Month: September 2020

How to Improved the Performance of Low Cement Castables

KilnRefractory

The low cement castable in the unshaped refractory is a castable with a CaO content of less than 2.5% in the refractory castable combined with calcium aluminate cement. That is to say, the amount of calcium aluminate cement added is about 1/2 to 1/3 of the castable of ordinary calcium aluminate cement. Rongsheng refractory material manufacturer has advanced and fully automatic monolithic refractories material production line. Next, let’s understand the use and advantages of low cement castables, as well as the performance improvement of low cement castables.

Low Cement Castable Refractory Material
Low Cement Castable Refractory Material

Application of Low Cement Castables

Low cement castables are mainly used in metallurgy, electric power, nonferrous metals, petrochemical, building materials, and other industries. Such as the bottom of the glass kiln, the front end of the front and rear kiln door cover coolers of the cement kiln, and other high-temperature resistant parts, the front, and rear kiln mouths, coal injection pipes, etc. Various heat treatment furnaces such as heating furnace and soaking furnace. Intermediate frequency induction furnace lining, the high-temperature wear-resistant lining of the petrochemical catalytic cracking reactor, lining of other industrial furnaces, etc. The construction methods of on-site pouring, smearing, and ramming can be used.

Rongsheng Low Cement Castable Manufacturer
Rongsheng Low Cement Castable Manufacturer

Advantages of Low Cement Castables

Different from traditional refractory castables, the matrix of low-cement castables replaces part or most of the calcium aluminate cement with superfine powder with the same or similar chemical composition as the main material of the castable with a cohesive bonding effect. Therefore, low cement castables are castables that coexist with hydration and cohesion. Due to the use of ultrafine powder (micro powder) to replace part of calcium aluminate cement, low cement castables have the following advantages.

  1. The low content of CaO in the castable can reduce the formation of the eutectic phase in the material. Thereby improving the refractoriness, high-temperature strength, and slag erosion resistance.
  2. The mixing water consumption of the castable during construction is only 1/3~1/2 of the ordinary castable, so the porosity is low and the bulk density is high.
  3. After pouring and molding, less cement is generated during curing. Therefore, there is no damage to a large number of hydration bonds during heating and baking, resulting in a decrease in the medium temperature strength. But as the heat treatment temperature increases, the strength gradually increases.
  4. With proper adjustment of the strength and composition of the castable, it can be formulated into self-flowing castable and pump castable.

Improve the Performance of Low Cement Castables

Low-cement castables have the advantages of less water addition, high density, good volume stability, and high strength, so they are widely used. However, due to its poor air permeability, it is prone to bursting, peeling, and peeling during baking and ignition. Severely, it even leads to the overall destruction of the construction body, causing serious losses to users. Therefore, how to improve and increase the explosion-proof performance of low-cement castables is of great significance to the practical application and development of low-cement castables. At present, the main method to improve the explosion-proof performance of castables is to add explosion-proof fibers to the castables to increase the permeability of the castables.

Studies have shown that the increase in the amount of explosion-proof fiber has a significant effect on increasing the apparent porosity of low cement castables and improving the explosion-proof performance of low cement castables. The reduction of the content of silicon carbide has an effect on improving the burst resistance of low-cement castables, but the effect is not significant. The increase of the content of silicon carbide has a significant effect on improving the thermal shock stability of the low cement castable heat-treated samples at 1400℃.

To learn more about refractory products, please visit our website: https://kilnrefractory.com/.

Learn More About Refractory Castables for Kiln Hood

KilnRefractory

During the cement clinker calcination process, the kiln hood is located at a very special position, and it rotates rapidly with the kiln body and is affected by rapid changes in temperature and heat. Therefore, the Refractory Castables for Kiln Hood is a part that needs to be paid attention to and maintained in production.

Cement Rotary Kiln Hood Construction
Cement Rotary Kiln Hood Construction

Why the Refractory Castables for Kiln Hood the Short Service Life?

The castable at the entrance of the kiln is at the end of the rotary kiln. It is easy to cause a large temperature difference in a short time, causing cracks in the traditional Refractory Castables for Kiln Hood. In severe cases, a large area of castable will fall off.

The axial thermal expansion of refractory bricks in the kiln is quite large. If no corresponding measures are taken, the axial stress generated is very surprising. Take magnesia bricks as an example. When the barrel is fired at 300°C, the brick will expand by as much as 50mm than the barrel. When the inner surface of the lining material reaches 1300°C and the outer surface reaches 200°C, the thermal stress of up to 660Mpa will be formed. This huge thermal stress acts on the front kiln hood, causing the back iron to tilt outward, which in turn causes the refractory to loosen and fall off.

The high-temperature clinker continuously scours and abrades the kiln hood part of the cement kiln, making the Refractory Castables for Kiln Hood mechanical damage more intense. In addition, because the metal shell of the kiln is not completely rigid, the ellipticity of the kiln is also affected. Large or small deformations occur in the kiln shell during rotation, causing compression, tension, and shear stress in the kiln lining. Coupled with the continuous relative displacement and local stress between the refractory bricks in the kiln, the castable at the kiln hood fractures and peels off.

Based on the above-mentioned reasons, the conditions for using the lining at the kiln hood are very harsh, and the requirements for Refractory Castables for Kiln Hood are extremely high.

RS Steel Fiber Refractory Castable Manufacturer
RS Steel Fiber Refractory Castable Manufacturer

Refractory Castables for Kiln Hood

The Refractory Castables for Kiln Hood include corundum steel fiber castable, kiln hood anti-stripping castable, new-type low-expansion castable, high-strength explosion-proof castable, and corundum mullite castable.

The corundum steel fiber castable is made of high-density, high-melting, tabular corundum as the main raw material, which has the excellent high-temperature performance. The high-temperature alkali resistance is good, and the alkali resistance level at 1350℃ can reach above level 2, which solves the problem of poor alkali corrosion resistance of corundum castables. It has good thermal shock stability and avoids the phenomenon of product peeling and falling off during use.

The kiln hood anti-stripping castable adopts in-situ synthesis reaction technology. The mullite phase is formed in the material matrix part at high temperatures to improve the high-temperature thermal strength of the material. Improve the material structure and mineral composition, and improve the thermal shock stability of the material. The material has a strong resistance to erosion and abrasion at high temperatures. It has excellent alkali resistance, and the alkali resistance level at 1350°C can reach level 2 or higher. The material is moderately priced, cost-effective, and has good results.

The high-strength explosion-proof castable uses raw materials with high purity, low impurities, and high refractoriness. In addition, the composition of the matrix is strictly controlled, and the mullite crystal phase is formed at high temperatures, which improves the thermal strength of the castable and has good thermal shock stability. It also enhances the anti-erosion performance and wear resistance of the castable, and extends the service life. This product is an explosion-proof castable with good anti-cracking performance and can meet the needs of emergency repairs.

Corundum mullite castable is also called corundum mullite wear-resistance castable. The refractory raw materials of corundum and mullite contain abrasion resistance, so they are refractory castables named after raw materials and properties. The characteristics of corundum and mullite castable have the common advantages of corundum and mullite castable. Part of the matrix reacts in situ to form a mullite phase at high temperature, which improves the high-temperature thermal strength and thermal shock stability of the cast lining. It has high temperature and high compressive strength, thermal shock resistance, and structural peeling resistance. Good high-temperature volume stability and thermal shock resistance, high load softening temperature, low high-temperature creep rate, and good chemical corrosion resistance.

Corundum Mullite Refractory Castable For Sale
Corundum Mullite Refractory Castable For Sale

Rongsheng Refractory Castable Manufacturer

Rongsheng is a manufacturer with advanced refractory castable production lines. Rongsheng’s monolithic refractories workshop adopts a fully automatic production line with an annual output of 80,000 tons. In the same industry, it is in the leading stage. In the process of accumulating many years of production and sales experience, Rongsheng Kiln Refractory Manufacturer is recognized by customers in more than 60 countries around the world. For more information about Rongsheng refractory manufacturers, or to purchase refractory castables for kiln hood, please contact us. We will provide you with services according to your specific needs.