KilnRefractory, Author at Kiln Refractories Blog

Effect of Barite Powder on the Strength of High Alumina Cement – High Temperature Cement

September 12, 2024November 9, 2024 KilnRefractory

High alumina cement, also known as aluminate cement, has the advantages of high early strength, high-temperature resistance, and strong resistance to sulfate corrosion. In recent years, due to the rapid growth of the early strength of high alumina cement, early de-moulding, and tight construction schedules, the number of projects using high alumina cement to prepare concrete has continued to increase. However, the later strength of high alumina cement is unstable, and there is great controversy about its application in engineering. Studies have shown that the use of ultrafine powder as a mixture of high alumina cement can improve the later strength of high alumina cement.

Effect of Barite Powder on the Strength of High Alumina Cement

Baryte powder, commonly known as barite, is a naturally formed white inorganic salt and a neutral filler. Its relative density is 4.16, and it has the characteristics of light resistance and corrosion resistance, low oil absorption value, opaque to ultraviolet rays and X-rays, and radiation protection. Using natural mineral barite as an additive for aluminate cement can reduce the water requirement of the standard consistency of aluminate cement, improve the strength of cement, reduce the later strength regression, and not reduce the refractoriness of cement.

Adding an appropriate amount of barite powder admixture to high alumina cement can not only improve the early strength of high alumina cement but also inhibit the later strength shrinkage of high alumina cement. The appropriate amount of barite powder can promote the hydration of high alumina cement. The main reason why barite powder inhibits the later strength shrinkage of high alumina cement is that it inhibits the crystal transformation of CAH10 and C2AH8 to C3AH6 in the hydration products of high alumina cement. It should be noted that excessive addition of barite powder may cause the strength of high alumina cement to decrease. Therefore, in practical applications, it is necessary to make adjustments according to specific circumstances.

In general, the effect of barite powder on the strength of high-aluminum cement is a complex issue that requires comprehensive consideration of multiple factors. Future research can further explore the optimal addition amount of barite powder and the differences between different types of high-aluminum cement to better play the application value of barite powder in high-aluminum cement.

What is High-Temperature Resistant Cement? Aluminate, High Aluminum, Refractory

Rongsheng refractory cement sales. Rongsheng high-temperature cement, has many aliases, aluminate cement, high aluminum cement, high strength refractory high temperature resistant cement. It is a special cement that maintains good performance in high-temperature environment. It has high compressive strength, heat resistance, chemical corrosion resistance and low thermal expansion coefficient. It is suitable for engineering projects in harsh environments such as slag, high-temperature gas and chemically corrosive substances. Contact Rongsheng for a free quote.

Rongsheng Calcium Aluminate Cement - High Alumina Cement — Rongsheng Calcium Aluminate Cement – High Alumina Cement

High-temperature resistant cement is mainly used in high-temperature industrial fields such as metallurgy, petrochemical, and electric power. As well as the construction and maintenance of high temperature facilities such as furnaces, chimneys, smelting furnaces, and chemical equipment. Rongsheng high-temperature resistant cement, aluminate cement, refractory cement, high aluminum cement.

The main characteristics of high-temperature resistant cement are as follows:

High-temperature resistance. The sintering temperature of high-temperature resistant cement is as high as 1300-1600 degrees Celsius. It can maintain stable performance in a long-term high-temperature environment and is suitable for various high-temperature facilities and equipment.
High compressive strength. High-temperature cement has high compressive strength, can withstand large mechanical loads, and is suitable for high-strength and high-pressure engineering applications.
Good chemical corrosion resistance. High-temperature resistant cement has good corrosion resistance to a variety of acid, alkali, salt and other chemical media, and can maintain a long service life in harsh chemical environments.
Low thermal expansion coefficient. High-temperature-resistant cement has a low thermal expansion coefficient, can adapt to thermal expansion and contraction in high-temperature environments, and reduces the generation of cracks.
Excellent fire resistance. High temperature-resistant cement has good fire resistance, can effectively prevent the spread of fire, and improves the fire safety performance of buildings.

Detailed Explanation of Ingredients and Process of High-Strength Sulphoaluminate Cement

Take the production of 100 kg of high-strength sulphoaluminate cement as an example. Among them, sulphoaluminate cement clinker: 76 kg; silica fume: 9 kg; dihydrate gypsum: 10 kg; lithium carbonate 1 kg, calcium hydroxide 2 kg and aluminum sulfate 1.5 kg; retarder: 0.5 kg. Weigh the raw materials of each component according to the above mass percentage. After mixing evenly, grind them together to a fineness of 360m2/kg specific surface area to make a finished cement product.

Sulphoaluminate cement. The high-strength sulphoaluminate cement produced by this method has a simple production process, is easy to implement and has low cost. It can effectively adjust the setting time of sulphoaluminate cement to meet the construction requirements of actual projects.

Rongsheng High Alumina Cement Manufacturer

Rongsheng Refractory Material Manufacturer is a powerful manufacturer and seller of refractory materials. Rongsheng’s high alumina cement (CA50/CA60/CA70/CA80, etc.). High temperature resistance and excellent performance. Rongsheng’s refractory products have been sold to more than 120 countries around the world, such as South Africa, Chile, Egypt, Colombia, Uzbekistan, Italy, Indonesia, Ukraine, Hungary, Spain, Kenya, Syria, Zambia, Oman, Venezuela, India, Peru, the United States, Ethiopia, etc. Contact Rongsheng for more information on refractory lining materials.

The Importance of Zirconium Silicate 63-65% in High-Performance Ceramics

August 15, 2024 KilnRefractory

In the realm of advanced manufacturing, high-performance ceramics have become indispensable due to their unique properties, including hardness, thermal stability, and resistance to wear and corrosion. Among the various materials used to produce these ceramics, zirconium silicate, particularly in the 63-65% purity range, stands out as a crucial component. This blog post delves into the importance of zirconium silicate in high-performance ceramics, exploring its properties, applications, and why it is favored by manufacturers.

Zirconium Silicate (ZrSiO₄) 63-65%

Zirconium silicate (ZrSiO₄) is a naturally occurring mineral derived from zircon. It is processed into a fine powder, which is then used in various industrial applications, most notably in ceramics. The 63-65% purity range of zirconium silicate refers to the concentration of zirconium in the material, which is essential for achieving the desired performance characteristics in high-performance ceramics.

Key Properties of Zirconium Silicate

Zirconium silicate possesses several properties that make it ideal for use in high-performance ceramics:

High Melting Point: With a melting point of approximately 2550°C, zirconium silicate exhibits excellent thermal stability. This property is vital in ceramic manufacturing, where materials are subjected to extreme temperatures during processing and in their final applications.
Chemical Inertness: Zirconium silicate is chemically stable and does not react with most substances. This chemical inertness is crucial in preventing degradation or unwanted reactions during the production and use of ceramics, ensuring that the material retains its integrity over time.
Hardness: The hardness of zirconium silicate contributes to the strength and durability of ceramic products. It enhances the resistance of ceramics to mechanical wear and tear, making them suitable for demanding applications.
Low Thermal Expansion: Zirconium silicate has a low coefficient of thermal expansion, meaning it does not expand or contract significantly with temperature changes. This property helps to prevent cracking and warping in ceramics, particularly during rapid heating or cooling.
Opacity: In ceramic glazes, zirconium silicate is often used as an opacifier, giving the ceramics a bright, white appearance. This opacity is important for achieving consistent color and finish in ceramic products.

The Role of Zirconium Silicate in High-Performance Ceramics

Zirconium silicate 63-65% plays a vital role at various stages of ceramic manufacturing, contributing to both the aesthetic and functional properties of the final products.

Structural Ceramics:

High-performance structural ceramics are used in applications where strength, durability, and resistance to extreme conditions are paramount. Zirconium silicate is often incorporated into these ceramics to enhance their mechanical properties. The material’s hardness and low thermal expansion make it ideal for components that must withstand heavy loads, high temperatures, and thermal cycling without losing their structural integrity.

For example, zirconium silicate is used in the production of ceramic engine components, cutting tools, and protective coatings. These applications demand materials that can perform reliably under stress, and zirconium silicate’s properties make it a preferred choice for such uses.

Refractories:

In the production of refractory ceramics, which are used to line furnaces, kilns, and other high-temperature environments, zirconium silicate 63-65% is invaluable. Its high melting point and chemical inertness ensure that refractory ceramics can endure extreme heat and exposure to aggressive chemicals without degrading.

The inclusion of zirconium silicate in refractory ceramics improves their thermal shock resistance, allowing them to withstand rapid temperature changes without cracking. This makes these ceramics ideal for use in industries such as metallurgy, glass manufacturing, and petrochemicals, where reliable performance in harsh conditions is essential.

Ceramic Glazes:

Zirconium silicate is widely used in the production of ceramic glazes. It acts as an opacifier, providing the glaze with a bright white color and enhancing its opacity. This is particularly important in the production of decorative ceramics, such as tiles, dinnerware, and pottery, where consistent color and finish are key to the product’s aesthetic appeal.

Additionally, zirconium silicate improves the hardness and durability of ceramic glazes, making them more resistant to scratching, chipping, and wear. This ensures that the finished ceramics not only look good but also have a long lifespan, even in demanding environments.

Advanced Ceramics:

Zirconium silicate 63-65% is also used in the production of advanced ceramics, which are engineered for specific industrial applications requiring exceptional performance. These advanced ceramics are used in fields such as electronics, aerospace, and biomedical engineering, where materials must meet stringent standards for strength, durability, and resistance to extreme conditions.

In the electronics industry, for instance, zirconium silicate is used in the production of ceramic substrates and insulators that must operate reliably at high temperatures and in the presence of electrical stress. In the biomedical field, zirconium silicate ceramics are used in the production of implants and prosthetics, where biocompatibility and wear resistance are critical.

Rongsheng Zirconium Silicate for Sale — Zirconium Silicate in High-Performance Ceramics

Advantages of Using Zirconium Silicate in High-Performance Ceramics

The use of zirconium silicate 63-65% in high-performance ceramics offers several significant advantages:

Enhanced Durability: The hardness and thermal stability of zirconium silicate contribute to the durability of ceramic products, ensuring that they can withstand wear, heat, and chemical exposure without degrading.
Improved Aesthetics: Zirconium silicate’s ability to enhance the opacity and whiteness of ceramic glazes leads to visually appealing products with consistent finishes, which is important in both decorative and functional ceramics.
Consistency and Quality: The fine particle size and chemical stability of zirconium silicate powder ensure uniform distribution within the ceramic body and glaze, resulting in high-quality, defect-free products that meet industry standards.
Versatility: Zirconium silicate can be used across a wide range of ceramic applications, from structural components and refractories to decorative glazes and advanced ceramics. Its versatility makes it a valuable material for manufacturers seeking to produce high-performance products.
Cost-Effective: While zirconium silicate is a high-performance material, it is also cost-effective, offering manufacturers a reliable and affordable solution for enhancing the quality and performance of their ceramic products.

Zirconium Silicate 63-65% is an Essential Material

Zirconium silicate 63-65% is an essential material in the production of high-performance ceramics, offering unique properties that enhance the strength, durability, and aesthetic appeal of the final products. Its high melting point, chemical stability, hardness, low thermal expansion, and opacity make it a preferred choice for a wide range of ceramic applications, from structural and refractory ceramics to glazes and advanced industrial components.

As the demand for high-performance ceramics continues to grow, zirconium silicate will remain a cornerstone of ceramic manufacturing, enabling manufacturers to produce reliable, high-quality products that meet the stringent demands of modern industry. Whether in traditional applications or cutting-edge technologies, zirconium silicate 63-65% will continue to play a crucial role in shaping the future of ceramics. Free quote at Sales@kilnrefractory.com.

Advantages and Disadvantages of Hot Blast Furnace Checker Bricks Silica Checker Bricks and High Alumina Checker Bricks

June 26, 2024July 1, 2024 KilnRefractory

The hot blast stove is a typical regenerative heat exchanger. The regenerator is mainly a porous checker brick, which transfers the heat generated by combustion to the blast furnace blast. The heat transfer of the hot blast stove is an unsteady heat transfer process. The heating and cooling of the checker bricks in the regenerator change periodically with the height and time of the hot blast stove.

The shape of the checker brick is a regular hexagonal prism, that is, the upper and lower end faces are regular hexagons. There are a varying number of through holes arranged in regular triangles between the two end faces. The checker bricks are made of different materials according to their different working temperatures. For parts close to the combustion chamber where the temperature is high, materials with good high-temperature performance and strong anti-adhesion ability should be used, mostly silicone or high-aluminum materials. The temperature of the checkered bricks close to the cold air chamber is low, so clay materials with good low-temperature performance and high strength are selected.

Advantages and Disadvantages of Silica Checker Bricks and High Alumina Checker Bricks

Silica refractory materials are acidic refractory materials and have good resistance to oxides such as CaO, FeO, Fe2O3, etc. It has the advantages of high softening temperature under load, stable volume at high temperatures, and high thermal conductivity. However, the thermal stability at low temperatures (below 800°C) is poor. The specific realization is that the load softening temperature can be as high as (1640-1680℃), which is close to the melting point of tridymite (1670℃). It has very good thermal stability above 800℃ and can adapt to large changes in temperature. The silica bricks used in hot blast stoves have tridymite as the main crystal phase and have stable volume and low creep rate under high-temperature loads. Its anti-adhesion performance is also better than other refractory materials. Proper use can make the hot blast stove structure more stable. However, at 200-300°C and 573°C, the volume suddenly expands due to crystalline transformation, which can easily cause structural damage. Therefore, drastic temperature changes below 600°C should be avoided.

Compared with silica bricks, high-alumina refractory materials have a lower softening temperature under load and poor high-temperature volume stability. However, high-aluminum refractory materials have the advantages of large capacity and good thermal shock stability.

Silica refractory materials have less adsorption of dust in coal gas and have good resistance to oxides such as CaO, FeO, Fe2O3. High-aluminum refractory materials have strong adsorption to dust in coal gas, and the main component is Al2O3, which easily forms a low eutectic with CaO and total iron in the dust. It adsorbs to the body of the checker bricks and then penetrates and erodes.

In terms of damage mechanism, high-aluminum refractory materials have poor adaptability to dust in gas.

Compared with silica bricks, low-creep high-alumina bricks have the disadvantages of poor performance and high price. It is a reasonable choice to use silica bricks in the high-temperature zone of hot blast stoves with high blast temperatures. Silica bricks are almost all used in the high-temperature zones of foreign hot blast stoves.

Comparison of Heat Storage between High Alumina Checker Bricks and Silicon Checker Bricks

High alumina check bricks and silicon check bricks are common heat storage materials, and they have their own advantages and characteristics in different application scenarios.

High-aluminum checker bricks are usually made of high-aluminum materials. Their main features are high heat capacity and excellent high-temperature resistance. High-aluminum checker bricks are widely used in high-temperature equipment such as industrial furnaces and kilns, and can effectively store heat and maintain temperature stability. Therefore, it is more suitable for high-temperature operations of 1400-1500℃.

Silicon lattice bricks are usually made of siliceous materials, which are characterized by good thermal conductivity, low density, and strong corrosion resistance. This brick material performs relatively well at 1600°C. For example, long-term operation of industrial furnaces or long-term stable high-temperature environments.

When comparing these two materials, specific application needs and work environments need to be considered. If it is necessary to maintain high temperatures for a long time, silica checker bricks may be more suitable. If frequent temperature changes are required or rapid heating and cooling are required, high-aluminum checker bricks may be more suitable.

Checker Bricks for Hot Blast Stoves Regenerators

How to Increase the Heat Balance and Shorten the Heating Time of Hot Air Furnace Checker Bricks?

Due to the development of modern ironmaking technology, the requirements for blast furnaces are getting higher and higher, and the air temperature requirements are around 1200°C. Obviously, in order to meet the requirements of the blast furnace, in addition to high-intensity combustion to achieve high combustion temperatures, it can only be achieved through efficient and reasonable heat transfer between the airflow and the regenerator structure. Whether the flue gas flow velocity field after combustion can enter the regenerator in a uniformly distributed manner, and whether the uneven airflow distribution can be adjusted to a more uniform distribution after entering the regenerator, is whether the utilization rate of the regenerator can be improved. The key factor to enhance the heat transfer effect.

High-temperature far-infrared radiation coatings have an emissivity above 0.9 in the spectral range of 0.7-15μ. Painting on the surface of hot air stove check bricks can increase the heat and speed of heat absorption and heat storage (heat release) of the check bricks without increasing the weight and weight of the check bricks.

During the combustion period, the high absorption characteristics of the infrared radiation coating are used to enhance the heat absorption speed and heat absorption on the surface of the regenerator. Improve heat storage capacity.
During the air supply period, the high radiation characteristics of the coating are used to increase the air supply temperature and heat release capacity.

In addition, R&D personnel stabilized the blackening agent to improve the anti-aging performance, and make the coating dense, high in strength, and high in temperature resistance, thereby reducing the high-temperature impact of the checker bricks. Increase its corrosion resistance and extend the service life of checkered bricks by more than 25%.

Construction Technology of Alumina-Magnesia Carbon Bricks in Ladle Lining

June 12, 2024 KilnRefractory

Application of alumina-magnesia carbon bricks in ladles. In order to improve the service life of continuous casting ladles and meet the needs of the development of efficient continuous casting technology, alumina-magnesia carbon bricks for ladles were developed. It can be used in various types of continuous casting ladles to greatly increase the service life of the ladles. Aluminum-magnesium carbon ladle bricks are used in a 300t continuous casting ladle in a steel plant. The ladle age has increased from more than 20 times when first-class high alumina bricks were used to more than 80 times, and the highest is 126 times. There is also a 200t fully continuous casting ladle in a steelmaking plant with out-of-furnace refining, which uses alumina-magnesia carbon bricks and has an average lifespan of 64 times and a maximum of 73 times. The promotion of high-quality aluminum-magnesia-carbon refractory bricks for ladles and the use of aluminum-magnesia-carbon ladle lining bricks have significantly increased the life of the ladle. For example, after using alumina-magnesia carbon lining bricks for a 160t ladle, the average service life is increased to 90 times, and the maximum is 115 times.

Alumina Magnesia Carbon Bricks for Ladle Lining

Alumina-magnesia carbon bricks are unfired products made of special-grade high-alumina bauxite clinker, fused magnesia or sintered magnesia and graphite as raw materials, and liquid phenolic resin as a binder. This product has good slag erosion resistance, strong corrosion resistance, good thermal shock resistance, and low price, and is mainly used in the non-slag line parts of the ladle.

Construction Technology and Requirements of Alumina-Magnesia Carbon Bricks as Ladle Lining

Construction sequence of alumina-magnesia carbon bricks as ladle lining. Pouring of the permanent layer of the cladding → Pouring of the permanent layer of the bottom of the cladding → Placement of nozzle seat bricks → Construction of breathable bricks and bottom alumina-magnesia carbon bricks → Filling the gaps with corundum cement → Construction of wall-clad alumina-magnesia carbon refractory bricks and slag-clad magnesia carbon bricks Brick masonry → Aluminum-magnesium castable masonry → Curing → Baking.

Wall-clad alumina-magnesia carbon brick masonry construction

1) Use aluminum-magnesium fire mud for wet masonry, and the masonry mud should not be too thin. The mud between the brick joints needs to be full, and the brick joints should be less than 1mm.
2) Each layer of bricks is laid flat, and the brick joints between layers must be staggered. During masonry construction, the principles of “solid backing, tight seams, and arc closing” should be followed, and the joints between the upper and lower layers must be staggered.
3) The size of the cutting door closing brick should be no less than 50mm, and the door closing part should avoid the trunnion position. The door closing positions between layers should be staggered by more than 200mm.

Bottom masonry construction technology

1) The breathable bricks and nozzle seat bricks must be placed flat and in the correct position.
2) After the nozzle seat bricks and breathable bricks are in place, the gaps between them and the surrounding bottom bricks are filled with corundum cement.

Pouring construction requirements

1) Check construction equipment, mixers, water supply, vibrators, etc.
2) Turn on the mixer, add the mixture, dry mix for 1 minute, then add 2/3 of the water. Then slowly add the remaining water and mix wetly for 3 to 5 minutes before discharging.
3) Use a vibrating rod to vibrate after each pouring of the rolling material, and the pouring material is required to be fully exhausted.
4) The pouring construction must be consistent before and after, and the stop time during the process shall not exceed 20 minutes.

Construction requirements for bottom excavation and repair

1) Remove the seat bricks and their surrounding cementing material and clean them.
2) Lift the new breathable bricks and seat bricks into their placement locations.
3) Use corundum cement to fill the gaps between the breathable bricks, the nozzle bricks and the bottom alumina-magnesia carbon bricks.

Good construction technology, coupled with the correct construction by skilled construction workers, can not only ensure the high performance of the refractory lining material but also very likely increase the service life of the refractory lining. To purchase high-quality ladle lining refractory materials, please choose RS Kiln Refractory Factory. We not only provide high-quality refractory lining materials, but we also provide comprehensive customer service to ensure the efficient operation of refractory materials.

Price of Mullite Insulation Bricks with Bulk Density 1.0g/cm3

April 2, 2024April 2, 2024 KilnRefractory

Mullite brick is a high-quality refractory brick. Mullite brick is made of high-quality high-alumina bauxite clinker as the main raw material. Mix the appropriate amount of clay, ingredients, and water to create a malleable mud or mud. High-quality thermal insulation bricks that are extruded and fired at high temperatures.

Rongsheng Lightweight Mullite Insulation Bricks for Sale

Mullite Insulation Brick Price

According to the brand name, mullite bricks are generally divided into JM23 mullite bricks, JM26 mullite bricks, JM28 mullite bricks, and JM30 mullite bricks. The price of mullite bricks is generally between 2,800 yuan/ton and 4,500 yuan/ton. So, how many mullite bricks are there? The common body densities of mullite bricks are 0.8g/cm³ and 1.0g/cm³. There are about 735 mullite bricks with a body density of 0.8g/cm³ per ton, and there are about 588 mullite bricks with a body density of 1.0g/cm³ per ton. Then you can calculate how much a mullite brick costs.

For example, a ton of 0.8 JM23 mullite bricks is 2,800 yuan, so the price of a piece of JM23 mullite bricks is 2,800 yuan ÷ 735 pieces = 3.8 yuan. 1.0 A ton of JM23 mullite bricks is 2,700 yuan, so the price of a piece of JM23 mullite bricks is 2,700 yuan ÷ 588 pieces = 4.59 yuan.

According to changes in market conditions, if a ton of 0.8 JM28 mullite bricks costs 3,500 yuan, then the price of a piece of JM23 mullite bricks is 4,500 yuan ÷ 735 pieces = 6.12 yuan. 1.0 A ton of JM28 mullite bricks is 4,200 yuan, so the price of a piece of JM23 mullite bricks is 4,200 yuan ÷ 588 pieces = 7.14 yuan.

Rongsheng Mullite Brick JM28 Factory

Zhengzhou Rongsheng Kiln Refractory Materials Factory is a professional manufacturer of refractory bricks and castables. The company produces refractory products of different specifications, sizes, and standards for different usage environments, and has a professional refractory construction team. The company’s refractory brick products mainly include mullite bricks, high alumina refractory bricks, clay refractory bricks, lightweight insulation bricks, castables, silica bricks, and magnesia bricks. Rongsheng Company has a complete and scientific quality management system and perfect customer service. If you need to purchase insulation material products for your high-temperature industrial furnace project, please contact us.

JM23 JM26 JM28 Mullite Insulation Bricks for Furnace Insulation

The Difference between Lightweight Mullite Insulation Bricks Jm23/Jm26/Jm28/Jm30

The lightweight mullite insulation bricks Jm23/Jm26/Jm28/Jm30 have different indicators such as alumina content, refractoriness, volume density, and normal temperature compressive strength, which affect the insulation performance and stability. When selecting, physical and chemical indicators need to be considered based on specific needs.

Jm23/Jm26/Jm28/Jm30 in lightweight mullite insulation bricks respectively represent different grades of brick numbers. Different grades of lightweight mullite insulation bricks will have differences in insulation performance, physical and chemical indicators, and scope of use. So what are their differences?

Al2O3 content is different

The alumina content of lightweight mullite insulation bricks Jm23/Jm26/Jm28/Jm30 is 38-44%, 50-58%, 65-70%, and 70-73% respectively. The higher the grade, the higher the alumina content, which affects the thermal insulation performance and fire resistance.

Different refractoriness

The four levels of lightweight mullite bricks have refractory resistances of 1350°C, 1430°C, 1540°C, and 1600°C respectively. The higher the grade, the higher the refractoriness. This is because as the alumina content increases, the refractory degree also increases. The better the stability of lightweight mullite insulation bricks in high-temperature environments.

Different volume density

Among them, the volume density of JM23 is 1.3g/cm3, the volume density of JM26 and JM28 is the same at 0.8g/cm3, and the volume density of JM30 is 1g/cm3.

Different normal temperature compressive strength

The compressive strengths of lightweight mullite insulation bricks Jm23/Jm26/Jm28/Jm30 are 1.3Mpa, 2Mpa, 3Mpa, and 3.5Mpa respectively. The higher the normal temperature compressive strength, the load-bearing capacity and service life of the brick will increase accordingly.

In addition to the above common differences, they have differences in thermal conductivity, reheat line change rate, etc. These indicators reflect the thermal conductivity and stability of the material, and we can choose based on detailed physical and chemical indicators when selecting.

Rongsheng Insulation Bricks Materials for Sales

Proper insulation of the kiln can also save production energy and production costs. Rongsheng manufacturer has many successful cases in kiln insulation. Help enterprises reduce the temperature of the outer wall of the kiln by 50~60℃. Moreover, our new insulation material products have also been tested and will soon be promoted to various industrial kilns. Contact us for free information and quotations on the latest insulation bricks.

High-Strength Wear-Resistant Silicon Carbide Castable

March 8, 2024 KilnRefractory

Silicon carbide castable uses high-purity silicon carbide (SiC) raw material as the main component and adds a certain proportion of micro-powder additives. An unshaped refractory material produced with high-purity refractory cement as a binder. It has excellent properties of high-temperature resistance, wear resistance, erosion resistance, peeling resistance, erosion resistance, and crusting resistance. Amorphous refractory materials with silicon carbide as the main raw material also include silicon carbide spray coatings, silicon carbide plastics, etc., which can be poured, sprayed, and smeared.

Advantages of Silicon Carbide Castables

Anti-wear. Since the main component of the material is silicon carbide (SiC), it is also called emery. There are very few natural ones, and those used in industry are all synthetic raw materials. It has two crystal forms. The low-temperature form of β-SiC has a cubic structure; the high-temperature form of α-SiC has a hexagonal structure. Its true density is 3.21g/cm3, and its decomposition (sublimation) temperature is 2600°C. It is a hard material with a Mohs hardness of 9. Synthetic SiC powder is used as an abrasive. The grinding ability of silicon carbide is 0.25~0.28, which is higher than corundum.
High-temperature resistance. Silicon carbide has good high-temperature resistance. Under normal pressure, the inconsistent melting temperature of silicon carbide is 2760°C, reaching 625MPa.
Anti-erosion, anti-oxidation and anti-scaling. When heated to 1000°C, the surface of SiC is oxidized and a layer of SiO2 protective film is formed. This film hinders the diffusion of oxygen and slows down the oxidation rate. The silicon carbide covered by the film is protected and the service life of the silicon carbide material is improved.

At 1300°C, cristobalite begins to precipitate in the film. The crystal form transformation of cristobalite causes cracking of the film and accelerates the oxidation rate.

At 1500~1600℃, the oxidation rate accelerates, but the SiO2 layer produced is also thick, and silicon carbide can still work for a long time. When the temperature rises to 1627°C, the SiO2 layer is destroyed and the silicon carbide oxidation reaction intensifies. Therefore, 1627°C is the highest temperature at which silicon carbide can work in an oxidant-containing atmosphere.

The chemical properties of silicon carbide are relatively stable and have good acid resistance. Silicon carbide does not react with boiling hydrochloric acid, sulfuric acid, or nitric acid. When the temperature is ≤1300℃, it will not be corroded by H2, N2, and COR2O, and it will be corroded by oxides above 1000℃. At high temperatures, silicon carbide is corroded by Cl2, F2, and H2, and can also react with H2O. When the temperature is ≥1370°C, silicon carbide and Cr2O3 react to form metal silicide.

Silicon carbide is not suitable for cutting steel. When the temperature rises, SiC will react with Fe to form ferrosilicon alloy and iron carbide. But silicon carbide can be used to grind cast iron. This is because cast iron has a high carbon and silicon content and is not sensitive to the reaction of silicon carbide.

Thermal shock resistance. When the silicon carbide powder is 150 mesh, SiC is not completely oxidized. Creating gaps or partial gaps around the SiC particles improves the thermal shock resistance and strength of the castable. The SiC that has not been completely oxidized also plays the role of particle reinforcement.

High conductivity. Silicon carbide has strong electrical conductivity and is a semiconductor. When the temperature reaches 2000°C, the electrical conductivity of silicon carbide is equivalent to that of graphite.

Silicon Carbide Castable Refractory Lining

Application of Silicon Carbide Castables

Molten iron preconditioner linings, cupola furnaces, and induction furnace linings in the steel industry.
Combustion chamber side wall linings and boiler tube protective linings for waste incinerators in the solid waste treatment industry.
In the cement industry, the cement kiln preheater lining, rotary kiln head, and grate cooler wear piers.
The cyclone separator lining the body of thermal power plants in the electric power industry, the combustion chamber, lining, and high-temperature separator return part of the circulating fluidized bed furnace.
Firing kiln shed panels for the ceramics industry.
Reduction of furnace linings such as silicon outlets and aluminum outlets in the non-ferrous metal smelting industry.
Biomass pellet stove burners and other easy-to-wear parts in the energy industry.

Introduction to Silicon Carbide Castable Mix Ratio and Performance

There are very few natural silicon carbides, and most of them used in industry are synthetic raw materials, commonly known as emery. Silicon carbide is one of the non-oxide refractory raw materials commonly used in the field of refractory materials. Clay-bonded silicon carbide castables, oxide-bonded silicon carbide, nitride-bonded silicon carbide, recrystallized silicon carbide, reaction sintering siliconized silicon carbide and other products produced from silicon carbide as raw materials, as well as amorphous refractory materials. It is widely used in blast furnaces, zinc smelting furnaces, ceramic industry kiln furniture, etc. in the metallurgical industry.

Silicon carbide castable has the characteristics of high strength, good wear resistance, and strong slag resistance. The operating temperature is 1500-1700°C. It is generally used in parts that are prone to wear such as cyclone furnaces, boiling furnaces, and boilers, and can meet the technical requirements of thermal equipment. Mix ratio and properties of silicon carbide castables. The density of the aluminum phosphate solution is 1.5g/cm³. The sample without coagulant is dried at 110°C. Aluminum powder with a fineness of 0.09mm is greater than 85%. For castables with added alum powder, the high-temperature compressive strength at 1200°C is 22.5MPa, the load softening temperature at 4% deformation is above 1710°C, and its starting point temperature is 1680°C.

When the kiln lining is thicker, the particle size of the refractory aggregate should be increased to 5mm or larger to reduce the specific surface area of the refractory raw materials. Reduce the amount of aluminum phosphate solution and improve the performance of silicon carbide castables. As we all know, silicon carbide castables will begin to oxidize in an oxidizing atmosphere at about 1000°C. Significant oxidation occurs at 1350°C, and a SiO2 protective layer is formed at the same time, which can prevent SiC from continuing to oxidize. Therefore, aluminum phosphate silicon carbide castable is used in an oxidizing atmosphere, and its long-term use temperature is about 1500°C.

It should be pointed out that as a binder for silicon carbide castables, aluminum phosphate is more commonly used. There are also magnesium phosphate, sodium phosphate, zinc phosphate, boron phosphate, calcium phosphate ammonium phosphate, etc., which can also be used as binding agents but are rarely used in actual projects. Aluminum phosphate binder can be used with any silicon carbide castable. The prepared silicon carbide castable has better performance and achieves better use results. However, the reaction between silicon carbide castables and magnesia materials is severe. When using aluminum phosphate solution as a binding agent, inhibitors or retarders should be added, or solid aluminum phosphate-containing inhibitors should be used as a binding agent, both of which can achieve good construction and use effects.

Rongsheng Kiln Refractory Material Manufacturer

Of course, except for silicon carbide castables whose main component is silicon carbide. There are also silicon carbide added to high aluminum and corundum amorphous refractory materials. SiC can be used as the main component to make SiC castables, or it can be used as an additive component to improve the properties of other castables, especially slag resistance and thermal shock stability. In 1999, Wang Xitang et al. researched and developed the Al2O3-SiC-C blast furnace tap trough self-flowing castable. The castable has high strength, good corrosion resistance, high iron flow, and good thermal shock resistance and oxidation resistance. The most common application of SiC in monolithic refractory materials is for the working lining of blast furnace tap trenches. It has a history of more than 20 years and has good results. At present, Al2O3-SiC-C castables are commonly used in larger blast furnaces at home and abroad, which greatly extends the service life of the iron trench.

Thermal Insulation Materials for Aluminum Electrolytic Cells

February 1, 2024 KilnRefractory

Aluminum electrolytic cell is the main thermal equipment for aluminum electrolysis production. Electrolytic aluminum is the process of converting aluminum in alumina into metallic aluminum. There is an outstanding problem in the aluminum electrolytic plant. The bottom of the tank is cold. Improvement measures include blocking the windows in the lower part of the two-story structure, laying bricks within the tank shell frame, and coating the outside of the tank with an insulation layer.

Aluminum electrolytic cells are divided into bottom type and bottomless type according to the structure of the tank. According to the shape of the tank shell, it is divided into square and rectangular. According to the anode structure, it is divided into a prebaked anode and a continuous self-baked anode. According to the conductive mode, it is divided into side conductive and upper conductive.

The lining materials used in aluminum electrolytic cell-related equipment include calcium silicate boards, clay-insulating refractory bricks, clay refractory bricks, and dry anti-seepage materials. Cathode carbon block, carbon paste, water glass asbestos putty, silicon nitride silicon carbide thermal insulation coating, etc. The heat insulation layer refractory material can be placed between the tank bottom and the asbestos board to increase the heat insulation. The thermal insulation performance is more than five times stronger than calcium silicate boards of the same thickness.

High-Temperature Thermal Insulation Coating for Aluminum Electrolytic Cells

High-temperature thermal insulation coating is processed from specially synthesized inorganic silicate solution, aluminum silicate fiber, heat-reflective material, and selected hollow ceramic beads. Water-based, environmentally friendly, non-toxic, and harmless. The characteristics of high-temperature thermal insulation coating products for aluminum electrolytic cells are as follows:

Thermos bottle thermal insulation mechanism.
The hollow ceramic beads in the coating greatly reduce heat convection.
Inorganic film-forming substances with relatively low thermal conductivity.
Sound insulation and noise reduction, fire-retardant, wear-resistant and pressure-resistant, insulation-resistant and puncture-resistant, acid and alkali-resistant, lightweight, easy construction, and long service life.

The curing principle of high-temperature thermal insulation coating for aluminum electrolytic cells:

Silicate coatings are composed of a variety of silicates and a small amount of organic and inorganic binders. Its curing principle: a special silicate solution acts as a gelling agent. Aggregation process:

The condensation of silanol and the condensation between silanol and the aluminum hydroxyl group of the silicate. Form a three-dimensional skeleton network.
Silicates are polymerized according to layered and framework molecular-level silicone groups. The mixed metal oxide acts as a space filler between the three-dimensional skeleton of the main body.

Application of High-Temperature Thermal Insulation Coating

Surface painting. High-temperature molds and outer surfaces of injection molding machines. On the inner surface of high-temperature flues and exhaust pipes. Paint the thermal insulation surface of hot water tanks and dye vats.
Ceramic production, ceramic roller kiln, refractory rotary kiln. Cement plant applications, cement rotary kiln, preheater, decomposition furnace.
Steel plant applications, ring furnaces, heating furnaces, and quenching furnaces. Molten steel tundish. Blast furnace workshop steel structure insulation, coke oven.
The inner wall of the furnace shell of the smelting furnace in the metallurgical copper industry. The inner wall of the electrolytic aluminum furnace (aluminum industry).
The outer surface of the power plant turbine shell/shaft seal; and the outer surface of the steam pipe are painted. Petrochemical heating furnace, vacuum heating furnace, cracking furnace.
The top of the boiling furnace is insulated and sealed. Industrial heating furnace. Vacuum furnace insulation.
Driving cab (Crane Crane). Explosion-proof vehicles, asphalt vehicles, engineering vehicles, and military armored vehicle chassis.
Spinning box, high-temperature oven surface. New energy batteries and intermediate frequency furnaces.

Calcium Silicate Board for Aluminum Electrolytic Cell

Calcium silicate board is a new type of building material, also called “calcium silicate board”, “calcium magnesium silicate board”, “MgO board”, etc. It is a composite building material made of a variety of materials and has multiple functions such as fire protection, waterproofing, sound insulation, heat preservation, and corrosion resistance. Calcium silicate boards can be widely used in various fields such as building walls, roofs, partitions, and floors. It has high economic and social benefits.

The main components of calcium silicate board are inorganic mineral fibers as reinforcing materials, and siliceous, calcium, and other materials as the main materials. These materials are made by high-temperature pressing after certain stabilization treatments. Calcium silicate board has good flexural strength, tensile strength, and compressive strength. At the same time, it also has multiple functions such as fire resistance, corrosion resistance, sound insulation, and heat preservation.

Calcium silicate boards also have a wide range of applications and can be used on walls, roofs, partitions, and floors. Calcium silicate board has the characteristics of water resistance, corrosion resistance, etc. Therefore it is widely used in relatively humid places.

Compared with traditional building materials, the installation process of calcium silicate boards is simpler and faster. When installing calcium silicate boards, you only need to install them directly on the frame, and few other materials are used. Therefore, no construction waste and pollutants will be generated. As a thermal insulation material, calcium silicate boards are also widely used in aluminum electrolytic cells.

How to Solve the Heat Insulation Problem of Cement Kiln?

December 28, 2023 KilnRefractory

The sintering system of the cement plant has been operating at high temperatures for a long time. Choosing a better insulation material can effectively reduce heat dissipation by lowering the shell temperature without increasing or even reducing the insulation thickness. In order to maintain a better thermal condition of the system, thereby reducing energy consumption, reducing production costs, achieving the goals of energy conservation, environmental protection, and increasing production and efficiency.

The traditional custom for thermal insulation materials in fired systems is to choose microporous calcium silicate boards or ceramic fiber boards. Its thermal insulation performance can no longer meet the current higher needs for thermal insulation and energy saving. New nano-scale microporous thermal insulation materials, referred to as nano-thermal insulation materials, provide technical and material support for the higher requirements for thermal insulation and energy saving of cement kiln firing systems and the improvement of system production capacity.

Inorganic Thermal Insulating Boards in RS Factory

Micro-nano Thermal Insulation Materials for Cement Kilns

Recently, cement companies have replaced the original insulation materials of cement burning systems with nano-insulation materials. A good thermal insulation effect has been achieved, which can be used as a reference for other cement companies.

Thermal insulation of the cyclone of the cement kiln preheating and predecomposition system

The cyclone of the preheating and predecomposition system of a cement company was originally insulated with 114mm refractory bricks and 112mm calcium silicate boards. In order to enhance the heat insulation effect of the refractory lining, the company repaired the cyclone on the east side of Line 3 C5. 25 mm nano-insulation boards were used to replace the original calcium silicate boards of the same thickness, keeping the total thickness of the thermal insulation lining unchanged at 112 mm, and the remaining calcium silicate boards with a thickness of 87 mm were used.

Construction of C5 Cyclone Nano Heat Insulation Board

C5 cyclone insulation lining transformation effect. It was discovered after a period of time that the original calcium silicate board was replaced with nano-insulation board. The heat dissipation loss of the C5 cyclone is reduced by 336W/m2, the shell temperature drops by 21°C, and the heat loss is reduced by 43%. The thermal insulation effect of the refractory lining has been improved.

Improvement of the heat insulation layer in the pre-decomposition zone behind the transition zone of cement rotary kiln

Another cement company’s new special cement line project is to reduce the shell temperature of the rotary kiln’s pre-decomposition zone. In the pre-decomposition zone after the transition zone of the rotary kiln, new nano-insulation panels and grooved brick structures are used to replace the traditional insulation structure. During on-site construction, a 15 mm thick nano-insulation board is inserted into the grooved bricks to form a thermal insulation layer between the rotary kiln shell and the refractory bricks.

Combination form of Rotary Kiln Grooved Bricks and Nano Insulation Panels

The production line uses 15 mm thick nano-insulation panels. Ten days after ignition and production, during normal production of the rotary kiln, the temperature scan of the rotary kiln shell at 35 to 63 m was all green low-temperature areas, and there was no transition color between the two connected areas. It fully reflects the heat insulation effect of the grooved brick composite nano-insulation board. Compared with traditional insulation methods, the surface temperature of the cylinder is reduced by 110°C. The heat dissipation loss is reduced by 4785W/m2, and the annual heat dissipation loss is reduced by 870,000 yuan. The investment can be recovered in about 2 months. Thermal insulation effect of rotary kiln preheat zone.

Regular maintenance and replacement of refractory bricks and thermal insulation lining in the transition zone of the cement rotary kiln

When a cement company was regularly repairing and replacing refractory bricks in two rotary kiln transition zones, it decided to use grooved bricks combined with 15 mm thick nano-insulation panels to reduce the temperature of the shell of the rotary kiln transition zone. After a period of construction, according to theoretical calculations, the shell temperature of the transition zone of the traditional refractory brick rotary kiln can be reduced by 70 to 110°C. It can greatly reduce the ovality deformation of the rotary kiln shell and reduce energy consumption.

Rongsheng Micro-nano Thermal Insulation Board

Rongsheng Kiln Refractory Factory has accumulated rich experience in the application of thermal insulation materials in various industries. In order to reduce the outer wall temperature of high-energy-consuming and high-temperature industrial furnaces and save production costs, micro-nano thermal insulation materials have been introduced. It better meets the needs of the domestic market and solves many domestic and worldwide thermal insulation problems.

Inorganic Thermal Insulating Boards for Cement Rotary Kilns

Nano-thermal insulation material is a nano-scale microporous thermal insulation material produced by using nanotechnology, adding unique anti-infrared radiation materials, and adopting a special process. Compared with traditional micron-sized pore insulation materials such as ceramic fibers and microporous calcium silicate boards, the pores of nano-insulation materials are around 20 nm. The thermal insulation performance at the same temperature is 4 times better than traditional insulation materials.

So far, it has been unanimously proven by many cement companies that the use of nano-insulation materials in the rotary kiln firing system can significantly reduce the heat loss of the rotary kiln barrel. Reducing the kiln operating load and achieving energy saving and consumption reduction are worthy of further research and promotion.

Refractory Material Manufacturers Respond – How to Correctly Choose Refractory Castables?

November 30, 2023 KilnRefractory

Refractory castables are divided into acidic, alkaline, and neutral castables according to their resistance to chemical attack. According to the volume density, it is divided into dense castable refractory and light castable. According to the materials used, it is divided into aluminum silicate, magnesium, magnesium chromium, corundum castables, etc. There are many types of refractory castables, and it is difficult to make a choice without clear indicators and operating temperatures. RS refractory material manufacturer responded to “How to correctly choose refractory castables” and gave some more reliable methods for reference.

(1) Refractory castables must meet the requirements of the kiln’s usage environment.

Dense refractory castables have different requirements depending on where they are used. When selecting, it should be selected according to the characteristics of the castable. For parts that come into contact with high-temperature flames, high-temperature-resistant castables should be selected. Castables with high-temperature resistance and strong penetration resistance should be selected for parts that come into contact with high-temperature solutions. The parts that come into contact with slag should use castables that are highly resistant to the chemical erosion of slag. High-strength and wear-resistant castables are used for parts that come into contact with the impact and friction of various materials. For parts with frequent temperature changes, castables with excellent thermal shock resistance should be used. As long as it meets the requirements of the main production conditions, it is a suitable refractory castable.

The main uses of lightweight refractory castables are heat insulation, reducing load-bearing structures, lowering furnace shell temperature, and reducing heat loss, thereby achieving energy-saving effects.

(2) Economy of investment cost of refractory castables.

After determining which refractory castable to choose, it is also necessary to economically reduce costs. For example, if the use temperature is 1500°C, castables with a use temperature greater than 1600°C will not be selected if the castables can meet the working conditions. If high alumina bauxite clinker is used as the main material in the wear-resistant parts to meet the wear resistance requirements, castables with corundum as the main material should not be selected. The main reason is that the price of refractory castables varies greatly depending on the content of the main materials used. There is no need to ignore economic costs in pursuit of high quality. This requirement is especially important for parts that are subject to daily wear and tear.

(3) Particle size selection of refractory castables.

The construction parts of refractory castables may be thick or thin, and the particle size ratios used are different. For example, when pouring a lining with a thickness greater than 100mm, more large-grained critical aggregates need to be added to improve structural strength and wear resistance. The parts with a thickness of 10mm when poured or painted have fewer large particles of aggregate. Avoid adding large aggregates to make them protrude from the lining, which not only affects the appearance but also causes large particles to wear easily in terms of use. This causes holes in the lining, which in turn affects the service life. Depending on the pouring thickness, the pouring method or the smearing method can be used. Therefore, the selection of particle size of refractory castables is also very important.

(4) The shelf life of refractory castables.

The storage time of refractory castables in dry areas is about 6-9 months. Before use, check whether there are any agglomerations. During transportation or handling, the castable will agglomerate due to extrusion. If it can be easily patted away, the use effect will not be affected. However, the shelf life of the castables is a secondary consideration, because the configuration processes of the castables are different and most parts are not in stock. All need to be produced according to user needs and the production process adjusted.

It can be seen from the above that the selection of refractory castables is variable and must be used flexibly. To quickly select castables, it is necessary to mention the specific use location, working conditions, use temperature, pouring thickness, and construction method of the castables. The main thing is to find the right method to choose high-quality refractory castables while reducing costs.

Performance Characteristics of Dense Refractory Castables

Dense refractory castable is a construction material used in high-temperature operations. Its main function is to fill and support the furnace while providing oxidation resistance at high temperatures. Dense castables refractory are further divided into aluminate cement castables, chemically bonded refractory castables, clay bonded refractory castables, low cement series refractory castables, self-flowing castables, and new technology refractory castables. The body density is generally around 1800Kg/m³-3500Kg/m³.

Dense refractory castables are generally used for furnace lining, working layer, and permanent layer. According to the use environment, use location, and use requirements, different refractory castables are used to extend the service life of the castables.

High-temperature antioxidant properties. Medium and Dense castables refractory can withstand high temperatures and high oxidation temperatures, and their oxidation resistance is better than other types of castables. Can be used in high-temperature furnaces for a long time.

Reusability. Medium and Dense refractory castables can be reused, reducing environmental pollution and waste of resources.

Density and weight. Medium-Dense castables refractory have a lower density and weight than other types of castables, making them easier to move and fill within the furnace.

chemical composition. The chemical composition of medium and Dense refractory castables can be adjusted according to different requirements to meet different high-temperature environments and application needs.

Stability and reliability. Medium and Dense castables refractory can withstand high temperatures and high oxidation temperatures and maintain stability and reliability over long periods of use.

manufacturing cost. Medium-Dense refractory castables are more expensive to manufacture than other types of castables, but their performance value and cost of use make them a popular high-temperature building material.

RS Kiln Refractory Factory

RS Kiln Refractory Factory can provide high-quality refractory lining materials for high-temperature industrial furnace linings, including various refractory bricks, refractory castables, refractory plastics, etc. If you need to buy Dense castables refractory, Dense refractory bricks for the working lining of high-temperature industrial furnaces. Please contact us. We can provide you with high-quality refractory materials at competitive prices.

How to Use Low Cement Castables Efficiently?

November 9, 2023 KilnRefractory

Low cement castables are widely used in the steel industry because of their advantages such as high density, good fire resistance, and excellent slag resistance. At the same time, low cement castables also have some disadvantages. Such as instantaneous coagulation, delayed hardening instantaneous loss of fluidity, etc. Failure to achieve the construction effect will cause losses to users and cause worse effects. So how to use low cement castables efficiently?

Problems that easily occur during the construction of low cement castables. Since low-cement castables contain various additives, they are easily affected by external influences during construction. Its operating performance and quality are prone to changes over time. The main manifestations of on-site construction include excessive condensation, delayed hardening, and reduced fluidity. In the past, low cement castables have experienced phenomena such as instantaneous setting, delayed hardening, and instantaneous loss of fluidity during construction. RS Kiln Refractory manufacturer found through research that the above problems are related to the construction performance of low cement castable itself.

(1) Condensation too fast and too slow

The setting and hardening process of low-cement castables is caused by hydration bonding and cohesion bonding, or cohesion bonding alone. After the water-reducing agent in the castable is determined, the fluidity of the castable will also vary greatly depending on the amount of pure calcium aluminate cement added. When the addition amount exceeds 9%, the flow value of the castable is lower than 110mm, and the normal construction fluidity of the castable can no longer be guaranteed. This may be due to the excessive amount of pure calcium aluminate cement that accelerates the setting and hardening process of the castable.

The following measures can be taken to solve the aging changes of low cement castables. (1) Double-sealed packaging, especially in the rainy season or when the storage time is long. (2) Choose a dispersant with a strong dispersing ability. (3) Consider adding some newly opened packages of cement during construction and mixing. (4) Use a powerful mixer to mix and control the mixing time. (5) Add an accelerator or retarder to adjust the hardening speed of the castable. (6) In terms of on-site management, prevent moisture absorption during storage.

At present, the most effective way to solve the aging change of low cement castables on site is to add a setting accelerator or retarder to the castables. The accelerators and retarder used, especially the carbonate accelerator and citric acid retarder, are used in small quantities have significant effects, and have no adverse effects on the strength of the castable at all temperatures.

(2) Instantaneous loss of liquidity

Instantaneous loss of fluidity sometimes occurs during castable construction. The analyzed reason should be due to the failure of the water-reducing agent in the castable material or improper operation during construction.

Water reducing agent is a surface active substance. The surface activity of inorganic water-reducing agents is not significant. It mainly increases the zeta potential through chemical adsorption, effectively destroying the flocculation structure between particles. Give full play to the filling effect of micro powder and the lubrication effect of free water to increase fluidity. The anionic group N ionized by the organic water-reducing agent in water has a strong surface activity. Its lipophilic end is adsorbed on the surface of colloidal particles by physical adsorption and enters the fixed adsorption layer. The ζ potential increases in the negative direction, and the oil-repellent ends repel each other to achieve the purpose of dispersion. However, the water-reducing agent easily absorbs the moisture in the castable ingredients during the storage process and causes deliquescence and hydrolysis, which increases the acidity of the castable ingredients. This results in loss of water-reducing effect and instantaneous fluidity loss. Therefore, measures should be taken during the production and storage of castables. For example, use a water-reducing agent with poor hygroscopicity, separate the water-reducing agent from the castable, etc. At the same time, instantaneous fluidity loss may also occur during the construction of high-tech castables, especially when the mixing time is too long. We believe that the reason should be caused by the temperature rise caused by long-term stirring.

In addition, when using low-cement castables, avoid adding too much water. If too much water is added, its performance will decrease and even cause the following hazards:

Reduced intensity. Adding too much water will make the water-cement ratio of low-cement castables too high. This results in a reduction in its strength and reduces the load-bearing capacity and service life of the refractory material.
Decreased slag resistance. Adding too much water to low-cement castables will lead to a decrease in slag resistance. It is susceptible to slag erosion and reduces the service life of refractory materials.
Poor thermal shock performance. Adding too much water to low-cement castables will result in a decrease in the thermal shock properties of the material. It is prone to cracking, peeling and other phenomena, which greatly shortens the service life of the material.
Construction difficulty increases. Adding too much water will result in increased flowability of low cement castables. Problems such as slurry leakage and looseness are prone to occur during construction, which affects the quality of the project.

According to the above content, it is known that adding too much water to low-cement castables will have a serious impact on its performance and service life. During construction, the amount of water added must be strictly followed to ensure the quality and performance of the material.

Before construction and storage, pay attention to moisture-proof and avoid contact with water; when using, control the amount of water added and use additives rationally. Storage and use in strict accordance with the construction instructions will basically enable low-cement castables to effectively exert their advantages in high-temperature industrial furnace linings. Contact RS Kiln Refractory Factory for a free quote and sample of low cement castables.