly fired at 1350-1430°C in a reducing atmosphere. It has high-temperature strength and the load softening temperature is 1620℃.
Magnesite is the main raw material for making magnesite refractory bricks. Its basic component is MgO. Magnesium oxide has high refractory insulation properties. It can be transformed into crystals after being burned at high temperatures above 1000°C and becomes sintered magnesia when the temperature rises to 1500-2000°C. Then it can be made into magnesia bricks or magnesia ramming materials after being crushed to a certain particle size or powder. Magnesia refractory bricks are alkaline refractory bricks, which have strong energy resistance to alkaline slag but cannot resist the erosion of acidic slag. The refractoriness is above 2000℃, but its load softening point is only 1500℃, and its thermal shock stability is poor.
Refractory bricks are inorganic non-metallic materials
Inorganic non-metallic materials, organic polymer materials, and metallic materials are listed as the three major materials. Common inorganic non-metallic materials are characterized by high compressive strength, hardness, high-temperature resistance, and corrosion resistance. In addition, ceramics have excellent corrosion resistance, and refractory materials have excellent properties in heat protection and insulation. These are incomparable to metal materials and polymer materials. However, compared with metal materials, it has low breaking strength and lacks ductility. Compared with polymer materials, they have higher density and complex manufacturing processes.
Forming and sintering of refractory bricks
The production process of refractory bricks is through mineral crushing-raw material mixing-mechanical molding-high temperature firing. This process finally produces a product that can withstand high temperatures. The sintering temperature of the green body passing through the high-temperature tunnel kiln will be higher than the load-softening temperature of the product. Generally, the sintering temperature is above 1500℃, the refractoriness is above 1770℃, and the high-temperature resistance is good. Refractory bricks are mainly used to build kiln linings such as steelmaking electric furnaces, glass furnaces, and cement rotary furnaces.
To summarize, there are three main reasons why refractory bricks can resist high temperatures. ① The raw minerals used in refractory bricks have high refractoriness. ② As an inorganic non-metallic material, the level of its use is determined by the level of raw materials. ③ The finished body has passed through a high temperature of over 1500°C in a high-temperature tunnel kiln, so the refractory bricks can resist high temperatures and are suitable for use in high-temperature kiln linings.
Performance advantages of low porosity refractory bricks
Clay refractory products are extremely versatile and are made of high-quality raw materials. It is an indispensable refractory material for various industrial kilns. Low-porosity clay bricks were originally designed and widely used in hot blast stoves and glass kiln regenerators. Nowadays, it is widely used in lime kilns due to its good density and good resistance to chemical corrosion, especially alkali corrosion.
Low-porosity clay bricks are refractory products made from high-quality burnt gemstones as the main raw material, and their performance has been fully upgraded. The performance advantages of low porosity refractory bricks include.
Strong corrosion resistance.
Low porosity and high density.
High mechanical strength.
Strong anti-penetration ability.
High strength and high fire resistance.
The organization is dense.
Good thermal shock stability and resistance to peeling.
RS refractory brick manufacturer
RS Refractory Brick Manufacturer is a powerful manufacturer of refractory brick production and sales. Our refractory brick products have an annual output of 60,000 tons, and the quality is reliable and guaranteed. We have also made certain breakthroughs in thermal insulation material products. It has contributed a small step forward for energy-saving and heat preservation of high-temperature industrial furnaces. Our RS company can provide comprehensive refractory services for high-temperature industrial furnaces. Our professional technical team can also provide suitable solutions for the lining of high-temperature industrial furnaces. Material design and construction of refractory linings, and turnkey refractory projects. Contact us to get a free quote and samples.
With the advancement of the times, reducing consumption and improving production efficiency have always been the primary goals of major enterprises. In the field of high-temperature industry, regenerative industrial grid bricks are widely recognized and accepted as a heat-carrying and heat-storage body with many superior thermal properties such as strong heat exchange capacity, large heat storage area, smooth ventilation, and low resistance. Checker bricks are a heat transfer medium used in blast furnaces hot blast furnace regenerators, coke oven regenerators, glass kiln regenerators, etc. Checker bricks are usually arranged in an orderly manner in the regenerator. It plays the role of heat storage during the “burning period”. During the “air supply period”, the cold air is heated into hot air through convective heat exchange and radiation heat exchange.
Basic characteristics of regenerator checker bricks
It has a plurality of transparent holes parallel to the side surfaces, as well as positioning protrusions and positioning grooves located on the two parallel surfaces.
Good volume stability, excellent creep performance under high-temperature load, high density, and low porosity. Modern blast furnace hot blast stoves usually adopt a checkered brick regenerator structure.
Construction of Checker Bricks in Hot Blast Stove Regenerator
(1) The regenerator checker bricks usually use seven-hole checker bricks. During masonry construction, each layer should be arranged in a staggered manner, and the upper and lower grid holes should be aligned.
(2) The checkered bricks around the edges of the masonry and at the joints of the walls should be pre-processed according to the designed dimensions before masonry. During construction, the processed checker bricks will be laid in sequence according to the construction drawings. Be careful not to process checker bricks in the furnace. When building the wall of an internal combustion hot blast furnace with the furnace shell as the guiding surface, checker bricks can be processed appropriately in the furnace while taking protective measures.
(3) Before laying checkered bricks, the cross center lines should be drawn at the four angular directions of 0°, 90°, 180° and 270° of the wall masonry. Then pull out two rows of masonry center lines on both sides of the 90° and 270° lines, with the center column being the first row of masonry center lines.
(4) The checkered bricks on the first floor should be dry laid and laid in advance. The bricks can be laid formally after the center grid position is verified to be accurate and qualified. After the masonry is completed and it is confirmed that the surface flatness of the masonry meets the requirements, the second layer of checkered bricks will be laid.
(5) Each layer of checkered bricks is controlled according to the three rows of masonry center lines pulled out from the fence. Starting from the center line of each layer of checker bricks, lay the cross row of center bricks first. Then build the bricks along the four angles in the direction of the furnace wall.
(6) Allowable deviation of expansion joints between adjacent checker bricks
1) Clay checker brick: 4mm;
2) High alumina checker brick: 8mm;
3) Silica checker brick: 12mm.
Use yellow cardboard or foam plastic board to fill the expansion joint tightly. Before filling, process the board according to the reserved size and thickness of the expansion joint. Then when the checker bricks are being laid, the expansion joint plates are tightly attached to the sides of the checker bricks. Carry out simultaneously, build, and paste at the same time.
(7) After the first layer of checker bricks is completed, the processed checker bricks at the edge positions are laid in sequence. And check to confirm compliance.
(8) The expansion joint between the checker bricks and the furnace wall should be reserved according to the design and construction requirements. Use wooden wedges to wedge the expansion joint tightly.
(9) After the checker bricks are laid, clean the construction area. Check the hole position and smoothness of the grid holes again. If the electric light can pass through the grid hole or the inspection tool passes through the full height of the grid hole, the grid hole will be regarded as qualified.
Coke Oven Regenerator Checker Brick Construction Process
After the furnace body is completed, blow air to clean the secondary grooves on the roof of the regenerator. Mark the control line between the central partition wall and the sealing wall on the regenerator wall.
Blow the checker bricks clean with compressed air and start preparing to lay the checker bricks.
When the first layer of checker bricks is dry-layed, check the location and stability of the checker bricks before dry-laying the lower layer of checker bricks.
The checkered bricklayer after the second layer should be stepped back from the central partition wall to the furnace head.
Always check whether the holes of each layer of checker bricks are unobstructed, and the upper and lower checkerboard bricks should be aligned.
Yellow cardboard can be used to maintain the width and stability of the gap between the grid bricks and the regenerator wall and non-flammable materials must not be used for the padding.
After the dry-laying of checker bricks in each regenerator is completed and the inspection is qualified, the construction of the regenerator sealing wall begins.
The regenerator walls and checker bricks of divided regenerator coke ovens should be constructed alternately in sections. Before each section of checkered bricks is dry-layed, the section should be sealed or partitioned, and the wall grooves should be cleaned. During the dry-laying process of checker bricks, pay attention to prevent refractory mortar from falling into the lower checker bricks. Once the dry-laying is completed and inspected to be qualified, immediately cover it with a protective board. The protective board should be set firmly and tightly, close to the wall of the regenerator to prevent refractory mud from leaking into the checker bricks.
Hot Repair Method of Checker Bricks for Glass Kiln Regenerator
After long-term high-temperature operation of the glass melting furnace, the refractory brick for the glass kiln lining and various equipment used have aged to varying degrees. In particular, the checker bricks in the regenerator were seriously damaged and blocked, seriously affecting the atmosphere in the glass-melting furnace. This situation not only increases energy consumption but also causes a large number of quality problems in the glass products produced. Therefore hot repair of checkered bricks is by far the most effective way.
Thermal repair process of checker bricks in the regenerator
Hot repair preparation
Before hot repair, a specific hot repair plan must be developed. Equipment, tools, and checkerboard tiles should be ready for use. During hot repair, the ratio of raw and clinker should be adjusted, the pulling amount and pressure in the kiln should be controlled, and the temperature should be controlled to ensure the normal production needs of the furnace.
Replacement of checker bricks
After opening the regenerator, first clean out the old checkered bricks that have worn out inside. Special attention should be paid when dismantling old checker bricks, as the heat storage gradually decreases and the working conditions in the kiln change. The fire exchange should be manually controlled according to the situation and adjusted in time to ensure the hot spot temperature and melting.
Laying out new checkered tiles. The material of the regenerator grid bricks is the same as the original regenerator grid structure. It mainly uses three types: clay bricks, magnesia chrome bricks, and high-purity magnesia bricks. Layer clay bricks, magnesia chrome bricks, and high-purity magnesia bricks from bottom to top. Seal the thermal chamber door and withdraw the water tank. Seal the water tank door.
After the checker bricks in the regenerator are replaced and the door is sealed, it is very important to perform reasonable heating operations and monitor the temperature in the regenerator. During the entire heating process, the principle of “slow heating and no cooling” should be followed.
The effect of thermal repair of checkered bricks in regenerator
After the hot repair of checker bricks in the regenerator, the heat in the regenerator will be stable and the heat energy consumption will be reduced. Glass defects and frying time caused by material problems have been greatly reduced, and fuel consumption has been reduced.
