What are the Lining of the Heating Furnace?

The heating furnace is divided into furnace, fuel system, air supply system, smoke exhaust system, and cooling system. The furnace is a space composed of the furnace wall, the furnace top, and the furnace bottom, and different pouring materials are used for each part. Let us understand the refractory materials used in the lining of the heating furnace.

Refractory Lining of the Heating Furnace
Refractory Lining of the Heating Furnace

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  1. Low-cement castables are used to wrap the structure of water beam-columns. The column tube and the lower part of the supporting beam in the furnace are all made of low cement castables. Low-cement castables are also used in the low-temperature zone of the heating furnace, flue parts, and furnace body parts that do not exceed 1300°C.
  2. Self-leveling castables are used in the heating furnace where the structure is complicated and cannot be vibrated manually. The use temperature is 1500℃, which is characterized by good thermal shock resistance, high refractoriness, easy construction, and almost no need for vibration.
  3. Phosphate castables are suitable for heating furnace bottoms and other parts that are severely affected by material friction and hot air erosion. The operating temperature is between 1000-1600°C. It is a castable with phosphoric acid or phosphate as the binder and aluminum calcium cement and magnesia as the accelerator.
  4. Mullite castable. Because mullite refractory castable has high thermal shock resistance, erosion resistance, good erosion resistance, good volume stability, and high service temperature. It is generally used in key parts such as furnace walls, furnace roofs, and press beams.
  5. Anti-dry slag castable, suitable for the bottom of the heating furnace, and the place where iron oxide slag is deposited. The use temperature can reach 1600℃. Its main characteristics are high refractoriness, good thermal shock resistance, and good resistance to the corrosion of iron oxide slag in the heating furnace.
  6. Lightweight castable, suitable for heat insulation layer of the furnace wall, furnace roof, flue, etc. High-strength lightweight castables can also be used as working linings for smoke exhaust systems and hot air ducts. It is characterized by low bulk density, good thermal stability, low thermal conductivity, and certain refractoriness.
  7. Bauxite cement castable is a castable produced by mixing various refractory aggregates and powders in a certain proportion with aluminate cement as a cementing agent. It has the characteristics of fast solidification, high strength, thermal shock resistance, and slag resistance. It not only meets the refractory performance of the heating furnace body but also improves the construction performance of the furnace body.
  8. The advantage of fire-resistant plastic is that there are no gaps in the overall construction and good airtightness. The furnace lining uses a large number of plastic materials instead of castables and is mainly used for the top of the furnace.
Low Cement Castable Refractory Material
Low Cement Castable Refractory Material

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What is the Meaning of the Refractory Castables Grades?

The various castables used for the lining of the heating furnace have been introduced above. How to make a specific distinction between them? This introduces the definition of refractory castable grades. What is the meaning of refractory castable grades? It is usually used in combination with numbers and pinyin letters to distinguish the material, performance, and purpose of the castable. Refractory castable grades have refractory standards and the settings of different castable manufacturers. Next, we will learn about the types and grades of common refractory castables.

Classification of Refractory Castables

1. Classified by material, silicon castable, clay castable, high alumina castable, mullite castable, corundum castable, aluminum-magnesium castable, etc.

2. According to the purpose, it can be divided into several types of castables for industrial furnaces, such as castables for steel rolling furnaces, castables for tapping channels, castables for mixing furnaces, and castables for cement kilns.

3. According to the bulk density, it can be divided into light castable and heavy castable.

4. According to its characteristics, it can be divided into refractory steel fiber reinforced castable, anti-skinning castable, low cement castable, high-strength castable, etc.

Mullite castable price
Mullite Refractory Castable with High-Quality

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Grades of Refractory Castables

1. Brands of silicon castables: rsg-70, rsg-60, rsg-50, etc. Among them, rs is the manufacturer of Rongsheng castables, G is the main material selected for castables is silicon, and the quantity is the silicon content.

2. Brand of castable clay: nn-45. Among them, the first n is clay as the binder, and the second n is the main material selected for the clay castable. The number is the main component content of the clay castable)

3. Grades of high-aluminum castables: nl-70, nl-60. Among them, n is clay as a binder, l is the main material selected for the castable is high aluminum material, and the quantity is the aluminum content of the high aluminum castable.

4, aluminum-magnesium castable grades: amc-70, amc-80, etc. Among them, a, m, and C are the English initials of alumina, magnesia, and castable. The number is the content of the main raw materials selected for aluminum-magnesium castables.

  1. Castable grades for steel rolling heating furnace: zj-42, zj-60, zjs-65, etc. Among them, Z is the steel rolling heating furnace, J is the castable, and s is a part of the water-cooled tube of the heating furnace. The number is the main material content selected for the castable of the steel rolling heating furnace.

6. Grades of castable for iron ditch: Asc-1, Asc-2, Asc-3. Among them, a, s, and C are the English initials of alumina, silicon carbide, and carbon. The number is only used to distinguish the castable grade.

The above is the introduction of a refractory castable brand. Hope you can understand the meaning of the casting brand after reading it. There are many brands of refractory castables, some are set by the castable manufacturers themselves, and some are set in accordance with refractory standards. No matter what way the refractory castable is named, it is to distinguish the material, grade, performance, and purpose of the refractory castable.

Rongsheng Refractory Castable Manufacturer
Rongsheng Refractory Castable Manufacturer

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Rongsheng Refractory Castables Manufacturer

Rongsheng refractory castable manufacturer has an advanced and fully automatic unshaped refractory castable production line with an annual output of 80,000 tons. Rongsheng has provided high-quality refractory castables, mullite castables, self-flowing refractory castables, wear-resistant refractory plastics, corundum mullite refractory plastics, etc. for many turnkey projects. For more information about the refractory castables Lining of the Heating Furnace, Rongsheng’s monolithic refractory products, and Rongsheng refractory manufacturers, please contact us. We will provide you with services according to your specific needs.

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How to Improve the Performance of Refractory Castables?

With the continuous progress in the production and use of refractory castables, it is necessary to improve the wear resistance and thermal shock resistance of refractory castables. The research and development of new refractory castables with excellent high-temperature strength, good thermal shock resistance, and good corrosion resistance will help improve the life of cement kiln linings. Rongsheng refractory manufacturer. There are two important measures to improve the performance of refractory castables. In this article, you can also learn another two ways to improve the performance of refractory castables.

Corundum Self-flowing Wear-resistant Castable
Rongsheng Corundum Self-flowing Wear-resistant Castable

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Improve the Wear Resistance and Thermal Shock Resistance of Refractory Castables

  1. Measures to improve the wear resistance of wear-resistant castables
  • Reduce the critical particle size of the castable. From 8mm to about 5mm.
  • Improve the flexural strength of the castable in the medium temperature and hot state. At a medium temperature of 900°C, the flexural strength of the castable indirectly reflects the wear resistance of the castable. The current development trend is to require the hot flexural strength of the castable to be no less than 20MPa.
  • Improve the bonding ability of the castable matrix. It is formulated with multi-level micro powder and super micro powder to form the tightest accumulation. Promote sintering at medium temperature and improve the bonding ability of the castable matrix.
  • Use high-hardness refractory materials as aggregates.
  1. Measures to improve thermal shock resistance of wear-resistant castables

Firstly, It adopts composite aggregate and composite powder, that is, complex phase technology. The difference between the linear expansion coefficient of aggregate and matrix is used to balance the strength and thermal shock resistance of the castable.

    •  High expansion aggregate + low expansion matrix. This combination is very resistant to thermal shock.
    •  Low expansion aggregate + low expansion matrix. This combined castable has uniform bonding and high mechanical strength. General thermal shock will not produce huge stress in the castable, and cracks will appear.

Then, Reduce the thermal expansion rate of the material. Try to choose materials with a relatively low thermal expansion rate to improve the thermal stability and mechanical impact of the castable.

Low Cement Castable Refractory Material
Low Cement Castable Refractory Material

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How to Improve the Performance of Refractory Castables?

In addition, the performance of refractory castables can also be improved according to the application characteristics of refractory materials.

Add water reducing agent to refractory castable

Seeing such topics, it is estimated that everyone is like me, the first thing that comes to mind is what is the use of refractory castables added to water-reducing agents.

The water reducing agent is added to the castable, which can significantly reduce the amount of mixing water added during the construction of the castable. In the case of constant water consumption during the construction of the castable, it can also increase the fluidity or plasticization of the castable.

Water reducing agent is an electrolyte material of surface-active substance, which is dissolved in castable and can be adsorbed on the surface of particles. By increasing the repulsive force between the ion surface and the particles in the solution, the free water which is composed of fine particles and wrapped in the castable structure is released. It plays a role in wetting and dispersing. Water reducing agents can also be called a dispersing agent.

Water reducing agent is a dispersant or flow agent of high alumina cement, which plays a plasticizing or deflocculating role in refractory castables. Under the condition of keeping the flow value of the refractory castable basically unchanged, the water reducing agent does not chemically react with the comprehensive components of the raw and auxiliary materials in the castable, nor does it generate compounds, but only plays a physical and chemical role on the surface.

Because the water reducing agent can release the free water in the castable structure. Therefore, while keeping the fluidity of the castable unchanged, the water consumption during the construction of the castable can be reduced. Or under the condition that the castable does not change the unit water consumption, increase the rheology of the castable, improve the working skills, and make the refractory castable easier to construct and shape.

Steel Fiber Refractory Castable for Sale
Steel Fiber Refractory Castable for Sale

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Add steel fiber to refractory castable

In the production of refractory castables, steel fiber refractory castable products of different diameters are added. Steel fiber is a product made of heat-resistant and wear-resistant stainless steel or other steel types. Common steel fiber specifications are 20mm, 25mm, 30mm, and 35mm. Steel fiber castable is a refractory castable with high strength, good thermal shock resistance, and good wear resistance. Adding steel fiber to the refractory castable can enhance the performance of the castable and increase the use effect.

The effects of adding steel fiber to refractory castable are:

(1) Enhance the toughness of the lining, improve the resistance to mechanical impact, and wear resistance.

(2) Improve thermal shock resistance, improve cracking, and peeling resistance.

(3) Suppress linear shrinkage after curing, drying, and heat treatment.

The refractory castable is added with steel fiber to enhance the use effect after pouring, but the amount of steel fiber added to the castable is determined according to the requirements of the technical department. Too much steel fiber added to the castable can cause damage to the lining at high temperature after pouring, reduce the corrosion resistance of the lining, and affect the performance of the kiln lining.

Rongsheng Refractory Castable Cement Manufacturer
Rongsheng Refractory Castable Cement Manufacturer

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Rongsheng Refractory Castable Manufacturer

The Rongsheng refractory castable manufacturer has an advanced and fully automatic refractory castable production line with an annual output of tons. Rongsheng is a strong refractory material manufacturer and sales company. Rongsheng has served customers in more than 60 countries around the world. For example, etc. Moreover, our refractory family R&D team is also working hard to provide customers with refractory linings that best suit their production needs. If you want to know the manufacturer of Rongsheng refractory materials or want to obtain a quotation of refractory materials, such as low cement castable, phosphate bonded castable, high alumina castable, corundum castable, etc. please contact us. We will provide you with services according to your specific needs.

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What are the Functions of Micro-Powder in Refractory Castables?

The basic mechanism of micro-powder in refractory castables is filling and lubrication. The micro powder can be used to fill the gap between aggregate and powder, reducing the amount of water used. After the molded body removes water, there are fewer holes left, which can increase the bulk density and reduce the apparent porosity. Thereby improving the structural strength of the material and optimizing material performance. In addition, the fine powder particles can form colloidal particles in water. When there is a dispersant, the particle surface forms an overlapping electric double layer to generate electrostatic repulsion, which overcomes the van der Waals force between the particles. Reduce the interface energy and prevent the particles from adsorption and aggregation. At the same time, the dispersant is adsorbed around the particles to form a solvent layer. Therefore, the fluidity of the castable is also increased, and the performance of the refractory castable material is optimized.

Silica Micro-powder in Refractory Castable
Silica Micro-powder in Refractory Castable

Micro-powder Used in Refractory Castables

In refractory castables, the most used micro powders are active SiO2 powder and a-AL2O3 powder. Followed by SiC powder, high alumina powder, white corundum powder, brown corundum powder, zircon powder, and spinel powder. The function of micro-powder in refractory castables is to fill and lubricate and increase fluidity.

The Silica Powder Added in the Refractory Castables

The SiO2 powder used in the refractory industry is mainly micron-sized. There are many types of SiO2 micro powders, among which silica fume has good performance and a wider range of applications. It is a by-product of ferrosilicon alloy plants and metal silica plants. In addition, there are natural mineral powder quartz, SiO2 powder milled by a grinder, and white carbon black powder. Electronic industry by-products, active SiO2 powder on the surface treated by silane coupling. Fused silica powder. When using zircon to produce desiliconized zirconium dioxide, the collected by-product-silica powder, and the silica powder collected in the production of metal silica.

Aluminum Silicon Carbide Castables
Aluminum Silicon Carbide Castables

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What is the role of silica powder in refractory castables?

Silica powder is added to the refractory castable to supplement the tiny pores. Through the precise particle gradation of ultra-fine powder, the strong performance of the castable is improved.

The strength of refractory castable comes from high alumina cement, and the CaO in high alumina cement reaches 5% to 8%. It will reduce the medium temperature strength of refractory castables. If the amount of low melting material is large at high temperature, it will also reduce the high-temperature performance of refractory castable. The CaO in high-alumina cement will produce hydration, and the amount of water used will increase after hydration. If the amount of water is large, the castable structure will become loose. If the superfine powder is added, the cement content in the castable can be reduced to 6%. Reduce the CaO and water consumption in the high alumina cement, thereby increasing the strength of the castable. This is the importance of silica powder in refractory castables.

High alumina refractory cement
High Alumina Refractory Cement

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Silica powder is an essential raw material in refractory castables. Adding silica powder to the castable will increase the flow value of the castable. The silica powder has a small particle size and is a spherical particle, which is extremely easy to enter the tiny voids of the castable. Therefore, adding silica powder has good water reducing effect. It can also increase the density of refractory castables and reduce porosity. So that the strength of the refractory castable is better.

The compressive strength of the refractory castable after adding silica micro powder will also change significantly at different temperatures. The initial strength is 110°C, and the medium temperature strength is 1100°C. Due to the fineness activity of SiO2 powder and the fluxing effect of CaO and other impurities in the refractory castable, a strong ceramic bond will be produced. When the high-temperature strength is 1450℃, the silica powder and the alumina powder will form mullite at high temperatures. The porosity of the refractory castable is reduced and the high-temperature strength is better.

α-Al2O3 Powder

The α-Al2O3 micro powder is made after calcining industrial alumina. Its characteristics are good dispersibility, small particles, easy sintering at high temperature, and small volume effect. Adding a certain amount of α-AL2O3 micro powder in refractory castables has a significant impact on its construction performance. Adding an appropriate amount of α-AL2O3 micro powder to the castable can improve the refractoriness of the refractory castable, and cause caramelization and multimerization reactions at high temperatures. On the other hand, it plays the role of filling micro powder and reduces the porosity of the castable. This reduces structural defects in the castable, improves its strength and resistance to slag erosion, and improves the overall performance of refractory materials.

Corundum Castable
Corundum Castable
Corundum Mullite Refractory Castable for Sale
Corundum Mullite Refractory Castable for Sale
Corundum Silicon Carbide Wear Resistant Refractory Plastic
Corundum Silicon Carbide Wear Resistant Refractory Plastic

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Rongsheng Refractory Castable Manufacturer

As a manufacturer of refractory castables, Rongsheng’s unshaped refractory workshop is equipped with advanced, fully automatic production lines. The annual output of 80,000 tons. According to different kiln types and operating conditions, we configure exclusive monolithic refractory formulations for customers. The types of products we have sold include wear-resistant refractory plastics, corundum castables, corundum mullite castables, refractory mortar, refractory ramming materials, etc. Want to know more about Rongsheng refractory manufacturers, or you need to buy monolithic refractory products. Please contact us, we will provide you with services according to your specific needs.

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Application of Zirconia Unshaped Refractories in Glass Furnace

With the continuous improvement and development of the glass furnace structure, the variety and demand of zirconia ramming materials are increasing. Domestic manufacturers of zirconia ramming materials have swarmed, forming a wave of production of zirconia unshaped refractories.

Zirconia Unshaped Refractories

Zirconia unshaped refractories can be divided into two categories: zirconia slurry and zirconia ramming material. Zirconia ramming materials are divided into two types: zirconite and zirconia alumina. The former is to add a certain proportion of crushed sintered zircon brick pieces to the zirconia mortar powder to form granular aggregates. The latter is added with granular aggregate after the fused corundum brick is broken. When using the above two ramming materials, add an appropriate amount of industrial phosphoric acid (H3PO4) with a concentration of 85%. After mixing, make the ramming materials wet and loose, and then ramming. After high-temperature sintering, it becomes a solid whole.

Rongsheng Zirconia Refractory Ramming Mass for Sale
Rongsheng Zirconia Refractory Ramming Mass for Sale

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Application of Zirconia Ramming Material in Glass Kiln

Among different zirconia ramming materials,

  • Some are zirconia ramming materials with aggregates. It is mainly used for the bottom ramming layer in the kiln for melting borosilicate glass.
  • Some are zirconia -alumina ramming materials. It is mainly used to melt the bottom ramming layer of soda-lime-silica glass, electric vacuum glass, and other alkaline glass furnaces.
  • Some belong to zirconia mortar. It is mainly used for mortar joints of zircon bricks or transition layers.
  • Some are intermediate repair materials. It is mainly used for repairing any refractory material that is not in contact with the molten glass in the flame space after corrosion.
  • There is also a mixture of ramming materials and intermediate repair materials.

Although the above-mentioned zirconia refractories have different uses, different chemical compositions, and various specifications, they are all called ramming mass refractory materials. Therefore, it often creates illusions for users. The manufacturer of Rongsheng refractory castables materials manufacturer reminds all customers that in the construction process, the wrong type should be avoided and the wrong place of the zirconia refractory ramming material should be avoided. So as not to cause the “ramming material” to peel off or be mixed in the glass liquid, causing stones and bubbles in the product. In severe cases, the glass furnace is damaged prematurely.

Zirconia Refractory Mortar
Zirconia Refractory Mortar

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The Curing Mechanism of Zirconia Unshaped Refractories

Both zirconia ramming material and zirconia refractory mortar use phosphoric acid as a binding curing agent. Both types of powders contain AL2O3. When phosphoric acid (H3PO4) is added, H3PO4 reacts with AL2O3 to form AL(H2PO4)3 at 150°C. ALPO4 is formed at 236℃ and then combined with ZrO2 in zircon sand to generate Zr(H2PO4)4, Zr(HPO4)2, and Zr3(PO4)4. At 300℃~340℃, compounds such as ZrP2O7 are formed to cause bonding and solidify. When the temperature continues to rise to 1520~1550°C, decomposition occurs again to produce (ZrO) 2P2O7+P2O5. Among them, the phosphoric acid is completely volatilized at this temperature, so that the zirconia amorphous refractory material becomes a solid and integral hard block. Therefore, it is necessary to empty the furnace and heat the kiln to make the furnace bottom temperature exceed 1550°C.

Rongsheng Refractory Materials Manufacturer

Rongsheng is an experienced refractory manufacturer. Rongsheng’s refractory materials have been recognized by customers in more than 60 countries around the world. For example, Thailand, UAE, Turkey, Kuwait, South Africa, Malaysia, Vietnam, Netherlands, Philippines, Singapore, Egypt, Russia, etc. Rongsheng’s refractories have also served many glass furnace projects. Learn more about zirconia refractory bricks and zirconia unshaped refractory products for glass kilns. Please contact us. We will provide you with services according to your specific needs.

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Refractory Material for Cement Rotary Kiln Hoods

For some large rotary kilns, the heat load on the lower part of the Kiln Hoods is relatively high. If the general high alumina castable refractory is not well maintained and temperature rise controlled, they are prone to bursting and falling off. The top of the Kiln Hoods is close to the tertiary air duct, and the dust-laden airflow is relatively serious. Moreover, the construction of the top castable is relatively difficult, and the fluidity and early strength of the material are relatively high. Rongsheng refractory castable cement manufacturer recommends that the Refractory Material for Cement Rotary Kiln Hoods adopts high-strength wear-resistant castables with good high-temperature performance, strong thermal shock resistance, and wear resistance.

Rotary Kiln Hoods Refractory Lining
Rotary Kiln Hoods Refractory Lining

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Why use the same refractory material for cement rotary Kiln Hoods and Coolers?

The Kiln Hoods is the kiln head part of the rotary kiln, and the cooler is supporting equipment for the rotary kiln. The top of the cooler has a high working temperature and large temperature changes. The low walls on both sides of the front end are long-term abraded by the high-temperature clinker coming down through the kiln mouth and also endured by certain mechanical and thermal stresses. The operating environment of these two parts is similar. Therefore, refractory manufacturers generally recommend the use of refractory materials of the same material. Rongsheng refractory manufacturers generally recommend the use of refractory castables in these two parts.

Cement Rotary Kiln Cooler Refractory Lining
Cement Rotary Kiln Cooler Refractory Lining

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Why should refractory castables be used for kiln hoods and coolers?

According to the use conditions of the Kiln Hoods and coolers described above, the reasons for the use of refractory castables in the Kiln Hoods and coolers can be roughly summarized.

  1. The refractory castable at the bottom of the kiln hood is subject to the rebound thermal shock of the high-temperature clinker coming down from the kiln mouth. For some large cement kilns, the daily output of the clinker is large, and the heat load on the premises is relatively high.
  2. The top of the Kiln Hoods is close to the tertiary air duct, and the dust flow is relatively serious, and the castable has better wear resistance at high temperatures. Moreover, the construction of the top castable is more difficult, and the fluidity and early strength of the material are relatively high.
  3. The bottom of the front end of the cooler is subject to the rebound thermal shock of the clinker, and the working temperature is relatively high and changes greatly. The low walls on both sides of the front end have been long-term abraded by the high-temperature clinker coming down through the kiln mouth and also endured certain mechanical and thermal stress damage.

<To sum up> According to the operating characteristics of the above parts of the cement rotary kiln, it is recommended to use high-strength wear-resistant castables with good high-temperature performance, strong thermal shock resistance, and wear resistance.

Rongsheng refractory material manufacturer provides special kiln hoods refractory castable products for cement kilns. Moreover, Rongsheng manufacturers can adjust the refractory formula of the kiln hoods according to the specific production needs of customers. Let every customer be able to do it in the production process, minimizing costs, and maximizing benefits.

Cement Rotary Kiln Hoods Refractory Castables
Cement Rotary Kiln Hoods Refractory Castables

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Construction of refractory material for cement rotary Kiln Hoods

General refractory construction plan for Kiln Hoods

  1. Exhaust holes should be left during the construction of the wall castables, and the holes should be drilled with a gas drill with a distance of 300*300mm. And it is embedded with Φ5mm wooden strips, the depth is half of the castable.
  2. After the pouring hole of the Cement Rotary Kiln Hood is closed, 8 ventilation holes should be reserved and waterproof function should be ensured.

Construction scheme of kiln hoods ceiling

  1. Use hanging anchors. Weld it on the L70*70 angle steel at a distance of 250mm*250mm. The angle steel is welded to the longitudinal I-beam of the original Kiln Hoods steel structure. The angles are arranged at a pitch of 250mm.
  2. The mold is supported from below. Before supporting the mold, paste F10D aluminum silicate fiber cotton on the vertical surface of the surrounding old castable with high-temperature bonding powder (BP-1).
  3. When pouring, pouring the castable in the order of ABCDEF. Then paste F10 aluminum silicate fiber cotton on the end surface with high-temperature bonding powder (BP-1).
  4. During the pouring process, use the H100 calcium silicate board for laying. Or after pouring, use high-strength lightweight heat-insulating castable (HN-1.3 or Q1.3) for complete covering pouring (δ=1000mm).
  5. After all, pouring is finished, use ordinary steel plate with δ=3mm to cover the surface (pay attention to the waterproof of the lap joint). And cut holes and weld steel pipes to leave several ventilation holes.

The technical scheme of brick masonry for kiln door cover vault

  1. Brick supporting board at the bottom of the arch on both sides of S and N. When the brick supporting board at the bottom of the arch on both sides of S and N burns more than 1/2 the thickness of the brick, the brick supporting board should be replaced in time. Its specifications: 4150mm*330mm*10mm. If time permits, remove the old board before welding. If time is tight, weld directly on the original pallet. The fixed three sides are required to be fully welded and the working surface is flat.
  2. Refractory brick masonry. The vault has a total of 17 rings of refractory bricks, which are built with the refractory mortar, and the mortar joint is controlled at 1mm. Before laying, the line must be laid out, three in the axial direction, three in the circumferential direction, and four in the circumferential direction. The masonry of refractory bricks must be based on this line.

Masonry of insulation bricks

  1. Build a layer of 114mm thick insulation brick on the above refractory bricks, using insulation refractory mortar. There are 3 models (230*114*55/65mm or (60/65 or 65/65)) to match and concentrically build with refractory bricks.
  2. The masonry of insulation bricks should be synchronized with refractory bricks. The upper gap is filled with aluminum silicate fiber cotton to facilitate the wedging of the rear refractory bricks.
RS Cment Rotary Kiln Burner Refractory Castable for Sale
RS Cement Rotary Kiln Burner Refractory Castable for Sale

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Rongsheng Refractory Castable Manufacturer

Rongsheng is an advanced refractory castable manufacturer with a fully automatic and environmentally friendly refractory castable production line with an annual output of 80,000 tons. Has served customers in more than 60 countries and regions, for example, India, Pakistan, Kuwait, South Africa, Malaysia, Vietnam, Netherlands, Philippines, Singapore, Egypt, Russia, etc. Rongsheng has customized kiln hoods’ refractory castables, burner refractory castables, high-alumina high-strength refractory castables, and high-strength wear-resistant castables for cement rotary kilns. The product quality and customer service of Rongsheng’s unshaped refractories are leading in the industry. Get more product quotations on refractory material for cement rotary kiln hoods. Please leave your contact information and specific requirements on our website page. We will provide you with refractory materials that best suit your production needs according to your actual working conditions. Save production costs and improve economic efficiency.

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Application of Low Cement Castable in Soaking Furnace

Low cement castable refers to a castable with low cement content. The cement dosage of refractory cement castables is generally 15% to 20%, and the cement dosage of low cement castables is about 5%, and some even reduce to 1% to 2%. Application of Low Cement Castable. The purpose of reducing the amount of cement is to improve the fire resistance of the castable. After molding and curing, less cement hydrate is formed. During heating and baking, there is no problem that a large number of hydration bonds are destroyed and the medium temperature strength is reduced. Instead, as the heat treatment temperature increases, it gradually sinters and the strength gradually increases. The water requirement of the castable is greatly reduced, so the porosity is low and the volume density is high. From the refractory castables manufacturer, it is very suitable for all kinds of heating furnaces and soaking furnace refractory lining materials.

Low Cement Castable Refractory Material
Low Cement Castable Refractory Material

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Construction of Low Cement Castable on Soaking Furnace

Low cement castables and ordinary castables are both refractory castables combined with calcium hard aluminate cement, which are widely used in thermal equipment in metallurgy, petroleum, chemical, and other industries, and have achieved good results. In the overall pouring of the soaking furnace, the installation of anchoring bricks, the retention of expansion joints, and the 20 Pa pressure operation of baking below 200 ℃ for 4 days are the key points.

When low-cement castable is cast as a whole, it is poured layer by layer from the bottom of the furnace wall up. Take the height of two anchor bricks as one layer, paste ceramic fiber felt, build light clay bricks, and support the template. The mixed low cement castable can be poured into the formwork through the funnel. Flatten and shake with a vibrating rod, which is very important. Whenever it is poured to the horizontal position of the anchor brick, it is best to be 20 mm higher than it. Then the anchor bricks are kneaded, squeezed, and hung by hand so that they are stably placed on the required horizontal position. When pouring to the furnace mouth, spread two layers of oil felt paper to ensure easy removal during intermediate repairs. It can be demoulded 2 days after pouring.

Construction of Low Cement Castable
Construction of Low Cement Castable

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Hardening Mechanism of Low Cement Castable

Low cement castables rely on the addition of several special raw materials to obtain good performance. In the Application of Low Cement Castable, First, pure calcium aluminate cement, due to the high content of effective mineral CaO·Al2O3, can obtain the required strength with less mixing. The second silica fume is glass beads with a SiO2 content between 93% and 98% and an average particle size of about 0.5 μm. After adding silica fume, the castable has good fluidity, low molding water requirement, and low sintering temperature, which improves the performance after heat treatment. Third, alumina powder is easier to participate in the reaction and improve the fire resistance of the material. Fourth, the water reducing agent, which can be adsorbed on the surface of the powder, and then generate electrostatic repulsion to disperse the powder, so as to further play the role of fine powder.

Oven-drying after Casting Low Cement Castable

The oven-drying is an important part that directly affects the service life of the soaking pit of the low cement castable. During the Application of Low Cement Castable, they contain ultrafine oxide powders, so they have the weaknesses of poor air permeability and poor chipping resistance. Cracking is a phenomenon produced when the internal steam pressure of the castable increases beyond its strength during the drying period. It is closely related to the diffusion rate of steam, that is, the air permeability of the pouring body. For this reason, the oven-drying curve should be controlled within 200°C in the first 4 days, and the temperature should be lower at the beginning, and the oven-drying should be operated with slight positive pressure. The practice has proved that this method effectively overcomes the cracking and lays an extremely favorable foundation for the subsequent heating of the oven-drying.

Low Cement Wear Resistant Castable
Rongsheng Low Cement Wear Resistant Castable for Sale

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The Effect of Using Low Cement Castable

Since the first furnace pit was poured, more than 2,400 tons of low cement castables have been successfully used. From construction, oven-drying to formal production, low-cement castables have the characteristics of good pressure resistance, high flexural strength, good high-temperature volume stability, and good thermal shock stability at low, medium, and high temperatures. The average life of each furnace pit is more than 3 years. Practice shows that low cement castables are good materials for soaking furnace pits. For more information, please contact rs low cement castable manufacturers.

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Advantages and Applications of Lightweight Insulating Castables

Lightweight insulation castables are composed of high-quality, high-strength raw materials, aggregates and ultra-fine powders, and compound additives. Because the light-weight insulation castable is a powdery and granular refractory material made of certain refractory materials such as alumina and some binders. It has high fluidity and is mainly formed by pouring in construction. Lightweight insulating castables have the advantages of high strength, small volume density, low thermal conductivity, good insulation performance, and convenient construction. It is an ideal choice for industrial boiler insulation materials.

Lightweight Insulation Refractory Castable

RS Lightweight Insulating Castable for Sale
RS Lightweight Insulating Castable for Sale

Construction method: vibration or manual ramming construction.

Main function: Insulation and heat insulation to reduce the external temperature of the furnace wall.

Q: How to mix light-weight insulation castable?

A: The mixing of castables requires the use of forced mixers and special mixers.

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Advantages of Lightweight Insulating Castable

The light-weight castable insulation is made of aluminate cement, high-alumina fine material, ceramsite, plus several additives. It has the advantages of high refractoriness, high strength, and low thermal conductivity. The heat preservation casting material of the invention has the characteristics of low thermal conductivity and small volume density, which can reduce the heat and heat energy consumption of industrial kilns and reduce the weight of the furnace lining. In the high-temperature light-weight insulating castable, the raw material of the high-temperature light-weight castable that can be used above 1200°C is a porous material. Mullite, corundum, high aluminum, siliceous and magnesia and other porous clinker or light refractory brick. This castable can be directly used in the lining of 1350℃ atmosphere furnace.

Insulating castable supplier
RS Insulating Castables Supplier

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Lightweight thermal insulation castable has the following advantages:

  1. The high-temperature resistance and high strength.
  2. Low thermal conductivity.
  3. The small volume density, reduce kiln heat consumption.
  4. Convenient construction and reduce labor intensity.
  5. Light texture, reduce the weight of kiln lining.
  6. resistant to acid and acid gas corrosion.
  7. Characteristics of heat insulation, heat preservation, and low water absorption.

In addition, the lightweight insulating refractory castable is not only easy to construct but also the most ideal product for construction with alkali-resistant parts at high temperatures. Moreover, the workability is good, the bonding force is strong, and the initial setting time and the construction operable time are long. The strength increases quickly, the impermeability is strong, no acidification treatment is needed, and it is easy to ensure the denseness and fullness of the masonry gray joints. Can significantly improve the airtightness, integrity, and anti-corrosion ability of the chimney lining wall. It is an ideal cementing material for a high chimney, high-temperature flue, and air duct lining.

The Use of Light-weight Insulation Castable

It is suitable for unshaped refractory materials formed by pouring. It is easy to ensure the denseness and fullness of the masonry gray joints, which can significantly improve the airtightness, integrity, and corrosion resistance of the chimney lining wall. It is suitable for a high chimney, high-temperature flue, and air duct lining. Lightweight insulating castables are mainly used for lining thermal insulation devices such as high-temperature industrial kiln insulation. It can also be used in acid-resistant projects such as acid-resistant tanks and tanks in petroleum, chemical, nonferrous metallurgy, and other industries.

Mullite Insulating Castable
Mullite Insulating Castable

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Lightweight Insulating Castables Manufacturer

Rongsheng refractory castable manufacturer has an annual output of 80,000 tons’ production workshop. As a manufacturer of high-quality refractory castables, the light-weight heat-insulating castables produced have the advantages of moderate strength and good insulation performance. Lightweight insulating castable is made of aluminate cement, high-alumina fine material, ceramsite, and some additives. Lightweight insulating castables have the characteristics of lightweight, high compressive strength, acid and acid gas corrosion resistance, heat insulation, heat preservation, and low count rate. In addition, Rongsheng’s acid-resistant bricks, acid-resistant clay and wipe fabrics, acid-resistant bricks, acid-resistant clay, and wipe fabrics are self-developed refractory materials suitable for thermal insulation of power plant boiler chimneys and heating network pipes. They have the characteristics of acid corrosion resistance, temperature resistance, heat resistance stability, and convenient construction.

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Lightweight Refractory Castable Preparation

Lightweight castable is mainly made of aluminate cement, high alumina fine material, ceramsite and other additives. Lightweight refractory castable sales with light volume, high compressive strength, acid and acid gas corrosion resistance, heat insulation, heat preservation, low water absorption characteristics.

The series of refractory insulation castable is composed of lightweight refractory aggregate and powder, and the binder admixture is called lightweight castable. Lightweight refractory castable sales are mainly used in high chimney, high temperature flue and air duct lining, petroleum, chemical, nonferrous metallurgy and other industries acid tank, tank and other acid resistant engineering.

 

Lightweight refractory castable sales
Lightweight refractory castable sales

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The type and amount of cement, refractory powder and light aggregate used in lightweight castable refractory are not the same, so are their functions. The reduction of water consumption and the improvement of strength with the addition of water-reducing agent are remarkable. The addition with small bulk density can reduce the volume density of castable and improve its heat insulation function, but the strength is reduced twice, and the more the dosage is, the more significant it is. Therefore, according to the working conditions of the furnace and the position of castable, the reasonable selection of lightweight refractory castable can achieve the intention of energy saving.

The manufacturing and molding of lightweight refractory castables are essentially the same as refractory castables. The difference is that the bulk weight of light aggregate is small, easy to absorb water, so the weight of light aggregate should be weighed, poured into the forced mixer, first add half of the water, wet mixed evenly, then add refractory powder and cement, and add the rest of the water mixing. When forming, aggregate is easy to float up, forming layers, so the vibration time to be shorter, should be controlled. Lightweight refractory castable sales shall be maintained in a wet environment after initial setting in accordance with a professional process. 1 day after the removal of mold, Portland cement and CA-50 cement lightweight refractory castable samples, should be maintained for 6 days and 2 days. Then, check its functionality. The drying compressive strength is greater than 6Mpa. With the increase of heating temperature, the strength decreases. When it reaches 1300℃, the strength increases, which is caused by the sintering of powder.

This series of refractory castable is easy to construct and is the most ideal product for alkali resistant parts at high temperature. Mainly according to the porosity, binder, aggregate classification. In practice, it is often classified by the use of temperature or functional characteristics. According to the porosity, there are two kinds of dense castable material and insulation burning material with the porosity not less than 45%. According to the binder there are hydraulic binding, chemical binding, coagulated binding castable. There are clay aggregate, high alumina aggregate, silicon aggregate, alkaline aggregate, special aggregate and insulation aggregate.

 

Lightweight refractory castable for sale
Lightweight refractory castable for sale

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Zhengzhou Rongsheng Kiln Refractory Co.,Ltd. is professional refractory castable manufacturer. Over the years, we are committed to the production of high-quality refractory materials, and more than 60 countries and regions reached friendly relations of cooperation with customers. Refractory products stable quality, complete varieties, worthy of customer trust, welcome to purchase, we will serve you wholeheartedly.

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Rongsheng Low Cement Refractory Castable Supply

Low cement castable refers to the new castable with very little fusion usage. What matters is the choice of extremely fine particles no more than 1 m. Its high temperature shock resistance, slag resistance, corrosion resistance ability significantly improved, beyond similar insulation bricks. Ultra low cement refractory castable and non-cement castable can be obtained by further reducing the content of fusion agent.

 

Low cement refractory castable
Low cement refractory castable

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This series of refractory castable is mainly made of fire-resistant stone, granular material as fire-resistant raw material, with fusion agent and preservative added, and then made of mixed rubber. Low cement refractory castable is generally used as the fusion agent for aluminate cement, the amount of cement added can harm the overall process performance of the castable, high temperature compressive strength, corrosion resistance, and so on. Refractory castable with aluminate cement as the fusion agent can be called low cement castable if CaO content is less than 2.5%. Castable with CaO content between 1.0 and 2.5% May be called ultra-low cement castable. Low cement castable is a high-end refractory castable, low content of CaO in cement, so called low cement castable.

Low cement refractory castable is mainly used for lining of heat treatment furnace, various heating furnace, heating furnace cover, shaft kiln, machinery, iron blast furnace outlet, ladle, molten iron ladle, etc. Gravity type low cement castable for metallic materials of high temperature fire prevention of the exterior wall rock wool board lining of prefabricated body, such as heat treatment furnace water-cooled heat outside the pipe line, spewing metallurgical industry with overall body spray gun line, RH, DH vacuum degassing device of presoak pipe lining, ladle and petrochemical gas path components of tubular reactor for catalytic cracking equipment lining of high temperature wear resistance of the body; It can be used for structural analysis of the location of the project construction, can further improve the overall application of practical results.

 

Low cement castable
Low cement castable

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Before the choose and buy, remind everybody to want to confirm first is the low cement castable of what material, common have clay qualitative, tall aluminous qualitative, mullite qualitative, aluminous magnesia qualitative, just jade qualitative, below the condition that material is different, the price of low cement castable also is completely different. Then the same refractory material of low cement castable, according to its main technical indicators and a key index for Al2O3 content, the higher the content of characteristic is, the more good, the match with extremely high content of calcium oxide content is, the more low, the higher the pressure test the compressive strength, the higher the compressive strength, compressive strength and line after burning rate is lower. The refractoriness of clay and high aluminium is above 1790℃ except that of clay and high aluminium.

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Construction of High-Strength and High-Alumina Mullite Castables

When selecting refractory materials, the technical performance requirements of refractory materials must be put forward according to the specific conditions of the furnace. The Rongsheng refractory castable manufacturer believes that the technical performance of the refractory used in the bloom heating furnace should be considered. Such as high softness, resistance to rapid cold and heat, small linear change, high strength at room temperature, medium-temperature, and high temperature, and slag resistance in several aspects. Therefore, high-strength and high-alumina mullite castables are the best choices. In this castable, part of mullite and additives are added. In order to promote the formation of a large number of mullite as much as possible, and to ensure high strength at room temperature, medium-temperature and high temperature, and good construction performance. The properties of high-strength and high-alumina mullite castables are shown in Table 1.

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High-Strength Mullite Castable for Sale

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Performance of High-Strength and High-Alumina Mullite Castable

Table 1 Performance of High-strength and High-alumina Mullite Castable
Al2O3 (w/%) 70
Drying at 110℃, Bulk Density (g/cm3) 2.5
1350℃ × 3h, Linear Change Rate -0.2 ~ +0.3%
Flexural Strength (MPa) 110℃ × 24h 4
1350℃ × 3h 10
Compressive Strength (MPa) 110℃ × 24h 22
1350℃ × 3h 90
Max Use Temperature (℃) 1600
Refractoriness (℃) 1790

Requirements for On-site Construction of High-Strength and High-Alumina Mullite Castables

In order to obtain the expected effect of mullite castable, in addition to reasonable design and good quality of the castable itself, the construction quality is also an important factor.

(1) Preparation before construction

High-strength and high-alumina mullite castables are formulated with multiple components. Active composite ultrafine powder and a small amount of pure calcium aluminate cement are added, which is more active. Therefore, the storage conditions and time requirements are relatively high, and it must be strictly protected from moisture. If the packaging is damaged or affected by moisture, it is not allowed to use. Its storage period should not exceed two months from leaving the factory. Construction machinery must be cleaned up to ensure the normal operation of construction machinery, such as forced mixers, vibrating rods, scales, and drill drills.

(2) Installation of anchor bricks

The arrangement of anchor bricks in the refractory castable lining must be horizontal and vertical. The proper distance is 400~500mm. The anchor bricks should be fixed during construction, and they should not be displaced due to construction forces. In order to prevent displacement, wooden wedges can be used for positioning.

(3) Setting of expansion joints

Expansion joints are determined according to the linear rate of change of mullite castable and experience. The high-strength and high-alumina mullite castable is reserved for 4 to 5 mm per meter of cast body. After pouring, the outside of the expansion joint should be covered and sealed with clay bricks. After putting into production, there should be no fire, and the plugging material should be easy to melt.

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(4) Construction of mullite castable

Before construction, the operator should be able to grasp the operating points and quality requirements of each process. After the ingredients are added to the mixer, dry mix and mix for 1 minute, and then add water. If the material is too dry or too thin, it will affect the quality. Generally, it can be kneaded into a dough and made into a slurry by hand. It is strictly forbidden to add water temporarily when pouring out of the tank. Once the amount of water added is determined, it should not be changed easily to ensure the consistency of each mixing.

Generally, the stirring time is 5 minutes, too long or too short is not good. The mixed castable should be poured immediately, and parked in the middle should not exceed 20 minutes. The pouring material should be laid evenly at the construction site, and the formwork, expansion board, anchor brick, and other facilities should not be touched and dislocated due to excessive force.

Generally, the vibrating rod is used to vibrate the material about 300mm, and each part should be re-slurried. When pulling out the vibrator, you should lift it slowly to avoid leaving holes. If you find that there is no vibration, dig out and re-tighten it. After pouring, the surface of the pouring body does not need to be polished.

Normally, it is naturally maintained for 2 to 3 days, and it is strictly forbidden to step on or touch it during the maintenance period. When the castable is solidified, vent holes should be pierced in time to help eliminate water vapor. The mold can be demolded after confirming that it has sufficient strength.

construction of high-alumina mullite castables
construction of high-alumina mullite castables

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Oven-drying after On-site construction of high-strength and high-alumina mullite castable

The quality of the lining on-site pouring is of course very important, but the baking quality of the lining is directly related to the success or failure of the castable application. The pouring body contains a large amount of free water and crystal water, which need to be fully removed by the oven-drying, which is an extremely important link for the longevity of the furnace lining. As the volume and pressure increase sharply when the moisture becomes water vapor, if the baking temperature rises too fast, it will cause the furnace lining to crack, peel off or explode.

High-strength and high-alumina mullite castables are dense and high-strength types, with low porosity, and it is not easy to remove moisture. Especially in the removal stage of a large amount of free water in the temperature range of 100-300 ℃, it is easy to cause excessive steam pressure and cause the furnace lining to peel off or explode. Therefore, special attention should be paid, and sufficient time should be given for elimination. As the temperature continues to rise, free water and crystal water are continuously removed. When it reaches 500 ℃, the moisture content of the castable only accounts for about 10% of the total water content.

Therefore, the temperature of the castable should be slow before 600℃, and there should be enough holding time. After 1000 ℃, mullite began to form in large quantities. After the formation of the primary crystals of mullite is basically completed at 1300 ℃, the mullite grains continue to grow so that the castable is densified, the bonding force increases, and the strength increases. On the basis of summing up the experience of the last few oven-drying, we assigned four working teams to oven-drying. Record the temperature changes and fuel consumption of the heating section, soaking section, and preheating section every hour. Finally, through everyone’s joint efforts, the oven-drying task was completed satisfactorily. It can be seen that the oven-drying after the on-site construction of high-strength and high-alumina mullite castables is a very important step, and it is also a step that requires more attention and careful operation!

Rongsheng Refractory Castable Manufacturer
Rongsheng Refractory Castable Manufacturer

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Rongsheng Refractory Castable Manufacturer

Rongsheng refractory material manufacturer is an experienced manufacturer of refractory castables. Rongsheng’s refractory products have been sold to more than 60 countries around the world. Rongsheng’s advanced monolithic refractory castable production line has an annual output of 80,000 tons. We not only have strong strength in the production of refractory castables but also have rich experience in providing customers with solutions for uncertain refractory linings. If you want to buy high-strength and high-alumina mullite castables, Corundum mullite castable, mullite insulating castable, etc., or want to get more information about Rongsheng refractory manufacturers, and learn more about the prices of monolithic refractory products, please contact us. We will provide you with services according to your specific needs.

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