Refractory Blog Archives - Rongsheng Refractory Castable Manufacturer

Application Advantages of Refractory Precast Shapes

April 27, 2024April 26, 2024 by rsrefractorycastable

Application cases of RS refractory prefabricated parts. Refractory prefabricated parts are most commonly used in small high-temperature kiln equipment. The products required at the construction site are produced in advance by the manufacturer to facilitate customer construction. Used for special-shaped or special-shaped refractory products. Refractory prefabricated parts are widely used in various industrial kilns due to their irreplaceable advantages. Its biggest advantage is that it can be pre-baked and directly hoisted, so the construction period is greatly shortened, and the quality is stable and easy to control.

Application Solutions for Refractory Precast Shapes

Refractory prefabricated parts are an important variety of refractory materials, and their applications account for an increasing proportion. Refractory prefabricated parts are made by dividing the parts of the high-temperature kiln to be constructed into small pieces in advance. And design it into a special shape, and make the mold according to the shape. In the factory, refractory castables and other materials are pre-cast, cured, and baked before being transported to the site for hanging and assembly before use.

Ultra Low-Cement Castable Precast Shapes for Iron Trough

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Castable precast shape refractories can be preformed into various shapes at will, with good thermal shock stability, high strength, and good spalling resistance. No joints, good air tightness, less heat loss, and energy saving. It can quickly repair the kiln and improve the furnace operation rate. It can realize direct hoisting and mechanized furnace construction, and the construction efficiency is high. It can solve technical problems in furnace construction for users and can be customized according to user requirements and furnace-type conditions. Consider lining body design and multiple construction options for users.

There are the following solutions for the shaping of unshaped refractory materials in cement kilns. As a result, the unshaped refractory materials used in special parts of the cement kiln are customized and produced. The product has the following characteristics:

(1) There is no need for on-site pouring construction or formwork pouring, which reduces labor costs and material costs.
(2) Heat-resistant anchors are not required, eliminating the material and construction costs of anchors.
(3) The pouring, curing, drying, and baking steps of prefabricated parts have been completed when delivered, saving a lot of construction time.
(4) It is not restricted by environmental and climatic conditions, which solves the problem that castable materials cannot be constructed on-site under natural conditions during hot summer and severe winter.
(5) It can be made into various special products with different sizes and shapes. Such as grate cooler low wall, tertiary air duct elbow, lifting gate valve, kiln tail smoke chamber, coal injection pipe, kiln mouth, and other refractory materials.
(6) Maintenance is easy to replace, has little waste loss, and saves labor and time. Corundum, fused mullite, special grade bauxite aggregate, and special wear-resistant materials are added to the material, and a certain proportion of special additives are added. Vibration forming. Therefore, the product has high strength, wear resistance, corrosion resistance, good mechanical impact resistance, and excellent thermal shock resistance. It has excellent peeling resistance and cracking resistance, long service life, convenient construction, safety, and reliability, and greatly shortens the construction period.

Application Advantages of Refractory Prefabricated Parts

Refractory Preforms refer to components with a certain shape and size made of refractory materials according to specific ratios and process conditions. The main raw materials of refractory precast shapes usually include refractory castables, refractory bricks, refractory fibers, and other special refractory materials. Refractory prefabricated parts are prepared under certain process conditions, which usually include mixing, molding, curing, and drying.

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Refractory Precast Shapes have the Following Advantages

stable quality. During the production process of prefabricated components in the factory, raw materials, proportions, and process conditions are strictly controlled. Therefore, product quality is stable and reliable.
Save construction time. The use of refractory prefabricated parts can significantly shorten the construction period and improve construction efficiency.
Reduce on-site labor. Prefabricated components are produced in factories, reducing the workload of construction workers and material handling on-site.
Good performance. Because the production process of prefabricated components is strictly controlled, their performance is often better than that of refractory materials constructed on-site.

Refractory prefabricated parts are widely used in various industrial furnaces and equipment in petrochemicals, metallurgy, building materials, electric power, and other industries. Such as heating furnaces, smelting furnaces, converters, gas generators, glass kilns, etc. Depending on the actual application environment and needs, refractory prefabricated parts can be customized with different shapes, sizes, and properties. When selecting refractory prefabricated parts, factors such as the working environment, usage conditions, performance of refractory materials, and construction requirements should be considered.

When using refractory prefabricated parts, you need to pay attention to the following points.

Storage and transportation. During storage and transportation, prefabricated parts should be protected from moisture, heat, and external force damage. It is recommended to store prefabricated parts in a dry, ventilated, and cool warehouse. And pay attention to reasonable stacking to avoid extrusion and deformation.
Install. When installing refractory prefabricated parts, design requirements, and construction specifications should be strictly followed. For different types of prefabricated parts, corresponding installation methods and connection methods need to be adopted. During the installation process, it should be ensured that the position of the prefabricated parts is accurate and that good connection and sealing properties are maintained.
Seam treatment. Seams between precast parts should be kept clean and tight to prevent heat loss and the penetration of aggressive gases. Depending on the actual working conditions and precast material, appropriate filling materials can be used for joint treatment. Such as refractory mud, refractory fiber, etc.
temperature control. During the initial heating and operation of the furnace, the heating rate and temperature should be strictly controlled. To prevent the refractory prefabricated parts from being damaged due to thermal stress caused by excessive heating. At the same time, regularly check the use of prefabricated parts to detect and deal with potential problems in a timely manner.
Maintenance and overhaul. During use, the refractory prefabricated parts should be inspected and maintained regularly. If damage, cracks, and other problems are found, they should be repaired or replaced in time. For prefabricated parts with a long service life, timely cleaning and maintenance can be carried out to extend their service life.
With proper selection, installation, and maintenance, refractory prefabricated components can provide efficient and stable performance for industrial furnaces. Save construction time and cost at the same time. In the continuously developing industrial field, the application of refractory prefabricated parts will continue to expand to meet the needs of various working conditions and environments.

Precast Shapes with Refractory Anchor Bricks for Heating Furnace Top

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What Should We Do if These Problems Arise with Refractory Castables and Castable Precast Shapes?

Unshaped refractory castables and castable refractory precast shapes have the advantages of convenient and fast construction and low labor intensity. It has been widely used in more and more high-temperature industrial kilns.

However, many corporate users have discovered some abnormal phenomena in refractory castables or prefabricated parts during storage or maintenance. For example, some have chalking, some have white hair, etc. In fact, these are caused by the contact between the high alumina cement hydration products in the refractory castable and the acidic gases in the atmosphere. As the water in the castable evaporates, salt substances continue to migrate and precipitate to the surface, and then slowly intensify the damage process of the refractory castable. Powdering occurs during the storage of prefabricated parts made from cement-containing refractory castables. Some of them have “white hair” growing on the surface, commonly known as white alkali, which causes the surface of the castable to become powdery. In severe cases, the strength of the castable will decrease.

Solution

Dry the castables as soon as possible after construction to remove moisture. Eliminate the carrier of sodium salt in the pouring body, so that the alkali stays in the construction body and no longer migrates to the surface.
When the construction conditions do not allow for timely drying, the castable environment must be sealed and the surface covered with plastic film to prevent moisture from carrying alkali from migrating to the surface.
Use refractory raw materials with low alkali content in the refractory castable to increase the viscosity and rapid hardening of the refractory castable, which can reduce the migration speed of sodium salt. Strengthen quality management and strictly control the amount of water added during construction.

Tips: Leave a message to ask your questions about kiln refractory castables, and we can provide solutions for free.

Steel Fiber Refractory Castable Precast Shapes

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RS Unshaped Refractory Castable Manufacturer

RS unshaped refractory castable manufacturer is a powerful manufacturer of refractory materials production and sales. Our environmentally friendly, fully automatic unshaped refractory material production line customizes unshaped refractory lining materials for high-temperature industrial furnaces. Extend the service life of the kiln lining, save the cost of production energy, and improve economic benefits. Customize refractory precast shapes, wear-resistant refractory castables, insulation castables, refractory plastics, refractory ramming materials, etc. from Rongsheng unshaped refractory material manufacturer. Contact us to get a free customized plan and quote.

The Difference between Hot Ramming and Cold Ramming of Carbon Ramming Materials

April 25, 2024April 18, 2024 by rsrefractorycastable

[Introduction] There are two types of carbon ramming materials, hot ramming and cold ramming. Hot pounding requires crushing and heating, and the wind pressure cannot be less than 0.5MPa. Cold ramming does not require heating, and the maximum thickness of each ramming cannot exceed 100mm. Carbon ramming materials are mainly used for gap filling and leveling of blast furnaces to achieve non-leakage requirements. Cold ramming changes the traditional hot ramming process and improves the performance of the lining. RS, a manufacturer of unshaped refractory castables, can provide high-quality carbon ramming materials and advanced construction technology guidance to help you extend the service life of your kiln lining and save production costs.

Construction Technology of Carbon Ramming Material

Carbon ramming material–Refractory Encyclopedia. RS Refractory Castable Manufacturer. There are two types of carbon ramming materials: hot ramming materials and cold ramming materials. Both hot and cold ramming carbon materials are monolithic refractory materials composed of powdery and granular refractory materials and binders. Under normal circumstances, it is recommended to use cold-rammed carbon materials.

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Before ramming hot carbon ramming materials, the carbon ramming materials must be crushed and heated. The heating temperature is set evenly according to the mixing temperature of the finished material. There are no hard lumps in the heated carbon material, so it can be laid and pounded. Use a hot hammer when pounding, and the material temperature should not be lower than 70°C. When using hot pounding, the hammer head should be heated to dark red, and the wind pressure should not be less than 0.5MPa. The upper and lower material layers should be staggered at a certain angle, and the pounding should be done continuously to prevent delamination. RS Castable Refractory Manufacturer. When each joint is made, the surface should be “scraped” or adhesive should be brushed, and then the material should be spread and pounded. When pounding, hammer half or one-third of the hammer back and forth 2-3 times in a straight line.

When adopting cold carbon ramming materials, due to the product process upgrade, there is no need to reheat the materials, and there is no need to stir during construction, and the materials can be poured directly into the use site. Subsequently, manual or mechanical methods are used for construction, and the ramming material is also rammed with one hammer and half hammer. RS Castable Refractory Manufacturer. However, it should be noted that the thickness of each pounding should not exceed 100mm until it is dense. The reference compression ratio is 40-45%. If additional thickness is required, a second layer can be laid for pounding. However, before laying, the surface of the upper layer must be roughened to make the upper and lower layers densely bonded. The wind pressure during ramming is the same as that during hot tamping, and cannot be less than 0.5Mpa.

Carbon ramming material is mainly used in the gap between the blast furnace bottom carbon bricks and the furnace bottom sealing plate, or between the hearth carbon bricks and the cooling stave. There is also leveling above the center line of the furnace bottom water-cooling tube and filling of the cooling staves, filling every corner and small gap to meet the requirements of no leakage of molten iron and gas. RS Castable Refractory Manufacturer.

The biggest difference between hot ramming and cold ramming of carbon ramming materials is that cold ramming has changed the old process of traditional hot ramming, the working conditions have been improved, and the performance of the lining has been improved.

RS Castable Refractory Manufacturers

RS Castable Refractory Manufacturer is a powerful manufacturer and seller of unshaped refractory materials. We can provide high-quality refractory lining material products, including various castables, ramming materials, refractory precast shapes, etc. Our products are of reliable quality and our professional construction technical team can customize refractory lining solutions and construction techniques for you. Maximize the service life of high-temperature industrial furnace linings and save production costs for enterprises. Contact us to get a free refractory lining solution and quote.

24 Kinds of Refractory Raw Materials Commonly Used in Unshaped Refractory Castables (2)

April 5, 2024 by rsrefractorycastable

In recent years, the output of unshaped refractory products has become higher and higher, and their application range has become wider and wider. Refractory castables do not need to be fired at high temperatures and can be used directly after being baked during construction. It is a new refractory material with a simple production process, saving energy and labor, mechanized construction, good integrity, easy repair, and long life.

Refractory castables are a type of refractory material that is mixed with a certain grade of refractory aggregates and powdery materials, binders, and admixtures and is used directly without going through the molding and firing processes.

According to the combination of raw materials, refractory castables can be divided into oxide refractory castables, non-oxide refractory castables, and composite refractory castables. Oxide refractory castables can be subdivided into non-alkaline refractory castables and alkaline refractory castables. Therefore, the performance of refractory castables mainly depends on the raw materials used in the formulation. In order to improve the performance of refractory castables, most manufacturers have used high-purity raw materials, homogeneous materials, electrofusion materials, synthetic materials, transformation materials, and ultra-fine powders as main raw materials. Let’s talk about the 24 raw materials that are often used in the formula of refractory castables.

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The Main Raw Material of Refractory Castables (13-24)

(13) Magnesite.

Magnesite is a natural alkaline mineral raw material with magnesium carbonate (MgCO3) as the main component. Our country is rich in magnesite resources, with high quality and large reserves. Magnesite is mainly distributed in Liaoning Province. Magnesite is mainly used to produce sintered magnesia, fused magnesia, and raw materials for the production of alkaline refractory materials.

(14) Sintered magnesia.

Sintered magnesia is a product obtained by fully sintering magnesite at 1600~1900℃. The main mineral is periclase. The MgO content of high-quality magnesia is generally above 95%, the particle volume density is not less than 3.30g/cm3, and it has excellent resistance to alkaline slag erosion. Sintered magnesia is one of the main raw materials for the production of alkaline refractory materials.

(15) Fused magnesia.

Fused magnesia is made by melting selected magnesite or sintered magnesite at a high temperature of 2500°C in an electric arc furnace. Compared with sintered magnesia, the main crystal phase periclase grains are coarse and in direct contact, with high purity, dense structure, strong resistance to alkaline slag, and good thermal shock stability. It is a good raw material for high-grade carbon-containing unburned bricks and amorphous refractory materials.

(16) Silicon carbide.

Silicon carbide is usually made from a mixture of coke and silica sand as the main raw materials through high-temperature smelting in an electric furnace. β-SiC (cubic crystal) is generated at a temperature of 1400-1800°C, and α-SiC (hexagonal crystal) is generated when the temperature is higher than 1800°C. Silicon carbide has high hardness, high thermal conductivity, low thermal expansion rate and excellent resistance to neutral and acidic slag. The composition range of commercial silicon carbide is 90%~99.5% SiC. Refractory castables, gunning materials, ramming materials and plastics often use silicon carbide with higher purity.

(17) Silica fume.

Silica fume is a by-product of the production of ferrosilicon and silicon products. Appearance: white to dark gray fine powder with round particles. The particle diameter is generally 0.02~0.45μm, the specific surface area is about 15~25m2/g, and the volume density is 0.15~0.25g/cm3. In recent years, some silica fume has become the leading product and is no longer a by-product. It has high purity, white color and stable ingredients. Shows good rheology when used in self-flowing castables.

(18) Graphite.

Graphite is divided into artificial graphite and natural graphite. Artificial graphite is made by sintering petroleum coke (heating to above 2800°C) or using graphite electrodes. Natural graphite crystal is a hexagonal crystal system with rhombohedral symmetry. There are usually three forms: amorphous, flake graphite and pure crystalline. Amorphous graphite (no form) and artificial graphite have better fluidity than flake graphite and crystalline graphite in castable applications.

(19)Asphalt.

Coal tar pitch has a higher residual carbon content than petroleum pitch, and both can effectively provide carbon components to refractory materials. According to the formula design requirements of the material, it can be used in the form of fine powder or granules. The use of bitumen is preferred over other forms of carbon (such as graphite) in amorphous refractory applications. Because asphalt has a low melting temperature, it can coat particles and thus provide a good protective layer against slag erosion.

(20) Calcium aluminate cement.

The main method for producing high alumina cement is the sintering method. Pureer limestone is the calcium oxide raw material from which all calcium aluminate cements are produced. Sintered alumina is used to produce high-grade calcium aluminate cement, while low-iron, low-silica bauxite is used as alumina raw material for mid-grade and low-grade high-alumina cement. Pure calcium aluminate cement or high alumina cement is the most important hydraulic cement used in the binding phase of refractory castables and shotcrete. During the construction of the refractory castable lining, the water temperature, water addition amount, mixing intensity and time, temperature and heating rate must be strictly controlled. Among them, temperature is the most important parameter, which significantly affects the generation of cement binding phase and the discharge of water in the early stage of heating.

(21) Silica sol.

Silica sol is a water-containing colloid with dispersed silica particles. It is a milky white liquid that is slightly sticky to the touch and has a high specific surface area. Silica sol can be cemented by dehydration, changing the pH value, adding salt or water-miscible organic solvents. When drying, silicon-oxygen (Si-0-Si) bonds are formed on the surface of the particles through rapid dehydration, resulting in polymerization and internal bonding. Silica sol is converted from solution into solid, commonly known as cementation. Commonly used in coatings, castables, pumped materials, ramming materials and gunning materials.

(22) Sodium silicate.

Commonly used silicates are sodium silicate (Na₂O·mSiO·nH₂O), potassium silicate and lithium silicate. The dehydrated product of sodium silicate is usually as transparent as glass and soluble in water, so it is also called water glass. The molar ratio of SiO₂/N₂O (called the modulus of water glass) in industrial products is between 0.5 and 4.0, and the molar ratio of sodium silicate for refractory materials is 2.2 and 3.35. The viscosity of sodium silicate aqueous solution is affected by its molar ratio and concentration, and changes significantly with temperature. Sodium silicate hydrates in aqueous solution, and the solution becomes alkaline. The smaller the molar ratio, the more obvious the hydration of sodium silicate is, and the pH value decreases as the molar ratio decreases. Sodium silicate with a high molar ratio reacts slowly. The choice of curing agent for sodium silicate combined refractory materials needs to be determined based on the application of the refractory materials. Commonly used curing agents include sodium fluorosilicate, polyaluminum chloride, phosphoric acid, sodium phosphate, polyaluminum phosphate, polymagnesium phosphate, ammonium pentaborate, glyoxal, citric acid, tartaric acid, ethyl acetate, etc.

(23) Phosphoric acid and phosphate.

Orthophosphoric acid itself has no binding properties. When it comes into contact with refractory materials, the two react quickly to form phosphate, which makes it show good adhesion. Different forms of phosphates can be used as binding agents. The salt most commonly used in refractory materials is aluminum phosphate. As a binding agent, aluminum dihydrogen phosphate is known for its solubility in water, binding strength and stability. Sodium phosphate is mainly used in refractory materials for cohesion, depolymerization and as a binding agent for alkaline gunning materials. Sodium polyphosphate is often used as a water reducing agent in castables. In addition, sodium phosphate can react with alkaline earth metal compounds (such as CaO and MgO), resulting in agglomeration. It is based on this performance of sodium phosphate that it is used in magnesia alkaline gunning materials.

(24)ρ-Al₂O₃

ρ-Al₂O₃ is a kind of activated alumina. It is different from other crystalline Al₂O₃ and is the worst crystallized Al₂O₃ variant. Among the various crystal states of Al₂O₃, only ρ-Al₂O₃ has a spontaneous hydration reaction at room temperature. The gibbsite and boehmite sol generated by hydration can play a cementing and hardening role. ρ-Al₂O₃ is eventually transformed into α-Al₂O₃ (corundum), an excellent refractory material at high temperatures. Therefore, this ρ-Al₂O₃ combined castable can be regarded as a self-bonding castable of refractory materials, which also acts as a binder. It itself is a high-grade refractory oxide with obvious excellent properties.

(THE END)

By selecting different raw materials as the main raw materials of refractory castables, castables with different properties, operating temperatures, and ranges can be made. Of course, only the main raw materials are not enough. Binders, admixtures, and some special additives are also needed. These are all to improve the performance of refractory castables. Rongsheng Unshaped Refractory Castables Manufacturer is a powerful manufacturer and seller of refractory castables. Our environmentally friendly, fully-automatic unshaped refractory material production line provides high-quality customized refractory lining materials for high-temperature industrial furnaces. Contact us to get a free refractory lining solution and quote.

24 Kinds of Refractory Raw Materials Commonly Used in Unshaped Refractory Castables (1)

March 29, 2024 by rsrefractorycastable

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The Main Raw Material of Refractory Castables (1-12)

(1) Sintered corundum.

Sintered corundum, also known as sintered alumina or semi-fused alumina. It is a refractory clinker made from calcined alumina or industrial alumina as raw material, ground into balls or green bodies, and sintered at a high temperature of 1750~1900℃. Sintered alumina containing more than 99% of aluminum oxide is mostly made of uniform fine-grained corundum directly combined. The gas appearance rate is less than 3.0%, and the volume density reaches 3.60%/m³. The refractoriness is close to the melting point of corundum, and it has good volume stability and chemical stability at high temperatures. It is not corroded by reducing atmosphere, molten glass and molten metal, and has good mechanical strength and wear resistance at room temperature and high temperature.

(2) Fused corundum.

Fused corundum is artificial corundum made by melting pure alumina powder in a high-temperature electric furnace. It has the characteristics of high melting point, high mechanical strength, good thermal shock resistance, strong corrosion resistance and small linear expansion coefficient. Fused corundum is a raw material for manufacturing high-grade special refractory materials. Mainly include fused white corundum, fused brown corundum, sub-white corundum, etc.

(3) Fused white corundum.

Fused white corundum is made from pure alumina powder and smelted at high temperature. It is white in color. The smelting process of white corundum is basically a process of melting and recrystallization of industrial alumina powder, and there is no reduction process. The Al₂O₃ content is not less than 9%, and the impurity content is very small. The hardness is slightly smaller than brown corundum and the toughness is slightly lower. Often used to make abrasive tools, special ceramics and advanced refractory materials.

(4) Fused brown corundum.

Fused brown corundum is made from high-alumina bauxite as the main raw material and mixed with coke (anthracite), and is smelted in a high-temperature electric furnace at temperatures above 2000°C. The main chemical components are Al₂O₃, TiO₂ and contain a small amount of SiO₂ and Fe₂O₃. Fused brown corundum has a dense texture and high hardness and is often used in ceramics, precision castings and advanced refractory materials.

(5) Sub-white corundum.

Subwhite corundum is produced by electromelting special grade or first grade bauxite under reducing atmosphere and controlled conditions. When melting, add reducing agent (carbon), settling agent (iron filings) and decarburizing agent (iron scale). Because its chemical composition and physical properties are close to white corundum, it is called sub-white corundum. Its bulk density is above 3.80g/cm3 and its apparent porosity is less than 4%. It is an ideal material for manufacturing advanced refractory materials and wear-resistant materials.

(6) Mullite.

Mullite is a refractory raw material with 3Al₂O₃·2SiO₂ as the main crystal phase. Natural mullite is very rare and is usually synthesized artificially by sintering or electrofusion. Mullite has the characteristics of uniform expansion, good thermal shock stability, high load softening point, small high-temperature creep value, high hardness, and good chemical corrosion resistance.

(7) Zirconium corundum mullite.

Zirconium corundum mullite is made of industrial alumina, kaolin, and zircon as its main raw materials. It is synthesized by fine grinding, uniform mixing, semi-dry briquetting, and high-temperature calcination at 1600~1700℃. Increasing the zircon content will increase the sintering temperature, reduce the total shrinkage, and increase the closed pores. These reactions give sintered zirconium corundum mullite higher density and strength as well as better thermal shock resistance and slag resistance.

(8) Magnesia-aluminum spinel.

Magnesia-aluminum spinel is synthesized from industrial alumina and light-burned magnesium oxide through high-temperature sintering or electric fusion. The chemical formula of magnesia-aluminum spinel is MgO·Al₂O₃, in which the MgO content is 28.2% and the Al₂O₃ content is 71.8%. It has the advantages of high-temperature resistance, wear resistance, corrosion resistance, high melting point, small thermal expansion, low thermal stress, good thermal shock stability, strong resistance to alkaline slag erosion, and good electrical insulation properties.

(9) Sillimanite, andalusite, and kyanite.

The chemical formula is Al₂O₃·SiO₂, and the theoretical composition is Al₂O₃63.1% and SiO₂36.9%. After heating, they are irreversibly converted into mullite and cristobalite, which have the advantages of good slag corrosion resistance, good thermal shock stability, and high load softening point. Kyanite mineral products are high-quality raw materials for amorphous refractory materials. Because sillimanite and andalusite change little in volume when heated, they can be directly made into bricks or used as refractory aggregates. Kyanite expands greatly when heated and can be used directly as an expansion agent for amorphous refractory materials.

(10) High alumina bauxite.

my country’s high-alumina bauxite resources are mainly distributed in Shanxi, Henan, Guangxi and Guizhou. High-alumina bauxite clinker calcined at high temperature is mainly used for high-aluminum refractory materials, and can also be used to make fused brown corundum and sub-white corundum. In recent years, the homogenized alumina clinker produced in my country has been developed due to its low absorption rate and stable performance. The application in unshaped refractory materials has achieved good results.

(11) Soft clay.

The mineral composition of soft clay is mainly kaolinite or halloysite, mixed with other impurity minerals. The Al₂O₃ content can range from 22% to 38%, and the average refractoriness is around 1600℃. Soft clay is mostly earth-like, with fine particles, easily dispersed in water, and has strong plasticity and cohesiveness. It is widely used in plastics, ramming materials, gunning materials, refractory mud, and medium and low-grade refractory materials.

(12) Clay clinker.

Refractory clay clinker can be divided into two types according to the raw materials used and production methods. One type is obtained by calcining hard clay blocks directly in a kiln. The other type is made of kaolin or hard clay, which is finely ground, homogenized, filtered, dehydrated, dried, and finally burned in a kiln. It is a high-quality clay clinker. The main mineral phase of hard clay clinker is mullite, accounting for 35% to 55%. Followed by glass phase and cristobalite. Clay clinker is the main raw material of ordinary aluminum silicate refractory materials.

(To be continued. Since the article is too long, I will post it in two parts.)

By selecting different raw materials as the main raw materials of refractory castables, castables with different properties, operating temperatures and ranges can be made. Of course, only the main raw materials are not enough. Binders, admixtures and some special additives are also needed. These are all to improve the performance of refractory castables. Rongsheng Unshaped Refractory Castables Manufacturer is a powerful manufacturer and seller of refractory castables. Our environmentally friendly, fully-automatic unshaped refractory material production line provides high-quality customized refractory lining materials for high-temperature industrial furnaces. Contact us to get a free refractory lining solution and quote.

Phosphoric Acid bonded High Aluminum Castable with Good Wear Resistance and Air Tightness

February 4, 2024 by rsrefractorycastable

What are the advantages of phosphate-bound high-aluminum castables? Phosphoric acid combined with high aluminum castable is one of the castables. Compared with other castables, its advantage is that high-aluminum phosphate castables have the advantages of high medium-temperature strength, good thermal shock resistance, wear resistance, and good air tightness.

Phosphoric Acid Bonded High Aluminum Castable

Phosphoric acid-bonded high-aluminum castables are not only resistant to high temperatures and corrosion but also have excellent thermal shock resistance and wear resistance. It is widely used in metallurgical heating furnaces water-cooled tube wrapping, heating furnace top prefabricated blocks, high-temperature flame furnace burner bricks, and kiln car table prefabricated blocks. The overall lining of induction furnaces in the precision casting industry, as well as the abrasive parts of power plant boilers and other thermal kilns.

High-Strength Aluminum Phosphate Bonded Refractory Plastics

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Phosphoric acid combined with high alumina castables generally uses high alumina cement as a setting accelerator. When the amount of high alumina cement is increased, the castable hardens and sets too quickly, making construction difficult. When the amount of high alumina cement is increased, the castable does not solidify, and there is no way to demould it later, and the castable needs to be baked after demoulding to develop strength.

Although phosphoric acid combined with high-aluminum castables has many advantages, the amount of high-aluminum cement added is difficult to control and the construction is too difficult, which affects the progress of castable construction. These problems also hinder the widespread application of high-aluminum phosphate castables. In a large number of practical applications by castable manufacturers, continuous exploration and research have found that fused spinel fine powder has an accelerating effect on phosphoric acid. This procoagulant effect is relatively mild and easy to control. At the same time, the phosphoric acid-bound castable can produce high strength without baking after demolding.

Phosphoric acid combined spinel high alumina castable, after adjusting the formula of the castable manufacturer and adding fused spinel powder. In various industrial kilns and in various temperature ranges, it has higher strength than ordinary phosphate-bonded high-aluminum castables. The high-temperature resistance is more than 200 ℃ higher than that of ordinary phosphoric acid combined with high aluminum castables. At the same time, it can produce strength without baking, overcoming the disadvantages of the difficult construction of ordinary phosphate-bonded high-aluminum castables. The adjusted phosphoric acid combined with high aluminum castable material does not absorb moisture after natural curing and is not afraid of water, which brings great convenience to on-site construction and storage and transportation of prefabricated parts. Its good thermal shock resistance greatly extends the service life of furnace linings or objects working under alternating hot and cold conditions.

High-Quality High Alumina Castable of Rongsheng — High-Quality High-Alumina Castable of Rongsheng

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High Alumina Cement Combined Refractory Castable

High alumina cement refractory castables are made by using high alumina cement as a cementing agent, mixing refractory aggregates and powders in proportion, adding water, mixing, shaping, and curing. Refractory aggregates and powders are generally made of clay, high alumina, corundum, etc. Commonly known as clay castables, high alumina castables, corundum castables, etc.

The main mineral of high alumina cement is calcium aluminate (CA), which hydrates quickly and does not precipitate calcium hydroxide. Therefore, refractory castables formulated with high alumina cement have the characteristics of rapid hardening and high strength.

Factors Affecting the Performance of Aluminate Cement Bonded Castables

The general ratio of aluminate cement combined with refractory castables is. Refractory aggregate 62%-76%, refractory powder 17%-28%, cement 10%-24%, water 7%-14%, and appropriate amount of admixtures. This is also the general ratio of refractory castables. On the premise of meeting construction and use requirements, the amount of cement and water should be minimized. This type of castable is divided into many categories based on aggregate types, and many factors affect performance.

Cement dosage.

Cement is one of the important components of refractory castables. It is an important material that determines the strength of the material and also affects other properties. Different types of cement and their dosages have different effects on performance. As the amount of cement increases, the normal temperature compressive strength increases, and later the compressive strength and high-temperature compressive strength decrease, and the linear change after burning changes from expansion to contraction. Therefore, while ensuring that the normal temperature strength meets the requirements, the amount of high-alumina cement should be reduced as much as possible to improve the high-temperature performance of refractory castables. However, while reducing the amount of cement, it is necessary to appropriately increase the refractory powder so that the mixture of powder and cement can fully wrap the refractory aggregate.

Water consumption.

When configuring aluminate cement combined with refractory castables, the amount of water used is very important. When too much water is used, the water will overflow after heating, resulting in increased pores and loose structure, resulting in a decline in overall performance. Therefore, under the conditions of ensuring construction, the amount of water added should be reduced as much as possible. Without adding a water-reducing agent, the suitable water content of aluminate cement castable is 10%-13%.

Refractory powder dosage.

The type, fineness, and dosage of refractory powder are important factors affecting the performance of castables. The fineness of the powder directly affects the strength, volume density, and apparent porosity of the castable. The finer the refractory powder, the better the performance of the castable. When the amount of powder is small, the mixture with cement cannot completely wrap the aggregate, resulting in a loose structure. When the amount of powder is too much, there will be a significant surplus of aggregate wrapped in the mixture with cement, resulting in an increase in the amount of water used and a large shrinkage during high-temperature sintering.

Amount of refractory aggregate.

The variety, grade, and particle matching of aggregates are the main properties that affect the performance of castables. It plays a skeleton role in the castable. The aggregates are divided into coarse aggregates and fine aggregates. It is very important to match the particles of the aggregates. The most ideal particle gradation is that the gaps caused by coarse aggregate are filled by the fine aggregate, and the gaps between the two are filled by powder, with no shortage or surplus.

In addition, high alumina cement refractory castables can also be added with admixtures (such as water-reducing agents, etc.) to improve construction performance and fire resistance.

Iron Ditch Anti-Scouring Silicon Carbide Refractory Castable

January 15, 2024 by rsrefractorycastable

The blast furnace tap trough system consists of a main tap trough, branch troughs, and slag troughs. It is an important system to realize the separation of molten iron and slag in the blast furnace. With the enlargement of iron-making blast furnaces and the development of high-temperature and high-pressure technology, higher requirements have been placed on the service life and iron flux of the blast furnace tap trough. The trough material is the main factor affecting the performance of the blast furnace tap trough. Its high-temperature resistance, thermal shock resistance, erosion resistance, erosion resistance, and other properties directly affect the iron flux and service life of the blast furnace tap channel. This in turn affects the production cost and labor intensity of the entire production process.

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Refractory Material Al2O3-SiC-C Castable for Tap Trough

At present, the refractory materials used in the blast furnace tap trough are mainly Al2O3-Si C-C castables. Although it has the advantages of good high-temperature mechanical strength, good resistance to slag erosion and permeability, good thermal shock resistance, and small changes in reburning. However, in the face of technological advancements such as increased molten iron temperature, increased iron tapping volume, prolonged iron tapping time, and faster-molten iron flow rate caused by modern large-scale blast furnace smelting. The original iron trench materials cannot meet production needs. Therefore, improving Al2O3-SiC-C castables or developing new refractory materials for blast furnace tap troughs are the research directions of many scholars.

Aluminum silicon carbide carbonaceous castables, which are unshaped refractory materials, are often used in blast furnace tap troughs, so they are also called trough castables. The blast furnace tap trough castable is made of fused corundum (or sintered corundum, special high-aluminum clinker) and silicon carbide. It is a high-performance refractory castable containing 90%-95% fixed carbon (or flake graphite), binder, and various admixtures.

Aluminum silicon carbide carbonaceous castable. The aggregate part can be made of one or two types of fused or sintered corundum, brown corundum, spinel, and bauxite clinker. Carbonaceous raw materials can be asphalt, coke, graphite, or electrode powder. The binding agent can be bonded clay, oxide micro powder or ultrafine powder, and pure calcium aluminate cement with good dispersion properties.

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The blast furnace tap trough is a channel through which high-temperature molten iron or molten slag flows. Its refractory lining should have the following characteristics. These features are complementary to each other and should be compatible with each other.

① Strong resistance to erosion and erosion from molten iron and slag.
② Good thermal shock resistance and small change in volume after reheating.
③ Strong antioxidant capacity.
④ Easy to construct, can be baked quickly without bursting, and is easy to repair and dismantle.
⑤ When used, it does not produce harmful gases, does not stick to slag iron, and has a long service life.

Iron trench castable is a high-tech refractory castable with exquisite preparation technology and excellent performance, which can significantly increase the service life of the trench lining. The key issue is that the amount of construction water must be strictly controlled, operated carefully, and maintained carefully to achieve the expected purpose.

At the same time, the specific selection of tap trough castables also depends on the size of the blast furnace. Generally speaking, high-aluminum silicon carbide carbonaceous castables can be used for the main ditch, slag ditch, and slag line of small blast furnaces. Corundum silicon carbide carbonaceous castables can be selected for medium and large blast furnaces.

Wear-Resistant Corundum Silicon Carbide Castable

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Erosion-resistant Molten Iron-Clad Aluminum Silicon Carbide Castable

Spheroidized ladle castable is an unshaped refractory material with high aluminum and silicon carbide materials as the main raw materials and refractory cement as the binder. It is widely used in molten running ladles, launders, and working linings of kilns. It has high strength and refractory resistance and has good impact resistance, corrosion resistance, wear resistance, and other properties. It has a long service life, convenient construction, and easy maintenance. It is suitable for the overall lining of ladles and is the refractory material of choice for spheroidized ladles.

Molten iron and slag react with the castable, resulting in chemical slag sticking. According to ASTM C01-91 Al2O3-SiO2 series castables, those with CaO content >2.5 are traditional cement-bound castables. The CaO content between 1.0% and 2.5% is low cement castable. The CaO content <1.0% is cement-castable. The lower the CaO content, the higher the temperature at which the liquid phase appears, and therefore the higher the fire resistance. The CaO content of the existing castable is 3.78%, which is a traditional high cement content castable. Aluminum silicon carbide castables are erosion-resistant, heat-exchange-resistant, refractory castables, and ladle castables.

The liquid phase of this material appears at a low temperature, about 1300°C. The temperatures of molten iron and slag are generally >1300°C, and the interface is prone to reaction at this time. For example, the components in the refractory material, especially the liquid phase in the matrix, easily react with CaO, SiO2, Fe2O3, etc. in the slag to form Al2O3-SiO2-CaO-Fe2O3 series low-melting materials. The molten iron, molten slag, and refractory materials are melted together to form sticky slag. The sticky residue that occurs in this form is strong and difficult to clean.

Low Cement Silicon Carbide Castable in RS Factory

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Development of Aluminum Silicon Carbide Refractory Castables for Tap Trench

Al2O3-SiC-C castable is the most widely used iron trench refractory material in my country. Improving the quality of Al2O3-Si C-C castables is an important factor in reducing the cost of molten iron and achieving efficient production. RS Unshaped Refractory Castable Manufacturer puts forward several suggestions based on the current development situation.

(1) Different companies have different compositions of molten iron and slag. The reasons why molten slag and molten iron corrode the iron trench materials should be analyzed based on the actual situation to achieve “prescribing the right medicine”.

(2) Using slag or other industrial waste residues as raw materials to prepare Al2O3-Si C-C castables has extremely high added value. At the same time, it can also solve problems such as waste residue accumulation and environmental pollution.

(3) Improve the production of Al2O3-Si C-C castables in the direction of green and environmental protection, and remove or replace toxic and harmful components in the raw materials. It not only achieves green production but also protects the health of workers.

(4) Many new Al2O3-Si C-C castables have been applied in enterprise blast furnace production, achieving mutual benefit and win-win results between scientific research and enterprises.

How to Choose Refractory Materials for Circulating Fluidized Bed Boilers?

December 12, 2023 by rsrefractorycastable

Circulating fluidized bed boiler refractory lining. Material circulation path in circulating fluidized bed furnace. Pulverized coal (generally with a particle size of 0~10mm) and limestone powder are fed into the fluidized bed combustion chamber (dense phase area) through a feeder, and the fuel boils and burns in this area. The flue gas rises, passes through the dilute phase zone to the separator inlet and enters the cyclone separator. The coarse particles sink and return to the combustion chamber through the return valve for combustion again. The flue gas carries the fly ash and rises through the convection flue into the external heat exchanger. Refractory materials are mainly lined in the combustion chamber, ceiling, separator inlet, high-temperature cyclone separator, and return valve.

Taking a 220t circulating fluidized bed boiler in a certain factory as an example, the working conditions of the refractory materials in each part are as follows.

(1) Dense phase area. The depth of this area is 220~1530mm. A 2100mm long sandy medium (pulverized coal and limestone powder) is boiled here. The pressure in this area is 13818~20580pa, the flue gas flow rate is about 1.2~1.8 m/s, and the normal operating temperature is 820~900°C.
(2) Dilute phase area. The area above the secondary air outlet is where the fine particles of fuel combustion are concentrated. The solid material concentration here is about 12~16kg/m3, the flue gas flow rate is 1.2~3 m/s, and the normal operating temperature is 930~980℃.
(3) Stovetop area. The normal operating temperature is 850~1100℃, and the flue gas flow rate increases by 18m/s at the separator inlet.
(4) Cyclone separator. The normal operating temperature is 850~930℃, and the flue gas flow rate at the cyclone outlet can reach 29m/s.
(5) Cyclone separator air outlet main pipe. The dust content of the flue gas here is 70~530g·m-3, the normal operating temperature is 850-930°C, and the maximum flue gas flow rate is 18m/s.

Monolithic Refractory Castables for CFB Boilers Refractory Linings

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According to the design requirements, the average working time of the boiler is 8600 hours, and the boiler starts and stops 2 to 10 times a year. Each ignition takes 12 to 24 hours. After ignition, the temperature is raised to 800°C at a rate of 65°C/h and kept warm for 8 hours. The service life of the furnace lining is required to be at least 2 years.

Circulating Fluidized Bed Boiler Refractory Materials

(1) Medium temperature, the working temperature of each part of the circulating fluidized bed boiler lining is 800~1000℃. From the perspective of refractory materials, this belongs to the medium-temperature range. When selecting refractory materials, first consider the medium-temperature physical and chemical properties of the material. For fired products, the sintering temperature is generally higher than this temperature range, so its physical and chemical properties at high temperatures can be directly used as a basis for selecting refractory materials. For unshaped refractory materials and unfired products, the physical and chemical properties at mid-temperature must be examined. Organically bonded materials or hydration-bonded hydraulic materials tend to have the worst strength at medium temperatures. These materials create a ceramic bond at high temperatures, which greatly increases their strength. Therefore, its physical and chemical indicators at high temperatures cannot be used as a basis for selecting refractory materials.

(2) Thermal shock. Under normal operating conditions, circulating fluidized bed boilers start and stop 2 to 10 times a year. In the early stages of operation, due to improper operation, the refractory lining was subjected to a strong thermal shock every year when starting and stopping. If the refractory material has poor thermal shock resistance, the spalling of the refractory material caused by thermal shock will become a fatal factor in its damage.

(3) Sand blasting wear, flue gas flow rate in circulating fluidized bed boilers is high (up to more than 29m·S-1), and solid material concentration is high. At medium temperatures, high-speed flue gas entrains a large number of solid particles, causing strong erosion and wear on the refractory lining. Especially in the impact zone of the cyclone, the erosion is most serious. For circulating fluidized bed boilers and cyclones with single-side return, the cyclic flow of materials causes wear areas on the refractory lining walls.

Monolithic Refractory Construction for CFB Boiler

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Causes of Wear of Refractory Materials in Circulating Fluidized Bed Boilers

(1) Wear caused by thermal stress and thermal shock. Wear caused by thermal stress and thermal shock mainly manifests as cracks and spalling of refractory materials caused by temperature cycle fluctuations, thermal shock, and mechanical stress.

(2) Wear caused by erosion of solid materials. The wear caused by the erosion of solid materials is mainly the damage caused by the strong erosion of refractory materials by materials. The wear areas of refractory materials in circulating fluidized bed boilers include corner areas, cyclone separators, and solid material return paths. In general, refractory material wear increases with the increase of impact angle.

(3) Wear caused by changes in the properties of refractory materials. Wear caused by changes in the properties of refractory materials is mainly manifested as damage caused by the deterioration of refractory materials and the reduction of physical and chemical properties. The main manifestation is that the penetration of alkali metal causes the deterioration of refractory materials. Some refractories and bonds have lost strength, and some ovens have not met requirements, causing linings to delaminate and collapse.

The above technical guidance on refractory materials for circulating fluidized bed boilers mostly summarizes the requirements for the use of wear-resistant refractory materials from the combustion temperature of the fuel, wear values, theoretical data, etc. Start from the overall performance.

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Refractory plastic for circulating fluidized bed boiler repair

Refractory plastics are suitable for the construction of thin parts such as furnace water-cooled walls. It is mainly used in the dense phase area of the furnace and steam-cooled and water-cooled cyclone separators.

The wear-resistant refractory material in this area is designed as a single-layer ramming structure and is fixed with wear-resistant pins. Its design thickness is thin and can be laid directly on the construction surface.

In the application of repairing circulating fluidized bed cyclone separators, it’s super strong bonding performance can repair any irregular wear parts at will. There is no need to use steel formwork or moulds, and it can be ignited immediately after construction is completed without special maintenance. Thereby shortening the construction period and saving costs.

Refractory materials for circulating fluidized beds, refractory plastics for circulating fluidized beds, wear-resistant refractory castables, etc. RS refractory material manufacturer can provide high-quality refractory materials products and comprehensive customer service. Product quality is guaranteed and the delivery cycle is short. Effectively ensures the long life and safe operation of high-temperature industrial furnace linings.

Why Should High-Strength Wear-Resistant Castables be Used in Cement Kilns?

September 26, 2023 by rsrefractorycastable

During the production and operation of cement rotary kilns, highly worn parts such as tertiary air duct bends and grate coolers need to withstand high-temperature alkali corrosion of about 1200°C, as well as continuous erosion by high-speed tertiary air flows, and are very easy to be damaged. The traditional refractory lining mainly adopts a combined construction structure of wear-resistant bricks and mullite corundum castables. However, it often only lasts about half a year. Therefore, Rongsheng Refractory Materials Manufacturer recommends the use of high-strength wear-resistant refractory castables in this part of the cement kiln.

High-Strength Wear-Resistant Corundum Refractory Material — High-strength Wear-Resistant Corundum Refractory Castable Material

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Performance of high-strength wear-resistant refractory castables used in cement kilns

High-strength and wear-resistant refractory castables incorporate high-quality refractory raw materials with very high strength, such as corundum and silicon carbide. The castable has the characteristics of high density, low porosity, high strength, high refractoriness, high wear resistance, erosion resistance, and strong integrity. Therefore, it is recommended to use high-strength wear-resistant castables in areas prone to wear in cement kilns.

Application of high-strength wear-resistant refractory castables

High-strength wear-resistant refractory castables can be used in high-wear parts such as the tertiary air duct elbows of cement kilns, the throat of grate coolers, and the air intake of waste heat power generation. As we all know, corundum and silicon carbide have very strong wear resistance and high strength. High-strength wear-resistant castables configured with micro powder, mud, and chemical agents have excellent wear resistance. The lining constructed with this castable will produce a strong and reliable combination after high temperatures, which can effectively prevent the intrusion of kiln materials and the strong erosion of high-temperature gas and dust.

Wear resistant castable for sale — Rongsheng Wear-resistant Castable for Sale

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How to Efficiently Select High-Strength and Wear-Resistant Castables?

High wear-resistant castables are generally used in furnace areas where dust erosion is severe. Some manufacturers of refractory castables regard high medium-temperature strength, extreme corrosiveness, and erosion resistance as the key points to overcome in production technology.

High wear-resistant castable is a good wear-resistant amorphous material currently used in boilers. The wear-resistant castable is sintered the high temperatures during the use of the furnace, completing the necessary physical and chemical processes and automatically adapting to the requirements during its own use. The current circulating fluidized bed boilers have high thermal efficiency and low pollution emissions and are mostly used in thermal power plants and heating projects. The furnace lining temperature ranges from 800°C to 1100°C and has been severely eroded by dust for a long time, thus placing higher requirements on the wear resistance of the castables in the location. Manufacturers of wear-resistant castables are also constantly adjusting the process to correspondingly reduce the amount of fine particles added to continuously improve the wear resistance.

However, during the user’s use, it depends on the situation that occurs during use. Rongsheng refractory castable manufacturer also adopts different furnace types and different temperatures. To develop some production processes to meet the needs of users for various furnace types and actual situations.

However, there are also many customers who only pay attention to the price of refractory castables and do not pay attention to the actual operating temperature of their own furnaces. However, it is understandable that people often do not buy genuine products without comparing the price and usage. Good products have a long service life and do not delay production time, as well as maintenance costs. Don’t just look at the low price to decide the base of the product you want to buy.

As mentioned above, different castable manufacturers provide different high-strength, good wear-resistant, wear-resistant aggregates, and advanced dense matrices, and their costs are also different. Therefore, the price of refractory castables will vary.

Generally, high-strength and wear-resistant castables are used in hot water boilers, chain furnaces, waste incinerators, CFB boilers, cement plant grate coolers, kiln mouths, etc. However, users must also consider the size and temperature of the furnace to determine the level of high wear-resistant castables that are the best choice.

In terms of the construction of high-strength wear-resistant refractory castables, high-strength wear-resistant castables can be cast in formwork or constructed in the form of more advanced prefabricated parts. Rongsheng refractory castable manufacturers’ high-strength and wear-resistant castables have achieved good results in the large-scale cement production lines of many customers. Its use effect far exceeds that of castables made of other materials, and its service life can reach more than 3 years. Contact us to get free samples and quotes.

What Kind of Ramming Material Should be Used for the Working Layer at the Electric Furnace Bottom?

September 12, 2023September 11, 2023 by rsrefractorycastable

The working layer at the bottom of the electric furnace is in direct contact with molten steel and slag, and is subject to high-temperature heat loads and erosion by molten slag. The erosion of molten steel, mechanical impact of scrap steel, and oxidation and reduction operations at high temperatures in the furnace will all lead to erosion and thinning of the furnace bottom. Therefore, the choice of ramming material for the working layer of the furnace bottom will have a great impact on the service life of the refractory lining of the furnace bottom working layer.

When the furnace bottom is operating, the dicalcium silicate in the slag absorbs moisture in the atmosphere and collapses. The durability of eroded ramming material is reduced and its service life is shortened. Therefore, the refractory material selected for the furnace bottom must be sufficient to resist the mechanical impact of the charge. At the same time, it must have suitable expansion performance. Its expansion and contraction will not produce excessive cracks to reduce the intrusion of molten steel and steel slag.

Excessive shrinkage will cause local floating. The natural bulk density and post-fired density of the ramming material can avoid uneven density caused by construction and sintering. It also has high resistance to penetration of molten steel and steel slag.

Magnesia Refractory Ramming Mass Material from Rongsheng

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It is a ramming material with strong resistance to erosion by molten steel and steel slag, low erosion rate, uniform erosion, and long service life. The furnace bottom hot surface and the furnace bottom ramming material must have a strong affinity to ensure the repair effect. The working layer of high-power and ultra-high-power electric furnaces is generally constructed with magnesia dry ramming material. It is made of synthetic magnesia and fused magnesia as a fine powder, with a critical particle size of 5mm, without adding any binder and using multi-stage ingredients.

Through strong ramming construction, the density and thickness after construction are guaranteed. It can be sintered into a solid whole at the appropriate temperature, and its lifespan will be improved several times by knotting and bricklaying methods. If hot repair is used in time during use, the service life can be extended to 800-1400 heats. Not only the number of furnace shutdowns is reduced, but the consumption of ramming materials per ton of steel is significantly reduced.

Technical Characteristics That Electric Furnace Bottom Refractory Ramming Materials Should Have

The bottom of the electric furnace is built with ramming materials, mainly magnesia-calcium dry ramming materials. It has ceramic bonding, low silicon, high calcium, a moderate amount of iron, and many fine powders. It has a thin sintering layer, dense sintering, high density, and high thermal strength. Good resistance to molten steel penetration and volume stability. For different furnace masonry, the thickness of the furnace slope ramming material and the thickness of the furnace bottom ramming material are different. During construction, materials should be laid in layers, each layer being 150mm. Tread it firmly with your feet, poke it with a steel drill to facilitate exhaust, and finally vibrate it with a special vibrator.

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The ideal electric furnace bottom refractory ramming material should generally have the following technical characteristics:

(1) Rapid sintering to form a solid working layer.
(2) Use medium and low melt cementing phase to transform into high melting point phase.
(3) Prevent molten penetration to the greatest extent and maintain appropriate looseness of deep-seated materials.

There are also electric furnace manufacturers that convert steel parts and iron parts for use. If the electric furnace burns iron parts, then acidic ramming material should be used at the bottom of the furnace. It uses fused quartz and some other auxiliary materials as raw materials. The price is much different from that of magnesia or neutral furnace bottom ramming materials, but it is suitable for use when sintering iron parts. The choice of neutral ramming material, magnesia ramming material, or acidic ramming material for the furnace bottom is selected according to the different sintering conditions of the furnace lining. If it is burned iron parts, neither neutral nor magnesia ramming materials are suitable. If it is burned steel parts, acidic ramming materials will basically not be used.

Rongsheng Refractory Castable Material Manufacturer

Rongsheng unshaped refractory material manufacturer is a powerful refractory material manufacturer. Our environmentally friendly monolithic refractory production line has an annual capacity of tons and provides refractory services to the world. In addition, our new factory mainly produces various refractory precast shapes. In order to better serve high-temperature industrial furnaces, Rongsheng Refractory Materials Manufacturer is constantly improving our service content and service quality. To operate high-temperature industrial furnaces efficiently, contact us for free refractory solutions.

Acid Resistant Castables – Furnace Linings Resistant to Acid Attack

August 29, 2023 by rsrefractorycastable

Acid-resistant castables are divided into dense, semi-light, and light, and their main function is to be used for furnace linings resistant to acid corrosion. Acid-proof castables are generally combined with acid-resistant cement and are applicable to acid-resistant chimneys and liquid sulfur tank linings in the petrochemical industry.

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Acid-Resistant Refractory Castable Used in Acid-Resistant Atmosphere Furnace Lining

Other refractory castables of this kind of castable are also different, and they belong to an acidic medium. During production, it is also raw material processing granules and fine powder in an acidic medium, adding a certain proportion of ultra-fine powder and additives. However, this castable cannot be used in an atmosphere with a large temperature difference, and it cannot be used for construction in a place that is too humid. If the temperature is not suitable, it will reduce the later use strength and acid resistance of the acid-resistant castable, and it will peel off.

For example, acid-resistant castables for chimneys are generally semi-light, which can not only keep warm but also resist erosion and acid gas erosion. Because the semi-lightweight acid-resistant castable can save energy. Improve the operating rate and service life of the chimney, and at the same time, the weight of the chimney body will not be too heavy.

The acid-resistant refractory castables are all used in the lining of the acid-resistant atmosphere, and cannot be used in the neutral or alkaline lining atmosphere. Because the high-temperature resistance of this castable is not as good as the high-alumina series castables used in neutral atmospheres. The use of Castables that are not as good as the magnesium series in alkaline atmospheres are mainly used in chimneys, flues, and nitric acid pus tower linings in acidic atmospheres, as well as container linings for acidic gases. The high-temperature resistance of acidic materials is not as good as that of the high aluminum series and magnesium series.

However, acid-resistant castables can be used as a separate lining material. Used in a furnace with a consistent atmosphere will play the role of acid resistance of the castable itself, and cannot be used as a furnace lining for other atmospheres. The first is high-temperature resistance, and then there is a gap in the effect of corrosion resistance in other atmospheres.

That is to say, acid-resistant castables, whether heavy, semi-light, or light, can only be used as a lining for acid gas.

Acid Resistance Castable Directly from Factory

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Characteristics and Configuration Methods of Acid-Resistant Castables

Acid-resistant castable is a castable refractory material prepared with water glass as a binder, acid-resistant refractory aggregate, powder, and admixture. Acid-resistant castables have higher binder and moisture content and better fluidity, so monolithic refractory materials have a wider range of applications. Specifically, the materials and binders used can be selected according to the conditions of use. It can be directly poured into a lining body, and can also be used as a prefabricated block by pouring or shaking.

The products of acid-resistant castables are inseparable from the environment and pigments, so you must pay attention to these when using acid-resistant castables. Many customers know what castables are, but in terms of subdivision, they don’t know much about acid-resistant castables, nor do they know what the composition ratio of acid-resistant castables is.

The composition ratio of the acid-resistant castable is acid-resistant refractory aggregate 60%-75%, powder 25%-30%, and water glass 13%-16%. The general classification standard of acid-resistant castables is to classify according to the actual use situation, use temperature, and functional characteristics. The main varieties of acid-resistant castables produced by Rongsheng manufacturers include ordinary calcium aluminate cement, pure calcium aluminate cement, and Portland cement. The basic technical characteristics of acid-resistant castables are similar to those of general water glass refractory castables. The products of acid-resistant castables are inseparable from the use environment, which is directly related to the quality of acid-resistant castables. Acid-resistant castables are very picky about the construction environment. When we use acid-resistant castables, the construction temperature must be properly controlled. Too high or too low temperature will be harmful to the castable, and the use environment will also affect the corrosion resistance of the castable.

Because acid-resistant castables have excellent anti-corrosion properties, acid-resistant castables can not only meet the anti-corrosion requirements in corrosive environments but also meet the performance fatigue requirements of alternating performance. Acid-resistant castables can survive in extremely harsh environments for a long time. The shrinkage rate, hardness, toughness, wear resistance, and high-temperature resistance of the acid-resistant castable itself have laid a solid foundation for its long-life use in harsh environments. In terms of acid resistance, the acid resistance of aggregate and powder is mainly considered. Factors such as the acid resistance after being formulated into an acid-resistant castable and the change in the strength of the castable after pickling. Acid-resistant castables are easy to harden and can be hardened by hydration at room temperature. For example, soaking in different concentrations of the sulfuric acid solution, as the concentration of the acid solution increases, the strength of the castable also increases. It has good strength stability when soaked in concentrated acid. The strength not only does not decrease after soaking but increases slightly with the extension of soaking time.

Lightweight Acid-Resistant Castable For Chimney

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Advantages and Construction Precautions of Lightweight Heat-Insulating and Acid-Resistant Castables

Lightweight heat-insulating and acid-resistant castables have the advantages of light volume, strong compression resistance, high acid corrosion resistance, and low water absorption. Fully play the role of heat preservation. It can ensure the compactness of the masonry especially when it is used in the parts with serious acid corrosion. It is an ideal refractory material for a high chimney, high-temperature flue, and pipelining.

Lightweight heat-insulating and acid-resistant castables are easy to construct and have strong cohesive force. The initial setting time and construction operation time are long, and the strength increases rapidly, the impermeability is strong, no acid treatment is required, and it is easy to ensure the denseness and fullness of the masonry mortar joints. It can significantly improve the airtightness and integrity of the chimney lining wall and the acid corrosion resistance of the lining.

When the lightweight heat-insulating and acid-resistant castable is used, it can be dry-mixed and then wet-mixed with water. The amount of water added to acid-resistant castables also needs to be strictly controlled. The amount of water added is directly related to the performance and strength of the castable. Therefore, attention must be paid during construction, and the mixed water must be added according to the amount of water added in the construction instructions.

Lightweight heat-insulating and acid-resistant castables can be used as acid-resistant castables and refractory castables without heat insulation. The main component of the lightweight acid-resistant castable binder is water glass. However, some require different parts to be used, and they are also combined with phosphoric acid, and the acid-resistant castables combined with phosphoric acid have low calcium content.

Due to the large porosity of the lightweight aggregate structure, rough surface, and particle size of about 5mm, the water absorption and hygroscopicity of the aggregate and powder are large. Therefore, according to the mixing ratio, the fluidity is poor after stirring, the thermal conductivity is small, and the linear expansion coefficient is small. It can also be used as filling material in the lining of a blast furnace.

Lightweight acid-resistant castables must be protected from moisture. Rongsheng monolithic refractory manufacturers will mix the aggregate and powder into a mixture before leaving the factory, and pack it in a woven bag before transportation. For temporary storage, it should be stored in a dry warehouse with good drainage and moisture-proof.

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High-Quality Monolithic Refractory Manufacturers

Rongsheng Refractory Material Manufacturer is a refractory material manufacturer with rich production and sales experience. Our environmentally friendly fully automatic monolithic refractory production line has an annual output of tons. Specially provide solutions for refractory lining materials for various high-temperature industrial furnaces. We can not only provide various monolithic refractory castable products but also provide turnkey projects of refractory lining. Various refractory precast shapes. Contact us for free samples and quotes.

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Refractory Precast Shapes have the Following Advantages

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