Refractory castables in cement plants generally use high-alumina wear-resistant castables, steel fiber castables, low-cement castables, corundum castables, alkali-resistant castables, magnesia-chrome spray coatings, phosphate castables, etc. Of course, there are more high-end ones. For example, the castable for coal injection pipes uses alumina-silicon carbide series refractory castables, which is resistant to thermal shock and alkali. In addition, there are corundum-spinel castables, which have good high-temperature flexural strength and alkali resistance. Next, let’s learn more about the performance indicators of commonly used refractory castables in cement plants.
Refractory Castable in Cement Plants for Different Parts
The preheater uses a lower temperature, and generally uses cheaper alkali-resistant castables. The decomposition furnace is prone to skinning and blocking, and anti-skinning castables are generally used. The front and back of the rotary kiln have strong erosion at the mouth of the kiln. Generally, steel fiber castables, kiln mouth castables, and corundum castables are used. The temperature of the kiln door cover is relatively high and there is cold air. Generally, high alumina and low cement castable or steel fiber castable are used. The use conditions of the coal injection pipe are the most demanding, and the special castable for the injection pipe is generally used. When choosing refractory castables for cement plants, you need to look at the life cycle of the refractory castables. No matter how the name and grade of refractory castables change, it is important to meet the production needs of cement kilns. Rongsheng refractory material production and sales manufacturer is specialized in refractory materials for the cement industry. If your cement kiln needs refractory materials, please contact us.
High-Strength Refractory Castable
High-strength refractory castables are mainly used for parts that are easy to wear in thermal kilns, such as kiln mouths and coal injection pipes. It is formulated with corundum as aggregate, high-quality high-alumina cement as a binder, and a small number of additives. However, this kind of castable is prone to porosity during the pouring process, and it is easy to peel off during the pouring process, and strong growth is relatively slow. In the process of pouring and subsequent curing, drying, and heating, it should be more careful and delicate. JC498-92 “High-strength Alkali-resistant Castable” stipulates its main physical and chemical performance indicators as follows:
|High-strength Alkali-resistant Castable Physical and Chemical Performance Indicators|
|Items||Excellent Grade||Grade I|
|Al2O3 (%) ≥||93||93|
|SiO2 (%) ≤||0.5||1.0|
|CaO (%) ≤||4.0||4.0|
|Crushing Strength (MPa) ≥||110 ℃||80||60|
|Flexural Strength (MPa) ≥||110 ℃||8||6|
|Linear Change Rate (%) ≤||1100 ℃×3h||0.5||±0.5|
|Bulk Density after 110 ℃ drying (kg/m3) ≥||2900||2900|
|Refractoriness (℃) ≥||1800||1800|
|Note: The initial setting time is not less than 30min and not more than 240min.|
Steel Fiber Reinforced Refractory Castable
Steel fiber-reinforced refractory castables are made of high alumina bauxite clinker or corundum as aggregates and powders, adding binding agent and the appropriate amount of heat-resistant stainless steel fiber, or adding appropriate additives. The proportion of steel fiber in the clinker should be 4% (weight ratio). Steel fiber in the refractory castable greatly improves the anti-stripping performance of the refractory building material. The distribution of steel fibers has a great influence on the quality of concrete, and random distribution is better. Therefore, the time of vibrating should not be too long. The steel fiber castable must be poured at one time, otherwise, the possibility of peeling between the two layers is very high. The physical and chemical performance indicators specified in JC/T499-92 “Steel Fiber Reinforced Refractory Castables” are as follows:
|Steel Fiber Reinforced Refractory Castables Physical and Chemical Performance Indicators|
|Items||Ordinary Material||High-strength Material|
|Al2O3 (%) ≥||70||83||70||80|
|Crushing Strength (MPa) ≥||110 ℃||70||70||70||80|
|Flexural Strength (MPa) ≥||110 ℃||9.0||9.0||10.0||12.0|
|Linear Change Rate (%) ≤||1100 ℃×3h||±0.4||±0.5||±0.4||±0.5|
Other Refractory Castables
Common refractory castables often have a higher proportion of cement content (10%-15%, weight ratio). But this has caused a series of performance decline of the castable, the reasons are:
- In order to completely hydrate the cement, excessive water (10%-15%) is added during mixing, which will increase the porosity of the ceramic refractory castable and decrease the density.
- Calcium aluminate hydrate has a strong dehydration and recrystallization effect in the middle-temperature stage, which destroys the structure of the hard spots in the castable, and makes the strength of the refractory castable drop sharply in the middle-temperature stage.
- The cementitious binder brings more calcium into the castable, resulting in a decrease in the softening temperature of the ceramicist refractory castable under load and deterioration of thermal shock performance.
In view of the above problems, low cement refractory castables effectively avoid the regret of high-temperature section performance. Refractory castables with a cement content of less than 8% are called low-cement refractory castables; those with a cement content of less than 4% are called ultra-low cement refractory castables. Compared with ordinary refractory castables, its structure is dense, the apparent porosity is low, the refractoriness is high, the high-temperature strength is high, the load softening temperature is high, and the thermal shock performance is good. However, due to the low cement content, the setting time is long and the early strength is low, which is particularly disadvantageous for construction in winter and low-temperature conditions.
Chinese refractory materials companies have found in experimental research that adding a small amount of inactive powder (silica fume or Al2O3) below 5 microns into the castable can fill and lubricate the refractory, and can effectively reduce water consumption and increase the castable. The masonry is dense, thereby increasing the strength and resistance to chemical erosion. The low cement refractory casting performance indicators are as follows:
|Low Cement Refractory Castable Performance Indicators|
|Items||High Alumina Low Cement Refractory Castable||Corundum High-Strength Refractory Castable|
|GJ – 15B||LC – 160||GJ – 18S||C – 18S|
|Al2O3 (%)||70~75||75~78||≥ 90||≥ 93|
|SiO2 (%)||1.5~2.0||1.5~2.0||1.5~2.0||≤ 0.4|
|CaO (%)||15~20||12~15||5~7||≤ 0.5|
|Bulk Density (kg/m3)||2600||2700||3100||2880|
|Crushing Strength (MPa) ≥||110 ℃||100||100||100||80|
|Flexural Strength (MPa) ≥||110 ℃||12.0||14.0||14.0||8.0|
|Linear Change Rate (%) ≤||1100 ℃×3h||-0.4||-0.4||-0.4||–|
|Maximum Use Temperature (℃)||1500||1600||1700||1750|
|Reference Water Consumption (%)||5.5~6.5||5.5~6.5||5.5~6.5||7~9|
Rongsheng Refractory Castable Manufacturer
Rongsheng refractory castable manufacturer has an advanced and fully automatic unshaped refractory production line with an annual output of 80,000 tons. Rongsheng’s unshaped refractory products include high-aluminum refractory castables, wear-resistant castables, wear-resistant plastics, and anti-skinning castables. It can be applied to a variety of thermal kiln equipment, such as ladle lining, heating furnace lining, cement kiln lining, etc. It is widely used in steel, metallurgy, non-ferrous, chemical, and other industries. If you need to buy refractory castables, get the price of Refractory Castables in Cement Plants, please contact us. We will provide you with services according to your specific needs.