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Lining repair is a common item in heating furnace maintenance work. There are two main methods of repairing linings. One is to use the same refractory castable as the original lining for repair, and the other is to paste a certain thickness of refractory fiber felt. The construction method and quality requirements for repairing the lining with refractory concrete are the same as those for the new furnace lining. In addition, pretreatment of the repair surface needs to be done.

Construction Method of Repairing Lining with Refractory Castable

Commonly used for repairs of lightweight refractory castable linings. Before construction, materials must be prepared, a detailed understanding of the construction site, and construction tools must be cleaned. The specific pre-construction preparations are as follows.

• (1) Before construction, the repair scope should be reasonably determined based on the damage to the lining. Remove the failed furnace lining within the repair range to meet the pretreatment requirements for repair construction.
• (2) Containers and tools used for lining construction should be cleaned. Prevent lime, other cement, clay, and other impurities from mixing into the aggregate.
• (3) Ceramsite should be soaked for at least 12 hours before use, and excess moisture should be eliminated during use.
• (4) The parts of various pipe racks, casings, and other metal components (except insulation nails) buried in the lining should be coated with 0.5~1.0mm thick asphalt.
• (5) The construction site should be maintained between 10 and 25°C, and cooling or warming measures should be taken accordingly in summer or winter. After the curing is completed but not in the oven, the temperature should be kept above 5°C to prevent freezing damage to the lining.

The construction method of repairing the lining with refractory concrete can be carried out in the following three methods depending on the materials used.

1. Smearing method

During construction, the steel wire mesh must be filled with castable. There must be no holes and the concrete must be dense. When applying, spread the concrete and smooth it with a wooden trowel until the surface is rough. To prevent cracks, the castable surface cannot be calendered. This method is suitable for small-area lining repairs.

2. Spray coating method

The semi-dry method should be used for spraying, that is, the refractory material should be properly moistened with water and stirred evenly before adding it to the sprayer. When spraying, the material and water should be sprayed evenly and continuously, and there should be no dry material or flow on the spray surface. The nozzle should continuously move in a spiral manner to distribute coarse and fine particles evenly. Spraying should be carried out in sections and continuously, reaching the thickness at one time to avoid delamination. If the thickness cannot be reached at one time, layered spraying can be used, but the second layer must be sprayed before the initial setting of the previous layer of spray paint. When construction must be interrupted, diagonal stubble should be left at the joints. When construction continues, the joints must be cleaned and moistened with water. During spraying construction, the thickness of the spray coating should be checked at any time. The excessively thick parts should be shaved off, and the surface of the spray coating should not be smoothed. When spraying, a wooden box should be used to leave a test block at the spraying location to check its strength and bulk density. After construction, tap gently with a small hammer to check the density of the sprayed layer. If any holes or interlayers are found, they should be dug and repaired in time. This method is suitable for repairing or constructing new furnace linings in large areas with thick linings (greater than 50mm).

3. Mold pouring

The pouring and loading of the mold into the formwork should be done in layers, and the thickness of each layer should be 150~200mm. In order to prevent the delamination of light aggregate and cement during tamping, which increases the bulk density and affects the thermal conductivity, mechanical tamping should not be used. Manually tamped concrete must be dense and free of honeycombs and voids. When tamping, first tamp around the anchor pin, and then tamp it again with half a hammer, without over-tamping or missing tamping.

Pouring of refractory concrete is best done continuously. When construction must be interrupted, the joints should be “roughed” and covered tightly with plastic film. After 12 hours, pouring can be continued.

When pouring refractory concrete on top of the insulation block, prevent the upper insulation block from absorbing water. The best way is to paint a layer of asphalt on the insulation block, or you can lay a layer of plastic film. If plastic film is spread on a vertical surface, it should be fixed to prevent it from slipping. This method is also suitable for the repair of large-area, large-thickness vertical linings and the lining construction of new furnaces.

Refractory fiber paste repair method

The use of refractory fiber paste to repair the lining is a new method developed in recent years. It has the advantages of simple construction, no need for maintenance, and short oven and maintenance cycles.

When overhauling the lightweight heat-resistant concrete lining of the heating furnace, it was found that the surface of some linings was generally delaminated, powdered and peeled off, that is, the surface layer of the concrete lining lost its strength. The reason for this phenomenon may be the corrosion of the gas medium in the furnace. If you still use raw materials to repair it at this time, you will definitely make the same mistake again. The use of pasted refractory fiber felt is an effective method.

Scrape off the powdery layer on the original lining surface and roughly level it. Large cracks and peeling areas are hand-painted with raw materials, and then a layer of refractory fiber felt is pasted. The thickness of the paste should be determined through calculation, but it should not affect the heating of the furnace tube surface. This composite structure of ceramic fiber felt is vertically attached. The vertical ceramic fiber felt is cut by machine according to the required thickness and tied into bundles.

Before pasting, clean the flattened lining to remove any floating material. When pasting, start from the root of the wall and paste it from bottom to top. Use a paint brush to spread the adhesive on the furnace wall and the ceramic fiber bundle strips respectively, and apply it fully. Then attach the ceramic fiber bundle strips and compact them with your hands. If there is water on the furnace wall or top, the ceramic fibers will not be able to stick to it.

The adhesive should have properties such as high-temperature resistance, strong adhesion, lightweight, and the ability to cure at room temperature. Currently, commonly used adhesive types include:

• (1) Water glass: pulp waste liquid = 1:1 plus 10% clay clinker powder and a small amount of clay powder.
• (2) Aluminum silicate adhesive.
• (3) Methylcellulose.
• (4) Aluminum phosphate adhesive, phosphoric acid: aluminum hydroxide = 8:1.

For example, adding masonry powder to the adhesive to make it into a paste, and adding some MgO can make it stronger at room temperature.

Rongsheng refractory material manufacturers can provide customers with comprehensive refractory material services. Extend the service life of refractory lining materials in high-temperature industrial kilns and reduce the number of furnace shutdowns and repairs. Design and construction of refractory solutions for insulation layers, and turnkey projects of refractory lining materials for high-temperature industrial furnaces. If you are in need of purchasing heating furnace lining refractory materials, refractory brick linings, or unshaped refractory linings, please contact us. Get free quotes and samples.

Fused zirconia corundum brick is a high-quality, high-temperature performance refractory material, mainly made of zirconia and alumina through arc melting. The adobe has the characteristics of high density, high hardness, high heat resistance, corrosion resistance, etc., and has good use effects in high temperature and chemical erosion environments. Zirconia corundum bricks are refractory bricks made of industrial alumina and zircon sand. According to the manufacturing process, zirconium corundum bricks can be divided into two types: fused zirconium corundum bricks and fired zirconium corundum bricks.

Properties and Characteristics of Zirconium Corundum Bricks

Fused zirconia corundum bricks are commonly known as white iron bricks, also known as corundum-deleyite bricks. The main chemical composition is Al2O3 50% to 70%, ZrO2 20% to 40%, and the rest is SiO2. The main mineral composition is baddeleyite (ZrO2), corundum (α-Al2O3) and glass phase. Baddeleyite crystallizes to form the backbone of the brick body, ZrO2 has a high melting point (2715°C), has good chemical stability, and has strong corrosion resistance to acidic and alkaline media, especially glass liquid.

physical properties

Fused zirconia corundum bricks have some excellent physical properties, which make them work well in high-temperature and chemically erosive environments. The following will introduce its main physical performance indicators:

density and hardness

The density of fused zirconia corundum bricks is generally between 35.6-4.2 g/cm3, which is a high-density material. At the same time, its hardness is very high, usually above 9.0 Mohs, which is three times that of steel. This means that it can also maintain good wear resistance under high temperatures and strong acid and alkali environments.

heat resistance

The heat resistance of fused zirconia corundum brick is also one of its main physical properties. The material can withstand very high temperatures, generally above 2200. This enables it to operate at high temperatures for a long time without deformation, cracking, etc.

Corrosion resistance

The corrosion resistance of fused zirconia corundum bricks is also excellent, mainly due to their good chemical stability and oxidation resistance. Fused zirconia corundum bricks have good corrosion resistance in corrosive environments such as acid and alkali, high temperature, and humidity, which makes them able to withstand more severe working conditions during production.

Preparation Process of Fused Zirconia Corundum Brick

The preparation process of fused zirconia corundum bricks is relatively complicated. It is necessary to select high-quality zirconia and alumina raw materials and mix them evenly. Next, the mixture is poured into an electric furnace for high-temperature electric fusion to form solid adobes. The electric melting furnace usually inserts two electrodes into the furnace body at the same time, generates high temperature through the electric arc in the furnace, heats the raw materials to a molten state, and forms a hard adobe after melting.

During the preparation process, special attention needs to be paid to controlling the conditions such as atmosphere and temperature in the furnace to maintain the uniformity of the melt and the stability of the chemical composition. In addition, the baking and processing of Adobe is also an important link affecting product quality, which is directly related to the physical performance parameters such as density and hardness of Adobe.

Application Field of Zirconium Corundum Brick

Fused zirconia corundum bricks are widely used in the industrial field, especially where high-quality, high-performance refractory materials are required in high-temperature and chemically aggressive environments. The following will introduce its application fields in detail from several aspects:

glass melting furnace

In glass melting furnaces, fused zirconia corundum bricks are usually used as important parts such as the upper pool wall, small furnace flat wall, small furnace stack, tongue wall, and parapet. This is because a glass melting furnace is a high-temperature, high alkalinity, highly corrosive environment that requires the use of high-quality refractory materials that can withstand long periods of operation. The fused zirconia corundum brick not only has excellent heat resistance and corrosion resistance but also can maintain good physical stability, ensuring the smooth progress of the glass production process.

Application of Fused Zirconia Corundum Brick in Glass Furnace

Fused zirconia corundum bricks are used in industrial furnaces such as glass-melting furnaces. The parts used in the glass melting furnace are the masonry of the upper pool wall, the small furnace flat wall, the small furnace stack, the tongue wall, and the parapet. The following problems should be paid attention to in the use of fused zirconia corundum bricks:

① Irregular changes in thermal expansion. The expansion curve of the fused zirconia corundum brick has an abnormal section near 1000°C. Its internal ZrO2 crystal undergoes reversible crystal transformation and has a large volume change. Therefore, bricks containing ZrO2 should not be used in places where the temperature often fluctuates sharply around 1000 °C. When baking the kiln, the temperature change should not be too large at 900-1150 °C. Generally, it cannot exceed 15°C/h, and a steady temperature rise is required. Some parts need to be protected from cold wind and need to be protected by other bricks to prevent bursting.

②Shrinkage cavity. During pouring molding, shrinkage cavities often appear at the gate, where the brick body has more pores and poor density. Therefore, when building the wall of the glass melting tank, the shrinkage cavity is all directed towards the inner direction of the kiln. If the sprue is facing outward, when the brick body is corroded to a very thin thickness, it will cause a glass liquid leakage accident. When used in the upper flame space of the pool kiln, the service life is very long, and the problem of glass liquid running out will not occur. Therefore, the spout is used outwards to prolong the service life.

③ eutectic. Fused zirconia corundum bricks are built in contact with clay bricks, and the eutectic phenomenon will occur at a high temperature of 1300 °C. Therefore, when choosing refractory materials, it should be avoided to contact the two refractory materials with serious eutectic phenomenon for masonry. If the silica brick is under the fused zirconia corundum brick, it is most susceptible to erosion by the fused zirconia corundum brick.

Sintered zirconium corundum bricks are also known as ceramic-bonded aluminum-silicon-zirconium bricks. Compared with fused zirconia corundum bricks, the chemical composition of sintered zirconia corundum bricks is similar. However, it has the advantages of no carbon, low content of glass phase, uniform structure, no shrinkage cavity, good thermal shock stability, and corrosion resistance.

Metallurgical equipment

Fused zirconia corundum bricks are also widely used in metallurgical equipment, especially in the iron and steel industry. For example, high-quality, high-performance refractory materials are required in equipment such as blast furnace interiors, converter interiors, heating furnaces, and dryers. Fused zirconia corundum bricks just meet this requirement.

aerospace equipment

Fused zirconia corundum bricks are also more and more widely used in aerospace equipment. For example, in high-temperature components such as engine nozzles and combustion chambers, high-quality ceramic materials are required to withstand high temperature, high pressure, and severe airflow erosion. The fused zirconia corundum brick has excellent heat resistance and corrosion resistance, making it one of the ideal materials for these components.

AZS Bricks Fused Zirconia Corundum Brick Fused Bricks

With the increasing demand for high-quality refractory materials, the market prospect of fused zirconia corundum bricks is also becoming brighter. Especially in the fields of glass, metallurgy, aerospace, and other fields, the application prospect is very bright. zirconium bricks series, Fused zirconia corundum brick is an excellent refractory material with high density, high hardness, high heat resistance, and corrosion resistance. It is widely used in industrial production. The preparation of fused zirconia corundum bricks requires fine control in multiple steps to ensure their excellent physical properties. Buy High-Quality AZS-Fused Zirconia Corundum Bricks Fused Bricks – Refractory Bricks for Glass Kiln, Contact us to Get a Free Quote.

Silicon carbide crucibles and graphite crucibles are containers with good high-temperature resistance, which are usually more common in industrial metal smelting and casting. Compared with graphite crucibles, silicon carbide graphite crucibles are resistant to high temperatures and oxidation. Silicon carbide crucibles are larger than graphite crucibles and have a longer service life. Silicon carbide manufacturers produce silicon carbide, graphite crucibles, non-ferrous metal castings, and high-heat conduction crucibles. The size of the negative electrode material pre-carbonized crucible is 500*1200mm. Rongsheng manufacturers customize silicon carbide graphite crucibles.

Good Thermal Vibration, Corrosion Resistance, High-Temperature Resistance Silicon Carbide Crucible

Thermal conductivity: High thermal conductivity material is adopted, with dense structure, low apparent porosity, and fast thermal conductivity.

Long service life: Compared with ordinary clay graphite crucible, the service life of the same material can be increased by 2-5 times.

High Density: Using an advanced isostatic pressing molding process, the material is dense and uniform without defects.

High strength: material selection, high-pressure pressing, good high-temperature strength, scientific product shape, high pressure bearing capacity.

Corrosion resistance: Advanced material formula can effectively resist the physical and chemical effects of the melt.

Less sticky slag: There is less slag hanging on the inner wall, which greatly reduces the possibility of heat resistance and expansion of the crucible.

High-temperature resistance: the operating temperature is 400-1700°C.

Less pollution: The material design fully considers the relationship and process characteristics of the smelted metal, and contains almost or no harmful impurities.

Metal saving: Because the material contains special elements, it can effectively inhibit the oxidation of metals.

Energy saving and environmental protection: fast heat conduction can save a lot of fuel, reduce waste pollution, proper resistivity, and induction heating can significantly reduce reactive power loss.

High oxidation resistance: the advanced anti-oxidation mechanism makes the graphite in the crucible well protected.

How to Use the Silicon Carbide Crucible Correctly?

Many people do not preheat the new silicon carbide crucible when using it, which can easily cause the crucible to crack. So we must preheat the crucible before using it. So, how to preheat the crucible?

Preheating is to dehumidify the crucible. The new silicon carbide crucible can be placed next to the oil furnace for preheating 4-5 hours before use. Charcoal can also be burned in the crucible for about 4 hours before using a new silicon carbide crucible, which also dehumidifies the Lake Tana precious crucible. The temperature changes during the heating and preheating time of the new crucible furnace, and the temperature is slowly heated at 0°C-200°C for 4h. Heat slowly at 0°C-300°C for 1h. Heat slowly at 200°C-300°C for 4h. Heat slowly at 300°C-800°C for 4h. Heat slowly at 300°C-400°C for 4h. Rapid heating at 400°C-600°C for 24h. After the furnace is shut down, the preheating time of the furnace is as follows. Oil furnace and electric furnace: 0°C-300°C slow heating for 1 hour, 300°C-600°C slow heating for 4 hours, and when the temperature is above 600°C, it can be heated quickly to a certain degree.

When using a silicon carbide crucible, it must be operated in accordance with the operating procedures in order to better create more value for the silicon carbide crucible and bring more economic benefits.

650KG Silicon Carbide Graphite Crucible Manufacturer

The main products of 650KG silicon carbide graphite crucible manufacturers include graphite crucibles, graphite block rods, graphite molds, graphite rotors, and other processed parts. There are more than 200 varieties of non-standard graphite customized parts, silicon carbide products, special impregnated graphite products, vacuum furnace body parts, etc. These products are widely used in the non-ferrous metal smelting industry, experimental instrument industry, jewelry industry, and high-temperature industrial furnace industry. Machinery industry, glass machinery industry, new materials and new energy industries such as electronic semiconductors, special ceramics industry, diamond tool industry, aviation industry, etc.

New isostatic silicon carbide graphite crucibles, standard sizes. High-temperature resistance, wear resistance, thermal shock stability, and high flexural strength. It can be used in electric power, slag flushing trenches in steel mills, the coal chemical industry, and mines.

Silicon carbide products have strong stability. Silicon carbide graphite crucible, made of high-strength silicon carbide, has good load-bearing capacity. It has a higher charge softening temperature and a smaller re-burning rate of change.

Silicon carbide products have a long service life. Silicon carbide graphite crucible has the characteristics of a high load softening point, fast heat conduction, anti-oxidation, not easy to shrink and deform at high temperatures, and long service life.

Silicon carbide products, are not easy to scale and are more durable. The silicon carbide graphite crucible material produced by Rongsheng has a smooth surface and no pores, and the internal flow channel is smoother, less prone to fouling, and the atomization is more uniform.

Isostatic pressing of special crucible for electric furnace

Rongsheng Manufacturer is a professional crucible manufacturer. By introducing advanced production technology, using high-quality raw materials, and applying isostatic pressing technology to produce various types of crucible products. The main products include silicon carbide graphite crucibles, clay graphite crucibles, high-purity graphite crucibles, etc. The products are widely used in the smelting of pure aluminum, aluminum alloy, copper, lead, zinc, gold, silver, and other non-ferrous metals. The silicon carbide graphite crucible produced by Rongsheng has good thermal conductivity, long service life, and significant energy saving, which greatly saves the production cost of the enterprise.

Rongsheng Manufacturer Customized Silicon Carbide Graphite Crucible

If you need to customize a silicon carbide graphite crucible with special size or shape, please provide a description of the use conditions, size, quantity, thickness, and other information of the silicon carbide crucible product in advance. We can process and customize according to the drawings, manuscripts, and CAD/PDF drawings you provide. Since we need to grind and cut in the process at home, the process will cause certain tolerances, which are generally small. If you choose the exact size, please also inform us in advance.

Silicon Carbide Crucible for Non-Ferrous Smelting and Powder Metallurgy

Silicon carbide crucible adopts international advanced isostatic pressure crucible molding equipment and technology, high-quality refractory raw materials are selected, and high-tech formula is used. Silicon carbide crucible has the characteristics of high volume density, high-temperature resistance, fast heat transfer, acid and alkali corrosion resistance, high-temperature strength, high oxidation resistance, and stable quality. The service life is 3-5 times that of a clay graphite crucible. It greatly reduces fuel consumption, reduces labor intensity, improves work efficiency, and creates better economic benefits.

Silicon carbide crucible supporting furnace type. It can be used in gas furnaces, gas furnaces, coke furnaces, oil furnaces, resistance furnaces, induction furnaces, oil furnaces, biological pellet furnaces, etc.

Silicon carbide crucible range of use. Melting all kinds of gold, silver, copper, aluminum, lead, zinc, and other non-ferrous metals, as well as medium carbon steel and various rare metal alloys. Silicon carbide crucibles are suitable for different processes in the non-ferrous metal industry. Therefore, silicon carbide crucibles are divided into professional copper-melting silicon carbide crucibles, professional aluminum-melting silicon carbide crucibles, professional zinc oxide silicon carbide crucibles, professional zinc-melting silicon carbide crucibles, professional tin-melting silicon carbide crucibles, and so on.

Design & installation craft

In recent years, no matter in separation method or in anti-wearing technique, there is great progress in CFB boiler development. From the perspective of anti-wearing refractory materials, degrading the quality of refractory materials is not good for the normal operation of the CFB boiler. Even when the quality of anti-wearing refractory materials is very good, if installation craft can’t meet standards and lead to dimensional deviation, there will be severe abrasion, or if refractory material is not corrected constructed, it will also greatly affects the safe and economic operation of CFB boiler.

CFB boiler masonry craft

Construction quality is crucial to the service life of the CFB boiler. CFB boiler construction workers should not only be familiar with furnace construction standards and electric power specifications but should know refractory materials performance well. As to the aspect of CFB boiler design, construction workers should know the design draft well, for example, fastening device, sealing device, and expansion joints preservation should be thoroughly considered. When the irrational design is discovered, it should be pointed out and put forward reasonable measures to avoid operational problems.

CFB boiler roasting craft

CFB boiler main body structure is complicated, working lining construction area is large, water content is high, so proper roasting craft should be carried out after the finish of construction. If roasting is not done according to the designed craft or roasting time is shortened, material interior vapor pressure will be overlarge, when it exceeds the tensile strength of refractory material, there will have a structural rupture. After the operation of the boiler, the refractory lining will have structural sapling or thermal stress damage in the refractory material interior, the operation safety and the service life of the CFB boiler will be greatly affected. So, furnace roasting is very important to link before the operation of the CFB boiler.

CFB boiler operation craft

The successful blow-in rate is 100%. Although the boilers are produced by the same factory, are applied in the same region, and adopt the same kind of coal, there also have different problems during the operation of CFB boilers. The reason is that operational craft control is different. If workers don’t operate the CFB boiler according to specifications, there will have cracks, spalling, or even collapse during the CFB boiler operation. That is to say, the normative operation is the last factor affecting the service life of the CFB boiler.

May 2020, our refractory bricks are exported to Egypt. Totally 3 days, 23 trucks, 28 containers, 730mts Refractory Bricks finishing loading. Rongsheng Refractory will always be your best choice!

Rongsheng, specialize in refractory products for nearly 20 years, covering a full range of Graphite Electrode, High Alumina Bricks, Magnesia Chrome Bricks, Magnesia Carbon Bricks, Corundum Bricks, Corundum Castable and kinds of castables, and other related products for more sophisticated applications.

310 workers, 20000 sqm workshop, 20 years experience, years supplier of RHI, TATA, CODELCO, ROSAL, SIAM, PSM, CE & ISO 9001/2008 certificated, the biggest area of original bauxite in China, this is how we keep good quality and reliable cooperation for global valued customers.