Kiln Refractories Blog

Combination Method of Alumina-Magnesia Castable

March 18, 2021 KilnRefractory

In recent years, due to the vigorous development of out-of-furnace refining technology and continuous casting technology, the ladle is also used as a vessel for holding molten steel and molten steel refining equipment, which greatly extends the residence time of molten steel in the ladle. This is accompanied by an increase in the tapping temperature and more severe smelting conditions. As a result, the service life of the inner lining of the ladle is greatly reduced. The ladle uses alumina-magnesia castables, including spinel-containing castables, and it has always been a development trend for integral casting.

High-Quality Alumina-Magnesia Refractory Castable

The Combination Method of Alumina-Magnesia Castable

Binder is an important part of alumina-magnesia castables. The bonding methods used for alumina-magnesia castables are generally calcium aluminate cement bonding, silica micro-powder bonding, hydrated alumina bonding, sol bonding, magnesium silicon water bonding, and so on.

Cement bonding

At the initial stage of development of alumina-magnesia castables, pure calcium aluminate cement is used. This is because the cement calcium aluminate will react with the Al2O3 in the matrix to form CA6, which is a highly refractory phase. However, as the number of cement increases, the fluidity of the castable decreases. At the same time, due to the excessive content of CaO at high temperatures, it will react with SiO2, Al2O3, and MgO in the matrix to generate a low-melting phase, which will reduce the high-temperature performance of the castable. Some refractory researchers have studied the effect of the amount of water added in cement on the thermal expansion behavior of alumina-magnesia castables after high-temperature firing. The results show that with the increase of cement addition, the phases of CA2 and CA6 in the sample increase, and the linear change rate of the sample after high-temperature heat treatment increases. In addition, some people have studied the influence of silica powder, magnesia, and cement on the properties of high-purity alumina-magnesia castables. The study pointed out that the pure calcium aluminate cement and the Al2O3 fine powder in the matrix start to react at about 1000°C to form CA2 and CA6, and the reaction is accompanied by volume expansion. It can reduce the intensity ratio after high- and medium-temperature firing, and also contribute to the improvement of the high-temperature performance of the sample.

MgO-SiO2-H2O combination

There are many kinds of researches on the combination of MgO-SiO2-H2O. The combination of MgO-SiO2-H2O is used in the alumina-magnesia castable. On the one hand, due to the polymerization of SiO2 gel formed by the interaction of SiO2 powder and water, the amount of water added is reduced, and the fluidity of the castable is greatly improved. On the other hand, the combination of MgO-SiO2-H2O can inhibit the hydration of magnesia, but too much silica powder will form a low-melting phase with impurities in the matrix. At the same time, the forsterite phase formed by the reaction of magnesia and silica powder in the matrix has poor thermal shock stability at high temperatures.

Composition Materials and Properties of Low Cement Alumina-Magnesia Refractory Castables

The slag resistance of low-cement alumina-magnesia refractories is similar to that of alumina-magnesia spinel castables but superior to alumina-spinel castables. Therefore, it is selected by users at home and abroad, especially in the Japanese steel ladle. In addition, the material is used in the desalinization pouring channel of the large-scale blast furnace tapping channel, and its life is longer than that of the Al2O3-SiC-C iron channel material.

The high-tech basis of low-cement alumina-magnesia refractory castables is high-grade raw materials and scientific formulas. Construction, baking, and careful process operation and maintenance are the guarantees of its long life. This material is used on a ladle of about 100 tons, and the ladle age is 60 ~ 120 times.

The performance of low cement alumina-magnesia refractory castables is excellent. The content of MgO is not more than 8%, and the content of Al2O3 is 89% ~ 97.6%, indicating that the material is excellent. The linear changes after firing are all positive values, the pores are low, and the strength is high, which is beneficial to the use of castables.

Low-cement alumina-magnesia refractory castables are developed on the basis of sodium silicate alumina-magnesia refractory castables and have been used on medium and small ladles with good results. When higher-grade refractory raw materials are used and the material formula is designed with scientific methods, high-tech low-cement alumina-magnesia refractory castables can be successfully formulated. It can be used on large and medium-sized ladle to improve the age of the ladle.

For more detailed information about refractory castables for kiln furnaces, please visit the website of Rongsheng Kiln Refractories Website: https://kilnrefractory.com/.

How to Choose Refractory Plastic or Low Cement Castable for the Top of the Heating Furnace?

March 2, 2021March 2, 2021 KilnRefractory

Use refractory plastics or low cement castables in different areas of the heating furnace roof? The temperature of the heating furnace varies greatly from the preheating section, heating section, and soaking section, and each part has different functions. When choosing plastic refractory or low-cement castables, the use performance and price factors must be considered, as well as the convenience of construction and the storage of products.

Unshaped Refractory Material for Heating Furnace Roof

Refractory plastic can not damage its packaging before construction. If the packaging material is damaged, the plastic can lose its plasticity. When storing and keeping the plastic, pay attention to the integrity of the plastic packaging.

If low cement castables are used, anchors must be welded. If the plastic material is fixed on the furnace roof by anchoring bricks, the tightness of the plastic material and the anchoring brick affect the quality of the plastic furnace roof.

Ramming around the anchor is very important when the fire-resistant plastic is constructed. Make wooden molds based on the shape of anchor bricks. When the plastic is rammed, a wooden mold is used to mold the plastic around the anchor bricks, and then the anchor bricks are inlaid in the mold. Pram around the anchor brick with the wind to make it come in close contact with the plastic. But be careful not to smash the anchor brick.

But plastic is more shrinking. After removing the mold, use an expansion joint knife to cut a 30-50mm expansion suture on the surface with an interval of about 1.5m, which means that the plastic surface is cut into 1.5m square blocks. But if the plastic shrinks, it will only crack in the opened expansion joint, and no cracks or cracks will appear.

If low cement castables are used, 20 anchors per square must be welded. Support the mold first, then pour the low-cement castable, take off the film after 24 hours, and then grill according to the barbecue system.

In short, whether fire-resistant plastic or low-cement castable is used, depends on the situation. If there is no condition to store plastics, low cement castables can be used. If the construction of low cement castables is inconvenient, refractory plastics can also be used.

How Long is the Setting Time of the Refractory Plastic?

Refractory plastic is an amorphous material that can maintain good plasticity for a long time. Next, we come to understand some characteristics of the refractory plastic from the setting time of the refractory plastic.

$The Setting of Refractory Plastic$

The refractory plastic can be in the form of a mud paste, or it can be separated from the powder and the binder. If you are in a hurry for construction or repair, it can be made into a mud paste. If the construction time is long, the powder and the binder can be packaged separately, so that they can be mixed and used during pre-construction.

The plasticity of the plastic has a great influence on the bonding strength and volume stability of its hardened body. It is the properties of clay that control the properties of refractory plastics. The plasticity is related to the properties and dosage of the clay, which increases with the increase of the binding dosage. If the binding dosage is too high, the fire resistance and plasticity are not strong, and it is best to control it at 5%-10% so that the plasticity of the plastics will not decrease during the shelf life. The binding agent is a special glue preparation.

The refractory plastic can be taken out from a sealed container during construction, or a special bonding agent can be added on-site to trap the material. The trapping time cannot be less than 10 hours. Then lay it between the hanging bricks or anchoring bricks and tamping with a hammer. In particular, the plastic can be processed into any shape before being hardened.

Refractory plastic In order to facilitate the drainage of water, holes should be punched at regular intervals. Expansion joints should also be set according to the design. If the part to be constructed is integral, first construct on the bottom form and then hoist it after drying.

The setting time of refractory plastic is 1-3 hours for the initial setting and 6-8 hours for the middle setting. It can reach 60-80% strength after one day of curing, 85%-95% of the strength is reached after 3 days of curing, and it can be used after 7 days of final strength.

Unshaped Refractory Material Sales

Rongsheng refractories production and sales factory have advanced and fully automatic monolithic refractory production lines. The annual output is 80,000 tons. Our unshaped refractory products mainly include various refractory castables, ramming mass materials, refractory plastics, low cement castables, wear-resistant refractory castables, etc. We can customize the formula of unshaped refractory materials according to the specific needs of customers. Our monolithic refractory products have a high rate of return orders from our monolithic refractory customers. Customers’ trust in us stems from our strict control of product quality. And we are committed to providing customers with high-quality customer service. To purchase high-quality unshaped refractory products, please contact us. We will provide you with the most suitable products for your project production needs according to your specific construction needs.

Methods of Increasing the Service Life of Silica Bricks in Glass Melting Furnaces

November 26, 2020 KilnRefractory

Traditional and new refractory materials are used for glass kiln construction and repair. Traditional refractory materials for industrial use include clay bricks, dense clay bricks, mullite silica bricks, mullite bricks, mullite corundum bricks, and corundum bricks. High-temperature insulation materials and high-purity magnesium spinel refractory materials. Unshaped refractories include plasticized aluminum silicate cement, high-alumina cement, and low-cement castables.

The use of refractory materials in glass melting furnaces. Silica bricks are widely used in glass melting furnaces, and the main component is silicon dioxide (SiO₂). The silica brick used in the glass melting furnace requires a SiO₂ content of 94% or more, a maximum operating temperature of about 1600~1650℃, and a density of 1.8~1.95g/cm³. The apparent porosity is required to be less than 22%. The larger the porosity, the worse the quality of the silica brick. The appearance of silica bricks is mostly white crystals, and the microscopic composition is tridymite crystals. Because silicon bricks undergo crystallization conversion and volume expansion at high temperatures, especially at 180~270℃ and 573℃, the crystallization conversion becomes more intense. Therefore, in the process of the baking kiln and cold repair, it is necessary to adapt to the crystal transformation of silica bricks and take appropriate measures such as elastic strips. The silicon brick masonry should be left with expansion joints.

How to Improve the Performance of Silica Brick in a Glass Kiln

The advantages of siliceous materials are high-temperature strength, good creep resistance, low density, no pollution to glass, and low price. The working temperature of silica bricks is about 200℃ higher than that of clay bricks, but the corrosion resistance to molten glass and alkaline flying materials is poor. Therefore, it is used for masonry structures such as masonry, parapets, and small furnaces. When masonry, use high-silicon refractory mud or silica brick powder and other materials close to the composition of silica bricks as the cementing material.

Ways to Improve the Life of Silica Bricks

In the 1980s, my country introduced advanced silicon brick manufacturing technology for glass kilns from the United States. In order to distinguish it from the original product, the product manufactured with imported technology is called high-quality silica brick. The composition (W) of high-quality silica bricks is cristobalite 45%, phosphorite 50%, glass phase 1%~2%, and a small amount of residual quartz. Melt index (2R2O+Al2O3)<0.5%.

After adopting oxy-fuel combustion technology, the life of silica bricks has been drastically reduced from 5 to 10 years to 2 to 3 years. Rat holes and erosion are the main causes of damage. The rat-hole is caused by the alkali in the gas leaking from the kiln condensing in the cracks of the brick to corrode the silica brick. The methods to improve the life of silica bricks are as follows:

1) Improve the dimensional accuracy of bricks. Control size tolerance <0.5mm, brick gap width <1.5mm. The cracks between the bricks are narrowed, the kiln gas leaks less, the erosion is light, and the mouse hole is also small.
2) Reasonably design the kiln lining structure. Move the condensation temperature zone of the alkali to the sealing layer behind the silica brick.
3) Use low-calcium silica bricks with good corrosion resistance (w(CaO)≈0.8%). Figure 4 shows the corrosion resistance test results of low-calcium silica bricks and high-quality silica bricks. It can be seen from Figure 1 that when the alkali vapor pressure is low, the corrosion resistance of low-calcium silica bricks is better than that of high-quality silica bricks.

The influence of alumina content on the performance of silica brick for glass kiln

The increase of Al2O3 content is unfavorable to the refractoriness, softening temperature under load, true density, and mineral composition of the product. But it has no obvious influence on the apparent porosity, residual line change, and creep rate.

Development of High-Purity, Corrosion-Resistant Glass Kiln Silica Brick

China’s glass output has ranked first in the world. The main task for the future development of refractory materials for glass kilns is to improve the design, masonry, and maintenance of the kiln, reduce the adverse effects on the quality of glass, and extend the service life of the glass kiln. Silica brick is the main refractory material in the masonry of the glass furnace and is mainly used for the ceiling, hanging wall, and front and back walls of the glass furnace. To increase the service life of glass furnaces, higher requirements must be put forward on the quality of silica bricks. Therefore, the study of high-quality silica bricks for glass kilns with high purity and corrosion resistance can extend the service life of glass kilns to a certain extent.

Rongsheng Refractory Brick Manufacturer

Rongsheng refractory brick manufacturer is an experienced refractory material manufacturer and sales manufacturer. Rongsheng’s refractory products have been sold to more than 60 countries and regions all over the world. For example, Russia, South Africa, Kazakhstan, Philippines, Chile, Malaysia, Uzbekistan, Indonesia, Vietnam, Kuwait, Turkey, Zambia, Peru, Mexico, Qatar, etc. Obtain high-quality refractory products for glass kilns, such as AZS bricks, silica bricks, fused corundum bricks, checker bricks for regenerators, etc. Please contact us, we will provide you with services according to your specific needs.

A Widely Used Refractory Material – Fireclay Refractory Bricks

October 27, 2020October 27, 2020 KilnRefractory

Fireclay refractory bricks refer to fireclay products with Al2O3 content of 30%-40% alumina silicate. The refractory temperature is 1690~1730℃. It has good thermal stability, and the number of times of water quenching and heating is 10-25 times, and it increases with the increase of clinker and coarse particle content. Refractory clay bricks are weakly acidic refractory materials, which can resist the erosion of acidic slag, but their resistance to alkaline slag is slightly weaker. Among all refractory materials, refractory clay bricks have the widest application range. For example, the protective bodies of various heating furnaces, heat treatment furnaces, cupolas, and drying furnaces are mostly built with refractory clay bricks. In addition, fireclay refractory bricks can also be used to build steel drum linings.

Rongsheng Fireclay Refractory Bricks for Sale

Refractoriness of Lightweight Fireclay Refractory Bricks

Lightweight fireclay bricks are lightweight refractory products with a porous structure with an AL2O3 content of 30%-46%, which are shaped refractories. Mainly use plastic mortar burnout additives or mortar foam method or chemically made porous products. The product has a wide range of uses and can be used for the thermal insulation layer of various high-temperature furnaces.

The specifications and sizes of lightweight fireclay bricks are divided into standard and special shapes. Standard specifications are available at Rongsheng refractory brick manufacturers, and special-shaped specifications and sizes can be customized according to drawings. Lightweight fireclay bricks are characterized by high porosity, uniform pore distribution, low volume density, good stability, and excellent thermal insulation properties.

Indicator of light fireclay bricks. The bulk density of commonly used lightweight fireclay bricks is 0.75-1.2g/cm3. The smaller the bulk density, the better the thermal insulation, and the lower the use temperature. The compressive strength is 0.98-5.88MPa, and the abrasion resistance is poor. It should be handled with care when handling or building. The thermal conductivity at 300°C is 0.795-2.93W/(m.k). The operating temperature is generally 900-1250°C, and the maximum operating temperature is 1200-1400°C.

The use temperature of light fireclay bricks of different bulk density has certain differences, and the price is also different. Therefore, the choice of light clay bricks depends on the operating temperature of the kiln and is based on the economy and practicality.

Masonry of Clay Refractory Bricks

Before choosing fireclay refractory bricks to build the furnace, the factory can calculate the approximate quantity needed to purchase in the furnace building plan. It can reduce unnecessary waste, and pay attention to the use of first-grade mortar joint masonry for masonry mortar joint.

When building clay bricks, it is feasible to prepare clay refractory mortar by yourself, clinker: raw material = 70%: 30%. Clinker is obtained by calcination of hard refractory clay at high temperatures. Waste bricks can also be used after being ground. The raw meal is light refractory clay.

If you want to calculate the various compositions of refractory mortar, just substitute the known weight of refractory mortar into formula (1) and formula (2).

(1) Clinker weight = refractory mortar weight x 70%

(2) Raw meal weight = refractory mortar weight x 30%

When using T-3 standard bricks (230x114x65mm) for masonry. The following figures should be memorized:

Each refractory clay brick weighs 3.7kg.
About 270 pieces of refractory clay bricks per ton.
Each ton of clay bricks requires about 76kg of refractory mortar.
It takes about 594 bricks per cubic meter of masonry.
Approximately 2.2 tons of bricks are required for each cubic meter of masonry.

Rongsheng Fireclay Refractory Bricks Manufacturer

Rongsheng T-7 Fireclay Refractory Bricks Manufacturer

T-7 fireclay refractory brick, unit weight 4.1kg, alumina oxide is greater than or equal to 65. Zhengzhou Rongsheng Refractory Material Factory fire clay bricks for sale mainly produces various types of high alumina and fireclay refractory bricks, low creep high alumina bricks, high alumina balls, corundum bricks, light insulation bricks, and magnesia carbon bricks. Refractory mortar for all kinds of kiln masonry, unshaped refractories of various materials for smelting and steelmaking. Shaped refractory products and unshaped refractory materials can be produced in accordance with general standards and special requirements of users. Contribute to the longevity, high-quality, high-yield, energy-saving, and consumption reduction of high-temperature industrial furnaces!

How to Improved the Performance of Low Cement Castables

September 26, 2020 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.

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

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.

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.
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.
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.
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

September 15, 2020 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.

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

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

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.

Preparation of 65% Zircon Brick

July 17, 2020September 15, 2020 KilnRefractory

Zircon (ZrSiO4) belongs to the tetragonal system. The theoretical composition is 67.2% of Zr02 and 32.8% of SiO2, which is the only compound in the binary system of Zr02-Si02. 65% Zircon Brick. The thermal expansion coefficient is small, the load softening temperature is high, the thermal shock stability is good, and the thermal conductivity decreases with increasing temperature. Therefore, As the refractory materials manufacturer said, the zircon refractory brick is an indispensable material for industrial kilns such as building materials, light industry, electronics, metallurgy, and so on.

In recent years, with the advancement of glass industry technology and the application and promotion of kiln insulation technology, the amount of machined 65% Zircon Brick has been increasing. Mainly used in the gap, upper partition wall, fire observation hole, temperature measurement hole, and other parts of the glass kiln. The temperature of this part is high and it is eroded by flying materials and eroded by hot airflow, so the environment is very engraved.

RS Zircon Refractory Bricks Manufacturer

Preparation of 65% Zircon Brick

To produce zircon bricks with a Zr2O3 content greater than 65%, the content of the raw material Zr2O3 used must be greater than 66%. The decomposition temperature of the zircon is 1676℃. As the content of impurities increases, the decomposition temperature decreases. The high purity of the raw materials is the primary condition for the production of zircon refractory bricks with 65% zirconium with excellent properties.

The raw material of zircon is granulated and cannot be directly used for making bricks, but must be ground into a fine powder. Because zirconite has a large wearability index, the fine powder is obtained by vibrating mill and air-jet mill.

Due to the use of 65% zircon brick containing ZrO2. The material should have good high-temperature physical properties, and the aggregate is closely related to it. The zircon sand is ground first, then made into a green body, which is crushed into different particle sizes after high-temperature calcination. Because the zircon material is brittle, the broken particles are in the form of flakes. The normal temperature compressive strength of sheet materials is about 50% higher than that of granular materials. On the contrary, under the same conditions, the bulk density of granular granules is 0.12g/cm³ higher than that of flakes on average. Taking into account the compressive strength and density performance, the crushed material must be properly treated before it can be used.

The batch materials are mixed on a wheel mill mixer, and the materials are trapped for 16 hours, and then formed on a large-tonnage friction brick press. The forming pressure is 700~1000Kg/cm³. Applying large pressure can cause the average distance between adjacent particles to decrease and the contact area to increase, which is beneficial to sintering. But after increasing to a certain level, the effect is extremely insignificant. Appropriate pressure and pressurization methods are the keys to solving the formation of barren materials.

The sintering of zircon is more difficult, and its speed is slow due to solid-phase diffusion at high temperatures. Adding MgO, CaO, Y2O3, TiO2, ZnO2 can reduce the sintering temperature and promote its sintering. In this sintering, 1.5% to 2.75% of Y2O3 and TiO2 were added as sintering accelerator, sintered in a shuttle kiln, and the firing temperature was 1580 to 1650℃.

RS High Quality Zircon Bricks — RS High-Quality Zircon Bricks

Use Performance of Zircon Brick in Steel Ladle

The use performance of zircon bricks in steel Ladles is also called zircon bricks in steel Ladles. It is made of zircon as the main raw material and participates in the combination of a certain amount of fused alumina, high-silica content of clay soil, clay, and chromium oxide. This kind of steel barrel lining bricks has been developed abroad for a long time. In order to improve the uneven erosion of semi-silicon brick steel lining bricks, it gradually expanded from strengthening local lining to all lining bricks. As a result, the service life of large steel Ladles is increased by 2 to 3 times. In order to meet the use of the first phase of Baosteel in China, this brick has been developed and used.

The defects of zircon bricks are slag, steel, and spalling. The main reason is that it is not easy to reduce the porosity due to the zircon brick, and it is affected by the infiltration and the glass property generated in the matrix part. The advantage is that the service life can reach more than 100 times, which is conducive to the turnover of the steel drum. The high cost of this kind of brick is also limited by the source of domestic raw materials, which restricts its development.

Detailed Information of Alumina Silicate Refractory Mortar

July 8, 2020 KilnRefractory

Alumina Silicate Refractory Mortar includes clay, mullite, and high alumina refractory mortar. All alumina silicate refractory mortar is added with clay, the main purpose is to improve its adhesion.

The alumina silicate refractory mortar is made of 160-200 mesh powder. In general, different grades of refractory mortar are based on the grade of alumina silicate fire brick built with a refractory lining. For example, 75 high-alumina bricks, the refractory mortar with the aluminum content of 65 is used, and the 65-high-aluminum bricks are prepared with 55-60 high-alumina mortar. High alumina bricks with an alumina content of 55 are formulated with a slurry content of 45-50. Some refractory bricks with high alumina content also need to add corundum powder when configuring brick fire clay to meet the needs of brick distribution.

If it is used in the blast furnace hearth and other parts, phosphate combined refractory mortar is also used. In this way, the service life can be more guaranteed, and the gray seam does not shrink during use.

RS Castable Refractory Mortar Manufacturer

Some of the refractory mortar used in large-scale blast furnaces, many of which are added with andalusite, quartz powder, or kyanite, is to ensure that the crevice does not shrink when sintered.

Some refractory mortars with low aluminum content generally do not add a binder. However, in order to improve the bonding strength, a certain proportion of bonding agents will be added, such as phosphoric acid, water glass, polyphosphate, etc. With the change of the addition of the binding agent, the bonding strength also changes after firing, but the strength at the high temperature and hot state is opposite. Adding the binding agent will cause the liquid phase in the refractory mortar to increase at high temperatures. Sodium polyacrylate and methylene naphthalene sulfonate are added to the binder to prevent solid-liquid separation of the prepared refractory mortar during standing. The addition of methylcellulose can also be prevented.

Aluminum silicate refractory mortar belongs to a water-based refractory mortar and cannot be built with carbon bricks or the like. Because the water vapor volatilized by the water-based mortar in the oven and use has a destructive effect on the carbon brick masonry. Therefore, the non-aqueous refractory mortar is used. learn more from Rongsheng Refractory mortar manufacturer.

Volume Stability of High Alumina Castables

June 30, 2020June 30, 2020 KilnRefractory

For a long time, high silica bricks have been used for tundish refractory. Today, low-cement and high alumina castables have widely replaced high-silica bricks by increasing life to reduce costs and improve working conditions. Because MgO coating must be applied to the tundish permanent castable. For high aluminum castables, volume stability is very important.

Although high-alumina refractory castables have higher mechanical strength and better corrosion resistance, cracks occur due to insufficient volume stability. Metal attachments penetrate through the cracks, resulting in a reduction in their life and an increase in local maintenance.

Performance of Light-weight High Alumina Castable

High-performance light-weight high-aluminum castable improves its strength and reduces thermal conductivity. The castable has better construction performance and higher medium-high temperature strength. The compound combination method of hydration combination and coagulation combination can improve the normal temperature and high-temperature performance of the castable. The developed high-performance light-weight high-aluminum castable has low thermal conductivity, high high-temperature strength and volume stability. It is used in high-temperature parts of various industrial furnaces from 1200 to 1500 ℃ and has achieved good results. The energy-saving effect is obvious.

Experiments have shown that:

(1) The method of adding ultra-fine alumina powder can improve the construction performance of high-aluminum castables. However, as the ultrafine alumina content increases, the volume stability after firing decreases.

(2) If mullite is added to the matrix instead of alumina, the volume change after firing will decrease, but the construction performance will also decrease with the increase of mullite content.

(3) When andalusite is added to the matrix, the construction performance is reduced a lot, but the volume stability is greatly improved. Therefore, if the plasticity of andalusite is improved, andalusite is a good material of choice for the matrix of high-alumina castables that require high volume stability.

The high-performance light-weight high alumina castables are fully considered, and various related factors that affect the castables are fully considered. In the case of reducing production costs and meeting the conditions for the use of castables, optimize the composition and configuration of castables, formulate a reasonable production process, and strengthen process control. Castable manufacturers have produced a series of high-performance light-weight high-aluminum castables with a bulk density of 1.30 g/cm3, 1.50 g/cm3, and 1.80 g/cm3 to meet various working conditions.

Application of Lightweight High Alumina Castable

The performance of lightweight high-aluminum castables determines the energy-saving effect of thermal kilns. With the rapid development of various industries, the number and scope of light-weight castable applications are gradually expanding. From the permanent layer, the heat insulation layer to the working layer, from the low-temperature part to the high-temperature part, the transition from low load environment to high load environment. insulating castable. At present, the technology of lightweight high-alumina castables used in the working layer in the middle and low temperature (<1 200 ℃) and high temperature (>1 500 ℃) parts has basically matured performance. However, the performance of lightweight castables used in the medium and high-temperature range (1 200 to 1 500 ℃) needs to be improved to meet the new requirements for the use of lightweight high aluminum castables.

Rongsheng Refractory Castable Manufacturer

Rongsheng refractory castable manufacturer has a fully automatic refractory castable production line. The high-performance light-weight high alumina castables produced by Rongsheng are characterized by high strength, low thermal conductivity, and excellent construction performance in the working environment above 1200 ℃. And it has great significance in the research and application of energy-saving technology, energy-saving equipment, and energy-saving materials.

Refractories for Regenerators

June 19, 2020June 19, 2020 KilnRefractory

The regenerators chamber is a waste heat recovery device that exchanges heat through medium heat storage and heat release. The main structure includes wall, lattice, bottom flue, grate arch-supporting lattice, etc. Therefore, it is also called the regenerator checker chamber. Its internal structure, lattice structure and material are the key factors that affect heat recovery efficiency and process characteristics. Refractories for Regenerators, as it is listed in the following text, will help you understand more.

Checker Bricks for Hot Blast Stoves Regenerators

Selection of Checker Bricks for Regenerators of Hot Blast Stoves

The regenerator of the hot blast stove is a space filled with checkered bricks. Its main function is to use the internal checker bricks to participate in the heat exchange between high-temperature smoke and combustion air.

Therefore, the checker brick as heat storage and heat transfer medium should have a larger heat receiving area, higher thermal conductivity and quality to facilitate heat exchange and heat storage. The method of increasing the heating area is to increase the number of holes in the checker brick per unit area. Therefore, the number of holes in the lattice brick of the regenerator tends to increase. Refractories for regenerators.

In order to improve the thermal conductivity of the material, black silicon bricks are commonly used in lattice bricks inside regenerators in Europe. Because the content of iron oxide in the black silica brick is high, the density is large, the thermal conductivity is large, the heat storage capacity is strong, and the heat exchange efficiency is high.

Therefore, the upper part of the regenerator is made of silicon lattice brick. Low creep high alumina brick, mullite brick, sillimanite brick, andalusite brick, etc. are used in the middle of the regenerator. Clay bricks are generally used in the lower part of the regenerator.

Coke Oven Regenerator

The single vertical wall, partition wall, bottom, and lattice bricks of the small coke oven regenerator can be built with clay bricks. Refractories for regenerators. The large and medium-sized coke oven regenerators are all made of silicon bricks in the upper and middle masonry, so that the whole coke oven can be evenly expanded.

The small flue is located at the bottom of the regenerator and communicates with the flue. The small flue is made of clay bricks.

Refractory Material for Glass Kiln Regenerator

At present, there are two main options for the selection of checker bricks used in the regenerators of glass kilns:

(1) Alkaline brick scheme

The lattice bricks on the top layer of the regenerator of this scheme use directly combined high-purity magnesium bricks. The upper layer is made of ordinary fired magnesium brick. The middle layer is made of magnesia chrome brick or forsterite brick which is resistant to sulfate attack. The lower layer uses low porosity clay bricks. The transition material between magnesia brick and clay brick is made of anti-stripping high-alumina brick.

(2) Scheme of fused zirconium brick

The entire lattice body of the regenerator is made of the same cross-shaped fused zirconium corundum lattice brick (ER-1681). According to reports, recently, fused β-alumina material has been selected as the top checker brick.

The top of the regenerator is often made of fused AZS brick, directly combined with magnesium brick or silicon brick. The upper layer of the sidewall and the partition wall is made of magnesia brick, the middle layer is made of magnesia brick or low porosity clay brick, and the lower layer is made of low porosity clay brick. Grate bricks with low porosity are used for the grate.

After choosing a scheme suitable for the kiln regenerator, the quality of its refractory materials, the construction quality of the refractory bricks, and the subsequent oven, maintenance, and daily operations are also the key factors that affect the safe operation of the kiln. Therefore, these steps must be completed in accordance with the design requirements. Avoid economic losses caused by kiln problems.

Rongsheng Refractories for Regenerators Manufacturer

Rongsheng is an experienced manufacturer, who is a professional at refractories. The refractory products of Rongsheng refractory manufacturers have been sold to more than 60 countries and regions around the world. Such as Malaysia, South Africa, India, Indonesia, Pakistan, Netherlands, Kuwait, Kenya, Russia, United States, etc. Rongsheng’s experienced refractory brick production line, as well as the fully automated production line of unshaped refractory castables, are the symbol of Rongsheng’s strength. Rongsheng’s unshaped refractory materials production line, with an annual output of 80,000 tons. If you need to purchase refractories for regenerators, Please contact us or by mail with your specific needs. We will reply to you in the shortest time.