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The insulation layer of an alumina rotary kiln is to lay a layer of refractory fiber felt on the kiln shell, and then lay diatomaceous earth, floating bead bricks, or lightweight clay bricks. Some now use lightweight refractory castables. The working lining of the prezone is constructed with clay bricks, and the high-temperature calcined zone is constructed with high alumina bricks or phosphate-bonded unfired high alumina bricks. At present, unshaped refractory materials have been widely used in the aluminum industry, such as low-calcium aluminate refractory castables for the calcining zone, steel fiber-reinforced wear-resistant castables for the kiln mouth, kiln hood, kiln tail, and other parts. The flash furnace installs heat-resistant steel anchors or ceramic anchors on the furnace shell, then lays a layer of 20mm thick refractory fiber felt, and finally pours 200-300mm thick refractory castables. The working lining of the reverberatory furnace of the aluminum smelting furnace in contact with the aluminum liquid is generally built with high-aluminum bricks with an aluminum content of 80 to 85%. When smelting high-purity metallic aluminum, mullite bricks or corundum bricks are used. The combination of silicon nitride and silicon nitride bricks is used for the erosion and wear parts of the hearth...
Given the problems such as the short service life of forging heating furnace doors, high masonry repair costs, and heavy furnace doors, we can improve the use of furnace door castables by rationally selecting the raw materials of the castables, adjusting the component ratio, and adding additives performance. Causes of damage to heating furnace door The main function of the furnace door masonry refractory material is to protect the cast iron frame and block the flame in the furnace. To meet the requirements, refractory materials need appropriate fire resistance, mechanical strength, and related performance, but there are no special requirements for density. Therefore, we can reduce the density of the furnace door refractory material to reduce the weight of the furnace door. The problem of the short service life of the furnace door is mainly caused by the following reasons: poor thermal shock resistance of the refractory material of the furnace door, poor integrity of the refractory brick lining, and high temperature of the heating furnace. Due to the poor thermal shock resistance of refractory materials, serious brick breaking, and cracking will occur in the refractory brick lining under the working conditions of frequently opening the furnace door. In addition,...
Spheroidized ladle castable, also known as spheroidized ladle refractory castable, is a commonly used refractory material, mainly used for pouring molten iron in high-temperature environments. It is mixed with a variety of minerals and binders and has good fire resistance and fluidity. The working principle of spheroidizing castables During the smelting process of molten iron, slag, and impurities need to be separated from the molten iron to obtain pure molten iron. At this time, the spheroidizing bag castable plays an important role. The spheroidizing ladle castable is added to the pouring tank and then sprayed onto the conveyor belt via a nozzle. When the molten iron pours down from a height, the spheroidizing ladle castable will solidify quickly and form a strong protective layer to avoid contact between the molten iron and oxygen and prevent oxidation and combustion. In addition, the spheroidizing ladle castable can absorb impurities in the slag and improve the purity of the molten iron. It has excellent fire resistance and thermal stability and can withstand corrosion and erosion under high-temperature conditions. Advantages of spheroidizing castables Good fire resistance: The spheroidized ladle castable contains high-temperature stable minerals, which can resist corrosion and erosion in high-temperature environments. High...
The temperature resistance of refractory castables depends on their material composition and preparation process. Generally speaking, refractory castables can withstand high temperatures, but the specific temperature range will vary depending on the type and formulation of refractory castables. Some common refractory castables, such as high-aluminum refractory castables, corundum refractory castables, and low-cement refractory castables, have high-temperature resistance. These materials typically withstand high-temperature environments ranging from 1500°C to 1800°C. However, for higher-temperature applications, such as steelmaking, glassmaking, or other high-temperature processes, specially formulated and prepared refractory castables may be required. These special refractory castables can withstand higher temperature tests, reaching or even exceeding 2000°C temperature resistance. It should be noted that even if the refractory castable can withstand high temperatures, attention must be paid to the rate of temperature change and the temperature gradient to avoid rupture of the refractory castable or thermal shock due to rapid changes. Therefore, in practical applications, it is necessary to select appropriate refractory castables according to specific conditions and follow relevant usage instructions and operating specifications.
Issues that should be paid attention to when using refractory prefabricated blocks 1. When designing refractory prefabricated blocks, they should not be too large or too narrow (easy to break). They must be of moderate size. In addition to considering expansion joints between two adjacent pieces, special attention should be paid to them during masonry. Arrange the joints staggered, and the expansion joints can be filled with refractory fiber blankets to prevent “penetrating straight joints” from appearing during masonry, which will cause excessive heat loss through the straight joints and even burn out the furnace shell. 2. During masonry, an appropriate amount of refractory mud or high-temperature adhesive should be used to seal the seams between the refractory prefabricated blocks so that they form a whole after high-temperature sintering, which is not only strong but also reduces heat loss. 3. An appropriate amount of insulation layer should be left between the refractory prefabricated blocks and the furnace shell to prevent the furnace shell from overheating and causing large heat dissipation losses. 4. Larger fire-resistant prefabricated blocks must be designed with lifting hooks to facilitate transportation and installation. 5. The service life will be better if the oven is operated according...
In high-temperature working environments such as alumina gas suspension roasters and oil refining catalytic cracking units, the media content is high, high-speed airflow erosion and abrasion are serious, and the use conditions are very harsh. To improve the service life and stability of these parts, wear-resistant and refractory castables need to be used as lining materials. Wear-resistant refractory castables require dense and hard refractory aggregates, refractory powders of suitable fineness, excellent binders, ultrafine powders, and admixtures to achieve densification and high strength of the material. Selection and proportioning of refractory aggregates The refractory aggregate used in wear-resistant refractory castables must have high density and hardness to increase the material’s compression and wear resistance. Multi-stage particle gradation can achieve the maximum packing density and improve the density of the material. Through reasonable proportion design, high-quality refractory aggregate preparation can be achieved. Fineness requirements for refractory powder The refractory powder in wear-resistant refractory castables needs to have suitable fineness, which is generally required to be greater than 0.09mm and greater than 90%. By selecting the appropriate particle size and distribution range, the density and wear resistance of the material can be increased, and the strength of the castable can be improved. Application...
In a biomass burner, the flame nozzle is an important component for putting biomass pellet fuel into the combustion chamber, so the refractory castable used at the flame nozzle is crucial to the normal operation of the biomass burner. Selection factors for fire-throwing nozzle castables: 1. High-temperature resistance: The flame nozzle will be impacted by high temperatures during the biomass combustion process, so the castable needs to have good high-temperature resistance and be able to withstand thermal stress and corrosion in high-temperature environments. 2. Thermal conductivity: The thermal conductivity of the castable will affect the heat dissipation effect of the flame nozzle. Choosing castables with good thermal conductivity can improve the thermal conductivity of the flame nozzle and reduce heat loss. 3. Anti-corrosion performance: Ash and chemicals produced during biomass combustion will cause corrosion to the flame nozzle. Therefore, the castable needs to have good corrosion resistance to extend the service life of the flame nozzle. Based on the analysis of the selection of castables for biomass burner flame nozzles, we formulated refractory castables that meet the requirements for use. That is, the flame nozzle is castable. The flame nozzle castable has the characteristics of high refractory temperature, good compressive...
In winter, the use and maintenance of refractory castables require special attention because low temperatures may cause damage to the refractory materials. The following are some things to note when using refractory castables in winter. 1. Keep refractory materials dry In winter, the humidity is high, and refractory materials easily absorb moisture, causing them to lose part of their mechanical strength. At the same time, when the surface of refractory materials is frosted or covered with snow, the wear and corrosion of the materials will also be accelerated. Therefore, when using and storing refractory castables, they need to be placed in a dry and ventilated environment to avoid being affected by moisture and snowfall. 2. Control construction and hardening temperatures During the construction and hardening process, refractory materials require certain temperature protection measures. Application at temperatures lower than specified for the material will prevent the material from fully reacting, curing, and hardening. On the contrary, if it is applied at a temperature higher than the specified temperature, it will cause cracks and deformation of the material. Therefore, when using refractory castables, it is necessary to strictly follow the construction and hardening temperature requirements in the material instructions. 3. Prevent materials...
Portland cement refractory concrete is prepared with ordinary Portland cement, slag Portland cement, and Portland heat-resistant cement as binding agents, and refractory aggregates and powders. The maximum operating temperature is 1200℃ or 1200℃ The following medium and low temperature refractory concrete. It has the advantages of easily available materials and low cost and can be used to cast integral load-bearing and heat-resistant structures and kiln linings, especially in projects such as foundations and floors of thermal equipment, flues, chimney linings, and thermal storage tanks. More. Ordinary concrete prepared with Portland cement is not fire-resistant and is prone to damage or serious loss of strength when exposed to heat for a long time. Based on overcoming this defect, Portland cement refractory concrete was gradually formed. The preparation of Portland cement refractory concrete is generally divided into two aspects: 1. Add specific powder to Portland cement In Portland cement refractory concrete, specific powder is added, its main functions are: reducing the shrinkage of cement stone; binding free calcium oxide; and stabilizing dicalcium silicate. 2. Use appropriate aggregates From the analysis of the causes of thermal damage to ordinary concrete, it can be seen that the aggregate used to prepare refractory concrete should...
1. If construction conditions permit, the water-cement ratio should be reduced as much as possible to reduce water consumption. This is because water in refractory concrete is easily lost at high temperatures, resulting in increased concrete pores and reduced strength. 2. To meet the workability and normal temperature strength, the amount of cementing materials and cement should be reduced as much as possible. This is because the fire resistance of aggregates is generally higher than cementing materials and high-temperature cementing materials soften and deform before aggregates. 3. Adding appropriate admixture materials can improve the fire resistance of concrete, improve workability, and reduce the amount of cement. Commonly used blending materials include clay clinker, clay refractory bricks, alumina clinker, magnesia, chromite, fly ash, finely ground powder of high alumina bricks, and silica powder and corundum powder with high refractory properties. 4. Appropriate gradation of aggregates should be selected to maximize density, and attention should be paid to matching with cementitious materials. The sand rate is controlled at 40% to 60%. The mix ratio design is generally based on the empirical mix ratio and is determined after adjustment through experiments. Refractory concrete is generally not equipped with steel bars because the thermal...
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