aluminabricks, Author at RS Kiln Refractory Bricks

High Alumina Anchor bricks are one of the most efficient materials used in high-temperature furnace linings. These materials are highly durable and provide an excellent heat-resistant environment for the operation of the furnace. High alumina anchor bricks are also called hanging bricks. It is mainly used to connect and support the structure of refractory bricks and ordinary fired bricks. It is used for heating the furnace top, furnace wall, or other parts.

RS High-Quality Anchor Bricks used in high-temperature furnace linings — RS High-Quality Anchor Bricks

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High alumina anchor bricks are composed of special alumina-containing clay, followed by a high alumina anchor brick with an alumina content above 55%. The high aluminum content ensures excellent insulation and thermal shock resistance. Rongsheng high-alumina anchor bricks use natural high-grade bauxite as the main refractory raw material, add soft or semi-soft clay as a binder to the high-alumina clinker to start batching, mixing, then molding, drying, and finally firing. Shaped high alumina refractory bricks. High alumina anchor bricks can be customized for production and processing according to customer needs. The load softening temperature of the high-alumina anchor brick reaches 1550°C, which can meet the performance requirements of the furnace roof lining.

Benefits of Using High Alumina Anchor Bricks in High-Temperature Furnace Linings

High alumina anchor brick is a special-shaped high alumina refractory brick. The benefits of high aluminum anchor bricks compared to other materials are numerous. First of all, judging from the shape of the high-alumina anchor brick, it is a column composed of the hanging end and the anchor. Grooves are distributed at intervals on the surface of the anchor body. In addition, ribs are provided along the length direction on at least one surface of the anchor. Due to the reinforcement and pulling effect of the ribs, the tensile and flexural strength of the anchor body is significantly improved. Therefore, the stress generated at the groove is blocked at the rib and cannot continue to be transmitted, so the high-alumina anchor brick in High-Temperature Furnace Linings is not easy to break.

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The benefits of high alumina anchor bricks compared to other materials are numerous. Firstly, they have excellent refractory properties, meaning they can withstand extremely high temperatures and provide the necessary insulation for the furnace. In addition, their compressive strength is very good, enabling them to withstand the huge loads in the furnace linings. Furthermore, their chemical composition helps retain their dimensional stability, making them excellent for linings with long service life. Such as the following listed characteristics.

Characteristics of High Alumina Anchor Brick for Heating Furnace

Stable volume at high temperature.
Good corrosion resistance.
The high softening temperature under load.
Anti-stripping and high compressive strength.

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Advantages of Anchor Bricks

Cost-Effective
Low Maintenance
Wide Range of Applications

High-alumina anchor bricks refer to high-alumina refractory bricks with a specific shape that is installed on the steel structure of the industrial kiln shell or supporting the furnace lining and embedded in the refractory lining for anchoring and connection. At room temperature, a bar-shaped sample with a certain size is loaded according to the specified conditions, and the ultimate tensile stress per unit area can withstand it before fracture.

In summary, high alumina anchor bricks are a great choice for creating high-temperature furnace linings. They are highly durable, resistant to corrosion and thermal shock, and environmentally friendly. They are ideal for applications requiring extended service life and reduced maintenance costs. And, since they are made of natural materials, they are an excellent choice for implementing environmentally friendly construction methods.

High Alumina Anchor Bricks for Furnace Wall and Top — High Alumina Anchor Bricks for Wall and Top of Industrial Furnace

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High Alumina Anchor Bricks from Rongsheng Manufacturer

Rongsheng high aluminum anchor bricks use in high-temperature furnace linings. High-alumina anchor bricks are refractory bricks for the furnace roof and wall of the heating furnace. Rongsheng alumina refractory brick manufacturers can customize processing according to the size of high alumina anchor bricks provided by customers, also the refractory anchors with different shapes. In order to meet the high alumina bricks furnace lining requirements of the heating furnace and ensure the service life of the heating furnace lining, the index parameters can also be customized according to the actual working conditions of the customer’s kiln. In order to finally meet the economic benefits of improving the heating furnace.

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Industrial Refractory Steel industry refractories

Jan 12 2023

Cordierite Bricks for Hot Stove Burners

The hot blast stove burner is a device that mixes gas and air and sends them into combustion. The burner used in the hot blast stove is divided into two types: metal material and ceramic material. Among them, the ceramic burner is mainly made of mullite or cordierite-mullite refractory materials. The lining refractory material of the hot blast stove and its construction quality will directly affect the thermal insulation effect of the furnace body and the stability of the furnace lining structure, thus having a profound impact on the life of the furnace body and design efficiency.

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Brief Introduction of Cordierite Mullite Bricks

Friends who have not been in contact with cordierite mullite bricks will be very unfamiliar with this refractory brick. Today, Rongsheng Factory will introduce the product knowledge of cordierite mullite bricks to you, hoping to provide help to friends who need refractory bricks for ceramic burners in hot air stoves.

Cordierite mullite brick is a novel refractory material in the 1980s. It has the characteristics of high refractoriness, good thermal shock resistance, high load softening temperature, small expansion coefficient, and long service life. Cordierite mullite bricks are widely used in the light industrial ceramics industry, tunnel kiln car bricks, raceway kilns, pusher kilns, pusher kiln furniture, saggers of various specifications, etc. It is also suitable for kiln car surfaces in the ceramic industry, porous kiln push plates, roller kiln gaskets, and sagger for ceramics. It replaces clay refractory materials and high alumina refractory materials. It works well.

Cordierite Bricks for Ceramic Burner of Hot Stove

A burner is a device used to mix gas and air and send them into the combustion chamber. It is generally required to have sufficient combustion capacity, which is beneficial to shorten the burning period. It is necessary to ensure that the gas and air are mixed evenly and can be burned stably to avoid back spraying.

In order to improve the combustion capacity and meet the needs of high wind temperatures, ceramic burners are used. The ceramic burner is a burner made of refractory materials and installed in the combustion chamber. Gas and air pass through a special structure before combustion so that the airflow is divided into small streams (called trickle segmentation), mixed with each other after spraying out, and then burned in the room. Obviously, from the function of the ceramic burner, its working environment is subjected to the thermal shock of the sharp temperature change during the heat exchange process. Taking a steel factory as an example, each blast furnace has 4 hot blast stoves for the hot blast. When the hot blast stove is in normal production, it takes 35 minutes to heat up and 45 minutes to supply air. The brick temperature fluctuates from 500-600°C to as high as 1000°C at the moment when the ceramic burner starts to burn after the air is supplied. The thermal shock to refractory bricks is obvious. In addition, it is also impacted by combustion gas, so the corresponding refractory material should have better thermal shock resistance.

If the hot blast stove is an external combustion type. Traditional bricks for ceramic burners are cordierite bricks, but now they have been developed to use andalusite-mullite refractory bricks materials, high alumina cordierite bricks, mullite cordierite bricks, etc.

If it is a top-fired hot blast stove, the air temperature of the ceramic burner is relatively high (about 1360°C). Higher thermal shock resistance is required, which is reflected in the test conditions and the number of thermal shock stability. Originally required 1300°C, water cooling now requires 1100°C, and water cooling, thermal shock stability is not less than 100 times. The production of these bricks also uses three-stone minerals, especially andalusite minerals.

Rongsheng Refractory Bricks Prices — Rongsheng Refractory Bricks Manufacturer

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Rongsheng Refractory Brick Manufacturer

The cordierite bricks for hot blast stove burners produced by Rongsheng refractory brick manufacturers have good thermal stability and a small thermal expansion coefficient. Based on the principle of being responsible to customers, Rongsheng manufacturers strictly control the production standards of refractory products. To ensure that the produced refractory cement, refractory bricks, castables, and other products can have good high-temperature resistance and strong slag resistance. It can meet the operating temperature of the customer’s actual boiler. The product quality has been well received and supported by new and old customers. Buy cordierite bricks, cordierite mullite bricks, mullite refractory bricks, factory direct sales, and refractory materials at reasonable prices. Welcome to consult and purchase, Rongsheng refractory products and customer service will not let you down.

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Dec 6 2022

What Kind of Refractory Material is Used for the Lining of the Hydrogen Sulfide Incinerator?

The working temperature in the furnace of the incinerator burning hydrogen sulfide is about 1150 ℃, and the working conditions are harsh. It belongs to an acidic combustion atmosphere, but the temperature of the furnace will reach 1400 ℃ due to the fluctuation of materials and air volume in actual production. The amount of hydrogen sulfide gas is very unstable, and every combustion fluctuation in the furnace is a big thermal shock to the furnace lining.

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And this kind of acid gas furnace lining is made of refractory materials, so it is very important to resist acid corrosion and thermal shock stability. The main body of the furnace can adopt a three-layer structure. Corundum mullite bricks should be used for parts that are in direct contact with the flame. It is characterized by strong wear resistance and corrosion resistance. The middle layer can choose three grades of high alumina bricks. Because the working layer does not directly contact the flame, the flexibility of the three-grade high-alumina brick is relatively good. The outer layer can be used as an insulation layer, and high-aluminum heat-insulating refractory bricks are used to keep the temperature down and reduce the temperature of the outer wall of the steel shell.

Corundum mullite brick is a refractory product composed of mullite as the main crystal phase and corundum phase, which is sintered at a high temperature of 1650-1750 °C. It has good high-temperature strength, high-temperature creep resistance, thermal shock resistance, and corrosion resistance.
The third-grade high-alumina brick is a series of aluminum products made of high-alumina raw materials and clay as a binder fired at a temperature of 1400°C. High thermal stability, and strong flexibility.
Lightweight high alumina brick. It has the characteristics of small bulk density, large porosity, low thermal conductivity, and specific heat capacity, and has good thermal insulation performance for heat insulation layers. In the case of slow heat dissipation, it can save fuel and reduce the temperature of the steel shell.

The incinerator burning hydrogen sulfide is one of the rare furnace types, so the corundum mullite brick in the refractory brick used for its refractory lining is a high-grade refractory material. High-alumina bricks are neutral materials, and lightweight high-alumina bricks are used as a three-layer masonry lining to effectively improve the corrosion resistance of the incinerator. The refractory mortar of the same material is used for masonry during construction to ensure the long-term safe and reliable operation of the incinerator.

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Ceramics Refractories

Oct 9 2022

Application of Cordierite Mullite in Kiln Furniture

The cordierite matrix in cordierite-mullite kiln furniture endows the refractory with a low coefficient of thermal expansion and good thermal shock resistance. The low-aluminum mullite particles in the cordierite-mullite kiln furniture endow the material with a certain high-temperature resistance and volume stability under thermal conditions. Cordierite-mullite only contains oxides with stable valence, which will not pollute ceramic products due to oxidation-reduction problems. Therefore, cordierite-mullite refractory materials are often used to make refractory products such as shed plates, backing plates, and supports of ceramic kilns. What are the characteristics of cordierite-mullite kiln furniture?

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Cordierite Mullite Kiln Furniture

Primary kiln furniture refers to refractory products such as shed slabs and pillars for building the firing space. Secondary kiln furniture refers to the small kiln furniture placed on the primary kiln furniture directly used to support or protect the products to be fired. In addition to primary kiln furniture, cordierite-mullite materials include secondary kiln furniture of various complexities and shapes.

Application of Cordierite Mullite in Kiln Furniture

Cordierite-mullite has good high-temperature properties such as thermal expansion and thermal shock stability. Cordierite-mullite composites are widely used.

Kiln furniture is a special-shaped refractory material that supports and protects the firing process of ceramic products and magnetic materials. It has an extremely important impact on the quality of ceramic products and the energy consumption of the ceramic industry, mainly including saggars, shed plates, pad cakes, columns, and push plates. The performance of kiln furniture directly affects the quality and production cost of fired objects such as ceramics. General kiln furniture materials should have the following basic properties: high refractoriness, good thermal shock resistance, and chemical stability; high strength at room temperature and high temperature. Because one of the functions of kiln furniture is to bear the load, it must withstand the load of the product and the kiln furniture itself. High-strength kiln furniture materials can make kiln furniture light and thin, so as to increase the density of the kiln and improve the quality of products. In addition, it is also required to have good thermal conductivity and low thermal storage, regular appearance, and precise dimensions.

The cordierite material has the characteristics of a small thermal expansion coefficient and excellent thermal shock resistance and is widely used in ceramic kiln furniture by domestic and foreign manufacturers. The thermal shock resistance of kiln furniture is a key parameter that determines the life of kiln furniture. When the main material is determined, the thermal shock resistance of kiln furniture must be improved from its microstructure. So that it has high elastic modulus, fracture surface energy and thermal conductivity, low thermal expansion coefficient, and so on. Improved thermal shock resistance can be achieved by reducing thermal stress caused by thermal expansion, forming microcrack networks, and introducing energy dissipation mechanisms during inter-particle interface fracture. The thermal shock resistance of cordierite kiln furniture can be further improved by doping andalusite to introduce the energy dissipation mechanism during interface fracture.

Although cordierite has a small thermal expansion coefficient and good thermal stability, it has a low softening temperature under load and a small operating temperature range. Although products such as mullite and silicon carbide have good high-temperature performance, their cost is high. Using the mullite effect of andalusite at high temperatures, by adding SiC and a small amount of artificial mullite, the organizational structure of cordierite ceramic kiln furniture materials can be significantly changed. Improve high-temperature performance and reduce the cost of kiln furniture materials. Cordierite and cordierite-mullite kiln furniture structure is a ring-shaped silicate. Since the tetrahedrons in the structure are connected into a special helical six-membered ring, there are large gaps in the structure. When the particle is heated, it can vibrate to the gap, so the cordierite kiln has the characteristics of a small thermal expansion coefficient and excellent thermal shock resistance. However, cordierite is an unstable compound that decomposes into mullite and glassy phases. And the firing temperature range is narrow, and the high-temperature performance is poor. The mullite material has high refractoriness and good high-temperature stability. The mismatch between the thermal expansion coefficients of cordierite and mullite results in the formation of micro-cracks at the two-phase interface, which makes the material have excellent thermal shock resistance and good high-temperature performance. Therefore, cordierite-mullite composite materials are widely used in high-grade ceramic kiln furniture at home and abroad.

With the transformation of the firing technology of the ceramic industry from the traditional saggar firing to the open flame saggarless firing technology, the demand for high-quality ceramic kiln furniture materials – shed slabs is increasing. As one of the special kiln furniture for supporting porcelain pieces shed plate has always been an important auxiliary material in the ceramic industry. The material is mostly cordierite-mullite composite material with good thermal shock resistance and high-temperature performance. The cordierite-mullite slab is sintered from mullite and cordierite. The mechanism is that cordierite has a much smaller thermal expansion coefficient than mullite due to the large voids in the ring structure of cordierite. The expansion coefficients of the two are matched, so that micro-cracks are formed at the interface of the two phases, preventing the propagation of destructive cracks. Thereby, the thermal stability performance of the cordierite-mullite shed plate is greatly improved.

High alumina refractory products containing cordierite, it is made of high alumina raw material, synthetic cordierite, and binder. The thermal shock stability of the product is very good, and it can be used as ceramic kiln furniture, heat exchanger, catalyst carrier (honeycomb ceramic) for purifying waste gas, etc. For a free quote on cordierite bricks, please contact us.

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Sep 21 2022

Requirements for the Use of Refractory Materials for Ladles

The steel ladles are the necessary equipment for receiving molten steel and for continuous casting. Because many steel grades need to be refined in the ladle, including argon blowing temperature adjustment, alloy composition fine-tuning, powder spray refining and vacuum treatment, etc. The working conditions of the ladle lining are getting worse and worse, and its working environment is.

(1) The temperature of molten steel is higher than that of the die-casting ladle.
(2) The residence time of molten steel in the ladle is prolonged.
(3) The inner lining of the ladle volatilizes itself under a high-temperature vacuum and undergoes the stirring effect of molten steel.
(4) The impact of the lining when it accepts molten steel.
(5) Erosion of slag to the lining.

Therefore, the requirements for ladle refractories are:

(1) High-temperature resistance. Can withstand high-temperature molten steel for a long time without melting and softening.
(2) Thermal shock. Can withstand repeated loading and unloading of molten steel without cracking and peeling.
(3) Corrosion is resistant to slag. Can withstand the erosion effect of slag and slag basicity changes on the lining.
(4) It has sufficient high-temperature mechanical strength. Can withstand the stirring and scouring of molten steel.
(5) The lining has a certain degree of expansion. Under the action of high-temperature molten steel, the inner linings are in close contact and become a whole.

Commonly Used Refractory Materials for Ladles

The bottom layer of the ladle. Clay bricks, also known as fired bricks. Clay bricks are made of clay (including shale, coal gangue, and other powders) as the main raw material, which is processed, shaped, dried, and fired with mud. There are solid and hollow.
Ladle working layer, high alumina brick. Among the refractory materials produced with aluminum-silicon-based raw materials, the bricks with Al2O3 as the main component are high-alumina bricks, mullite bricks, and corundum bricks.
The main body of the ladle is poured. Castable refers to the mixture composed of refractory aggregate, binder, and admixture, which is mixed with water (or liquid binder) to form mud that can be constructed by the pouring method. The difference from other unshaped refractories is that refractory castables have a certain setting and hardening time after construction. Therefore, after casting and molding, it needs to be cured for a certain period of time before it can be de-molded, and then it can be put into baking after an appropriate period of natural curing.
Ladle wall. Unburned bricks are also known as chemically bonded bricks. It refers to the refractory material that can be directly used for masonry without firing. The production process is relatively simple, it is made of refractory materials of different materials, and the combination of powder and granules in the product is mainly formed by the chemical action of the binder.

If the ladle is also used for refining, refractory materials that can also be used include zircon bricks, magnesia carbon bricks, magnesia carbon bricks, magnesia chrome bricks, magnesia chrome aluminum bricks, and the like.

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Improvement of High Alumina Bricks Used in Refining Ladle

Modern refining ladles use natural andalusite and bauxite to produce high-alumina bricks. Compared with bauxite, the former has higher purity and thermomechanical stability (such as thermal strength). Because it contains more SiO2, it has poor corrosion resistance. Especially under the condition of alkaline slag, the lining of high-alumina brick masonry refining ladle produced with bauxite clinker as the main raw material has the following shortcomings and is being eliminated.

①Due to the volume shrinkage, the molten steel and slag are seriously penetrated and eroded, especially a thick slag layer formed at the brick joints.
②Due to the inherent brittleness of the brick itself and its structure, the ladle lining forms a thicker erosion zone and a slag layer.
③ Due to the inherent wettability of the lining to molten steel and slag, the erosion and penetration of the slag are more serious, and flake spalling occurs.

In order to overcome the above shortcomings of high-alumina bricks lined with a refined ladle, Al2O3-MgO-C bricks were developed to replace them. Compared with high alumina bricks, Al2O3-MgO-C bricks have the following advantages:

(1) Good high-temperature resistance and tissue peeling resistance;
(2) Good corrosion resistance to molten steel and slag;
(3) Good residual expansion, even at higher temperatures, no cracks appear at the joints of the bricks.

Because, when the temperature is higher than 1650°C, the high-alumina bricks show obvious shrinkage, which will lead to the penetration of molten steel and slag into the brick joints. Different from high alumina bricks, Al2O3-MgO-C bricks will not shrink in the continuous casting temperature range (1650~1670℃).

Ladle Refractory Materials Manufacturers

Rongsheng refractory material manufacturer is a manufacturer of technical refractory lining material solutions with rich production and sales experience. Our excellent technical team specializes in solving the problem of refractory lining of high-temperature furnaces, including various ladle refractory problems. At the same time, our refractory brick production line and monolithic refractory production line are also the strong support of our team. From our customer base in more than 80 countries around the world, it is not difficult to see the strength of our team. Become a customer of Rongsheng Refractory Factory for free, our customer service will not let you down.

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Aug 13 2022

Castable Refractory for Circulating Fluidized Bed Boiler

There are many types of refractory castables, and the uses of each refractory castable are also different. Such as corundum wear-resistant refractory castables, low-cement refractory castables, lightweight heat-insulating refractory castables, and steel fiber refractory castables. Castables refractory for circulating fluidized bed boilers are mainly high-strength wear-resistant castables. Among them, corundum refractory castable has the characteristics of high strength and good fluidity, which is convenient for construction. It is mainly used for the parts that are easy to be washed and wear, such as the combustion chamber, separator, and flue of a circulating fluidized bed boiler.

Corundum Castable Refracotry for the C F B Boiler — Corundum Castable Refractory for the CFB Boiler

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High-Strength Corundum Wear Plastic Refractory

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Selection of Castable Refractory for Circulating Fluidized Bed Boilers and Precautions for Use

Selection of refractory castables and refractory plastics for circulating fluidized bed boilers. Taking the 75t/h circulating fluidized bed boiler as an example, the main refractory materials used are corundum wear-resistant plastics, diatomite thermal insulation castables, high-strength wear-resistant castables, phosphate refractory castables, lightweight thermal insulation bricks, diatomite thermal insulation bricks, refractory bricks, etc.

Among them, the wear-resistant layer at the lower part of the furnace and the outlet of the furnace are mainly made of corundum wear-resistant plastic. The inlet flue and target area of the separator use high-strength wear-resistant castables. The separator cylinder and cone are made of lightweight thermal insulation bricks, and the surface is made of high-strength wear-resistant castables. Phosphate refractory castables are used for air distribution devices, ignition air ducts, and furnace doors. Diatomite insulation bricks and refractory bricks are mainly used for the heating surfaces of the tail.

lightweight insulation castable — Insulation Castable

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Corundum silicon carbide wear-resistant refractory plastic — Wear Refractory Plastic

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Precautions when using refractory castables and refractory plastics for circulating fluidized bed boilers.

Clean water must be used, and the amount of water added is 6% ~ 8%.
Use a forced mixer, and all mixing tools must be cleaned. Mix until homogeneous. When stirring, the amount of material added should not be less than the whole package. Dry mix for 15min before adding water to achieve the purpose of mixing evenly.
The castable is reinforced with a large number of anchoring nails and the metal surface of the boiler. The anchoring nail is a metal material, and the thermal expansion coefficient is much larger than that of the refractory material, so the anchoring nail needs to be preheated before installation.
The pouring surface of all molds should be coated with a layer of oil.
Each batch of materials must be poured within 10 to 30 minutes after mixing. It needs to be poured to the specified thickness at one time and then vibrated until it is completely sealed.
The mold is demolded 24 hours after pouring, and the total curing time is 3 days.

How to remedy the falling off and cracking of castable refractory for circulating fluidized bed boilers?

During the operation of the circulating fluidized bed boiler, some castable refractory for boiler will fall off and crack. This part of the pipe is more prone to wear than other places because most of it occurs in the dense phase area such as the refeeder and below the water cooling screen. When this happens, the usual approach is to repair with refractory castables or plastic refractories. When repairing, the repairing materials should be mixed and stirred first, and then suitable templates and molds should be made at the repaired part. Finally, pour and repair. The repaired material should be basically cured and formed, and then gradually baked according to the heating curve. This repair method is time-consuming, labor-intensive, and quite uneconomical. If it is repaired with blue mud, it can be ignited immediately after construction, which saves time and effort, and is convenient and quick.

Monolithic Refractory Construction for CFB Boiler

Use special tools to repair the dropped boiler refractory castable to right-angle subsidence of not less than 20 mm, that is, the repair thickness is not less than 20 mm. Clean the repaired area with a brush, slice the blue mud, and stick the new side on the repaired area. Then ram it with a rubber hammer to make it firmly combine with the original refractory castable to form a flat surface.

If the refractory castable falls off and exposes the pin, it can be repaired by cutting it into pieces with blue mud and tamping and compacting. If the drop area is not large, it can be completed in ten minutes before and after. The practice has proved that repairing refractory castables with blue mud is much better than repairing refractory castables with other methods.

What boiler linings are refractory castables generally used for?

The main application scenarios of castable refractory for boilers, power generation boilers, heating boilers, waste incinerators, and other industrial kilns. Specific applications of refractory castables for boilers are as follows.

Water-cooled wall, cyclone separator, furnace, economizer, water-cooled air chamber, slag removal machine, cold ash bucket, etc. in the power generation industry.
In the lining of boiler equipment such as civil boilers, biomass boilers, steam boilers, chain furnaces, pulverized coal furnaces, etc.
Heating furnaces, soaking furnaces, forging furnaces, ladle furnaces, trolley furnaces, etc. in the foundry industry.

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Manufacturers of Refractory Castables for Boilers

Rongsheng refractory material manufacturer, environmentally friendly and advanced automatic unshaped refractory castable production line, with an annual output of tons. Can provide refractory castable lining materials for various industrial boilers. In addition, we can also provide high-quality refractory and wear-resistant plastics, refractory ramming materials, etc. It is matched with the high-quality refractory castable binder produced by Rongsheng, aluminum dihydrogen phosphate. Unshaped refractory lining materials can be formulated with the advantages of strong wear resistance, corrosion resistance, air erosion resistance, high strength, and stable performance. Improve the service life of boiler refractory castable lining. Rongsheng can also design various economical and practical unshaped refractory linings for boiler linings according to the needs of customers and the actual working conditions of boilers. Contact us for free samples and quotes.

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Industrial Refractory

Jun 30 2022

Corundum Mullite Bricks Used in the Burner of the Sleeve Lime Kiln

Generally, the burner of the sleeve lime kiln is made of magnesia refractory bricks. However, due to the fact that it is prone to breakage within a year of use, the service life of the burner brick is not synchronized with the service life of the kiln body. The burner brick of the sleeve lime kiln broke 1/3 in less than one year, and the service life of the lime kiln was more than 3 years. Therefore, the service life of the burner brick is not synchronized with the service life of the kiln body. Although the fracture of burner bricks does not affect the use of lime kilns, it has certain negative effects on the calcination process. Therefore, it is necessary to study the corundum mullite bricks used in the burner of the sleeve lime kiln.

The reason why the burner brick is easy to break is that the burner brick is made of magnesia refractory brick. In addition to excellent high-temperature resistance and lime resistance, the alkaline material also has the following unfavorable factors, which may lead to premature fracture.

Magnesium refractory has large thermal expansion and poor thermal shock resistance. The burner brick is scoured by the hot air flow of the flame, the thermal shock environment is harsh, and cracks caused by thermal shock are prone to occur.
Due to the large thermal expansion coefficient, the thermal stress of the magnesia refractory is high. When there is a local stress concentration, the fracture is easy to occur.
Magnesium refractories are easy to hydrate, resulting in bulging and cracking. Construction is greatly affected by environmental conditions. Improper baking is also prone to cracking, resulting in falling blocks. In cold and humid weather, the water in the fire mud is not easy to remove, and it is easier to hydrate the bricks. Therefore, it has strict requirements on construction environmental conditions and baking.
The thermal strength of magnesia refractories is low, and it is prone to creep under thermal stress.

Corundum Mullite Bricks Used in the Burner of the Sleeve Lime Kiln

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The improvement of burner brick material selection of burner brick prefabricated parts made of corundum mullite refractory castable has the following advantages.

The main crystal phase of corundum mullite refractory castable is corundum and mullite. Corundum has a high melting point of 2050°C, its hardness and strength can resist high temperature and airflow erosion, and it has excellent high temperature wear resistance. The melting point of mullite is also higher than 1840 ° C, which is characterized by a small thermal expansion coefficient and a needle-column mosaic structure, which has good thermal shock resistance. The refractory castable composite of corundum phase and mullite phase has the advantages of both, which can effectively resist the erosion of the burner brick by the hot air flow of the flame. At the same time, it can withstand the harsh thermal shock environment and prevent the burner brick from breaking.
Corundum mullite refractory castables do not have hydration problems. The construction is less affected by the environment, and the requirements for construction conditions are not harsh. And pouring, curing, and heat treatment can be carried out by the supplier, and the quality can be easily guaranteed. No hydration cracking during construction and baking.
The burner brick is a special-shaped brick, which is not easy to be machine-pressed. Using the casting method, it is easy to form integral or separate parts and to achieve precise control of shape and size. The critical particle size of machine-pressed bricks is limited, generally 5 mm. The critical particle size of the castable can be as large as about 20 mm, which is conducive to the stability of the structure and the improvement of thermal shock resistance.
When the burner brick is in use, since the gas (or fuel oil) is sprayed into the furnace, the CaO dust in the furnace is not easy to adhere to the burner cavity, and the reaction between CaO and the Al2O3-SiO2 material will not occur. Even if there is a small amount of CaO attached to the burner brick, the content of A12O3 in the burner brick is relatively high (greater than 75%), while the content of SiO2 and CaO is relatively low. According to the A12O3-SiO2-CaO ternary phase diagram, the reaction temperature is around 1500℃. It can be considered that the solid-phase reaction of Al2O3-SiO2-CaO does not easily occur at the working temperature of the lime kiln.

Summary: Through the analysis of the reasons for the phenomenon that the burner of the sleeve kiln is easy to break, and according to the combustion process of the lime kiln calcination zone, the structural design of the lining refractory material, etc. Production of corundum mullite refractory castable prefabs suitable for sleeve kiln burners. The corundum mullite bricks used in the burner of the sleeve lime kiln can synchronize the service life of the burner brick with the service life of the kiln body.

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Steel industry refractories

Jun 9 2022

Refractories for Sponge Iron Production by Direct Reduction Method for Sale

The main products produced by the direct reduction method are solid sponge iron, iron granules, and liquid pig iron. Among them, the production method of sponge iron is the most mature and has the largest output. The production of sponge iron mainly uses iron concentrates, iron oxide scales, and other raw materials with high iron oxide content, which are reduced to metallic iron under the action of reducing media. The reaction is a solid-phase reaction and emits a lot of gas. There are many pores in the generated solid iron, like a sponge, so it is called sponge iron. The reaction temperature is generally between 800 and 1300°C. The reducing media used are mainly non-coke reducing agents such as coal, natural gas, and coal gas. The equipment used in the production of sponge iron by the direct reduction method mainly includes a shaft kiln, square kiln, annular kiln, rotary kiln, tunnel kiln, and continuous furnace at the bottom of the trolley, etc.

Production of Sponge Iron by Shaft Kiln

It uses natural gas and steam to produce reducing gas, and then reducing gas reduces iron ore into sponge iron in a shaft furnace. The production process of HYL III sponge iron can be divided into two parts, the gas-making boundary area, and the reduction boundary area. The gas production boundary includes the generation and purification of reducing gas. The reduction boundary includes heating of reducing gas and reduction of iron ore. In the gas production boundary zone, steam and natural gas are mixed and then catalytically cracked in the reformer to produce synthesis gas mainly composed of hydrogen and carbon monoxide, which is dehydrated and sent to the reduction boundary zone. The cracking reaction is:

CH4 + H2O = CO + 3H2

CO + H2O = CO 2 + H2

In the reduction boundary area, after dehydration and decarbonation of the shaft furnace top gas, it is mixed with the gas from the gas production boundary area to form a reduction gas and enters the reduction gas heating furnace together. The heated reducing gas enters the furnace from the bottom of the reduction section of the shaft furnace and flows from bottom to top. Iron ore is added from the top of the shaft furnace and moves from top to bottom. The reducing gas and iron ore undergo a chemical reaction in reverse motion to produce sponge iron. Among them, the chemical reactions that take place are:

3CO + Fe2O 3 = 2Fe + 3CO 2

3H2 + Fe2O 3 = 2Fe + 3H2O

Process for Producing Sponge Iron in Tunnel Kiln

A tunnel kiln is a modern continuous firing thermal equipment, which is widely used in the roasting production of medium sponge iron in the metallurgical industry. It can also be used in other industries such as refractory production. The reason why the tunnel kiln has a wide range of industrial applications is inseparable from its stable firing system.

The tunnel kiln for firing sponge iron is a low-temperature kiln with a temperature range of 1000~1350℃. The heat source is clean energy natural gas, and the sponge iron reduction tank is transported by a kiln car for production reduction through a tunnel kiln. Tunnel kiln firing sponge iron is mainly divided into preheating zone, firing zone, and cooling zone. The temperature of these three parts can often be kept within a certain range. Therefore, the quality of the fired product is better.

Rotary Kiln for Producing Sponge Iron

The rotary kiln method, also known as the “SL/RN” method, uses solid fuel as a reducing agent and a rotary kiln as a reactor. The reducing agent and pellets (pig iron or pellets after oxidative roasting consolidation) simultaneously enter the rotary kiln for reduction roasting. The resulting sponge iron generally has a metallization degree of more than 90% and a particle size of 5 to 15 mm, which is usually used as a steelmaking raw material.

The working principle of the rotary kiln is to produce sponge iron. The raw material composed of solid carbon and ore particles (pellets) moves in the rotary kiln with the inclined furnace body and advances continuously. During the movement, the charge is preheated (<800°C region) and reduced (900-1000°C region) by the gas generated by the countercurrent or cocurrent combustion, and finally the product solid sponge iron is obtained.

Requirements for the Refractory Materials for Sponge Iron Production by direct reduction

At present, the sponge iron produced by shaft kilns with natural gas as the reducing medium in the world mainly accounts for about 80%. No matter what kind of kiln, the operating temperature is not high. Therefore, generally, aluminum-silicon-based refractories can meet the temperature requirements as kiln linings. However, it should be noted that Fe2O3 in the refractory material will be reduced to metallic iron and Fe3C under CO atmosphere conditions. The presence of Fe3C will promote the deposition of carbon, resulting in embrittlement cracking of the refractory. Therefore, in order to improve the service life of the furnace lining of the equipment, the Fe2O3 content in the refractory material should be reduced, and the structure of the selected material should be dense and the pores should be fine.

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Rongsheng Refractory Manufacturer

Rongsheng is a refractory manufacturer with rich production and sales experience. Rongsheng’s refractory products have been sold to more than 70 countries around the world, such as South Africa, Philippines, Chile, Malaysia, Indonesia, Vietnam, Kuwait, Turkey, Zambia, Peru, Mexico, Qatar, Egypt, Russia, Kazakhstan, etc. . In solving the problem of refractory lining materials for industrial furnaces, we have also accumulated many cases and solutions for thermal furnaces of customers. If your thermal kiln needs refractory lining materials, please contact us to purchase refractory materials for the production of sponge iron kilns. It is best to attach the working conditions of your refractory kiln, the working environment of the refractory lining, the working temperature, erosion conditions, etc. Based on the information you provide, we will recommend the most suitable refractory for your production needs. In order to reduce the number of furnace shutdowns and repairs, improve production efficiency and increase production efficiency.

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Industrial Refractory

Apr 19 2022

Refractory for Smelting Ferrosilicon Furnace

Ferrosilicon furnace, also known as electric arc furnace or resistance electric furnace, is a kind of submerged arc furnace, which is an industrial electric furnace with huge power consumption. The ferrosilicon furnace is a type of high energy consumption furnace, which reduces energy consumption and increases output so that the life of the furnace can be used for a long time. Only in this way can the production cost of the enterprise be reduced and the discharge of waste residue pollutants be reduced. Therefore, its requirements for refractory materials in use are also quite strict, as is the refractory factory.

The Working Characteristics of Ferrosilicon Furnace

Ferrosilicon furnace is mainly composed of a furnace shell, furnace cover, furnace lining, short net, water cooling system, smoke exhaust system, dust removal system, electrode shell, electrode pressing and lifting system, loading and unloading system, controller, burn-through hydraulic system, transformer, and various electrical equipment. Ferrosilicon furnace is mainly used for reducing and smelting ore, carbonaceous reducing agent and solvent, and other raw materials. Production of ferrosilicon, ferromanganese, ferrochromium, ferrotungsten, silicon-manganese alloy, calcium carbide, and other ferroalloys and chemical raw materials. Its working characteristic is to use carbonaceous or magnesia refractory material as furnace lining and use self-cultivation graphite electrodes. An industrial electric furnace with continuous feeding and intermittent tapping of iron slag.

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Refractory Lining Materials for Smelting Ferrosilicon Furnace

Different reaction temperatures of ferrosilicon furnaces, the use of refractory materials of different refractory lining materials in kilns. This scheme is for reference only. The specific kiln lining material to be used needs to be judged only after the technician understands the use of the ferrosilicon furnace.

New material preheating zone. The uppermost layer is about 500mm, and the temperature is 500℃-1000℃. The difference in heat comes from high-temperature airflow, electrode conduction heat and surface charge combustion, and charge distribution current resistance heat. The temperature of this part is different, and the kiln lining material is made of clay bricks.

preheat zone. After the water evaporates, the charge will gradually go down and make initial changes in the preheating zone. Silica transforms, expands in volume, and then cracks or bursts. The temperature in this section is around 1300°C. Built with high alumina bricks.

Sintering zone. It is the crucible shell, the temperature is 1500℃-1700℃. Liquid silicon and iron are formed and dropped into the molten pool. The sintering and air permeability of the charge is poor, the block should be broken, the gas ventilation should be restored, and the resistance should be increased. This area is hot and aggressive. It is built with semi-graphite-silicon carbide bricks.

reduction reaction zone. A large number of intense chemical reaction zones for materials, and the temperature of the crucible zone is 1750℃-2000℃. The lower part is connected to the arc cavity, mainly for the decomposition of SIC, the generation of ferrosilicon, and the reaction of liquid Si2O with C and Si. The high-temperature area must be built with semi-graphite-fired carbon bricks.

Arc zone. In the cavity area at the bottom of the electrode, the temperature is above 2000°C. The temperature of this zone is the highest temperature zone in the whole furnace, and it is also the source of the most temperature distribution in the whole furnace body. Therefore, when the electrode is inserted shallowly, the high-temperature area moves up, the temperature of the furnace bottom is low, and the slag is less removed, forming a false furnace bottom. As a result, the tap hole is moved up, and a certain false bottom has certain benefits for protecting the furnace. Generally speaking, the depth of electrode insertion has a lot to do with the diameter of the electrode. The general insertion depth should be kept at an extreme distance of 400mm-500mm from the bottom of the furnace. This part has a higher temperature and is built with semi-graphite-fired carbon bricks.

Phosphate concrete or clay bricks are used for permanent layers. The furnace door can be cast with corundum castables or pre-laid with silicon carbide bricks.

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In short, according to the furnace size, temperature, and erosion degree of the ferrosilicon furnace, choose suitable, environmentally friendly, refractory bricks and castables of different materials for the kiln lining. To buy refractory kiln lining material in kilns, please choose a strong refractory material manufacturer. As a refractory factory, Rongsheng refractory manufacturer has an advanced refractory production line and a professional technical team. Rongsheng Refractory Factory provides high-quality refractory kiln lining materials for industrial furnace refractory kiln linings to meet production requirements and save production costs.

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Jun 21 2021

Two Different Types of Low Cement Castables

In the refractory castable combined with calcium aluminate cement, the castable with CaO content less than 2.5%, that is, the castable with calcium aluminate cement added about 1/2 to 1/3 of the ordinary calcium aluminate cement castable, It is called low cement castable. Low cement castable materials are clay, high alumina, mullite, corundum, chromium corundum, zircon mullite, zirconium corundum, alumina-spinel, and carbon and silicon carbide, and many more. According to its operating performance, it is divided into vibrating castable and self-flowing castable. Rongsheng refractory manufacturer will introduce the above two different types of low-cement refractory castables for you.

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Two Different Types of Low Cement Castable Composition

The ingredients of vibrating low cement castables are generally: refractory aggregate 60% ~ 70%, refractory powder 18% ~ 22%. Calcium aluminate cement 3% to 7% (low cement type) or 1% to 2% (ultra-low cement type). Silica (soot silica) micro powder (or reactive alumina micro powder) 3% ~6%. Trace dispersant. The particle size composition can be according to Andreassen’s particle size distribution equation, and the q value is 0.26 ~ 0.35.

The batching composition of the self-flowing low-cement castable is similar to that of the vibrating low-cement castable, but the particle size composition and fine powder content are different. Generally, the maximum critical particle size of aggregate is not more than 6 mm, and the particle size distribution is in accordance with the Andreassen or Dinger-Funk particle size distribution equation. The value of the particle size distribution coefficient q should be controlled between 0.21 and 0.26, and a larger self-flow value (greater than 180) can be obtained between this value. When the q value is greater than 0.26, the flow value becomes smaller, and it is difficult to cause self-flow. When the q value is less than 0.21, the powder content is too large, which will affect the physical properties of the castable. The content of micro powder (silica micro powder) in the particle size composition is generally 5% ~ 6%. At the same time, high-efficiency dispersants must be used.

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Low Cement Castables Physical and Chemical Indicators

Table 1 shows the typical vibrating low-cement clay, high-aluminum, and corundum casting performance.

Table 1 Vibrating Low-Cement Castables physical and chemical indicators
Items		Clay Low Cement Castable	High-Alumina Low Cement Castable	Corundum Low Cement Castable
w(Al2O3) / %		45	75	92
w(SiO2) / %		50	12	5
w(CaO) / %		＜1.8	＜1.5	＜1.5
Bulk Density / g/cm3	110℃, 24h	2.30	2.60	3.00
Bulk Density / g/cm3	1350℃, 3h	2.26	2.61	3.10
Compressive Strength / MPa	110℃, 24h	72	75	85
Compressive Strength / MPa	1350℃, 3h	90	115	125
Linear change rate after burning / %	1000℃, 3h	-0.3	-0.2	-0.2
Linear change rate after burning / %	1350℃, 3h	±0.3	±0.5	±0.5
Max Use Temperature / ℃		1450	1600	1700
Mixing Water Demand / %		6.0 ~ 6.5	6.0 ~ 6.5	4 ~ 5

Table 2 shows the general self-flowing low-cement alumina-spinel casting performance.

Table 2 Self-Flowing Low-Cement Alumina-Spinel Castable
Items		A	B	C
w(Al2O3) / %		90	88	85
w(MgO) / %		6	6	6
w(CaO) / %		3	5	8
Bulk Density after Burning / g/cm3	110℃, 24h	3.20	3.10	3.05
	1000℃, 3h	3.10	3.08	2.92
	1600℃, 3h	3.15	2.95	2.86
Flexural Strength after Burning / MPa	110℃, 24h	6.5	9.5	10.0
	1000℃, 3h	5.5	7.6	7.8
	1600℃, 3h	30.0	21.5	20.5
Linear Change Rate after Burning / %	110℃, 24h	–	–	–
	1000℃, 3h	0.1	0	0
	1600℃, 3h	-0.1	+0.8	+0.9
Amount of Water / %		4.8 ~ 5.4	5.4 ~ 5.8	5.5 ~ 6.5
Self-Flow Value / mm		＞ 185	＞ 185	＞ 185

Low Cement Castable Refractory Material Application

Low cement castable refractory materials have a wide range of applications. In metallurgy, petrochemical, machinery manufacturing, electric power, building materials, and other industrial kilns, such castables have been widely used to replace some traditional fired refractory brick products as linings. Vibration-type low cement castable refractory materials are mainly used as thick-sized linings. Such as heating furnace, various heat treatment furnace electric furnace cover shaft kiln, rotary kiln, blast furnace tapping channel, ladle, hot metal ladle, etc. The self-flowing low cement refractory castables are mainly used as thin linings and linings for high-temperature refractory components with metal anchors. Such as the outer lining of the water-cooled pipe of the heating furnace, the lining of the integral spray gun for jet metallurgy, the lining of the immersion pipe of the RH and DH vacuum degassing device, and the air supply element of the ladle (breathable brick). And the high-temperature wear-resistant lining of the petrochemical catalytic cracking reactor.

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Refractory Castables Manufacturers

As one of the refractory castables, the unique advantages of low cement castables play an important role in refractory lining materials. Rongsheng refractory castable manufacturers have rich experience in production and sales. Its advanced environment-friendly and fully automatic unshaped refractory castable production line have an annual output of 80,000 tons. To provide our customers in more than 60 countries with high-quality refractory lining materials. For example, Russia, South Africa, Kazakhstan, Philippines, Chile, Malaysia, Uzbekistan, Indonesia, Vietnam, Kuwait, Turkey, Zambia, Peru, Mexico, Qatar, etc. Rongsheng used to customize low cement castables for customers, ultra-low cement castable, and high customer return rate. To obtain free refractory lining material configuration solutions for high-temperature kilns and solve difficult refractory lining material problems, please contact us. We will customize the refractory lining scheme for you according to your actual production situation.

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Production of Sponge Iron by Shaft Kiln

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