Chromium, nickel-iron ore oxidation roasting material for rotary kiln. A rotary kiln is a special kiln working under dynamic conditions. It is mainly used for calcination and roasting of cement clinker, petroleum coke, magnesia dolomite, limestone, iron oxide magnetization, nickel-iron laterite ore, and non-ferrous metal sulfide ore. Due to the particularity of the working conditions, there are higher requirements for the refractory lining to a certain extent, and the traditional refractory bricks are severely challenged in this type of kiln. According to the working characteristics of rotary kiln, Rongsheng Refractory Co., Ltd. ( http://www.aluminabricks.com/ ) has developed special refractory castables for the rotary kiln series.
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| Rotary Kiln Anti-Skinning Castable |
Refractory Castable for Rotary Kiln
In addition to the common feature that refractory castables for rotary kilns can be used directly without firing, the production process is relatively simple among many types of unshaped refractory materials, and no special equipment is required. Low cement castable for nickel-iron rotary kiln. Many manufacturers' new dry-process cement rotary kiln production lines have improved their ignition and feeding production conditions, and their operating rates have increased year by year. However, there are still some problems with the use of refractory castables. Through comparative analysis, Rongsheng refractory manufacturers have made a summary of the use of refractory castables in the lining of rotary kilns.
1. Rotary kiln refractory castable configuration scheme
High-temperature alkali-resistant castables for preheaters, high-aluminum high-strength low-cement refractory castables for kiln tail smoke chambers and calciners. Corundum high-strength low-cement refractory castables for grate coolers and kiln mouths. Steel fiber high-aluminum refractory castables are used for the kiln hood, and high-aluminum low-cement refractory castables are used for the tertiary air duct. Special castable for corundum coal injection pipe for coal injection pipe.
2. Shedding phenomenon of refractory castable
In many cases, due to the unreasonable design of the configuration scheme, there have been many accidents of pouring material falling off the rotary kiln just over a year after it was put into operation, and the kiln shutdown failure rate is very high. The main reason is that the junction between the calciner and the tertiary air duct has been burned through many times, the shrinkage of the calciner has been worn out, and the tertiary air duct has fallen off. The head of the coal injection pipe burst and fell off three times, the low wall of the grate cooler was worn out, the kiln head cover was burned three times, and the arch beam of the kiln tail smoke chamber collapsed.
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| Magnesia Refractory Castable for Rotary Kiln |
3. Analysis of the reasons for castable shedding
The change of fuel, especially after the use of anthracite, the coal ash content suddenly settled in a large amount, resulting in the slope of the kiln tail smoke chamber and the frequent shrinkage of the calciner. It needs to be cleaned manually with iron tools, which will inevitably cause mechanical damage to the refractory material. At the same time, the saturation ratio of the raw material entering the kiln fluctuates greatly, and chemical erosion and the infiltration of liquid alkali salts deteriorate the structure of the castable. Reduce thermal fatigue resistance, thermal shock stability, alkali corrosion resistance, and resistance to changes in oxidation and reducing atmospheres. Especially when used in kilns that start and stop frequently, the service life will be greatly shortened. Coupled with clinker dust erosion, erosion, and kiln temperature expansion due to cold and heat, many castables such as the kiln hood, tertiary air duct, and grate cooler have fallen off and failed.
Traditional cement refractory castables can obtain sufficient room temperature strength due to the high amount of cement. However, the crystal transformation of cement at medium temperature will significantly reduce the strength, which leads to the reduction of high-temperature strength and erosion resistance of the material.
Rapid cooling and rapid heating aggravate the frequent accidents of refractory materials. A large number of documents point out that the alkali expansion coefficient is large, and huge thermal stress is generated during the heating process. Therefore, when the kiln is baked, the temperature should be raised slowly, so that the expansion of the kiln system can supplement the expansion of the refractory material to play a compensating role. This is the key to how to use good refractory materials. However, it is difficult to accept a long kiln drying time in actual production, and when a problem is found, the high-temperature fan is directly turned on to quickly cool the kiln temperature. In order to grab the output after the overhaul, it is required to raise the temperature quickly, which paves the way for the damage of the refractory material.
4. Solutions to castable shedding
Different grades of refractory castables are selected for different parts of the pre-calciner kiln system. The shrinkage of the calciner is made of anti-skinning refractory castable, and the kiln hood is made of steel fiber high-aluminum refractory castable. The low wall of the grate cooler is easy to wear and tear, so mullite high-strength wear-resistant castable is used. Corundum castables are easy to burst and fall off when used on coal injection pipes, so steel fiber high-aluminum high-strength wear-resistant refractory castables are used instead, and high-aluminum refractory castables are used for quick repairs during emergency repairs.
Since the castables currently used are basically not crusted, it not only reduces the work intensity of the inspectors but also improves the running time of the rotary kiln stop material cleaning and decomposition furnace shrinkage crusting, which greatly enhances production efficiency.
Rongsheng refractory manufacturer, Rongsheng refractory manufacturer, is a refractory manufacturer with rich production and sales experience. In the design and solution of rotary kiln refractory lining materials, we also have many customer cases. Please contact us to design the configuration of refractory materials for the insulation layer of the rotary kiln for free. Our new type of insulation material products are of superior quality and can effectively reduce the temperature of the outer wall of the rotary kiln.
