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What are the Factors that Affect the Performance of Self-Flowing Castables?

2025-05-23 by globalrefractory

At present, most of the iron troughs of large blast furnaces use vibrating castables, which have many disadvantages due to the influence of many factors. For example, due to the influence of workers’ on-site operation technology, the vibrator does not vibrate enough, resulting in insufficient density of the cast body, excessive vibration and particle segregation, and it is easy to leave cavities when the vibrating spoon is pulled out. In addition, the vibrator is too noisy, affecting the construction environment. Self-flowing castables can automatically flow, flatten, compact and solidify without vibrating with a vibrator, avoiding the problems of vibrating castables. In order to meet the needs of the iron troughs of modern large blast furnaces, refractory manufacturers have developed self-flowing castables suitable for the iron troughs of large blast furnaces.

Rongsheng Self-Flowing Refractory Castable for Sale

Application Advantages of Self-Flowing Castables

After France developed self-flowing castables, Japan studied self-flowing iron channel castables, which were developed based on low-cement and ultra-low-cement castables. It is a viscoplastic material with a low yield value and a certain plastic viscosity developed based on the principle of rheology. Its advantages are:

(1) No vibration is required, and it can be automatically poured and compacted, greatly reducing labor intensity.
(2) Compared with vibrating castables, the pore size is small and evenly distributed.
(3) If the pumping process is used during construction, labor is reduced and work efficiency is improved.
(4) It has stronger adaptability than vibrating castables and can be cast in any shape.
(5) The performance is equivalent to or better than that of vibrating castables.
(6) Reduce noise pollution.
(7) It is easy to conduct construction performance tests on-site.

Therefore, the application of self-flowing castables has gradually become popular, and its scope is constantly expanding. Some people think that the performance of self-flowing castables is not as good as that of vibrating castables. It is outdated. By optimizing the particle size and matrix composition, self-flowing castables can be comparable to vibration castables of the same material in terms of water addition, density, and strength, and some properties are even better.

Factors Affecting the Fluidity of Self-Flowing Castables

There are many factors that affect the fluidity of self-flowing castables, mainly particle grading, water reducer, micro powder, cement type, and addition amount. They will be described below.

Effect of particle grading on the performance of self-flowing castables

The most famous and convenient stacking pattern in the field of refractory materials is the Andreassen distribution pattern. To obtain the best flow performance, an optimal stacking pattern is required. The Andreassen pattern basically solves this problem.

It is reported that when the particle composition is coarse particles (>1mm): 35%~50%; medium particles (1~0.045mm): 16%~30%; fine powder (<0.045mm): 23%~40%, vibration-free castables can be obtained. When the critical particle size is 8mm, the self-flowing castable can be obtained when its R (R=coarse particles/fine particles) is about 1.9. As the R value decreases, the self-flow value decreases significantly, and the viscosity of the castable increases. When the critical particle size is 5mm, the R value is between 1.5~1.85 to obtain self-flowing castables.

In addition, because self-flowing castables are developed based on rheological principles. It is a viscoplastic material with a low yield value and a certain plastic viscosity. Therefore, it requires a suitable particle size composition and an appropriate ratio of aggregate to matrix. As shown in the figure. When the particle composition is in zone 1, coarse and fine particle segregation will occur. When it is in zone 2, coarse particle collapse will occur. When it is in zones 3 and 4, a strong plastic state will occur. Only in zone 5 will it have self-flowing properties.

Effect of water reducer on the performance of self-flowing castables

Common water reducers include sodium hexametaphosphate, sodium tripolyphosphate, and high polymers. Different bonding systems should use appropriate water reducers. For example, sodium tripolyphosphate and sodium hexametaphosphate are more effective for silicon micropowder than for alumina micropowder. For silicon-free micropowder systems, high polymers are more effective as water reducers, and there are also quite strict requirements on the amount of water added.

Water reducer is a surfactant. The added inorganic and organic water reducers are both anionic. When dissolved in water, inorganic water reducers ionize anionic groups M and organic water reducers ionize anionic groups N. Since M is not a hydrophobic group, its surface activity is not significant, and it is mainly adsorbed on the surface of colloidal ions in the form of chemical adsorption. The organic anion group N is a hydrophobic group with strong surface activity, which is adsorbed on the surface of colloidal ions in the form of physical adsorption. A double electric layer is formed on the surface of cement and ultrafine powder particles, thereby changing the electromotive potential of the particle surface. Generate electrostatic repulsion between particles, so that cement ultrafine powder particles repel each other, disperse particles, and prevent the spontaneous formation of particle flocculation structure. And make the particles fully dispersed, homogenized and fill tiny gaps, release the water bound by the condensed particles, and fully wet the particle surface. It has a certain fluidity, and the macroscopic manifestation is that the rheological parameter shear stress of the slurry is reduced and the rheological properties are improved. In short, inorganic water reducers mainly rely on the electrostatic repulsion mechanism of changing and increasing the electromotive potential of the particle surface to achieve the purpose of dispersion. Organic water reducers mainly rely on the surface activity of organic water reducers to achieve the purpose of dispersion.

Effect of micropowder on the performance of self-flowing castables

1) Effect of silicon micropowder on self-flowing castables

Silicon micropowder has good rheological properties. When the same fluidity is achieved, as the amount of silica fume added increases, the amount of water added decreases, which enhances the filling property of the material, thereby increasing its volume density and reducing its apparent porosity. This is because there are a large number of ultrafine particles in SiO2 micropowder, which have a large specific surface area. In water, the surface of these particles is positively charged by adsorbing surfactants and has a certain zeta potential. The electrostatic repulsion between particles with the same charge causes the particles to disperse and form a uniform, low-viscosity slurry, which is dispersed between aggregate particles. It reduces the friction between aggregate particles, acts as a lubricant, and is conducive to improving the fluidity of the castable.

In ordinary castables, silicon micropowder becomes the first choice to obtain higher mechanical strength under the premise of lower water addition. The many chemical and physical properties of silicon micropowder directly affect the various properties of the castable. The higher the carbon content, the greater the pH value, and the construction time is drastically shortened. The higher the silica content, the better the construction performance when the pH value is around 7 and the carbon content is less than 0.5%.

When the same silicon powder is used, the mechanical strength at room temperature increases with the increase in the amount added, and the high-temperature flexural strength reaches the highest value at a certain value. After that, the flow value decreases with the increase in the amount added, the strength performance decreases, and the high-temperature performance also deteriorates. In particular, the linear change rate has a significant increasing trend.

Therefore, silica fume plays a good role in improving the construction performance of castables, but has an adverse effect on the strength after high-temperature firing.

2) Effect of alumina powder on the performance of self-flowing castables

In the Al2O3-SiO2 system, alumina powder is an indispensable filler. As a key parameter in the formulation, alumina powder affects the sintering degree and strength of the castable when determining the flow of the castable.

The literature points out that adding alumina powder with a moderate specific surface area and low Na2O content can obtain better flow properties. Of course, the additive system used for each alumina powder may be different.

Although alumina powder can promote sintering, it cannot be added too much because it can cause the castable to shrink significantly.

Both silicon powder and alumina powder have a filling effect on the capillaries, releasing the free water in them, increasing the solvent ratio of the system, weakening the thixotropic structure, and reducing the viscosity. When the amount of ultrafine powder added is small, there are a large number of capillaries, and the ultrafine powder mainly shows a filling effect. When the amount added is large, the capillaries are saturated and filled, and the ultrafine powder mainly shows a participating effect.

Effect of cement on the performance of self-flowing castables

The biggest influence of cement addition on the strength value of self-flowing castables is the strength value. As the amount of cement added increases, the drying strength also increases. For fluidity, it is not as sensitive as ultrafine powder and admixtures within a certain range. But relatively speaking, as the amount of cement added increases, its flow value tends to decrease.

In addition, the type and amount of cement added affect the initial setting time and final setting time. Therefore, the type and amount of cement added should be determined according to the construction conditions.

In addition to particle grading and particle shape, micro powder variety and addition, water reducer variety and addition, the factors affecting flow performance include cement fineness, activity and setting time, mixer type and mixing time, which all have an impact on self-flowing performance. This requires that, in the research and production of self-flowing castables, different measures should be taken according to the specific conditions of production and construction, and the best construction performance and use performance should be obtained through experiments.

The Important Role of Checker Bricks in Coke Oven Systems

2025-05-202025-05-02 by globalrefractory

Coke oven checker bricks play a vital role in the coke oven system. They are designed to absorb and release heat with high efficiency, transferring the heat of the exhaust gas to the cold air or blast furnace gas through the heat exchange process in the regenerator, thereby significantly increasing the temperature of these gases. This process not only helps to reduce the gas consumption required for coke oven heating, but also reduces energy consumption and carbon emissions in the coking process.

How do Checker Bricks Work in Coke Oven Systems?

Specifically, checker bricks work in the following ways:

‌Heat exchange‌: During the combustion process, when the hot exhaust gas passes through the regenerator, the checker bricks absorb most of the heat, significantly reducing the temperature of the exhaust gas. Subsequently, when the cold air or blast furnace gas passes through the regenerator, the checker bricks release their stored heat, preheating these gases to above 1000℃.

Reduce energy consumption and emissions‌: Through this heat exchange process of rising and falling airflows, the coke oven can effectively recover and utilize heat, thereby reducing dependence on external heat sources, reducing energy consumption and carbon emissions.

Maintain uniform furnace temperature‌: The unobstructed and good heat storage capacity of the regenerator is essential to maintaining uniform furnace temperature, which is of great significance for reducing production costs and reducing environmental pollution.

In summary, coke oven checker bricks, through their unique heat exchange mechanism, not only improve energy utilization efficiency, but also contribute to environmental protection, and are an indispensable component of the coke oven system.

Construction steps and methods for coke oven heat storage chamber masonry

Laying of sliding layer in coke oven heat storage chamber

Build the foundation platform first, adjust and correct the resistance wall, and prepare to lay the sliding layer after passing the inspection.
When using river sand to lay the sliding layer, the river sand must be flat and uniform in thickness.
A layer of petroleum asphalt felt must be laid between the refractory bricks and the river sand sliding layer before masonry.
When using thin steel plates as sliding layers, the following requirements should be observed:

- (1) The sliding layer should be laid once before bricklaying, and the bottom of the steel plate should be coated with yellow dry oil before laying.
- (2) After the steel plate is laid and inspected and passed, apply a thin layer of yellow dry oil on the surface of the steel plate, then lay a layer of petroleum asphalt felt, and then lay bricks.
- (3) It is strictly forbidden to recycle mud with oil stains.

Bricklaying process of small flue and regenerator wall in coke oven regenerator

Before laying the small flue, mark the width edge of each wall at the center line mark of the combustion chamber, and mark the height line of each brick layer on the vertical pole. You can also use the method of measuring and laying out the lines by wall.
The first layer of masonry of the small flue should be pre-laid dry. After checking that the width of the reserved expansion joint is qualified, lay out the lines to lay out the furnace head of the main wall of the small flue.
The furnace head position needs to be laid several layers of bricks at a time, and the wall should be stepped to prevent the furnace head from shifting on the sliding layer.
During masonry, check and verify the horizontal and vertical degree of the masonry according to the center line many times to prevent the furnace wall from twisting.
The masonry process should be cautious and careful, and the furnace head position should not collide. When changing shifts, first check and confirm whether the furnace head position has been moved and make adjustments.
Check the straightness of the masonry wall at any time. After the small flue wall is completed, check the brick layer elevation and gradually level it.

Laying process of lining bricks and grate bricks in coke oven regenerator

Lay the center partition wall first, and then lay the lining bricks after the masonry is completed and the construction area is cleaned. The laying order should be from the center to both sides.
Lay yellow cardboard when laying bricks, and use wooden supports to fix the lining bricks after they are laid to ensure that the width of the expansion joint between the lining bricks and the furnace wall does not change during laying.
After the lining bricks are laid, clean the bottom and wall of the small flue, lay a layer of 10-15 mm clean sawdust at the bottom of the small flue, and then lay the grate bricks layer by layer from the center to both sides. The refractory mud squeezed out of the brick seams of the brick layers should be cleaned at any time.
When laying grate bricks with holes, strictly check the aperture of the grate bricks, and then lay them after they are qualified. When laying grate bricks in air and gas regenerators, first carry out pre-laying dry laying and seam inspection respectively, and then formally lay them.
Use a wooden ruler to check the straightness of the grate brick leg platform. The gap error should meet the construction requirements.
After the grate brick is laid, clean the expansion joint and inspect it. If it is qualified, lay a wooden protective plate on the grate brick. The gap between the protective plate and the wall shall not exceed 15 mm.

Coke oven heat storage chamber wall brick laying process

Use the matching refractory mud for the corresponding masonry according to the design drawings. When changing the refractory mud material, the preparation utensils should be cleaned.
According to the elevation mark of the gas pipe brick, start from the first gas pipe brick on both sides of the furnace head, and then lay the gas pipe bricks in other parts in sequence.
During the laying process, the center distance between the gas pipe bricks should be corrected using a standard plate, and the length of the standard plate should be greater than half of the furnace length. The vertical center line of the coke oven, the front line and the center position of each gas pipe in between should be marked on the standard plate. The flatness of the masonry should be checked and aligned every two layers.
The refractory mud in the mortar joints of the gas pipe bricks should be filled full and dense, and the refractory mud entering the pipe brick hole should be cleaned. Before the end of work every day, the gas pipe bricks should be thoroughly cleaned from top to bottom to ensure that the gas pipe bricks are unobstructed.
The location of gas pipe bricks should be checked at any time during the construction, and the gas pipe bricks should not be collided or twisted when the heat storage room wall bricks are laid.
The central partition wall should be built after the main single wall is built to a certain height (generally not more than 1.2 meters). During the construction, expansion joints and sliding joints should be reserved according to the construction design requirements, and the filling should be full and dense.
The elevation between the main wall of the heat storage room and the adjacent single wall, between the main wall and the adjacent main wall, and between the walls should be checked frequently to keep them consistent.

Laying process of checker bricks in coke oven regenerator

After the furnace body is laid, blow and clean the secondary grooves on the top of the regenerator cover, and mark the control line between the central partition wall and the sealing wall on the regenerator wall.
Use compressed air to blow the checker bricks clean and start preparing to lay the checker bricks.
When the first layer of checker bricks is dry-laid, check the placement and stability of the checker bricks before the lower layer of checker bricks can be dry-laid.
The checker brick layers after the second layer should be stepped back from the central partition wall to the furnace head for dry-laying.
Frequently check the lattice holes of each layer of checker bricks for smoothness, and the upper and lower layers of checker bricks should be aligned.
Yellow cardboard can be used to maintain the gap width and stability between the checker bricks and the regenerator wall, and non-flammable materials must not be used as padding.
After the dry-laying of checker bricks in each regenerator is completed and the inspection is qualified, start laying the regenerator sealing wall.
The regenerator wall and checker bricks of the sectional regenerator coke oven should be laid alternately in sections. Before each section of checker bricks is laid, the sealing wall or partition wall of this section should be completed first, and the grooves on the wall should be cleaned. During the dry laying of checker bricks, pay attention to prevent the refractory mud from falling into the checker bricks of the next section. After the dry laying is completed and the inspection is qualified, immediately cover the protection plate. The protection plate should be set firmly and tightly, close to the wall of the regenerator to prevent the refractory mud from leaking into the checker bricks.

How to Repair Cooling Wall Damage After Carbon Bricks are Soaked in Water or Broken?

2025-04-142025-04-11 by globalrefractory

During the operation of the blast furnace, due to improper operation or different degrees of resistant material erosion, local cooling walls may burn out or wear and leak. Carbon bricks will undergo brittle fracture at a temperature of about 800°C. For cooling walls above the tuyere zone, the cooling walls can be quickly replaced by stopping the wind and lowering the material line or by emergency repair, and the lining can be hot-sprayed. Once the cooling wall in the furnace area leaks, the internal carbon bricks are soaked in water, or the carbon bricks are brittlely fractured, and heat conduction is blocked, there will be a risk of iron leakage from the furnace, causing major accidents. At present, the repair of carbon bricks in the furnace is generally to stop the furnace and clean the furnace. After replacing the cooling wall, carbon bricks are laid from the inside or high thermal conductivity materials are poured. The maintenance cycle lasting more than 20 days is inefficient and greatly affects the rhythm of blast furnace smelting.

In order to solve the defect of long repair period, a national new patent technology was developed – a repair method for damaged cooling staves and carbon bricks for blast furnace hearth after water immersion or brittle fracture. This repair method has the following characteristics:

First, the furnace skin at the damaged cooling stave is cut off and the damaged cooling stave is removed, the damaged carbon bricks are removed, and a new cooling stave and a new furnace skin are installed. There is a gap between the new cooling stave and the surrounding cooling staves. The lower part of the new furnace skin is provided with a first grouting hole, the middle part is provided with a second grouting hole, and the top is provided with an exhaust hole.
Second, the grouting pipe is passed through the first grouting hole and the new cooling stave in turn, and the pipe mouth is extended into the gap between the new cooling stave and the carbon brick after the gap between the surrounding cooling staves. The high thermal conductivity castable is injected through the grouting pipe at a certain pressure and begins to fill the gap between the new cooling stave and the carbon brick. During the injection process, the high thermal conductivity castable is injected into the gap between the new cooling stave and the surrounding cooling staves through the gap between the new cooling stave and the new furnace shell.
Third, observe the filling situation from the second grouting hole. When the high thermal conductivity castable spreads to the same height as the second grouting hole, stop filling and seal the first grouting hole.
Fourth, after the grouting pipe passes through the second grouting hole and the gap between the new cooling wall and the surrounding cooling wall in turn, the pipe mouth extends into the gap between the new cooling wall and the carbon brick. Pour the high thermal conductivity castable through the grouting pipe at a certain pressure and start filling the gap between the new cooling wall and the carbon brick. During the filling process, the high thermal conductivity castable is poured into the gap between the new cooling wall and the surrounding cooling wall into the gap between the new cooling wall and the new furnace shell.
Fifth, observe the filling situation from the exhaust hole. When the high thermal conductivity castable spreads to the same height as the exhaust hole, stop filling. Seal the second grouting hole and the exhaust hole.

The repair method has achieved the following beneficial effects:

First, the repair cycle of damaged cooling walls and carbon bricks is greatly reduced, and the repair can be completed in only 1 day.
Second, it ensures that each layer of gaps is fully filled, thereby ensuring normal heat transfer and gap-free insulation.
Third, the maintenance cost is extremely low, and only normal grouting is required.
Fourth, the economic benefits of blast furnaces are greatly improved, and the market prospects are extremely broad.

Raw Materials and Characteristics of Siliceous Refractory Materials

2025-05-192025-03-21 by globalrefractory

The raw material of siliceous refractory materials is mainly silica. Silica is not the name of a mineral but an industrial term. In industry, blocky siliceous raw materials are called silica. Its main mineral component is quartz, and its main chemical component is SiO₂. Silica can be classified according to the degree of structural density, crystal transformation speed and degree of heating expansion. For example, according to process classification, silica can be divided into crystalline silica, cemented silica, and silica sand. According to the rock classification method, silica can be divided into vein quartz, quartzite, quartz sandstone, flint rock, and quartz sand.

Silica Refractory Bricks Rongsheng Manufacturer

Quartzite

Quartzite is widely distributed in my country, mainly produced in Henan, Liaoning and other places. It has a grayish white or light gray appearance, and its SiO₂ content is above 98%. The main mineral composition is quartz, and the grains are generally between 0.15 and 0.25 mm. But it often contains clay, mica, chlorite, feldspar, rutile, hematite, limonite, etc. Its crystal form transformation is slow, and it can be used to make various silica bricks.

Vine quartz

Vine quartz is mainly produced in Jilin, and its appearance is milky white, and the SiO₂ content is above 99%. The main mineral phase quartz grains are large, generally larger than 2 mm, and the texture is pure, and some are interspersed with red or yellow-brown rust. Because of its slow SiO₂ crystal transformation, large expansion, and easy to loosen. If the process conditions are not appropriate when making silica bricks, cracks and cracking are prone to occur. The product has high porosity and low strength, but good slag resistance.

Quartz sandstone

Quartz sandstone is widely distributed in my country. There are quartz sandstone deposits of good quality and large scale in Hebei, Sichuan, Hunan, Hubei and other places. The appearance of quartz sandstone is light yellow and light red. The SiO₂ content is generally above 95%, mixed with certain impurities. The main crystal phase quartz coarse particles are about 1~0.5mm, and the fine particles are 0.25~0.1mm. Due to the large number of impurities in quartz sandstone, the density is poor, the strength is low, and the particles are small. The silicon oxide crystal form changes quickly during firing, and it is easy to loosen after firing. It can only be used to make general silica bricks.

Flint rock

Flint rock is mainly produced in Shanxi, China. The main component SiO₂ content is above 95%, and it also contains a certain amount of Al₂O₃, Fe₂O₃, MgO, CaO, Na₂O, K₂O, etc. The outside is red-white and bluish-white. When heated, the crystal form is easy to transform, and various silica bricks can be made.

Quartz sand

Quartz sand, also known as silica sand, has a main component SiO₂ of more than 90%, generally up to 95%. The main mineral phase quartz particles are uniform in size, smooth in surface, and excellent in sorting, with a particle size between 0.5 and 0.15 mm. Quartz sand can be used as a raw material for general silica bricks, mostly used as ramming material. There are quartz sand deposits with good texture in Shandong, Guangdong, Jilin, and Hunan, China. Siliceous refractory mud.

Crystalline silica and cemented silica

Crystalline silica has good purity and good density, and can be used as a raw material for brick making and preparing siliceous refractory castable. However, cemented silica contains more impurities and is easy to loosen after burning, so it is rarely used. Silica raw materials must be sorted and washed with water before use to reduce the content of Al₂O₃ in the raw materials. Because the source of Al₂O₃ in silica raw materials is mostly clay attachments on the surface of silica. One-third of the Al2O2 and residues bonded in quartz cracks can be removed by flushing.

Refractory Materials for Carbon Black Reactors

2025-05-192025-02-28 by globalrefractory

Carbon black is mainly an aggregate of approximately spherical particles of elemental carbon melted and combined. Today, it is mainly produced by oil furnace process, which can produce carbon black of different varieties and different particle sizes.

Brief Introduction of Carbon Black Production Process

Most of the production of carbon black uses an oil furnace. Usually, the oil furnace process uses a cylindrical reactor similar to a large oil burner, which consists of 4 zones (or chambers), namely the combustion zone (chamber), throttling ring (chamber), reaction zone (chamber), and quenching zone (chamber).

The preheated air and the burning raw materials added in the combustion zone provide the high temperature required for the production process, and it is also the starting point of the channel for the raw materials to enter the reaction zone. The throttling ring separates the combustion zone and the reaction zone, and at the same time increases the gas velocity entering the reaction zone. The reaction zone forms carbon black, and the particle size, shape, and hardness of the carbon black are controlled by temperature, gas velocity, and different “seed” materials introduced with the raw materials.

The quenching zone uses water to sharply reduce the temperature, thereby ending the reaction in the furnace. The operating temperature varies during the entire reaction process of the reactor. The heating operation starts from the front end of the combustion zone, and the temperature increases towards the throttling ring. The temperature is highest and the speed is fastest at the throttling ring. In the reaction zone, the temperature drops slightly, and the speed becomes quite slow. The reaction time is changed by spraying cooling water at different positions along the cooling zone, that is, the temperature is lowered by rapid water spraying.

In addition, when the type of carbon black changes, there will usually be drastic temperature fluctuations. When the position of the cooling zone changes, it will also cause a sharp change in temperature. Such a sharp temperature change will cause the refractory bricks to peel off and be damaged. The size of carbon black particles is limited by the size, structure, temperature of the furnace and the length of time they stay in the reaction zone before cooling. The bottom operating temperature and the position of the first water spray depend on the grade of carbon black.

Selection of Refractory Materials for Reactors

The most ideal refractory materials for carbon black reactors should have the advantages of high refractoriness, good thermal shock stability, high density, low porosity, high temperature corrosion resistance, and strong erosion. Most carbon black reactor linings are built with Al2O3-SiO2 refractory bricks, among which high alumina bricks or clay refractory bricks are used for the lining. Different grades of refractory materials need to be used for lining when the operating temperature range is different. The lining of the reactor operating in the low temperature range (1550-1750℃) is generally built with mullite corundum bricks. Sometimes high-purity high-alumina bricks are used for the cooling zone.

The lining of the reactor operating in the high temperature range (1750-1925℃) is usually built in sections. On the hot surface of the combustion zone, 90% A1203-10% SiO2 refractory bricks are generally used for lining. In the high-temperature throttling ring and the hot surface of the reactor, 99% A1203 corundum bricks and chrome corundum bricks with good thermal shock resistance are used for masonry. In the ultra-high temperature range (greater than 1925℃, i.e. 2000-2100℃), zirconium chrome bricks are used for masonry.

(1) Al2O3-SiO2 refractory materials.

In the SiO2-Al2O3 series of refractory materials, when W (Al2O3)>90%, it is called corundum brick. When pure SiO2 and Al2O3 materials are used to produce corundum bricks, the temperature at which the liquid phase appears is 1840℃. The physical properties and performance of corundum bricks produced by traditional processes cannot reach a very ideal level, and their thermal shock resistance is poor. Now, by using pure raw materials and in-situ forming bonding technology, the physical properties and performance of corundum have been greatly improved, and the variety is increasing. Among them, the original mullite combined with 90% Al2O3 corundum bricks and special Al2O3, combined with 94% Al2O3, and even 98% Al2O3 corundum bricks have been developed one after another.

These special corundum refractory bricks have lower porosity, higher density, greater strength, and outstanding thermal shock resistance than traditional corundum refractory bricks of the same material. The 50mm×50mm×76mm sample was kept at 1200℃ for 10min, water cooled for 2min, and placed in the air to dry for 8min as one cycle, which was more than 40 times. The traditional refractory bricks are only 2-7 times, and even the traditional mullite corundum bricks are only 10-15 times. Special mullite combined with corundum bricks are mainly used in low-temperature carbon black reactors, or in the cooling zone of high-temperature carbon black reactors. The actual use structure shows that when used in the combustion and restriction zones, the special mullite combined with 90% Al2O3 combined corundum bricks (95%-98% Al2O3) are mainly used in the reaction zone with harsh conditions in the carbon black reactor, and its use temperature limit can reach 2000℃.

(2) Al2O3-Cr2O3 refractory materials

a. Al2O3-Cr2O3 materials used above 1800℃

In order to be suitable for the lining of the combustion chamber and other parts of the carbon black reactor with a temperature exceeding 1800℃, and to have good corrosion resistance and high thermal shock resistance. The usual practice is to add a certain amount of industrial Cr2O3 powder to the corundum brick to improve its high-temperature performance.

Its high temperature flexural strength increases with the increase of Cr2O3 content. The research results show that the thermal shock resistance and wear resistance of this type of refractory brick are also improved with the increase of Cr2O3 content.

When Al2O3-Cr2O3 (10% Cr2O3) refractory castables are used as the working lining of the combustion chamber, throat, and reaction section of the carbon black reactor that are not in contact with high-temperature gas, it can ensure the safe operation of the carbon black reactor under operating conditions above 1800℃.

b. Cr2O3-Al2O3 materials used under ultra-high temperature conditions

Under the condition of temperature exceeding 1925℃, i.e. 2000-2100℃, corundum bricks are no longer competent. For example, the operating temperature of the hard carbon black reaction furnace used to manufacture low rolling friction tires is as high as 2100℃. Under such conditions, it is necessary to develop better quality refractory bricks to adapt to the ultra-high temperature conditions.

High-Quality Alumina Chrome Bricks from Rongsheng Factory

Research and development of performance requirements for lining refractory materials used under ultra-high temperature conditions of carbon black reactors:

① High refractoriness to avoid melting and allow higher operating temperatures;
② Good thermal shock stability to reduce cracking and spalling damage;
③ Low porosity (high density) to improve corrosion/erosion resistance.

Based on the research results of carbon black lining refractory bricks and the existing experience of using chrome alumina corundum bricks under high temperature conditions (1750-1925℃), the lining refractory bricks for carbon black reactors used under ultra-high temperature conditions should be selected from the Cr2O3-Al2O3 system.

When chrome corundum bricks with high Cr2O3 content are used as refractory materials for the lining of carbon black reactors, the service life can be extended under high temperature operating conditions. The normal operation of the reactor can also be ensured under ultra-high temperature operating conditions. In addition, the actual use results show that the service life is extended when the flow limiting chamber using high-temperature ash or high-vanadium combustion oil and the flow limiting chamber caused by intermittent high temperature melting are using Cr2O3-Al2O3 refractory bricks with high Cr2O3 content combined by solid solution. And the operating temperature in the carbon black reactor can be increased by 150-170℃ compared with the previous limit temperature.

Usually, because chrome corundum bricks with high Cr2O3 content are very expensive, they are only used in carbon black reactors operating at about 2100℃ (i.e., generating hard carbon black), and a comprehensive masonry scheme is adopted. That is, using 70% Cr2O3 and 25% Al2O3 refractory bricks to build the highest temperature, and using 20% Cr2O3 and 25% Al2O3 bricks to build the low temperature, better results can be obtained.

(3) ZrO2 refractory materials

Pure ZrO2 is extracted from zirconium-containing ores. High-purity ZrO2 is white powder with a high melting point and high density. Its mullite hardness is 6.5, its thermal conductivity is low, and its thermal expansion coefficient is large (25-1500℃, α=9.4×10-6/℃). Moreover, it has a weak relationship with temperature and good chemical stability. The high-temperature vapor pressure at 2000-2300℃ is very low, the evaporation rate is not high, and the decomposition pressure is also low. Therefore, ZrO2 refractory materials are an important type of refractory bricks for high-temperature furnace linings.

(4) High-purity MgO bricks

High-purity magnesia bricks are structural materials for high-temperature furnace linings, and their operating temperature can reach 2200°C. However, under such conditions, such as when used in ultra-high temperature environments in carbon black reactors, the purity and performance of high-purity magnesia bricks need to be carefully balanced.

Refractory bricks (including magnesia bricks) are not only resistant to high temperatures and corrosion (erosion), but must also be as stable as possible during use. It is generally believed that the purity of magnesia and the porosity and periclase grain size in terms of physical properties are key parameters for improving the service life of high-purity magnesia bricks.

The MgO content in magnesia is an important indicator of magnesia quality, but the MgO content alone is not enough as an evaluation criterion. The relative content of impurities, especially those that easily form melts under high temperature conditions, is also important. Among the impurity components, B2O3 and SiO2 are the first, followed by A12O3, Fe2O3, MnO and CaO. Their influence depends not only on their content, but also on the Ca0/SiO2 ratio to evaluate the influence of each component on the quality of magnesia sand. It is usually hoped that the magnesia sand has a high CaO and SiO2 ratio in order to obtain the best high-temperature performance.

Magnesia bricks used in ultra-high temperature environments require high purity because high-purity magnesia bricks have high temperature strength. The high temperature flexural strength of magnesia bricks tends to decrease slowly with the MgO content from 90% to 98%, but when the MgO content exceeds 98%, it suddenly increases. When the MgO content increases to more than 99%, its high temperature strength can be significantly improved. In this case, the influence of impurity types has become insignificant. Because, in this case, the impurities exist in isolation at the junction (corner) of periclase grains. Therefore, the MgO-MgO direct bonding organization is well developed, the high temperature strength is large, the material has high wear resistance, and strong corrosion (erosion) resistance.

Calculation and Laying Method of G-type Refractory Bricks for Lime Kiln

2025-04-122025-02-07 by globalrefractory

G1, G2, G3, G4, G5, G6, G7, G8 clay bricks and high alumina bricks, these types of refractory brick masonry circles need to be carefully calculated. At the beginning of kiln design, calculating the brick type and quantity required for G-size bricks often makes people dizzy. Today, we will bring you specific calculation methods and construction points to help you design furnace types, calculate purchase quantities and provide references for construction.

Calculation of the Amount of Furnace bottom Bricks

The volume of the bottom of the lime shaft kiln can be calculated by dividing the total volume of bricks by the volume of each brick. When calculating the number of bricks per layer, the horizontal cross-sectional area of the furnace bottom bricks can be divided by the corresponding surface area of each brick. Generally, a loss of 2% to 5% should also be considered. If the weight of the bricks needs to be calculated, the weight of each brick is multiplied by the number of bricks.

Calculation of the Amount of Ring Furnace Body

The other parts of the lime kiln are all ring cylinders or cones. Regardless of the upper and lower layers or the inner and outer layers, rings must be built, and wedge bricks must be used when building rings. If a ring of any diameter is built, wedge bricks and straight bricks must be used together. Generally, G-1 straight bricks are matched with G-3 or G-5 wedge bricks, and G-2 straight bricks are matched with G-4 or G-6 wedge bricks. Due to the different required ring diameters, the number of straight bricks and wedge bricks is also different.

If G-3, G-4, G-5, G-6 wedge bricks are used alone to build rings, the formula can be listed:

nx=(2πa)/(b-b1)

Where:

nx——Number of wedge bricks for building a ring, pieces;

a——Brick length, mm;

b——Width of the big end of the wedge brick, mm;

b1——Width of the small end of the wedge brick, mm.

From the above formula, we can know that the number n of wedge-shaped bricks used in each ring is only related to the width of the two ends of the wedge-shaped bricks and the length of the bricks, but has nothing to do with the diameter of the ring.

It can be concluded that:

Number of bricks needed to build a ring with G-3 is n=97

Number of bricks needed to build a ring with G-4 is n=87

Number of bricks needed to build a ring with G-5 is n=48

Number of bricks needed to build a ring with G-6 is n=54

At the same time, the inner diameters of the rings built with the above four wedge-shaped bricks are 4150mm, 3450mm, 1840mm, and 1897mm, respectively.

If you want to build a ring of any diameter, you need to use straight bricks and wedge bricks together. The number of straight bricks can be calculated by the following formula:

nz=(πd-nx*b1)/b

Where:

nz——Number of straight bricks, pieces;

nx——Number of wedge bricks, which is a constant after the brick type is determined;

b1——Width of the small end of the wedge brick, mm;

b——Width of the straight brick, mm;

d——Inner diameter of the ring, mm.

Example: Try to use G-3 and G-1 bricks to build a ring with an inner diameter of 7.2 m. Find the number of wedge bricks and straight bricks required.

Solution:

nx=97 pieces

nz=(πd-nx*b1)/b=3.14*(7200-97*135)/150=65 pieces

Construction points of G-type bricks

When building a lime kiln, two types of bricks can be used to build rings of different diameters to adapt to the size of the furnace and the change of furnace diameter with height. Generally, refractory bricks G1 are matched with G3 or G5 wedge-shaped bricks, and refractory bricks G2 are matched with G4 or G6 wedge-shaped bricks. Due to the different ring diameters during the masonry process, the number of straight bricks and wedge-shaped bricks is also different.

When the inner lining of the lime kiln is built, the ring seams are required to be built with all staggered seams, and bricks must not be cut. If bricks must be cut, the cut surface must be smoothed. The thickness and staggered seams of the masonry are combined with different brick types with brick lengths of 230 mm and 345 mm. The thickness of the masonry can be increased or decreased by 115 mm and staggered seams can be achieved by matching. When the thickness change is less than 115 mm, the filler seams between the masonry and the furnace shell or the masonry and the cold wall can be used to adjust.

Of course, the specific dosage calculation and construction methods of the above methods are not fixed. It depends on the on-site furnace conditions and usage requirements.

Self-Baking Carbon Bricks for Calcium Carbide Furnaces

2025-04-122025-01-17 by globalrefractory

Self-baked carbon bricks for calcium carbide furnaces are made of high-temperature treated anthracite as the main raw material and are made through a high-frequency vibration molding process. They are used to build the bottom of large and medium-sized calcium carbide furnaces and the lining of the melting pool.

Self-Baking Carbon Bricks for Calcium Carbide Furnaces

Self-baked carbon bricks are divided into two categories according to the capacity of the calcium carbide furnace transformer. The first category is suitable for calcium carbide furnaces greater than or equal to 10000kVA, code-named TKZ-1. The second category is suitable for calcium carbide furnaces less than 10000kVA, code-named TKZ-2.

Surface quality of self-baked carbon bricks

1) The surface of the carbon brick should be flat, and no local deformation, protrusions, cracks and oil defects are allowed.
2) Corner missing: depth not greater than 10mm and not more than 1.
3) Edge missing: length not greater than 50mm, depth not greater than 5mm and not more than 1.
4) Distortion: not greater than 1mm on the masonry surface of the carbon brick.

The cross-sectional structure of the self-baked carbon brick should be uniform, without stratification, local looseness, voids and dry material defects.

Self-Baking Carbon Bricks for Calcium Carbide Furnaces

Carbon Brick Standards and Performance Guide

Carbon Brick Size and Deviation:

The height tolerance of carbon bricks at the bottom and side of the furnace wall is ±3 mm, and the width tolerance is ±5 mm.
For carbon bricks without free end faces, the length tolerance is ±5 mm; for carbon bricks with free ends, the length tolerance is ±10 mm.

Carbon Brick Crack and Notch Standards:

The width of the crack on the carbon brick is less than 0.5 mm, the length is less than 200 mm, and there are no more than two cracks on each side.
The length of each side of the cross-edge crack is no more than 100 mm.
The width of the single notch and bee eye on the carbon brick shall not exceed 20 mm and the depth shall not exceed 10 mm.

Carbon brick size specifications:

400*400*400-1800mm
400*500*400-2500mm
600*650*600-2000mm
800*800*800-1900mm

The length can be customized according to customer needs, and various models and specifications of special-shaped carbon blocks and furnace mouth carbon blocks can be processed.

Performance requirements of carbon bricks:

Fixed carbon ≥50%
Silicon carbide content 15-22%
Volume density ≥1.7g/cm³
Apparent porosity ≤20%
Compressive strength ≥42MPa
Ash content ≤7%
Flexural strength 6.86MPa

Semi-graphite silicon carbide carbon bricks ensure efficient operation of your industrial furnaces! Contact the Rongsheng Manufacturer for detailed information.

What are the Formula, Proportion and Applicability of Refractory Plastics?

2025-03-112024-12-27 by globalrefractory

Refractory plastic is made of 70~80% granular and powdery materials, 10~25% plastic clay and other binders, and appropriate plasticizers. Refractory plastic is a hard mud paste and is an amorphous refractory material that maintains high plasticity for a long time.

Refractory Plastic Materials

Refractory plastics are mainly used in various heating furnaces that do not directly contact the molten material. The materials are mostly clay and high-alumina, but also silicon, magnesium, chromium, zircon, and silicon carbide. If classified by binder, there are clay-bonded, water glass-bonded, phosphate-bonded, sulfate-bonded plastics, etc.

Aggregates for Refractory Plastics

Aggregates for refractory plastics mainly include special-grade clay clinker, third-grade, second-grade, or first-grade alumina clinker, etc. The maximum particle size of the refractory aggregate is 10mm, and its particle grading is: 10~5mm, 33%~40%; 5~3mm, 28%~35%, less than 3mm, 28%~35%. It should be pointed out that particles of 0.5~0.09mm should be minimized or eliminated. The amount of aggregate is 55%~65%.

Refractory powder is generally made of special-grade, first-grade or second-grade alumina clinker. The fineness of ≤0.09mm should account for 95%, and the finer the better. It is strictly forbidden to use underburned materials or clay clinker as refractory powder. The amount of refractory powder is 20%~30%.

Performance of Refractory Plastics

In order to ensure smooth construction and normal use at high temperatures, refractory plastics should generally have the following basic properties: ① have a certain degree of plasticity to facilitate construction; ② have a certain shelf life to ensure that the molding performance remains unchanged during the specified storage period; ③ have a certain strength after room temperature curing to facilitate the removal of the frame or transportation after construction; ④ have a certain high temperature volume stability to prevent damage to the furnace lining structure due to excessive deformation.

Plasticity of Refractory Plastic

Since it is called refractory plastic, what does its plasticity have to do with?

The plasticity of plastic has a direct impact on the characteristics of clay and the amount of clay added. It is also related to the amount of water added. Plasticity increases with the increase of water added. But it cannot be too high, generally 5~10%. To improve plasticity, it is necessary to control the amount of clay and water added in the plastic, and plasticizers can be added.

The role of plasticizers in refractory plastics: ① Increase the hygroscopicity of clay particles, so that clay particles are dispersed and coated with water film; ② Make clay particles sol; ③ Increase the electrostatic repulsion between clay particles and stabilize the sol; ④ Exclude ions that hinder solification from the system as insoluble salts; ⑤ Increase the viscosity of water in clay to form a solid water film, etc. Commonly used plasticizers are pulp waste liquid, cyclohexane acid, lignin sulfonate, lignin phosphate, lignin chromate, etc. At the same time, the binder used in refractory plastics also has a certain influence on plasticity.

Soft clay is an important raw material for refractory plastics, and the main performance characteristics of plastics also come from soft clay. In refractory plastics, soft clay not only acts as a binder, but also as a plasticizer and sintering agent. It has a great influence on the plasticity, water retention, construction, room temperature, and high-temperature refractory properties of refractory plastics. Therefore, the soft clay used to prepare refractory plastics should have good plasticity, hygroscopicity, moderate viscosity, refractoriness and sintering properties. From the perspective of molding and water retention, the best viscoplasticity is Guangxi clay and ash clay, the worst is Fuzhou clay, Jiaozuo clay, camphor clay, and purple wood clay can be used in combination. Its fineness: less than 0.09mm accounts for more than 85%, and the dosage is 10%~15%.

The chemical binder is aluminum sulfate solution with a density of 1.2~1.3g/cm³. After mixing with this binder, the material should be trapped for more than 16h. Because the sulfate in aluminum sulfate reacts with the iron in the powder to generate iron sulfate and release hydrogen, which causes the mud to bubble or swell, the material should be trapped. After drying, there is a light yellow precipitate on the surface of the refractory plastic, which is identified as iron alum by chemical and petrographic analysis. Its molecular formula is FeO·Al₂O₃·4SO₃·22H₂O.

The 18 crystal waters contained in the aluminum sulfate solution are mostly removed at about 134°C. At about 330°C, a small amount of crystal water is lost. The endothermic peak at 835°C is the decomposition of aluminum sulfate into Al₂O₃ and SO₃, and SO₃ escapes in gaseous form. Therefore, the organizational structure of the refractory plastic is slightly loose and the strength is reduced. The endothermic peak in the low temperature section of the iron alum differential thermal curve is caused by the discharge of crystal water. The endothermic peak at 752°C is caused by the decomposition of iron alum and the release of SO₃. It also affects the strength of the plastic.

The amount of foaming of refractory plastic is directly related to the purity, density and addition amount of aluminum sulfate. Generally speaking, when the purity is high, the density is high and the addition amount is large, the amount of foaming is also large. This is due to the large amount of sulfuric acid brought in. Therefore, under the premise of meeting the plasticity, construction and fire resistance of the refractory plastic, crude aluminum sulfate can be selected to prepare a low-density solution and minimize its dosage. The dosage of aluminum sulfate solution is generally 9%~13%.

The additives used in refractory plastics mainly include preservatives, plasticizers, reinforcing agents and preservatives. Its additives include spodumene powder (LiO₂·Al₂O₃·4SiO₂), lithium mica powder (LiO₂·Al₂O₃·3SiO₂) and bentonite and other sintering agents (also known as mineralizers), and expansion agents such as kyanite or sillimanite.

There are many types of admixtures for refractory plastics, including polyvinyl alcohol, dextrin, starch, carboxymethyl cellulose, citric acid, gluconic acid and ethyl silicate. The dosage of admixtures is generally less than 1%, and when it is greater than 1%, it also acts as a binder. Other admixtures include andalusite, sillimanite, zircon and alumina powder, and their dosage is generally greater than 3%.

The maximum particle size of refractory aggregate is 10mm, the moisture content of plastic is about 9%, and the plasticity index is 17%~30%. Sunan mud refers to the composite use of Suzhou mud and Nanjing mud. The former has a high sintering temperature, while the latter has a low sintering temperature due to the high content of low melting points. Special clay and I alum, etc., represent special clay clinker and I alumina clinker, respectively. I and II alum are I and II alumina clinkers, which are mixed in a ratio of 1:1 to make refractory powder. Admixtures are selected according to the use requirements of refractory plastics. For example, if construction is carried out immediately after production, preservatives may not be added.

Rongsheng Refractory Material Factory is a powerful manufacturer and seller of refractory materials. Rongsheng Factory, an environmentally friendly, fully automatic monolithic refractory material production line, specializes in providing monolithic refractory products for high-temperature industrial furnaces, including various refractory castables, high-strength wear-resistant plastics, wear-resistant ramming materials, etc. Contact Rongsheng for free samples and quotation information.

Setting Time of Low Cement Castable Refractory

2025-01-242024-12-06 by globalrefractory

The initial setting time of low-cement castable refractory materials is 40 minutes, and the final setting time does not exceed 8 hours. Factors affecting the setting time include material composition, ambient temperature, and humidity. Specifically:

‌Material composition‌: The composition of refractory castables has a decisive influence on their setting time. For example, the higher the content of aluminate cement, the shorter the setting time; adding retarders can extend the setting time.
‌Environmental temperature‌: The higher the temperature, the shorter the setting time. When constructing in a high-temperature environment, the temperature needs to be controlled to avoid affecting the setting time.
‌Environmental humidity‌: Excessive humidity will cause condensation on the surface of refractory castables, affecting the setting effect. When constructing in a high humidity environment, measures such as strengthening ventilation and increasing the temperature are required.

In practical applications, accelerators or retarders can be added to adjust the initial and final setting times according to the construction conditions and temperature. Rongsheng Refractory Material Manufacturer can customize low-cement refractory castables according to actual working conditions and construction conditions. To purchase high-quality high-temperature industrial furnace lining refractory materials and customized refractory lining material solutions, please contact Rongsheng.

Solidification and Use Effect of Refractory Castables

Refractory castables are a kind of refractory materials widely used in high-temperature industrial fields such as metallurgy, petroleum, chemical industry, and electric power. It has excellent high-temperature performance, corrosion resistance, wear resistance and other characteristics, and can effectively protect equipment from damage caused by high temperature and chemical corrosion. However, when using refractory castables, we often encounter a problem: How long does it take for refractory castables to solidify? Will it affect its use effect if it solidifies too early or too late?

First, let’s understand the solidification process of refractory castables. When refractory castables are cast on equipment or structures, they will gradually solidify over a certain period of time. This process is mainly affected by factors such as material composition, construction conditions, ambient temperature and humidity.

Generally speaking, the solidification time of refractory castables can be divided into two stages: initial setting and final setting. Initial setting refers to the time when the castable begins to lose fluidity and hardens on the surface; while final setting refers to the time when the castable completely loses fluidity and reaches complete hardening.

So, how long does it take for refractory castables to solidify? There is no fixed answer to this, because different refractory castable formulas and construction conditions will lead to different solidification times. Generally speaking, the initial setting time is from a few hours to more than ten hours, while the final setting time may take several days or even longer.

In order to ensure the construction quality and use effect of refractory castables, we need to pay attention to the following points:

Before construction, the refractory castables should be fully stirred and mixed to ensure that its components are evenly distributed.
During the construction process, the construction temperature and humidity should be controlled to avoid the castables from being disturbed by external factors.
After the pouring is completed, the castables should be cured and insulated in time to ensure their normal solidification.

In short, the solidification time of refractory castables is affected by many factors and needs to be judged and adjusted according to the actual situation. At the same time, attention should be paid to details during the construction process to ensure the construction quality and use effect.

Rongsheng Lightweight Refractory Insulation Brick Manufacturer – Mullite Insulation Brick

2024-12-182024-11-22 by globalrefractory

Lightweight thermal insulation refractory materials. The common characteristics of this type of material are low bulk density, light weight and low thermal conductivity. Rongsheng lightweight refractory insulation brick manufacturer, refractory insulation bricks, use temperature between 1000 ~ 1500 ℃, mainly lightweight clay bricks, lightweight silica bricks, lightweight high alumina bricks, etc. High temperature insulation bricks, use temperature above 1500 ℃, and can be directly used as the lining of high temperature kilns, mainly lightweight corundum bricks, alumina hollow ball products and zirconia hollow ball products. This article mainly introduces mullite insulation bricks. Contact Rongsheng for more information.

Mullite Insulation Brick

Lightweight mullite brick is a new type of energy-saving refractory material that can directly contact the flame and has the characteristics of high temperature resistance, high thermal shock stability, high strength, and low thermal conductivity. Mullite insulation bricks are widely used in the lining, furnace door bricks, kiln car bricks, etc. of ceramic roller kilns, shuttle kilns, cracking furnaces, hot air furnaces and various electric furnaces. The advantages are high purity, low impurity content, high temperature resistance, direct contact with flames, resistance to various atmosphere corrosion, low thermal conductivity, low heat melting, high strength, and excellent thermal shock resistance, high dimensional accuracy, and can be cut at will. The body density can be between 0.5 0.6 0.8 0.9 1.0 1.2 1.5 according to user requirements. It acts on high-temperature kilns and directly contacts the flame. It has good insulation effect, high compressive strength, and low thermal conductivity. It is suitable for electric kiln insulation, various high-temperature rotary kilns, tunnel kilns, nitriding gas kilns, etc. The crystals of fused mullite are larger than those of sintered mullite, and its thermal shock resistance is better than that of sintered products. Their high temperature performance mainly depends on the content of alumina and the uniformity of the distribution of mullite phase and glass. 1400 degree mullite bricks are mainly used for the top of hot blast furnace, blast furnace body and bottom, glass melting furnace regenerator, ceramic sintering kiln, dead corner lining of petroleum cracking system, etc.

JM23 lightweight mullite brick is a high-temperature resistant and energy-saving lightweight refractory material produced by Rongsheng Refractory Material Factory. Lightweight mullite brick has light weight and good thermal insulation effect. It is a high-quality high-purity refractory powder. According to the required specific gravity of the product, organic composite fillers are added, vacuum extruded and sintered at high temperature to form lightweight mullite products. Rongsheng manufacturers can customize different specifications of lightweight mullite bricks according to the actual working conditions of high-temperature industrial furnaces, and the content of alumina ranges from 50% to 80%.

Low Iron JM23 JM26 JM28 Mullite Insulation Bricks

Characteristics of Mullite Lightweight Insulation Bricks

High temperature resistance can reach above 1790℃. The load softening start temperature is 1600-1700℃, and the compressive strength at room temperature is 70-260MPa. Good thermal shock resistance, high strength, low high-temperature creep rate, low expansion coefficient, small thermal coefficient, and resistance to acidic slag erosion. It can also greatly reduce the weight of the high-temperature furnace body, transform the structure, save materials, save energy, and improve production efficiency.

Lightweight mullite bricks are made of imported plate-shaped corundum and high-purity fused corundum as the main raw materials. They are made by mixing, drying, forming and firing in a high-temperature shuttle kiln using advanced ultrafine powder adding technology. Lightweight mullite bricks are widely used in equipment such as residual oil gasification furnaces, synthetic ammonia second-stage reforming furnaces, carbon black reactors and refractory kilns. The product’s dimensions, physical and chemical indicators and service life all meet customer requirements.

According to the chemical structure of lightweight mullite bricks, its outstanding performance is as follows:

1. Low heat melting. Due to low thermal conductivity, mullite series lightweight insulation bricks accumulate very little heat energy, and the energy saving effect is obvious in intermittent operation.
2. Low thermal conductivity, with good thermal insulation effect.
3. Low impurity content has very low content of oxides such as iron and alkali metals. Therefore, the refractoriness is high, and the high aluminum content enables it to maintain good performance under reducing atmosphere.
4. High hot compressive strength.
5. It can be processed into special shapes to reduce the number of bricks and masonry joints.
6. The appearance size is precise, which speeds up the masonry speed and reduces the use of refractory mud. The strength and stability of the masonry are guaranteed, thereby extending the life of the lining.

Application Scope of Mullite Insulation Bricks

Mainly used for high-temperature metallurgical hot blast furnaces above 1400℃, parts of torpedo cars impacted by molten iron, slag lines, furnace roofs of steelmaking arc furnaces, material channels of glass melting furnaces, regenerator arches, and upper structures. Ceramic sintering kilns, ceramic roller kilns, tunnel kilns, electric porcelain drawer kilns, and dead-angle furnace linings of petroleum cracking systems. Linings of glass crucible kilns and various electric furnaces, and the walls of clarifiers, which can directly contact the flame.