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Causes of Corrosion of Fused AZS Refractory Brick Pool Walls in Glass Furnaces

2023-10-31 by globalrefractory

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 AZS Refractory Brick Pool Walls in Glass Furnaces — 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.

Hazards of Magnesia-Chrome Waste Bricks and How to Prevent

2023-10-08 by globalrefractory

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.

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.

Methods for Repairing Blast Furnace Hearth-Side Walls with Refractory Materials

2023-09-152023-09-15 by globalrefractory

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.

The Difference Between Corundum Brick and Corundum Mullite Brick

2023-08-31 by globalrefractory

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.

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.

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.

What is the Mullite Refractory Castable Formula?

2023-08-222023-08-21 by globalrefractory

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.

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.

Tortoiseshell Net Wear-Resistant Castable – Tortoiseshell Net Wear-Resistant Material

2023-07-05 by globalrefractory

Tortoiseshell net wear-resistant castables and tortoise shell net ceramic wear-resistant materials are actually amorphous refractory materials combined with tortoiseshell nets for wear-resistant construction of industrial equipment. Tortoiseshell net ceramic wear-resistant material is a kind of wear-resistant coating commonly used in industry. The coating has the advantages of high hardness and wear resistance. It can improve the efficiency of enterprises, prolong the service life of equipment, and reduce the operating costs of enterprises, so it is very popular in the industry.

Tortoiseshell Net Castable, Flue Anti-Abrasive Material

Tortoiseshell net castable, tortoiseshell net wear-resistant clay. It is mainly composed of wear-resistant aggregates such as brown corundum and silicon carbide and fine powder. At the same time, add sintering agents, ultrafine powder, coating additives, ceramic powder, composite material powder, composite adhesive, etc. The particles are closely packed, forming quickly and having high strength. It can reach the design strength in three days, so there are no major defects in use. The bulk density is high, and its strength at room temperature can reach more than 200Mpa.

Application of ceramic wear-resistant castables. Ceramic wear-resistant castables are mainly suitable for pipes and flues with high dust concentrations and serious acid and alkali erosion and wear in cement plants, power plants, metallurgy, and other industries. Dust collector, vertical mill equipment, feeding hopper, feeding chute, powder classifier, and other equipment and conveying pipelines. This product has been applied in more than 400 cement plants, power plants, and mining enterprises. In the cement industry, this product has been supplied to Loesche vertical mill, vertical mill, Ube vertical mill, raw material mill, clinker mill, coal mill outlet air duct, grate cooler to electric dust collector duct. And the conveying pipelines such as the upper shell of the powder classifier. It is a new generation of wear-resistant materials that replace traditional ceramic sheets, wear-resistant steel plates, and cast stone plates.

Tortoiseshell Net Wear-Resistant Castable

The Characteristics of Wear-Resistant High-Strength Tortoiseshell Mesh Wear-Resistant Castables

Wear-resistant ceramic coating is a new type of artificial material, which is a non-metallic cementitious material. It is a powdered ceramic coating produced by using acid and alkali-resistant artificial synthetic raw materials through strict process ratio and advanced synthesis technology. It can be used to form a coating on the surface of other metals or non-metals to improve its performance.

The performance of wear-resistant mortar has high mechanical strength and rigidity, which is difficult for ordinary reinforced concrete to achieve. The main reason is that the combination of the internal atoms is mainly by the combination of ionic bonds, and the force between the ions is relatively large, so the macroscopic performance is high strength and rigidity. At the same time, the wear-resistant mortar also has good toughness and shock resistance, which ensures the stability of its work, and the temperature has little influence on it. But what is also important is that the environmental compatibility of wear-resistant cement is very good, because its main component is silicate, which does not pollute the environment and does not produce harmful substances such as metal ions. It is a new material.

Wear-resistant cement refers to the general term for ceramic coatings with high-temperature resistance for various purposes. There are many kinds of wear-resistant mortar and a wide range of uses, which are all derived from its performance characteristics.

High-temperature resistance. Ceramic anti-corrosion coatings have high-temperature resistance, and composite ceramic high-temperature anti-corrosion coatings can withstand temperatures up to 1200°C. The temperature resistance of general anti-corrosion coatings is only about 400 ℃.

High hardness. The coating can form a dense ceramic structure after high temperatures, and the hardness can reach 5-6H. Wear-resistant and impact-resistant, twice as hard as traditional anti-corrosion coatings.

Wide range of acid and alkali resistance. It can withstand the corrosion of weak acids and alkali and can withstand the corrosion of alkalis. It is waterproof and moisture-proof, and can also prevent the corrosion of acid and alkali gases. The range of PH resistance is wide, and the application range is wider than traditional anti-corrosion coatings. Strong corrosion resistance and long service life.

Application Advantages of High-Strength Tortoiseshell Mesh Wear-Resistant Castables

Wear-resistant clay belongs to the field of functional coatings and is a new type of water-based inorganic coatings. It is mainly composed of nano-inorganic compounds and water as a dispersant. After coating, it is usually cured by low-temperature heating to form an insulating coating film with properties similar to ceramics. After years of joint research and experiments, the company has successfully developed high-temperature-resistant ceramic insulating coatings, whose performance has surpassed that of insulating coatings. High-temperature and wear-resistant cement have excellent properties such as insulation, temperature resistance, wear resistance, high hardness and thermal shock resistance, and medium thermal expansion coefficient.

High temperature-resistant and wear-resistant cement, using the high-temperature solution, the long-term temperature resistance can reach 1800 ℃. Water-based inorganic ceramic materials, the coating is made of pure inorganic polymer high-temperature solution, and the pigment is made of high-resistance inorganic crystal materials. Insulating coatings can work at 1700°C for a long time. The volume resistivity is greater than 1016Ωm, and the dielectric strength (breakdown strength) is greater than 104KV/m. Good chemical stability, aging resistance, and corrosion resistance. No flash point, ignition point, high hardness, hardness greater than 7H.

High temperature resistant ceramic insulating coating, temperature resistant to 1700°C. A layer with high volume resistivity can be formed on the surface of the coated object, which can withstand a strong electric field without being broken down. The coating has high mechanical strength and good chemical stability and is resistant to aging, water, and chemical corrosion. It is also resistant to mechanical and thermal shocks. The insulating coating can work continuously at the corresponding working temperature. The high-temperature-resistant ceramic insulating coating is a water-based inorganic high-temperature coating. It adopts a proprietary pure inorganic polymer high-temperature solution and is composed of high-resistance inorganic crystal materials. As α-alumina, silicon nitride, mica flakes, etc. are used as fillers. The coating has high volume resistivity (greater than 1012Ωm) and high dielectric strength (higher than 104KV/mm). It is suitable for painting high-temperature insulation on various fire-resistant cables. The paint is fired to form the insulating layer of the hard ceramic-like shell. The insulating layer of this hard ceramic-like shell can prevent the flame from spreading and protect the normal state of the substrate from damage.

SK30, 32, 34, 36, 38, 40 Refractory Bricks

2023-06-19 by globalrefractory

SK30, SK32, SK34, SK36, SK38, and SK40 are relatively common foreign refractory brands, which are different from domestic refractory bricks. Among them, SK-30, SK-32, SK-34, and SK-35 represent clay bricks, and SK-36, SK-37, SK-38, and SK-40 refer to high alumina bricks.

Refractory bricks refer to shaped refractory products made of refractory raw materials, which can withstand high temperatures above 1580°C. The main raw material is refractory clay (bauxite) mixed with clinker (calcined and crushed clay), stirred, waked up, and pressed into shape by a strong machine. After drying, it is made by calcining at a high temperature of more than 1000 degrees.

SK32 clay brick, SK34 clay brick, SK36 high alumina brick, SK37 high alumina brick, SK38 refractory brick

High-temperature-resistant bricks are called refractory bricks. It is mixed with refractory clay into clinker (calcined and destroyed clay) and then stirred and pressed into shape. The finished product is obtained by calcining after drying. There are also silica and high alumina bricks. Can be divided into SK32, SK34, SK36, SK38, SK40 refractory bricks. Refractory bricks are mainly used for furnace lining, flue, chimneys, and other parts. According to its shape and size, it can be divided into two categories: standard shape and special shape. The specification of refractory bricks is 230 mm × 114 mm × 65 mm, and special-shaped refractory bricks can be customized according to customer needs. Refractory bricks can be divided into ordinary refractory bricks according to their refractory degree, and the refractory degree is 1580-1770 ℃. For high-grade refractory bricks, the refractory degree is 1770~2000℃. According to its chemical function, it can be divided into three types: acidic, alkaline, and neutral.

Refractory bricks SK30, SK32, SK34, and SK35 refer to clay bricks. AL2O3% (≥) 30%, 35%, 38%, 45%. It is made of refractory clay and its clinker through crushing, mixing, molding, drying, and drying. Belonging to weakly acidic refractory products, the acidity increases with the increase of SiO2 content. It has a certain corrosion resistance to acidity, but poor resistance to alkaline corrosion.

SK36, SK37, SK38, and SK40 refractory bricks refer to high-alumina bricks with alumina content of 55%, 65%, 70%, and 82%. High-alumina bauxite is selected as the main raw material, and soft raw clay is added as a binder. After molding, it is fired at a high temperature of about 1500°C. High-alumina bricks contain more than 48% Al2O3. Its refractoriness, load softening point, and refiring shortening are higher than clay bricks, and its resistance to rapid cooling and heat is worse than that of clay bricks. High alumina bricks belong to neutral refractory materials, and their slag resistance function increases with the increase of Al2O3 content.

Rongsheng High Alumina Bricks Manufacturer

Now, the standards/types of refractory bricks that are widely used abroad are SK32, SK34, SK36, SK38, and SK40 refractory bricks. Our factory makes customized special-shaped bricks, which can be processed and customized according to the shape of the equipment and drawings, and the delivery cycle is short.

Refractory bricks can be divided into three types according to their chemical functions: acidic, alkaline, and neutral. It is a shaped product in refractory materials. According to its refractoriness, it can be divided into three grades with a refractoriness of 1580-1770°C, a refractoriness of 1770-2000°C, and a refractoriness of more than 2000 degrees.

The size of SK30, SK32, SK34, SK35, SK36, SK37, SK38, and SK40 refractory bricks is divided into standard size and special-shaped size. The standard size of refractory bricks for Rongsheng refractory brick manufacturer is 230*114*65mm. The special-shaped size is different according to the location of use and the audit requirements of the kiln, and the size can be customized according to the drawing. Clay bricks are roughly divided into: clay bricks for coke ovens, clay bricks for blast furnaces, clay bricks for hot blast stoves, and clay bricks for glass kilns according to their used parts. According to the volume density, it can be divided into general clay bricks, low-porosity clay bricks (dense clay bricks), and low-creep refractory bricks.

The refractory bricks produced by The Rongsheng Refractory Manufacturer has the characteristics of wear resistance, corrosion resistance, spalling resistance, low creep, and good thermal shock stability. The operating life is 1.5 times that of general products. Used in blast furnaces, hot blast stoves, carbon roasters, carbon calciners, coke ovens, steel ladles, casting systems, boilers, cement kilns, glass kilns, and various kiln linings and thermal equipment, etc. It is suitable for metallurgy, machinery, building materials, casting, ceramics, electric power, petroleum, chemical industry, and other industries. Contact us to get prices and samples for free.

Castable Refractory, Insulating Castable and Dense Castable, Low Cement Castable

2023-05-29 by globalrefractory

Regarding the question “what is the specific gravity of castable refractory?”, refractory material manufacturers indicated that what many people want to ask is actually the weight (tons) of a cubic castable refractory. Enterprises generally purchase castable refractory according to the actual working conditions of their industrial kilns. Rongsheng refractory castable manufacturer published a popular science blog on the conversion of castable refractory specific gravity. Generally speaking, refractory castables have bulk density, including mizzou castable refractory. For example, 2.0, 2.6, and so on. The higher the bulk density, the heavier the castable refractory will be. For example, a cubic 2.0 body density castable is about two tons, and a 3.0 body density is about three tons.

High Alumina Castable Refractory - Rongsheng Company — High Alumina Castable Refractory

What factors determine the weight of the castable refractory?

The density of the aggregate. The greater the density, the heavier the weight of the castable refractory unit cube.
The level of aluminum content. Generally, the higher the aluminum content, the heavier the castable refractory.

The density of aggregate depends on its chemical composition and porosity. For example, the higher the alumina content in the aluminum-silicon-based lightweight aggregate, the greater the density, the greater the porosity, and the smaller the bulk density.

Is it true that the higher the density of the castable refractory, the better?

It is ridiculous to say that the denser the refractory castable, the better. In fact, the density of the castable refractory is determined according to the performance, the parts used and so on. For example, some places need to use high-density castables, but some places need small-density castables. Therefore, it is not that the higher the density of the castable, the better. It is necessary to choose a suitable castable refractory according to the specific construction site.

insulating castable for boiler

Insulating castable is mainly made of light insulation aggregate. It is a kind of hydraulic material that is prepared by dry mixing according to the optimal ratio with bonding material. It has the characteristics of small bulk density, low thermal conductivity, high strength, and small shrinkage. It can be poured directly after on-site mixing (video of insulating castable on-site construction). Insulating castable is widely used in boilers, industrial furnaces, and other body insulation engineering fields. Insulating castable for general boilers chooses lightweight castables with a bulk density of 0.8 or 1.0.

Bulk density and thermal conductivity of castable refractory

As a refractory manufacturer, it is certain that the greater the bulk density of the castable refractory, the greater the thermal conductivity. In general, different bulk densities of castable refractory have different thermal conductivity.

The thermal conductivity of the castable with a specific gravity of 1 is about 0.26 W/(m.k);
The thermal conductivity of the castable with a specific gravity of 1.4 is about 0.8 W/(m.k);
The thermal conductivity of the castable with a specific gravity of 2.2 is about 1.45 W/(m.k);

If the metal wire is added to the castable, the thermal conductivity value will be larger.

The density of 0.8 is 0.28 W/(m.k),
The density of 1.2 is 0.4W/(m.k),
The density of 1.6 is 0.6W/(m.k).

That is to say, the smaller the bulk density of the insulating castable, the smaller the thermal conductivity, and the better the insulation function. Boiler thermal insulation linings refer to the operating temperature and thermal conductivity to select thermal insulation castables with appropriate bulk density. Generally, companies that purchase insulating castables will customize insulating castables according to their needs. The insulating castable of different materials is used for the insulation layer of boilers and low-temperature kilns at different temperatures. In order to save the production cost to the greatest extent.

The difference between dense castable and insulating castable of the same material

The biggest difference between dense castable and insulating castable is the bulk density. The body density of the dense castable is above 2.0, while the body density of the insulating castable is below 1.5.

The castable refractory of the same material, the dense castable, and the insulating castable have very different uses. The insulating castable is used for heat insulation in the heat insulation area. Dense castable is used in the working layer, mainly for fire resistance and wear resistance.

Insulating castable has low thermal conductivity, good thermal insulation performance, and a relatively low price. It is used in the heat treatment lining of thermal kilns for both heat insulation and heat preservation. Therefore, lightweight castables are also called lightweight heat-insulating castables or lightweight heat-insulating castables. Lightweight castables can only be used for thermal insulation and cannot be used in the working layer.

dense castable has high body density, wear resistance, high-temperature resistance, and corrosion resistance. Therefore, it is also called wear-resistant refractory castable, which can be used in direct contact with the flame in the kiln, so the heavy castable plays the role of high-temperature resistance and wear resistance.

During construction, heavy castables have less water, good strength, and long service life, while light castables are twice as much water as heavy castables because light castables are non-absorbent materials. When pouring, the template should be painted with waterproof paint to prevent the loss of castables. If water is lost, the fluidity of the castable will decrease, and it will be difficult to discharge air bubbles, which will affect the strength. However, if the amount of water added to the quality castable is too large, it will affect the discharge of crystal water and free water. It affects the strength of later use, which is also a major difference between heavy castables and light castables.

low cement castable LC-70

low cement castable LC-70 is an ultra-low cement bonded high-strength no-bake low cement refractory castable with a service temperature of 1350°C. It is mainly used in heating furnaces, rolling steel heating furnaces, annular heating furnaces, well-type heating furnaces, pushing steel heating furnaces, etc. The product grade of low cement castable is named after the initial letter of the ingredient content. The letters are the abbreviations “L” and “C” for “alumina” and “calcium oxide” respectively, and the representative value of the content is 70% AL2O3.

How to Use High Alumina Refractory Bricks and FireClay Refractory Bricks?

2023-05-05 by globalrefractory

High alumina refractory bricks and fireclay refractory bricks are the two most commonly used refractory materials in shaped refractory materials. High alumina bricks have high refractoriness, good slag resistance, and high load softening temperature. The refractoriness of clay bricks is lower than that of high alumina bricks, and the slag resistance, especially the performance of acid slag resistance is better than that of high alumina bricks, and the thermal shock performance is good. Manufacturers of high alumina refractory bricks can provide methods of using high alumina refractory bricks to use high alumina refractory bricks more efficiently.

High-Grade High-Alumina Bricks in RS Factory

How to Use High Alumina Bricks

The lining of important parts and parts with complex shapes should be pre-built first. For the lining with a complex structure and a large amount of refractory brick processing, it can be considered to change to the castable lining.
The exposed metal parts left in the brick lining, including brick supporting boards, brick retaining boards, etc., should be sealed with special-shaped bricks, castables, or refractory fibers. It should not be directly exposed to hot kiln gas in use.
Anchor bricks are masonry structural bricks, which should be set according to the design regulations and must not be omitted. Cracked anchor bricks shall not be used around the hanging holes. The metal hooks should be laid flat and hung firmly. The hanging hole and the hook cannot be stuck, and the gap left can be filled with refractory fiber.
The expansion joints in the refractory brick lining must be reserved according to the design and must not be missed. The width of the expansion joint should not have a negative tolerance, and no hard debris should be left in the joint. And fill the seam with refractory fiber to avoid the phenomenon of being full on the outside and empty on the inside. Generally, expansion joints may not be provided in the heat insulation layer.
When building capping bricks, joint bricks, and curve bricks, if the refractory bricks cannot meet the sealing requirements, the refractory bricks should be finished with a brick cutter, and the hand-processed refractory bricks should not be used. The size of the processed refractory bricks should not be less than 70% of the original refractory bricks. In the joint bricks and corner bricks of the plane, it shall not be less than 1/2 of the original brick. Must use the original brick lock.

How to Use Clay Refractory Bricks — Fireclay Bricks

How to Use Fireclay Refractory Bricks

The selection of the starting point should be laid sequentially from the hot end to the cold end or from the low end to the high end.
Arranging and marking the operating points.
Brick selection, according to the need to use the fireclay refractory bricks of different materials in the hot and cold sections, select qualified bricks.
If there are anchor nails or supporting bricks, weld the anchoring nails or supporting bricks.
If there is a heat insulation layer (such as silicon-calcium board, etc.), it is necessary to install the heat insulation layer first.
For mortar preparation and application, the mortar mud should match the refractory bricks.
Laying bricks.
Reserve and fill the swelling gap.

How to ash the general refractory brick?

Ashing is to pre-apply mud on the bonding surface of the refractory bricks to be built. According to the change of the type, shape, and location of the refractory bricks, the method of ashing is also different. The unevenness of the dusting process has a great influence on the strength of the masonry. When the dusted refractory bricks are opened for inspection after the masonry is completed, it can be seen that the joints are evenly covered with mud. However, refractory bricks with poor ash removal will have gaps on the contact surface, which will reduce the cohesive force of the brick body and may cause air leakage in the masonry.

(1) Clay ash with a trowel. He holds a brick in his left hand and a tile knife in his right. When the plastering method is used to make gray strips, the mortar is first taken with a trowel, and then the bricks are taken. When laying the gray strips, place one large side of the brick upwards. When laying the bricks in place, press the bricks tightly with your left hand, and tap with a mallet in your right hand until the bricks are finally tightened.

(2) Shovel ash. Hold the refractory brick in your left hand and a large shovel in your right hand. First use a large shovel to beat the mortar, and then take the refractory bricks. These operations are the same as the trowel ash. Attention should be paid to the four movements in the picture. The tip of the shovel moves backward along the edge of the refractory brick so that the mortar will naturally form a raised back for masonry.

Regarding the use of high-alumina refractory bricks and clay refractory bricks, Rongsheng refractory material manufacturers have put forward the above suggestions, hoping to help you when choosing high-alumina refractory bricks and clay refractory bricks. The refractory brick products of Rongsheng refractory brick manufacturer include special grade high alumina brick, first-grade high alumina brick, second-grade high alumina brick, third-grade high alumina brick, clay refractory brick, clay insulation brick, high alumina insulation brick, corundum brick, Corundum mullite bricks, magnesia bricks, magnesia carbon bricks, magnesia chrome bricks, etc. Rongsheng refractory brick manufacturers can also customize refractory bricks according to the actual needs of industrial furnaces or construction drawings. Contact us for free prices and samples, Email: inquiry@global-refractory.com, Tel/WeChat/WhatsApp: +8618538312977.

Boiler Refractory Cement Manufacturer

2023-04-13 by globalrefractory

Whether to use refractory mortar or refractory cement for boilers is a question full of doubts. Rongsheng refractory manufacturers, what is certain is that when laying refractory bricks on the boiler, the firebrick refractory mortar of the same material as the refractory bricks are generally used. Firebrick mortar is composed of refractory powder, binder, and admixture. Almost all refractory raw materials can be used to prepare refractory mortar. So what is refractory cement for boilers? How is boiler refractory cement used?

Boiler Refractory Cement

Boiler refractory cement is a raw material for unshaped refractory lining materials for boilers, which can be used to cement various refractory aggregates (such as corundum, calcined high-alumina bauxite, etc.). Used to prepare refractory mortar or refractory castable. Therefore, refractory cement is also called refractory castable cement.

Firebrick mortar is an ordinary refractory mortar made of refractory clinker powder plus an appropriate amount of plastic clay as a binder and plasticizer. Its normal temperature strength is low, and it has high strength only when it forms a ceramic bond at high temperatures. The chemically bonded refractory mortar uses hydraulic, air-hardening, or thermosetting bonding materials as a bonding agents. Before the temperature is lower than the formation of ceramic bonding, a certain chemical reaction occurs and hardens. Firebrick refractory mortar is mainly used in coke ovens, glass furnaces, blast furnaces hot blast stoves, and other industrial furnaces.

The usage of different refractory mortar is different. For casting clay, it is used at the burner of the kiln head. It is often used as a protective refractory layer, and it can also be used as a refractory material in some key parts of the preheater. The construction method is common grouting. For insulating fireclay, it can be used for trimming the deformation of the kiln shell. At this time, it only needs to be directly painted on the plane. Sometimes it also insulates the coolant ceiling. Thermosetting cement is common when laying bricks. We can directly use it for stirring and add a certain amount of glass water. In this way, the bonding strength and stability of the bricks will be improved to a certain extent.

Characteristics of Refractory Mortar

Good thermal exfoliation.
Good resistance to slag invasion.
Good plasticity and convenient construction.
High bonding strength and strong corrosion resistance.
High refractoriness, up to 1650℃±50℃.

Furnace Refractory Cement Manufacturer

How to choose refractory cement manufacturers for boilers? Before that, we must first know what type of boiler we are using in our actual production. Because there are many kinds of boilers, such as gas boilers, heating boilers, power station boilers, etc., choose the appropriate refractory lining products according to different boilers. This can not only prolong the service life of the kiln lining but also save production costs for the enterprise.

Large boilers such as utility boilers require more than furnace refractory cement. Because refractory cement is only raw material, it cannot be used alone, and it is easy to cause cracks when used alone. A series of matching boiler refractories is your best choice, including shaped refractory materials (refractory bricks) and unshaped refractory castables.

CFB Boiler Refractory

Shaped refractory materials include clay bricks, ultra-light bead insulation bricks, and cement perlite insulation bricks.
Unshaped refractory materials: thermal shock-resistant castables, corundum wear-resistant castables, high-strength wear-resistant, lightweight thermal insulation castables, and wear-resistant refractory plastics.
Other materials include anchors, aluminum silicate fiberboards, insulation cotton, blankets, etc.

As one of the refractory cement manufacturers, we can not only provide high-quality boiler refractory cement, CA50, CA60, CA65, CA70, CA75, and CA80. Moreover, our experienced technical team can provide design and maintenance of refractory lining materials for various industrial furnaces. Design and construction of refractory materials for various rotary kiln insulation layers. The purpose is to improve economic benefits for industrial kiln enterprises between production costs.

The name of refractory cement is aluminate cement, which can be used to cement various refractory aggregates (such as corundum, calcined high alumina, etc.) to make refractory mortar or concrete. Because it has a refractoriness of not less than 1580 degrees, it is widely used as a lining for cement rotary kilns and other industrial high-temperature kilns.

Corresponding aggregate should be added to refractory cement, avoid simple use, otherwise, cracks will occur after high temperatures. In addition, please note: 1. Baking is required after pouring construction, and it can be baked at least 3 days later. 2. Baking should be slow to avoid partial bursting. 3. Baking and cooling should be slow accordingly, and forced ventilation is not allowed.

Kind Tips

If you don’t know how to choose a furnace refractory cement manufacturer or have questions about refractory maintenance and procurement, please contact us. We can provide free technical guidance and a sample trial. Rongsheng refractory manufacturers have produced and sold refractory materials for many years. We have an experienced technical team and a production team that strives for perfection. Kiln insulation, kiln lining construction, kiln maintenance, escort for high-temperature industrial kilns.