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How to do the boiler refractory repair of the worn of kiln lining refractory material?

2022-06-13 by globalrefractory

The kiln lining needs to be repaired after wear and tear. According to the wear of the kiln, choose the appropriate repair method. Plastic refractory materials repair, spray refractory materials repair and castable refractory repair can be used.

Refractory is the basic material of high-temperature technology and an important masonry material for kiln lining. In a high-temperature environment, it is in direct contact with slag, charge, decomposition gas, etc., and gradually changes during long-term use. The characteristics of the refractory itself can resist the erosion of slag, chemical, air flow, etc. for a certain period of time. However, over a certain period of time will cause local lining damage, peeling, and other phenomena. At this point, the refractory material needs to be repaired. The refractory material can continue to work through a series of repair operations to ensure the normal operation of the kiln. So, what methods can be used to repair the refractory lining of the kiln?

Converter repair material

Repairing damaged parts of the converter can significantly extend the service life of the converter. With the advancement of spraying technology, converter thermal spraying technology has experienced the direction from high water to low water and no water, that is, from wet and semi-dry to flame spraying.

Blast furnace gunning

The spray method uses high-pressure air to transport granular refractory materials. Mix with a suitable amount of water in a spray gun and spray on the surface of the repair lining. Attached to a certain thickness (up to several hundred millimeters), replacing the rebuilding of the refractory brick lining.

Repair method of the inner lining of the mixed iron car

Due to its function and operation characteristics, the maintenance of the inner lining of the mixed-rail car is generally divided into major repairs, medium repairs and hot repairs.

Hot blast furnace lining thermal repair technology

As the auxiliary equipment of blast furnace, hot blast stove needs 1-2 generations of blast furnace age. The actual service life of a blast stove is usually determined by the refractory lining of the blast stove system. Refractory linings often have problems during use, and online thermal repair of refractory linings is an effective method to prolong the service life of refractory materials.

Glass Furnace Hot Repair

The traditional furnace thermal repair method has a harsh environment and high labor intensity. Although a great improvement has been made with the use of advanced refractory materials, it is still relatively difficult and burdensome, interfering with normal production. At present, the furnace thermal repair method includes thermal repair methods and thermal oxygen spraying methods.

What are the repair methods for boiler refractory repair?

The pouring repair method is to pour the unshaped refractory material into the repaired part and combine it with the original lining to resist the erosion of the slag.
The thermal spraying repair method is to spray the unshaped refractory material to the part that needs to be repaired through the spray gun. And attached to its surface to reach a certain thickness, replacing the rebuilding refractory brick lining. Rebuild the residual brick lining or the furnace lining on the surface of the furnace shell to restore the furnace shape. Compared with other maintenance methods, the major feature of spray repair is that the integrity of the repaired furnace lining is good, and the furnace shape can be reconstructed.
The injection method is to project the unshaped refractory material to the part that needs to be repaired. The operation is simple and convenient.
The grouting repair method is also known as the press-in repair method. It uses special press-in equipment to transport specific refractory materials from outside the furnace to designated maintenance parts under certain pressure conditions. So as to achieve the purpose of filling the gap and repairing the furnace lining.
The digging method is also known as the masonry method, that is, the partially damaged part of the lining is removed first, and then the refractory tiles are used to rebuild the masonry. In this case, the kiln needs to be cooled before construction.

Different lining refractory repair methods are suitable for different furnaces.

The pouring repair method can be used for repairing any kiln, blast furnace, coke oven, electric furnace, iron tapping point, ladle, etc. after the furnace is stopped.
Thermal spray repair, which can be used for damage repair of the bottom furnace wall of hot blast furnace, coke oven head, open-hearth, electric furnace, converter, heating furnace, and other furnace linings.
Spray repair method, mostly used for ladle lining construction.
The grouting repair method is mostly used for filling between the blast furnace and the furnace wall.
Excavation repair method, suitable for medium or overhaul of various kilns, blast furnaces, coke ovens, ladle, tundish, etc.

The above is an introduction to the repair method of lining refractory materials. With the development of the refractory industry, the repair methods of refractories have gradually changed. As a refractory manufacturer, Rongsheng Global Refractories has always aimed at kiln refractory solutions, boiler refractory repair, providing users with better refractory materials, and optimizing refractory lining material repair solutions.

What is the High Alumina Castable Refractory in South Africa?

2022-05-27 by globalrefractory

High alumina castable is one of the best-selling refractory castables of Rongsheng refractory manufacturers. There are many customers who continue to buy high-alumina castables from our factory, including customers in South Africa. High alumina castables are suitable for various heat treatment furnace linings and burners, blast furnace hot blast stoves, heating furnaces, electric furnace tapping grooves, high-temperature sections of shaft kilns, rotary kiln heads, power plant boilers, and other industrial furnace linings. So, what is the high alumina castable refractory in South Africa?

Rongsheng High Alumina Castables Refractory

High alumina castable is a type of low cement castable with a cement content of less than 8%. It is a refractory castable made of high alumina bauxite clinker as aggregate, refractory clay as powder, adding aluminate cement and sodium tripolyphosphate according to the formula proportion. Its use temperature is above 1400 ℃, and the aluminum content reaches 74%. It is a commonly used castable for kiln lining.

High alumina castables have the characteristics of high refractoriness, strong thermal stability, and good thermal shock resistance. high alumina castable refractory in South Africa. Different from ordinary refractory castables, most of the calcium aluminate cement in the matrix is replaced by ultrafine powder, and at the same time, appropriate additives are added to achieve and exceed the performance of ordinary cement castables.

High alumina refractory castables are now widely used in the construction and daily maintenance of various industrial kilns. High-alumina castables generally have high strength at room temperature, and can also be made into prefabricated parts and installed on the kiln rotary site. High-alumina castables can work in parts that are eroded by molten iron, molten steel, and slag and have a higher working temperature. The variety of high-alumina castables has increased rapidly, and the quality of high-alumina castables has gradually improved. Rongsheng‘s new generation of high-alumina castables includes low-cement refractory castables, ultra-low cement castables, and cement-free castables.

There is a difference between high alumina castables and high alumina low cement castables.

The high alumina castable refractory cement is added at 12%, which is convenient for construction and fast setting in the early stage but has a high calcium content, and then later use strength is not as good as that of low cement castables. The high alumina low cement castable refractory cement is added at 6%, with low calcium content and good later uses strength.

If used for chimney lining, it is better to use high alumina castable. Due to a large amount of refractory cement added, the chimney lining will be impacted by flue gas and water mist. Due to a large amount of cement, the fast setting speed of construction, and the smooth surface of the high-alumina castable surface, the high-alumina castable is more suitable in this case.

For high alumina low cement castables, the amount of refractory cement binder added is small, the amount of water added during construction is small, it is easy to bake, and it has good strength and high-temperature resistance. Moreover, the raw materials and binders of high-aluminum low-cement castables are better than the matrix of general high-aluminum castables, and the refractory cement are also relatively different in terms of labels. The price is also relatively higher than that of high-aluminum castables.

High alumina low cement castables are relatively used in high-temperature areas. Better than high aluminum castables. The material matrix used is also different than high alumina castables. So these two castables are different.

high alumina castable refractory in South Africa. The construction of high alumina castables is very important. Especially the amount of water added. Be sure to control the amount added according to the construction instructions, and do not add more. When stirring, the aggregate should be used first, then the fine powder should be added, the binder should be added, and the stirring time should not be less than 5 minutes.

After the initial setting and final setting of the high-alumina refractory castable after construction, the high-alumina castable must be cured before it can be demoulded, and then it can be put into use for baking after an appropriate period of natural curing.

The price of high-aluminum castables is determined according to the bulk density and aluminum content. The price of castables produced from high-aluminum materials with low bulk density will be relatively low. If it is castable with high bulk density and high aluminum content, the price will be relatively high.

Buy High Aluminium Castables Quickly

Rongsheng refractory material manufacturer has an advanced and environmentally friendly unshaped refractory castable production workshop. The main castable products of our factory are steel fiber castable, wear-resistant castable, high-alumina castable, non-stick alumina castable, explosion-proof quick-drying castable, alkali-resistant castable, and so on. high alumina castable refractory in South Africa. Quickly buy high alumina castables, just send us an email. We will get in touch with you as soon as possible and provide you with a free quotation and sample service.

Development of Low-Carbon Magnesia-Carbon Bricks

2021-07-25 by globalrefractory

The carbon content in traditional magnesia carbon bricks is relatively high, generally in the range of 10-20%. Due to the presence of carbon in magnesia-carbon bricks, the performance of magnesia-carbon bricks is greatly improved, making them superior to magnesia-chrome bricks and magnesia-dolomite bricks in certain properties. However, due to the progress of metallurgical technology and the demanding requirements for refractory materials, a series of problems have appeared in the use of traditional magnesia-carbon bricks. For example, the excellent thermal conductivity of graphite increases the heat loss in the steelmaking process and wastes energy. Too high graphite content will increase the carbon content in the molten steel during the refining process outside the furnace, affect the quality of the molten steel, and is not conducive to the reduction of the carbon content in the steel. In addition, graphite is a precious non-renewable resource, and traditional magnesia carbon bricks rely too much on graphite, which is detrimental to the sustainable use of resources.

Rongsheng High-Quality Magnesia Carbon Bricks

However, simply reducing the graphite content in the magnesia carbon brick will not only reduce the thermal conductivity of the magnesia carbon brick but also increase the elastic modulus of the magnesia carbon brick, which will reduce the thermal shock stability of the material. In addition, due to the low wettability of graphite with molten steel and molten slag, if the graphite content in the magnesia carbon brick is reduced, the magnesia carbon brick will be more easily corroded by molten steel and molten slag, resulting in a decrease in the corrosion resistance of the material. Therefore, research on magnesia carbon bricks with lower graphite content and excellent thermal shock stability, and slag erosion resistance has become the focus of current research and a new direction for the future development of magnesia carbon bricks.

Low Carbon Magnesia Carbon Brick with High Performance

In order to solve these contradictions and improve the performance of low-carbon magnesia-carbon bricks, we can start with improving the carbon structure of the combined carbon, optimizing the matrix, and using high-efficiency antioxidants. The specific improvement measures are as follows.

(1) Modified magnesia particles

In order to solve the poor thermal exfoliation of low-carbon magnesia-carbon bricks, a thin asphalt coating is prepared on the surface of the magnesia particles to reduce the thermal expansion of the magnesia particles during use. In this way, the thermal shock stability of low-carbon magnesia-carbon bricks can be improved.

(2) Change the type of carbon source and the particle size of graphite

By adding a small amount of carbon black (carbon black is a mixture of single spherical carbon black and polymeric carbon black), magnesia carbon bricks show outstanding excellent properties, such as reduction of elastic modulus, and relaxation of thermal stress between different particles. Improve the thermal shock stability and corrosion resistance of low-carbon magnesia-carbon bricks.

A small amount of nano-sized carbon is added to make the new magnesia carbon brick with a carbon content of about half of the ordinary magnesia carbon brick still have excellent performance. Adding different amounts of nano-sized carbon has different effects on performance. The practice has proved that adding 0.9wt% of nano-sized carbon and 3wt% of graphite as a mixed carbon source makes the material have the best performance.

(3) Modified binder

The magnesia-carbon bricks after adding the nano-sized matrix, on the one hand, reduce the carbon content and at the same time ensure the thermal shock stability of the material, on the other hand, reduce the heat loss of the converter. The composite bonding agent increases the degree of graphitization after carbonization of the bonding agent, forms micropores in the matrix, and improves the mechanical properties of the magnesia carbon brick at room temperature, high temperature, and other mechanical properties.

(4) Highly effective antioxidants

Low-carbon magnesia-carbon bricks with special additives have the same thermal shock stability as traditional magnesia-carbon bricks.

To purchase high-quality magnesia-carbon bricks and low-carbon magnesia-carbon bricks, please contact refractory manufacturers.

What are the High Alumina Refractory Mortar and High Alumina Phosphate Mortar?

2021-06-09 by globalrefractory

What are high alumina refractory mud and high alumina phosphate mud? Through searching, it is not difficult to find that most refractory material manufacturers provide refractory slurries for use with refractory bricks. The high-alumina refractory mud is used to fill the joints of high-alumina refractory bricks.

High Alumina Refractory Mortar

High-aluminum refractory mud, high-aluminum fire mud is also called high-aluminum mud. It selects high-aluminum clinker as raw material, mixes with the binder, and mixes and mixes uniformly according to a certain ratio. Its function is to cooperate with the masonry of high-alumina bricks, and sometimes also act as a joint filler.

The high alumina refractory mud determines the Al2O3 content and the particle size of the high alumina clinker according to the brick composition and use requirements of the masonry part, so as to better match the high alumina bricks and resist the erosion of gas and slag.

High Alumina Refractory Mortar - Rongsheng Company — High Alumina Refractory Mortar

Precautions for the Use of Alumina Refractory Mortar

According to the refractory bricks used, use the corresponding refractory mortar.

Add water or binder in proportion, not too thick.
Stir well after adding water or binder.
Apply the thickness according to the requirements during masonry, even and appropriate.
Use the prepared mud as soon as possible. If it hardens, it cannot be used again.
When storing, do a good job of waterproofing and damp proofing to avoid agglomeration of mud and affect the use effect.

High Alumina Phosphate Mortar

High-alumina phosphate mud is used as a joint material for masonry-shaped refractory products. It is composed of refractory powder, water or liquid binder, and additives (such as dispersant, plasticizer, stabilizer, or water-retaining agent). It is a kind of paste-like slurry with a high concentration of solid particles, which has the characteristics of Bingham fluid.

Generally speaking, the chemical properties of refractory mud should be similar to the chemical properties of refractory products. Therefore, it is the same as the classification of refractory products. There are siliceous, semi-silica, clay, high-aluminum, corundum, magnesia, magnesia, magnesia, chromium, carbon, or silicon carbide slurries. The high-strength phosphate refractory slurry is formulated with five raw materials, including phosphoric acid, aluminum chips, high-aluminum powder, aggregates, and additives in a certain proportion. Phosphoric acid reacts chemically with aluminum chips to form Al(H2PO4)3. Al(H2PO4)3 is the binder of the mud, high alumina powder increases the chemical activity of the mud, high alumina aggregate improves the thermal stability of the mud, and additives enhance the adhesion of Al(H2PO4)3 to refractory bricks.

The preparation process of high-strength phosphate refractory slurry. Put a certain proportion (weight) of phosphoric acid into a non-metallic container and heat it to 60°C. Then add aluminum scraps and additives in proportion, and remove unreacted aluminum scraps after the reaction stops. Then put the high-aluminum aggregate and high-aluminum powder into the container in batches, mix well and let stand for 1 hour. The adjusted mud should be dry and wet properly. Too dry mud reduces free Al (H2PO4) 3 and reduces bonding strength. Too thin mud has too much free water so that the porosity of the mud is too large after it dries, and the strength of the mud itself is reduced. It is advisable to blend it to flow, draw into silk, and have adhesive strength after use. The bonded refractory bricks can be dried immediately or after a period of time.

High-strength phosphate refractory mud can be used in heating furnaces for clay bricks, light clay bricks, high alumina bricks, silica bricks, mullite bricks, corundum bricks, etc. Especially it has a better effect when used in heat treatment furnaces.

Buy High-Quality Refractory Products from Manufacturers

What should I do if the refractory material cracks, falls off, and is easy to wear? To completely solve the problem, it is necessary to conduct a specific analysis from the consolidation of the refractory lining and the working conditions. Only in this way can the real cause be analyzed. Rongsheng refractory manufacturers have been engaged in refractory production and R&D services for many years, and have helped solve refractory lining problems in more than 60 countries, for example, Russia, South Africa, Kazakhstan, Philippines, Chile, Malaysia, Uzbekistan, Indonesia, Vietnam, Kuwait, Turkey, Zambia, Peru, Mexico, Qatar, etc. If you want to learn more about refractory materials, please follow our blog. To purchase high-quality refractory lining products, please contact us.

What are Aluminum-Carbon Refractories?

2021-05-28 by globalrefractory

What are aluminum carbon refractories? Special aluminum-carbon refractories refer to alumina and carbon as raw materials. In most cases, other raw materials such as SiC, metal Si, Al, etc. are also added. Carbon composite special refractory material bonded with organic binders such as asphalt or resin. Broadly speaking, refractories with alumina and carbon as the main components are called aluminum-carbon refractories. Aluminum-carbon refractories can be divided into two categories according to their different production processes. Non-burned aluminum carbonaceous refractories and fired aluminum carbonaceous refractories.

Introduction of Aluminum Carbon Refractories

Non-burning aluminum carbon refractories belong to carbon-bonded refractories. Because its oxidation resistance is obviously better than that of magnesia carbon bricks, and the corrosion resistance of Na2O series slag is excellent. Therefore, it is widely used in hot metal pretreatment equipment such as blast furnaces and hot metal ladle. The fired aluminum-carbon refractory is a ceramic-bonded refractory. Because of its high strength, corrosion resistance, and thermal shock resistance. Therefore, there are a large number of slide bricks suitable for continuous casting sliding nozzle systems and three continuous casting parts, namely, shroud, immersion nozzle, and integral stopper.

Alumina has high resistance to acid, alkaline slag, metal, and glass solutions. Whether it is used in an oxidizing atmosphere or a reducing atmosphere at a high temperature, it can be used well. The carbon raw materials, especially graphite, have high thermal conductivity and low linear expansion coefficient, and at the same time have non-wetting properties with slag and high-temperature solutions. Therefore, aluminum-carbon bricks have the following properties.

(1) Aluminum-carbon refractories have excellent slag resistance and thermal shock resistance. Compared with magnesium-carbon refractories, aluminum-carbon refractories have better resistance to alkali corrosion and TiO2 slag erosion.
(2) For fired aluminum-carbon bricks, silicon carbide is formed by the reaction of additive silicon and carbon at high temperature, so that it has a dual bonding system, namely carbon bonding and ceramic bonding. Therefore, the fired aluminum-carbon refractory has high mechanical properties. In continuous casting, it not only acts as a traditional refractory material but also a functional structural material.

At present, aluminum-carbon refractories mainly use fused corundum, sintered corundum, or sintered tabular corundum, super-grade or grade I high-quality bauxite clinker as the coarse-grained components of the products. Use corundum fine powder or fused mullite, sintered synthetic mullite fine powder, or synthetic high mullite fine powder. Adding a certain amount of carbon to the product is beneficial to improving the properties of the product and prolonging the service life. The melting point of carbon is very high, the coefficient of linear expansion is small, and the thermal conductivity is good.

Carbon can penetrate into the pores of the particles in the product or form a vein-like network carbon chain structure between the particles to form a “carbon bond”, thereby reducing the porosity of the product and improving the high-temperature strength of the product. Carbon can also form a surface that is not corroded by metals and slag, improving the corrosion resistance and thermal shock resistance of products. In addition, the presence of carbon creates conditions for the reduction of iron and silicon oxides, and the resulting metal does not react chemically with refractory materials. When the oxide is reduced by carbon, the generated gas can prevent the molten oxide from penetrating into the refractory material. Carbon can also improve the thermal conductivity of the product, so as to prevent individual parts of the product from peeling and breaking due to uneven temperature overheating. Therefore, the carbon raw materials in the aluminum-carbon bricks are mainly flake-like natural graphite, and pyrolytic high-purity graphite can also be used, and carbon black is usually added. Antioxidants include metal Al, Si powder and SiC, B4C powder. Adding a small number of antioxidants can delay the oxidation of the carbon-containing layer and increase the service life of the product.

Purchase High-Quality Aluminum Carbon Refractory Materials from Manufacturers

To purchase high-quality aluminum-carbon refractories, please choose a strong refractory manufacturer. Rongsheng refractory material manufacturer has rich experience in the production and sales of refractory materials. Its customer base covers more than 60 countries all over the world. For example, Russia, South Africa, Kazakhstan, Philippines, Chile, Malaysia, Uzbekistan, Indonesia, Vietnam, Kuwait, Turkey, Zambia, Peru, Mexico, Qatar, etc. Moreover, a number of turnkey projects for refractory lining materials have been completed. Annual output of 80,000 tons of monolithic refractories. For more detailed information, please contact us.

Is It Better to Use Refractory Bricks or Castables for the Lining of Rotary Kiln Incinerators?

2021-05-20 by globalrefractory

The service life of refractory bricks used in the lining of the rotary kiln incinerator will affect the normal production of the rotary kiln. Of course, there are also rotary kiln-type incinerators that use refractory castables for integral pouring. So, is it better to use refractory bricks or castables for the lining of rotary kiln incinerators?

What are the Factors that Affect the Service Life of the Refractory Castable Lining of the Rotary Kiln Incinerator?

The thermal stress generated by the rapid cooling and rapid heating of the rotary kiln-type incinerator affects the service life of the inner lining. If the refractory castable for the lining is mainly alumina, add a certain proportion of silicon carbide to prevent acid corrosion. Refractory castables used in rotary kilns are also prone to falling off of tuyere materials. The performance of the castable itself and the on-site construction quality control is not in place, which easily causes abnormalities in the rotary kiln equipment. Coupled with frequent start and stop, it will aggravate the falling off of the lining of the rotary kiln.

To solve the problem of the castable burst. According to the requirements of different castables, the amount of water added should be less than more. The addition of an explosion-proof agent to the castable can make the refractory castable form a mesh-shaped micro-crack channel in the matrix when the refractory castable is heated and dry, which increases the air permeability of the refractory castable.

Different parts of the rotary kiln have different temperature requirements during normal operation and use, and it is necessary to select refractory lining materials according to the requirements of each part. A 50 mm thick thermal insulation refractory is built close to the outer layer, a 180 mm thick high-temperature refractory castable is poured in the high-temperature calcination part, and a 180 mm thick ordinary refractory concrete is poured in other parts. This effectively prevents the lining from falling off, reduces the number of maintenance, and prolongs the life of the rotary kiln.

Commonly, the refractory castable for rotary kiln-type incinerators is easy to fall off, the lining life is short, the operation rate is low, and the production cost is high. Of course, the proportion of refractory bricks used in the refractory lining of rotary kiln-type incinerators will be higher than that of refractory castables.

Advantages of the Refractory Brick Lining of Rotary Kiln Incinerator

The ratio of refractory bricks used in rotary waste incinerators is still higher than that of castables because of easy maintenance. Refractory bricks are sintered at a high temperature to perform better. But the material of bricks still needs to be cautious. Some users want to purchase silicon-molecular composite bricks for the refractory lining of incinerators. After analysis by refractory manufacturers, due to the bulk density of silicon-molecular composite bricks, in actual use, silicon-molecular composite bricks are not suitable for rotary waste incinerators.

So what kind of bricks are used in rotary waste incinerators? Refractory manufacturers recommend the use of anti-stripping high alumina bricks. With the addition of zirconia to the anti-stripping high alumina brick, it has high strength and resistance to acid and alkali corrosion, and its price is lower than that of silicon-mo composite bricks, and its service life is longer.

Regarding the selection of refractory lining materials for rotary kiln incinerators, whether it is to use refractory bricks or refractory castables, it is necessary to continuously summarize the experience in production practice. Strive for the best match between process and technical conditions, and finally achieve high-yield, high-quality, long-life, and low-cost efficient operation of the rotary kiln.

Application of Lightweight Mullite Refractory Castable on Heating Furnace

2021-04-09 by globalrefractory

Furnace materials are mainly refractory bricks, heavy fireclay castables, or high-alumina castables. Due to the large material capacity, large heat capacity, and large thermal conductivity, the heat storage and heat dissipation losses of the furnace body are relatively serious. Moreover, due to the large heat capacity of the material, it takes a long time for the oven and the shutdown to cool down, which limits the energy-saving and efficient operation of the heating furnace. In order to save energy and improve operating efficiency, the use of lightweight castables with light bulk density, low heat capacity, and low thermal conductivity is an effective method. However, most lightweight castables at present are difficult to meet the requirements of high temperature and flame erosion in the heating furnace due to the low use temperature. Lightweight composite furnace lining is used, that is, the heavy castable (contact fire filling) in the inner layer is covered with lightweight castable (heat preservation and energy saving). The construction process is complicated and the effect is not ideal. Due to the different expansion coefficients of lightweight castables, they will also cause greater shear stress to the hanging bricks and increase the risk of furnace roof collapse. This has been confirmed in practice.

Lightweight Mullite Refractory Castable and Its Application Advantages

The key raw material of lightweight castables is lightweight refractory aggregates that can make the bulk density of the castables lighter. Lightweight aggregates generally account for 50% to 70% of the total pouring, and the volume ratio can reach more than 90%. Therefore, the performance of castables also mainly depends on the performance of lightweight aggregates. In the past, the reason why the use temperature of lightweight castables was low was that the use temperature of its aggregates was low.

In order to use castables with a long-term use temperature of 1400 to 1500°C, lightweight mullite aggregates have been successfully used. Mullite is a refractory mineral with good mechanics and high-temperature properties. Its melting point can reach 1910°C, with high hardness and low creep. Refractory products with mullite as the main mineral phase have higher fire resistance.

Lightweight mullite refractory castables are prepared by using lightweight mullite aggregates. This castable has refractoriness of more than 1710°C, has the characteristics of small bulk density and high temperature, and can be used for a long time at an ambient temperature of 1500°C.

For example, the heating furnace in the 500 steel rolling workshop of a steelmaking plant is used to heat 325kg of steel ingots. The heating conditions are harsh, and the maximum temperature of the furnace is 1450°C. Adopt liquid slagging. The original furnace roof is made of high-aluminum castables, and the spalling is more serious in the high-temperature section, and the service life is less than one year. At the same time, due to the high thermal conductivity of high-aluminum castables, the heat dissipation of the furnace body is greater. In April 1992, the heating furnace used lightweight mullite refractory castables. By the time the furnace was shut down in October 1992, it had been in operation for nearly 6 months. The furnace top has no cracks, and the inner surface has no peeling, smooth as before.

The use of lightweight mullite refractory castables not only improves the life of the furnace top and reduces heat loss, but also because of the high porosity of the lightweight materials, the baking is simple, which can achieve rapid baking, rapid heating, and save maintenance time. This is unmatched by heavy castables. At the same time, because the flexible castable has good resistance to rapid cold and rapid heat, its peeling resistance is also much better than that of heavy castables.

When the 500 billet heating furnace was repaired and shut down, the inner surface of the furnace roof was only slightly peeled off after one year, and the furnace roof was still in good condition.

The successful application of the lightweight mullite castable in the 500 billet heating furnace has established a model for other heating furnaces, and the castable has been quickly promoted in other heating furnaces.

Lightweight Mullite Insulating Refractory Castable

Why Choose Lightweight Mullite Refractory Castable?

(1) Lightweight mullite castable is a high-temperature, lightweight castable with light bulk density, low thermal conductivity, and high operating temperature. It can be used for a long time under high temperature and direct flame environment, and it is extremely suitable for steel rolling heating furnace as furnace wall and furnace roof material.

(2) Because the lightweight castable has high porosity and small heat capacity, it can achieve rapid baking, rapid heating, and cooling. Save maintenance time and improve productivity.

(3) The application of light-weight mullite refractory castable has an obvious effect on heat preservation and energy saving.

(4) The castable has good resistance to rapid cold and heat and peeling resistance.

(5) After using the castable, the original light and heavy composite structures are canceled. On the one hand, it eliminates the shear stress caused by the different expansion coefficients of the light and heavy castables on the hanging bricks. On the other hand, it also reduces the load of hanging bricks and steel structures, greatly increasing the safety factor of the furnace roof and furnace wall.

Rongsheng Refractory Manufacturer

Rongsheng is a refractory manufacturer with rich experience in refractory production and sales. Its refractory materials have been sold to more than 60 countries around the world. For example, Russia, South Africa, Kazakhstan, Philippines, Chile, Malaysia, Uzbekistan, Indonesia, Vietnam, Kuwait, Turkey, Zambia, Peru, Mexico, Qatar, etc. And received unanimous praise from customers. High customer return rate. Moreover, Rongsheng‘s newly established advanced environment-friendly and fully automatic unshaped refractory production line have an annual output of 80,000 tons. It provides a reliable guarantee for the normal operation of the refractory lining of various thermal furnace equipment. Our high-quality lightweight mullite refractory castables can also provide better insulation for the lining of your kiln equipment so that your equipment can achieve the best energy-saving state during normal operation and save production costs.

What is Alumina Bubble Brick for Gasifier?

2021-03-22 by globalrefractory

Alumina bubble brick for gasifier is a new type of high-temperature insulation material. It is made by smelting and blowing industrial alumina in an electric furnace, and the crystal type is a-Al2O3 microcrystals. The content of AL2O3 in the alumina bubble brick of the gasifier is not less than 98%, the content of SiO2 is not more than 0.5%, and the content of Fe2O3 is not more than 0.2%. The bulk density is 1.3～1.4g/cm3, the apparent porosity is 60%～70%, and the compressive strength is not less than 9.8MPa. The load (0.2MPa) softening temperature is not less than 1700°C, and the thermal conductivity is 0.7～0.8 W/(m.k).

Alumina Bubble Brick - Rongsheng Refractory — Alumina Bubble Brick

Alumina hollow sphere brick for gasifier is mainly made of alumina hollow spheres, which can be made into products of various shapes, with a maximum operating temperature of 1800°C. The product has high mechanical strength, several times that of general lightweight products, and the bulk density is only one-half of corundum products. It is widely used in high temperature and ultra-high temperature furnaces such as petrochemical industry gasifiers, carbon black industrial reaction furnaces, metallurgical industry induction furnaces, and so on. And achieved a very satisfactory energy-saving effect.

The manufacturing method of alumina bubble brick. First, the alumina raw material is put into the dump-type electric furnace and melted into a liquid state. Then the furnace is poured at a certain angle so that the solution flows out of the casting trough at a certain speed. The liquid flow is blown away by a flat nozzle 60°～90° with the flow stream with a high-speed airflow with a pressure of 0.6-0.8 MPa to form a hollow alumina ball. Then, the alumina hollow spheres, the sintered alumina fine powder, and the binder are compounded in a certain proportion, formed, dried, and fired to obtain alumina hollow sphere bricks.

Alumina bubble brick for gasifier has the following characteristics:

High temperature and good thermal stability. The reheating line has a small change rate and can be used for longer.
Optimize the structure to reduce the weight of the furnace body. The alumina bubble brick is only 1.1~1.5g/cm. For the same volume of one cubic meter, the use of alumina bubble bricks can reduce the weight of 1.1-1.9 tons.
Save materials. To reach the same operating temperature, if alumina bubble bricks are used, 1.1-1.9 tons of heavy bricks can be saved per cubic meter, and 80% of refractory insulation materials can be saved.
Save energy. Alumina hollow spheres have obvious thermal insulation properties, low thermal conductivity, and can play a very good thermal insulation effect. Reduce heat dissipation and improve thermal efficiency, thereby saving energy.

FAQ1: Will the alumina bubble brick melt at 1700 ℃?

The alumina bubble brick will not melt at 1700 ℃. Alumina hollow sphere is a new type of high-temperature insulation material, which is made by smelting and blowing industrial alumina in an electric furnace, and the crystal type is a-Al2O3 microcrystals. With alumina hollow sphere as the main body, it can be made into products of various shapes, and the maximum use temperature is 1800℃. The product has high mechanical strength, several times that of general lightweight products, and the bulk density is only one-half of corundum products.

FAQ2: What is the general volume ruler of alumina bubble brick?

The high-temperature-resistant materials currently used are heavy bricks with a bulk density of 2.3-3.0g/cm³. The alumina bubble brick is only 1.3~1.5g/cm. For the same volume of one cubic meter, the use of alumina bubble bricks can reduce the weight of 1.1-1.9 tons. The size of alumina bubble brick is generally 230×114×65mm (T3 brick).

If you have a demand for alumina bubble bricks for gasifiers, please contact us. We will provide you with high-quality refractory materials and considerate service.

How are Alumina Bubble Bricks Prepared?

2021-03-04 by globalrefractory

Alumina Bubble Bricks and its products are a kind of light refractory material with excellent high-temperature resistance and energy saving, and it is very stable to use in various atmospheres. Especially it is used in the high-temperature kiln at 1800℃. Alumina hollow spheres can also be used as high-temperature and ultra-high-temperature insulation fillers, high-temperature refractory concrete lightweight aggregates, high-temperature castables, etc. Alumina hollow ball bricks can be used for high-temperature energy-saving (>30%) inverted flame kilns, shuttle kilns, molybdenum wire furnaces, tungsten rod furnaces, induction furnaces, nitriding furnaces, etc. Obvious effects will be achieved for reducing the weight of the furnace body, transforming the structure, saving materials, and saving energy.

Forming and Firing of Alumina Bubble Bricks

Molding methods include manual molding, vibration molding, and press molding. According to the size and complex shape of Alumina Bubble Bricks, the ingredients and forming methods are selected. Manual molding should be stratified and rammed, and the addition of each layer should not exceed 50mm. The vibration molding time is generally 2 minutes. The molding pressure of press molding is generally 50-80MPa. For molds processed by various molding methods, there is no need to add a ruler. After the semi-finished product is fully dried, the residual moisture should be less than 0.5%. Alumina hollow ball bricks are fired in a high-temperature kiln, the firing temperature is generally 1800-1850℃, and the heat preservation is 4-6h. Generally, it is to prevent Alumina Bubble Bricks from cracking during firing. When installing the kiln, consider that Alumina Bubble Bricks should not be directly impacted by the flame as much as possible. Add emulsified paraffin wax 0.5%-1.0%, plasticizer 4%-6%, high-efficiency dispersant 1%, and water generally 40%-45%. The slurry is made in a high-speed mixer, and the slurry is sent into the spray drying tower through a nozzle with a diaphragm pump for spray granulation drying. The inlet temperature of the drying tower is generally 420-440°C, and the outlet temperature is generally 120-130°C.

At the time of firing, the temperature is about 1680°C, the Alumina Bubble Brick has begun to sinter, and the bulk density and compressive strength are both high. The compressive strength is measured to reach 317.3MPa. Insulation materials are generally used to reduce heat accumulation and heat dissipation on the walls of the kiln, so as to reduce the energy consumption of the kiln. With the advancement of science and technology, many new refractory and thermal insulation materials with high-temperature resistance and high strength have emerged in recent years. The performance of Alumina Bubble Bricks is generally determined by the chemical composition, followed by the production process of alumina hollow ball bricks. Factors such as particle ratio, molding pressure, and firing temperature are also important.

Related Product Introduction

Alumina Bubble Bricks and zirconia hollow ball bricks are both heat-insulating refractory materials, also known as lightweight refractories. They are characterized by high porosity, which can generally reach 40%-85%. The bulk density is low, generally lower than 1.5g/cm3. The thermal conductivity is low, generally lower than 1.0W (m·K). Hollow ball bricks are used as heat insulation and refractory materials for industrial furnaces, which can effectively reduce the heat loss of the furnace and save energy. And because the body density is small, the weight of thermal equipment can be effectively reduced.

Regarding the alumina hollow ball brick, I will introduce it here, and I hope it will be helpful to everyone. Rongsheng refractory materials manufacturers provide customers with samples of various refractory bricks and insulation bricks, such as Alumina Bubble Bricks, mullite insulation bricks, etc., for free. As an experienced refractory manufacturer, Rongsheng Refractories not only pays attention to the expansion of its own scale but more importantly, always takes a long-term development perspective and continuously develops new refractory materials. The purpose is to continuously meet the more stringent market demand and conform to the trend of the times. Rongsheng refractory material manufacturer specializes in the production of various high alumina bricks, silica refractory bricks, magnesia bricks, magnesia carbon bricks, clay bricks, castables, and other products. Welcome customers to visit the factory and establish long-term cooperative relations.

Why are High Alumina Castables So Popular?

2021-02-07 by globalrefractory

The high-aluminum castable is based on the traditional ratio, adjusted the particle gradation, and added different additives to reduce the amount of cement and improve the performance. Improve the medium temperature strength and load softening temperature, reduce the thermal conductivity, and have good thermal stability. High-alumina castables are resistant to penetration, erosion, impact, and abrasion. Good mechanical properties, strong integrity of the furnace body structure, and better air-tightness than brick furnaces. Extend the furnace life, save the cost of repairing the furnace, and have the characteristics of high aluminum castables with significant economic benefits.

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

The Effect of Adding High Alumina Cement to Refractory Castable

The high alumina cement is added to the refractory castable for binding.

According to the content of alumina, alumina, and calcium oxide in high alumina cement, there are CA-50, CA-70, and CA-80. CA-50 high alumina cement is yellow cement, and its raw materials are bauxite and limestone. CA-70 high-alumina cement has fewer impurities and has better setting characteristics and refractoriness than CA-50 refractory cement. The binder used in the preparation of low cement refractory castables. The aluminum content of CA-80 high-alumina cement is 80%, and it contains α-AL2O3 fine powder, which is used as a binder in high-grade refractory castables. Because CA-70 and CA-80 have high aluminum content in cement, they can improve the weak links of the setting-speed and medium temperature strength of refractory castables. And because of the low calcium content, the later strength of the refractory castable has a longer service life.

The higher the alumina content, the higher the refractoriness; the lower the alumina content, the higher the calcium oxide content. Add high-alumina cement as a binder to demould the refractory castable within 24 hours. High alumina cement will affect the fluidity, construction time, and demoulding time of refractory castables. If used improperly, it will have a great impact on the construction of refractory castables.

The use of high alumina cement is divided into three stages: dissolution, nucleation, and precipitation. For example, CA-50 high alumina cement is generally used in medium and low-grade refractory castables. CA-50 cement has the weakest strength at 800℃. Therefore, if the temperature of the furnace lining is 800℃, it is also the most embarrassing temperature. The temperature is not high, instead of using general refractory castables, low cement castables must be used. Low-cement castables have low calcium content, good strength at medium temperature, and good strength in later use.

CA-70 and CA-80 high-alumina cement have high aluminum content and a low addition ratio. Therefore, it is used in low cement refractory castables, which not only enhances the strength of the refractory castable but also reduces the calcium content of the refractory castable. It can also improve the use of medium temperature strength.

Therefore, adding high-alumina cement to refractory castables not only depends on the combination but also pays attention to the use temperature to determine whether to add CA-50 high-alumina cement or CA-70 and CA-80 high-alumina cement.

Is there a difference between high-alumina castable and high-alumina low-cement castable?

There is a difference between high-aluminum castables and high-alumina low-cement castables.

The high-aluminum castable refractory cement is added in 12%, which is convenient for construction and fast in the early stage, but the calcium content is high, and the later use strength is not as good as the low cement castable. High-aluminum low-cement castable refractory cement is added in 6%, low calcium content, and good strength in later use.

If used for chimney lining, it is better to use high aluminum castable. Because of a large amount of refractory cement added, the chimney lining will encounter the impact of smoke and water mist. Due to a large amount of cement on the surface of high-aluminum castables, the construction speed is fast and the surface is smooth. Therefore, in this case, high-aluminum castables are more suitable.

High-aluminum low-cement castables have a small amount of refractory cement binder added, and a small amount of water added during construction. It is easy to bake and has good strength in later use and high-temperature resistance. In addition, the raw materials and binders of high-alumina and low-cement castables are better than those of general high-alumina castables, and the refractory cement is also relatively different in grades. The price is also relatively higher than that of high-aluminum castables.

High-alumina and low-cement castables are relatively used in high-temperature parts. It has a better effect than high aluminum castable. The material matrix used is also different than the high-aluminum castable. So these two castables are different.

Rongsheng Refractory Material Manufacturer and Sales Factory

Rongsheng is a refractory castable manufacturer with rich production and sales experience. Rongsheng’s advanced environment-friendly and fully automatic unshaped refractory production line have an annual output of tons. If you need to buy high-quality high-aluminum refractory castables and high-alumina low-cement refractory castables, please contact us. We will provide you with refractory products that best suit your production needs according to your specific production needs.