How to Choose Refractory Materials for Rotary Kiln

The rotary kiln is divided into a discharge end, a cooling zone, a firing zone, and a preheating zone from the kiln head end. The temperature in each section of the kiln ranges from 1000°C to 1350°C, and the requirements for refractory materials are also different. Refractory materials not only withstand high-temperature impact, but also withstand material corrosion, wear, and stress generated by kiln rotation. Therefore, there are strict requirements not only for the physical and chemical indicators of refractory materials. 1. Rotary kiln discharge port and cooling zone Demand: Due to the joint action of high-temperature clinker, secondary air, and high-temperature flame, strong mechanical wear and chemical erosion are caused. Therefore, it is required to have good wear resistance, slag resistance, and thermal shock resistance. Selection: Generally, first-grade high alumina bricks, thermal shock-resistant high alumina bricks, spinel bricks, chrome magnesia bricks, phosphate bricks, etc. are used as high alumina bricks, Refractory concrete (corundum aggregate), and silicon carbide bricks. 2. Rotary kiln firing zone Purpose: The refractory layer fired in the rotary kiln is mainly subject to high-temperature impact and chemical corrosion (alkali corrosion). Therefore, magnesia bricks and chrome magnesia bricks should be selected as high-temperature refractory materials that are...

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The Difference between Refractory Bricks and Insulation Bricks

During the construction of a high-temperature kiln, different types of refractory bricks are used in various parts of the kiln. Generally, refractory bricks are needed in the production parts of high-temperature kilns, which can withstand constant erosion and high temperatures. Some less important parts generally use insulation bricks, which are mainly responsible for preserving the temperature in the furnace, but what is the difference between the two? The difference between physical and chemical indicators 1. The thermal conductivity of insulation bricks is generally 0.2-0.4 W/(m·K), while the thermal conductivity of refractory bricks is above 1.0 W/(m·K). The thermal insulation function of insulation bricks is better than that of refractory bricks. 2. The refractory temperature of insulation bricks is generally below 1400 degrees Celsius, while the refractory temperature of refractory bricks is above it, sometimes reaching about 1700-1800 degrees Celsius. 3. The density of insulation bricks is 0.8-1.0g/cm3, while the density of refractory bricks is above 2.0g/cm3 Different usage locations Insulation bricks are mainly used to preserve the temperature of high-temperature kilns and are generally used in the insulation layer of furnace roofs and furnace walls. Refractory bricks are generally used in thermal boilers, glass kilns, cement kilns, fertilizer gas furnaces,...

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Precautions in Refractory Mud Masonry

Refractory mud is the joint material for connecting refractory bricks, so ensuring the adhesion of refractory cement is the key during the construction process. Today I will take you to understand the precautions in refractory mud masonry. 1. Control the water consumption of refractory cement During the use of refractory mud, the water consumption must be strictly controlled. If too much water is added, the water slurry will separate. If too little water is added, uneven mixing of the raw materials may occur, which will lead to the inability to carry out construction on site. 2. Control the construction environment temperature During the use of refractory mud, the temperature of the construction environment must be controlled. When the temperature exceeds 35°C, the refractory mud solidifies too quickly, causing the refractory bricks to harden without time to put the refractory mud between the bricks. If the construction is carried out in winter when the temperature is lower than 5℃, the refractory mud will not have enough viscosity, and construction will not be possible. In this case, it is necessary to add CMC or other binders or find ways to improve the construction. The temperature on site allowed construction to proceed normally....

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Service Life and Spalling Countermeasures of Refractory Materials Used in Rotary Kilns

Industrial waste incineration rotary kilns are prone to temperature fluctuations during operation. Rotary kiln refractory materials must not only have good fire resistance and wear resistance but also have good thermal insulation properties and resistance to rapid cooling and heating. Moreover, due to the complex composition of incinerated waste, it has a strong corrosive effect on refractory materials. Due to these reasons, the refractory bricks of the rotary kiln are prone to cracking after running for some time. The cracks in the bricks loosen, causing different steps between the rings and falling off. The service life and spalling of rotary kiln refractory materials are key issues that directly endanger system reliability and safe operation. To address these issues, the following specific measures can be taken: 1. The refractory materials are effectively configured according to the internal combustion conditions and harsh environment of the rotary kiln. In the garbage input part of the incinerator, since the garbage input and sliding need contact materials, and the temperature of the input port changes frequently, the refractory material is required to have excellent wear resistance and thermal shock resistance. Wear-resistant castables or wear-resistant chrome corundum bricks can be used, when there is a large...

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What Are the Characteristics of Refractory Cement?

Refractory cement is a special type of cement with high-temperature resistance and is commonly used in construction, industrial equipment, and furnace linings in high-temperature environments. The main components of refractory cement are cement clinker, silicate, aluminate, and other substances. Refractory cement has good fire resistance and is therefore widely used in the construction of high-temperature kilns. Features of refractory cement 1. Good high-temperature resistance: The main feature of refractory cement is its ability to maintain stable performance in high-temperature environments, and can usually withstand high temperatures up to 1500°C. 2. Good chemical corrosion resistance: Refractory cement contains a large amount of chemical components such as alumina and silicon oxide, which can resist the erosion of strong corrosive substances such as acids and alkalis. 3. High compressive strength: Refractory cement has high compressive strength and can withstand greater pressure, so it is widely used in construction, metallurgy, and other industries. 4. Refractory cement has strong plasticity: Refractory cement has good processing properties and can be made into refractory products of various shapes and sizes through different processing techniques. Refractory cement is widely used in construction, metallurgy, chemical industry, electric power, and other fields. In the field of construction, refractory cement is...

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Refractory Materials for Lime Kilns

Lime kilns are mainly divided into square kilns and round kilns. According to the classification of fired products, there are lime kilns and ceramic kilns. It is divided into a preheating zone, a firing zone, and a cooling zone. The operating temperature of the preheating belt on the top of the lime kiln is not very high, but when firing products, the raw materials are easy to cause great wear and tear on the refractory bricks, and the furnace gas will cause serious chemical erosion of the refractory bricks. Therefore, attention must be paid to the strength, density, wear resistance, and corrosion resistance of refractory bricks. Although the preheating zone does not have high-temperature requirements for refractory bricks, the other performance requirements for refractory bricks are very strict. Many factories use high alumina bricks and clay bricks, which are different. Calcining area. The calcining zone is the area with the strongest chemical reaction of the refractory bricks used in lime kilns, and the calcining zone is also the stage with the highest temperature. So be careful when you have bricks. Has good thermal shock resistance, corrosion resistance, and wear resistance. Use dense high alumina bricks. The calcining zone was initially...

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Characteristics of Corundum Castable Prefabricated Parts

As we all know, the purpose of adding steel fibers to castables is to improve the mechanical properties of the castables, inhibit the occurrence of cracks, or limit the expansion of cracks when they are formed. Prefabricated blocks of castables made of refractory materials such as steel fiber castables can be made into a certain shape according to the process location and needs, and are heat treated according to the working conditions after demoulding. Precast castable blocks have better application performance and construction advantages than ordinary corresponding castables. Its main features are: 1. Compared with ordinary products, castable prefabricated blocks have higher compressive strength, which is increased by about 2 times. 2. Good thermal shock resistance: The thermal shock resistance of castable prefabricated blocks is increased by 8 to 10 times. 3. The wear resistance of prefabricated blocks is better than that of castables of the same material. 4. Save masonry time, no on-site pouring, supporting, and dismantling of molds, and no need for construction machinery. Once the molded parts arrive at the site, they only need to be installed and assembled on-site, which is convenient and fast. The on-site construction process time is greatly reduced, the quality is stable,...

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Classification and Characteristics of Various Unshaped Refractory Materials

There are many types of unshaped refractories, which can be classified according to the materials or binders used. According to its process characteristics, it can be divided into castable materials, ramming materials, spray materials and refractory mud. Broadly speaking, refractory coatings are also considered unshaped refractory materials. The chemical and mineral composition of unshaped refractory materials mainly depends on the granular and powdery refractory materials used. It is also closely related to the type and amount of adhesive used. The density of a structure or product made of unshaped refractory materials is primarily related to the constituent materials and their proportions. At the same time, much depends on the construction method and craftsmanship. Generally speaking, compared with sintered products of the same material, most amorphous refractory materials have higher porosity before sintering or even after sintering due to smaller external forces during the forming process; chemical reactions before sintering may change the structure or product Some properties, while some medium temperature strength may be slightly reduced due to the presence of non-high temperature stable materials such as binders, the volume stability at high temperatures may be slightly lower, the porosity may be higher, and the corrosiveness may be lower, but...

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Construction Precautions for Refractory Castable Production Enterprises in Different Environments

Castables are granular and powdery materials made by adding a certain amount of binder to refractory materials. They have high fluidity and can be cast into shape. Refractory castables have certain requirements on the surrounding environment during the construction process. Now Xinhongji Refractory will briefly introduce the precautions for the construction of refractory castables in winter, summer, and rainy days. 1. Winter construction refers to construction where the ambient temperature is between +5℃ and -5℃. When the temperature is below -5°C, reliable cold protection measures must be taken before construction can begin. 2. Winter construction techniques must be used during winter construction. The working environment should be sealed, windproof, and warm, and the lining temperature should be kept above +5°C after masonry construction. 3. When constructing castables in winter, dry materials should be stored in the heating room and mixed with boiling water. The temperature of the mixture should be maintained above 10°C. It is not advisable to add chemical accelerators or antifreeze. 4. When constructing the furnace in winter, the insulation layer should be built first to mobilize the anti-freeze ability of the refractory layer. After the masonry is completed, it should be covered first with plastic sheeting and...

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Refractory Materials Used in Cupola Furnaces

What is the refractory material of a cupola furnace? A cupola furnace, also known as an iron furnace or stir-fry furnace, is mainly used for ironmaking. The working temperature of the cupola furnace is generally 1400~1600℃. The cupola furnace body consists of a furnace bottom, a furnace body, a forehearth, and a bridge. The bottom of the cupola furnace is in direct contact with the molten iron and is responsible for the quality of all charges. Therefore, ASC ramming materials or carbon ramming materials and products should be used to improve the service life of the cupola furnace bottom. The upper working layer of the cupola furnace body is affected by the impact and wear of the feeding machine. It is built with fan-shaped hollow iron bricks and filled with quartz sand outside. The lower working layer of the cupola, especially the burning area above the tuyere, has a higher temperature and is corroded by slag, airflow, and charge. Therefore, magnesia chrome bricks or magnesia bricks with strong corrosion resistance are used. Since the oxidation atmosphere of the working layer in the lower part of the furnace body is weakened, ASC ramming materials and their products can be used. Due...

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