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The Use Nature of Refractory Cement in Refractory Materials

2022-10-11 by globalrefractory

What is refractory cement? What are the precautions in the use of refractory cement? Rongsheng REFRACTORY CEMENT FACTORY will provide you with high-quality refractory inorganic binders, including refractory cement, aluminum dihydrogen phosphate, etc. Next, we will introduce the use nature of refractory cement in refractory materials.

What is refractory cement?

Cement with refractoriness not less than 1580℃. The different compositions can be divided into aluminate refractory cement, low calcium aluminate refractory cement, calcium magnesium aluminate cement, and dolomite refractory cement.

Historical data show that with the discovery and understanding of the heat resistance of calcium aluminate, the yield of calcium aluminate in Europe in 1913 had a rapid increase. In the 1920s, indestructible refractory casting materials began to take their own steps of development. In the late 1980s and 1990s, new pouring techniques gradually emerged. The pump and flow gating technology with low cement castables is introduced. Then came wet spray or jet technology. In these technological changes, refractory cement was produced.

Refractory cement is also called aluminate cement. Aluminate cement is made of bauxite and limestone as raw materials, calcined with calcium aluminate as the main component, the alumina content of about 50% of clinker, and then grinding into hydraulic cementitious materials. Aluminate cement is often yellow or brown, but also gray. The main mineral composition of aluminate cement is calcium aluminate and another aluminate, and a small amount of dicalcium silicate.

Refractory Cement for Refractory Materials

The use nature of refractory cement in refractories

Aluminate cement is a kind of binder (permanent binder) that can be combined at room temperature and high temperature. The refractoriness of amorphous refractories is very important. In general, the higher the Fe2O3 in cement, the lower its fire resistance. The type and content of calcium aluminate affect the fire resistance of cement. Practice shows that ordinary high aluminum cement is used at less than 1300℃, high aluminum cement (bauxite cement) is used at less than 1500℃, and low calcium high aluminum cement (high aluminum cement) is used at higher than 1600℃ temperature.

Aluminate cement often refers to calcium aluminate as the main component of cement. Calcium aluminate cement is the basic binder of amorphous refractories, especially cast refractories. The properties of aluminate cement mainly depend on its mineral composition. The main mineral composition of aluminate cement, calcium aluminate (CA), has a high hydrohard activity, the setting is not fast but hardening is very rapid, and the hardening time is not more than one day. It is the main source of the strength of high aluminum cement, especially the early strength. Calcium dialuminate (CA2) has a slow hydration hardening, low strength in the early stage, and high strength in the later stage. Dodecalcium heptaaluminate (C12A7) has the characteristics of quick hydration and rapid condensation, but the strength is not high. In ordinary high alumina cement containing inclusions, impurities affect the hardening effect of the cement and its strength.

Calcium aluminate cement contains these 5 kinds of calcium aluminate minerals, which will be along with the hydration reaction and show an intense heating phenomenon. The temperature of common high-alumina cement (53~55% A12O3) reaches the peak after 5~8h, reaching 80~90℃. The temperature of advanced high alumina cement containing 70% A12O3 reaches the peak value after 10~12h and that of 80% A12O3 after 8~10h. The temperature is 80C and 70C respectively.

The heating temperature and the time to reach the highest temperature of single castable of different kinds of high aluminum cement are determined by the heating characteristics and content of calcium aluminate. Therefore, the calorific value of high aluminum cement will also change due to the different calcium aluminate contents. If too much high aluminum cement containing C12A or CAF as the main component is added to the cast refractory, it will cause cracks and surface spalling due to intense evaporation of water in the castable hardening body due to concentrated heat. Therefore, the choice of cement dosage and quality is very important.

Precautions for the use of refractory cement

At a room temperature of 350 degrees, it is most likely to cause local bursting, and special attention should be paid to slow baking. If there is still a lot of steam bubbling up after 350 degrees of insulation, the heating rate should still be slowed down.
in the condition of poor ventilation, water is not easy to discharge, to appropriately extend the holding time.
When baking with heavy oil, it is necessary to strictly prevent heavy oil from spraying on the surface of the furnace lining to prevent local bursts.
When using wood to bake, direct contact with the flame often causes local heating to be too rapid, which should be protected.
the newly poured refractory cement, at least after 3d can be baked.
the cooling of refractory cement furnace lining should also be slow to avoid forced ventilation.

What is Alumina Silicate Refractory Brick?

2022-09-26 by globalrefractory

Alumina Silicate Refractory Bricks, for those who do not understand the refractory industry, maybe this is a kind of refractory bricks containing aluminum and silicon. But for people in the refractory industry, there is no such name, only aluminum-silicon-based refractory bricks. So, what are Alumina Silicate Refractory Bricks? What is Alumina-Silicate Refractory Brick? First of all, let’s take a look at the definition, what does aluminum-silicon refractory brick mean?

Silicon Bricks - Rongsheng Refractory Bricks — Silicon Bricks

Alumina Silicate Refractory Bricks, also known as aluminum-silicon refractory bricks, are refractory products containing Al2O3 and SiO2 and are a series of aluminum-silicon refractory bricks. Aluminum-silicon-based refractory bricks have a wide range of applications and occupy a very important position in the refractory application industry. Its usage accounts for more than 40% of the entire refractory products.

By definition, Alumina Silicate Refractory Bricks are a series that includes multiple types of refractory bricks. Below we categorize them to give you a deeper understanding.

High Alumina Refractory Bricks - Rongsheng Company — High Alumina Refractory Bricks

Aluminum-silicon-based refractory bricks are classified in the order of increasing composition from SiO2 content to Al2O3 content.

(1) Silica brick: SiO2 content ≥93%;
(2) Semi-silica brick: Al2O3 content is 15%-30%;
(3) Clay brick: Al2O3 content is 30%-48%;
(4) High alumina brick: Al2O3 content ≥48%;
(5) Mullite brick: Al2O3 content ≥72%, SiO2 content ≥28%;
(6) Corundum brick: Al2O3 content ≥90%.

It can be seen from the classification that silica bricks, clay bricks, and high alumina bricks are all commonly used refractory bricks for kilns. Often used for masonry kiln working layer, permanent layer, etc. Below we introduce the application of aluminum-silicon-based refractory bricks.

Alumina Silicate Refractory Bricks and Their Application Range

Silica brick. Partition wall and lining of coke oven carbonization chamber and combustion chamber, the lining of hot blast stove roof and regenerator, small electric furnace roof masonry, glass kiln roof, acid steel furnace, and firing kiln dome.
Semi-silica brick. Mainly used in coke ovens, acidified iron furnaces, metallurgical furnace flues, ladle linings, molten iron tanks, glass kilns, heating furnaces, hot blast stove tops, boiler combustion chambers, etc. Semi-silica bricks are not only used in these parts but can also be used as raw materials to make refractory materials with better quality, such as flow steel bricks.
Clay bricks. Clay bricks are used to build heating and heat treatment furnaces, flues, open hearth regenerator checker bricks, and the bottom of regenerator walls. The lining of air ducts and gas ducts, dust collectors of iron furnaces, and linings of flues. The drying zone and preheating zone of the rotary kiln are lined. It is also a commonly used refractory material in furnaces such as boilers, lime kilns, glass kilns, and ceramic kilns.
High alumina brick. Masonry blast furnace, hot blast stove, ladle, rotary kiln lining, and other metallurgical kilns. High-alumina bricks can also be used as lattice bricks on hot blast stoves to stack regenerators.
Mullite bricks. Mullite bricks are commonly used in hot blast furnaces for ironmaking at high temperatures above 1200°C, parts of torpedo tankers impacted by molten iron, and slag lines. Furnace roof of steelmaking electric arc furnace, ceramic industrial furnace, regenerator arch, the superstructure of glass melting furnace, cement, rotary kiln lining, etc.
Corundum brick. Used in blast furnaces, hot blast furnaces, and refining furnaces in the metallurgical industry. Second-stage furnaces, gasification furnaces, gas-making furnaces, cracking furnaces, and various high-temperature heating furnaces in ceramics, building materials, and other industries in the petrochemical industry.

It can be seen from the above list that aluminum-silicon-based refractory bricks are widely used in various kilns. One kind of refractory brick can be used for the refractory lining of many kinds of thermal furnace equipment, and one kind of kiln needs many kinds of refractory bricks. Therefore, when users communicate with refractory manufacturers about aluminum-silicon-based refractory bricks, they should determine the location of use and the use environment, so as to choose the correct Alumina Silicate Refractory Bricks.

Good quality refractory bricks are the basic conditions for increasing the service life of the kiln lining. Choosing a strong refractory manufacturer not only saves procurement costs, but also ensures the quality of refractory materials, reduces the number of furnace shutdowns and repairs, and briefly increases production costs. Contact Rongsheng refractory manufacturers to get the most competitive price of Alumina Silicate Refractory Bricks.

Corundum Mullite Wear-Resistant Refractory Castable

2022-09-08 by globalrefractory

Corundum (mullite) wear-resistant refractory castable is made of corundum and mullite as the main material, plus a special matrix and binder. The product has high strength wear resistance, erosion resistance, erosion resistance, good high-temperature volume stability, and thermal shock resistance. Mainly used for the wear-resistant lining of large CFB boilers with special requirements and lining of other high-temperature furnaces.

Lightweight Mullite Insulating Refractory Castable

Mullite castable is made of porous mullite aggregate as raw material, plus fine powder and additives. The critical particle size of mullite aggregate is 12mm, and the long-term use temperature is 1350 degrees.

Product features of mullite castables

The mullite castable has a high temperature and can be used as a working lining in direct contact with the flame to achieve high temperature and energy saving. The unit density is light, the structural weight is reduced by 40-60%, and the hidden danger of broken bricks is eliminated. Low thermal conductivity, porous mullite aggregate ingredients, low thermal conductivity, and good thermal insulation performance. The oven can be quickly baked, shortening the oven construction period, and the economic benefit is high.

Product application of mullite-corundum castables

Mullite castables are used in the petrochemical industry in tubular heating furnaces, light diesel oil, ethane cracking furnace linings, atmospheric and vacuum furnaces, and sulfur recovery devices. Steam boilers, tortoiseshell mesh insulation layer, two-piece cylinder and pipeline insulation single layer, other industrial furnace doors, fire holes, observation hole door linings, etc.

The aggregate of the mullite-corundum castable is high-purity fused mullite produced by our castable manufacturer, and the fused white corundum fine powder produced by our factory is used as the main matrix material. And introduced a small amount of active silica fume (SiO2 micro powder recovered from the ferroalloy factory), kyanite powder, and additions such as sodium tripolyphosphate or sodium hexametaphosphate. Based on initial success in use in steel company pellet furnaces. We also prepared mullite-corundum low-cement castable precast blocks for a large-scale pellet furnace of a steel company. It was built in the hot spot of the combustion chamber of the pellet furnace and the corresponding combustion chamber built with high alumina bricks was used for a comparative use test. After three months of ignition operation, the masonry of the combustion chamber built with high-alumina bricks peeled off seriously, and local fires occurred. The mullite-corundum prefabricated block masonry of the corresponding combustion chamber is intact, and there is no peeling phenomenon. The combustion chamber built with high alumina bricks was re-ignited and operated for 6 months after cold repair and was observed after being forced to shut down for maintenance due to mechanical failure. The high-alumina brick masonry has been peeled off in a large area and is seriously damaged. The corresponding mullite-corundum castable precast block masonry has not found obvious signs of spalling.

Rongsheng Unshaped Refractory Castable Manufacturer

Compared with pure corundum castables and high alumina bricks, mullite-corundum castables and prefabricated blocks have better thermal shock resistance and spalling resistance. It is a new type of refractory castable and prefabricated block worthy of promotion when used at high temperatures with severe thermal shock, and it can be expected to obtain better results. Rongsheng refractory manufacturer provides high-quality monolithic refractory lining solutions for industrial furnace linings. Our environmentally friendly advanced monolithic refractory castable production line has an annual output of 6W tons. Contact us for free refractory castable configurations, quotes, and samples. The quality of our products never disappoints customers.

Refractory Castable for Waste Heat Boiler Lining

2022-08-15 by globalrefractory

Working principle of waste heat boiler. Fuel, gas, and coal are burned to generate high-temperature flue gas to release heat. The high-temperature flue gas first enters the furnace, then enters the waste heat recovery device of the front smoke box, and then enters the pyrotechnic tube. Finally, it enters the waste heat recovery device in the flue of the rear smoke box, and the high-temperature flue gas becomes low-temperature flue gas and is discharged into the atmosphere through the chimney. Because the waste heat boiler greatly improves the utilization rate of the heat released by fuel combustion, this kind of boiler is very energy-saving. The refractory castable for waste heat boiler lining is a mixed powdery granule composed of various aggregates or aggregates and one or more binders. When used, it needs to be mixed with one or more liquids and stirred evenly, and has strong fluidity and plasticity. Refractory castables for waste heat boiler lining usually use unshaped refractories such as high-strength wear-resistant castable, self-flowing corundum castable products, lightweight thermal insulation castable, and thermal shock-resistant refractory products.

Corundum Self-Flowing Refractory Castable

Corundum self-flowing castable

Rongsheng self-flowing refractory castable products have good fluidity, reasonable setting time, labor-saving, fast and convenient. High strength and long life. It has good thermal insulation performance, high temperature resistance, good thermal shock stability, corrosion resistance and erosion resistance. And it can pump mechanized construction, shorten the time of building the furnace, and can bake quickly and shorten the time of the furnace. It is a substitute for low-cement, ultra-low-cement, and no-cement castables. Especially used for heating furnace roof, furnace wall, water-cooled pipe wrapping system and other thin-walled linings and thermal repair of various kilns.

Lightweight thermal insulation castable

Lightweight thermal insulation castables are light in volume, high in compressive strength, and resistant to acid and acid gas corrosion. Heat insulation, heat preservation, low water absorption and other characteristics. The construction is simple, and it is an ideal product for the construction of parts with alkali corrosion resistance at high temperatures. Lightweight thermal insulation castables have the characteristics of low bulk density, low thermal conductivity, lightweight, high compressive strength, acid resistance, and acid gas corrosion resistance. Thereby, the thermal energy consumption of the industrial kiln can be reduced, and the weight of the furnace lining can also be reduced.

High-strength wear-resistant castable

Rongsheng high-strength wear-resistant castable, refractory products can be used by adding water and stirring on site. It has high bonding strength with basic concrete (steel silo), strong impact resistance, compressive strength and good workability. A certain thickness of anti-wear layer is formed on the surface of the silo or mine by manual plastering. It can meet the technical requirements after normal maintenance, and has the characteristics of high wear resistance, good durability and long service life.

Selection of refractory materials for lining of waste heat boiler cooling chamber

When refractory materials are required for the lining of the cooling chamber, these requirements must be followed. In the cooling room without water wall, when the temperature of the inner wall of the furnace wall is below 1300 ℃, the vault and the firewall directly scoured by the flue gas can be made of clay refractory materials for boilers with an Al2O3 content of not less than 40%. For the inner wall of the furnace wall with a wide tube water wall, because of the cooling effect of the water wall tube on the flue gas, a general clay refractory material with an Al2O3 content of less than 40% can be selected. When there is a water wall composed of finned tubes, because the finned tubes have a good shielding effect on the flue gas radiation, the lining of the furnace wall directly laid with refractory materials can be sintered clay water glass refractory concrete or sintered Portland cement refractory concrete. When there is a membrane-type water-cooling wall, because the membrane-type water-cooling wall can completely block the flue gas radiation, it is only necessary to directly lay the thermal insulation material and the thermal-insulation material on the membrane-type water-cooling wall.

RS Global Refractory Manufacturer

Rongsheng refractory material manufacturers provide high-quality refractory lining materials for various industrial furnaces. Our unshaped refractory castable workshop has an annual output of tons. Our products have been sold to more than 70 countries around the world. If you need to buy high-quality refractory castable products and refractory castables for waste heat boiler lining, or other refractory materials, please contact us.

Checker Bricks for Heat Storage – Checker Bricks Reheating Furnace

2022-06-27 by globalrefractory

Checkered bricks for heat storage of hot blast stoves. Clay checker bricks for hot blast stoves refer to the refractory materials for building the regenerators of hot blast stoves, which are mainly used for the lower part of the regenerators. Checker bricks for heat storage – checker bricks reheating furnace. According to different furnace types and different heat storage areas, it is usually divided into 7 holes, 19 holes, and 37 holes. Clay checker brick is a heat transfer medium used in the regenerator of blast furnace hot blast stove.

Checker Brick - Rongsheng Refractory Bricks — Checker Brick

Comparison of the heat storage area of checkered bricks:

(1) Traditional 7-hole lattice bricks: the diameter of the lattice holes is 43Mm, and the heat storage area is 38.1m2/m3;
(2) High-efficiency 7-hole lattice brick: the diameter of the lattice hole is 30mm, and the heat storage area is 47.08m2/m3;
(3) High-efficiency 19-hole lattice brick: the diameter of the lattice hole is 30mm, and the heat storage area is 48.6m2/m3;
(4) High-efficiency 37-hole lattice bricks: the diameter of the lattice holes is 20mm, and the heat storage area is 68.7m2/m3.

Checker Bricks Product Category

Checker bricks for heat storage – checker bricks reheating furnace. Because clay bricks are widely used, in addition to conventional sizes, most of them are designed and customized according to furnace type requirements. The hole bricks have 7 holes, 19 holes, 37 holes, 65 holes, etc., and support customization.

Clay grate bricks for coke ovens use bauxite clinker, mullite, and coke gemstone as the main raw materials and soft bonded clay. Formed by high pressure and sintered at high temperature. Commonly used checker bricks have three rows of nine holes, three rows of fifteen holes, three rows of twelve holes, and two rows of fourteen holes (7.63 meters of coke oven).

Advantages and disadvantages of silica lattice bricks and high alumina lattice bricks

The checkered bricks in the middle and upper part of the regenerator are still in a higher temperature area, and at the same time, the checkered bricks in this area also bear the load of the upper checkered bricks, so the collapse of the checkered bricks occurs. That is to say, the damage to the checkered bricks in the quasi-high temperature zone is mainly caused by the uneven subsidence of the checkered bricks caused by creep. Especially when the high-temperature airflow on the cross-section of the checkered brick is unevenly distributed, the situation is particularly serious. For the checker bricks in the middle and lower parts of the regenerator, high alumina and clay refractory materials are usually used. With the increase in the height of the regenerator of the large-scale hot blast stove, the pressure of the upper lattice bricks on the lower refractory materials is also increasing. In addition, according to the damage investigation of large-scale high-temperature hot blast stove lattice bricks abroad, it was found that the cracking and breaking of lattice bricks caused by the influence of periodic temperature fluctuations on the lower lattice bricks is increasing. Therefore, in addition to continuing to control the creep characteristics of the lower clay bricks, higher requirements must be put forward for the normal temperature compressive strength and thermal shock stability of the products.

Silicon refractory is an acidic refractory material, which has good resistance to oxides such as CaO, FeO, and Fe2O3, and has the advantages of high softening temperature under load, stable volume at high temperature, and high thermal conductivity. However, the low temperature (below 800°C) has poor thermal stability. The specific realization is: that the softening temperature under load can be as high as (1640-1680°C), which is close to the melting point of tridymite (1670°C), and the thermal stability above 800°C is very good. Adapt to large changes in temperature. Silica bricks for hot blast stoves use tridymite as the main crystal phase, which has stable volume and low creep rate under high-temperature load, and its anti-adhesion performance is also better than other refractory materials. Proper use can make the structure of hot blast stoves more stable. However, at 200-300°C and 573°C, due to the crystal form transformation, the volume expands suddenly, which is easy to cause structural damage. Therefore, severe temperature changes should be avoided below 600°C.

Compared with silica bricks, high-alumina refractories have lower softening temperature under load and poor volume stability at high temperatures, but high-alumina refractories have the advantages of large capacity and good thermal shock stability.

Checker bricks for heat storage – checker bricks reheating furnace. Purchase high-quality regenerator checker bricks. Please contact Rongsheng Global refractory manufacturers.

How to do the boiler refractory repair of the worn of kiln lining refractory material?

2022-06-13 by globalrefractory

The kiln lining needs to be repaired after wear and tear. According to the wear of the kiln, choose the appropriate repair method. Plastic refractory materials repair, spray refractory materials repair and castable refractory repair can be used.

Refractory is the basic material of high-temperature technology and an important masonry material for kiln lining. In a high-temperature environment, it is in direct contact with slag, charge, decomposition gas, etc., and gradually changes during long-term use. The characteristics of the refractory itself can resist the erosion of slag, chemical, air flow, etc. for a certain period of time. However, over a certain period of time will cause local lining damage, peeling, and other phenomena. At this point, the refractory material needs to be repaired. The refractory material can continue to work through a series of repair operations to ensure the normal operation of the kiln. So, what methods can be used to repair the refractory lining of the kiln?

Converter repair material

Repairing damaged parts of the converter can significantly extend the service life of the converter. With the advancement of spraying technology, converter thermal spraying technology has experienced the direction from high water to low water and no water, that is, from wet and semi-dry to flame spraying.

Blast furnace gunning

The spray method uses high-pressure air to transport granular refractory materials. Mix with a suitable amount of water in a spray gun and spray on the surface of the repair lining. Attached to a certain thickness (up to several hundred millimeters), replacing the rebuilding of the refractory brick lining.

Repair method of the inner lining of the mixed iron car

Due to its function and operation characteristics, the maintenance of the inner lining of the mixed-rail car is generally divided into major repairs, medium repairs and hot repairs.

Hot blast furnace lining thermal repair technology

As the auxiliary equipment of blast furnace, hot blast stove needs 1-2 generations of blast furnace age. The actual service life of a blast stove is usually determined by the refractory lining of the blast stove system. Refractory linings often have problems during use, and online thermal repair of refractory linings is an effective method to prolong the service life of refractory materials.

Glass Furnace Hot Repair

The traditional furnace thermal repair method has a harsh environment and high labor intensity. Although a great improvement has been made with the use of advanced refractory materials, it is still relatively difficult and burdensome, interfering with normal production. At present, the furnace thermal repair method includes thermal repair methods and thermal oxygen spraying methods.

What are the repair methods for boiler refractory repair?

The pouring repair method is to pour the unshaped refractory material into the repaired part and combine it with the original lining to resist the erosion of the slag.
The thermal spraying repair method is to spray the unshaped refractory material to the part that needs to be repaired through the spray gun. And attached to its surface to reach a certain thickness, replacing the rebuilding refractory brick lining. Rebuild the residual brick lining or the furnace lining on the surface of the furnace shell to restore the furnace shape. Compared with other maintenance methods, the major feature of spray repair is that the integrity of the repaired furnace lining is good, and the furnace shape can be reconstructed.
The injection method is to project the unshaped refractory material to the part that needs to be repaired. The operation is simple and convenient.
The grouting repair method is also known as the press-in repair method. It uses special press-in equipment to transport specific refractory materials from outside the furnace to designated maintenance parts under certain pressure conditions. So as to achieve the purpose of filling the gap and repairing the furnace lining.
The digging method is also known as the masonry method, that is, the partially damaged part of the lining is removed first, and then the refractory tiles are used to rebuild the masonry. In this case, the kiln needs to be cooled before construction.

Different lining refractory repair methods are suitable for different furnaces.

The pouring repair method can be used for repairing any kiln, blast furnace, coke oven, electric furnace, iron tapping point, ladle, etc. after the furnace is stopped.
Thermal spray repair, which can be used for damage repair of the bottom furnace wall of hot blast furnace, coke oven head, open-hearth, electric furnace, converter, heating furnace, and other furnace linings.
Spray repair method, mostly used for ladle lining construction.
The grouting repair method is mostly used for filling between the blast furnace and the furnace wall.
Excavation repair method, suitable for medium or overhaul of various kilns, blast furnaces, coke ovens, ladle, tundish, etc.

The above is an introduction to the repair method of lining refractory materials. With the development of the refractory industry, the repair methods of refractories have gradually changed. As a refractory manufacturer, Rongsheng Global Refractories has always aimed at kiln refractory solutions, boiler refractory repair, providing users with better refractory materials, and optimizing refractory lining material repair solutions.

What is the High Alumina Castable Refractory in South Africa?

2022-05-27 by globalrefractory

High alumina castable is one of the best-selling refractory castables of Rongsheng refractory manufacturers. There are many customers who continue to buy high-alumina castables from our factory, including customers in South Africa. High alumina castables are suitable for various heat treatment furnace linings and burners, blast furnace hot blast stoves, heating furnaces, electric furnace tapping grooves, high-temperature sections of shaft kilns, rotary kiln heads, power plant boilers, and other industrial furnace linings. So, what is the high alumina castable refractory in South Africa?

Rongsheng High Alumina Castables Refractory

High alumina castable is a type of low cement castable with a cement content of less than 8%. It is a refractory castable made of high alumina bauxite clinker as aggregate, refractory clay as powder, adding aluminate cement and sodium tripolyphosphate according to the formula proportion. Its use temperature is above 1400 ℃, and the aluminum content reaches 74%. It is a commonly used castable for kiln lining.

High alumina castables have the characteristics of high refractoriness, strong thermal stability, and good thermal shock resistance. high alumina castable refractory in South Africa. Different from ordinary refractory castables, most of the calcium aluminate cement in the matrix is replaced by ultrafine powder, and at the same time, appropriate additives are added to achieve and exceed the performance of ordinary cement castables.

High alumina refractory castables are now widely used in the construction and daily maintenance of various industrial kilns. High-alumina castables generally have high strength at room temperature, and can also be made into prefabricated parts and installed on the kiln rotary site. High-alumina castables can work in parts that are eroded by molten iron, molten steel, and slag and have a higher working temperature. The variety of high-alumina castables has increased rapidly, and the quality of high-alumina castables has gradually improved. Rongsheng‘s new generation of high-alumina castables includes low-cement refractory castables, ultra-low cement castables, and cement-free castables.

There is a difference between high alumina castables and high alumina low cement castables.

The high alumina castable refractory cement is added at 12%, which is convenient for construction and fast setting in the early stage but has a high calcium content, and then later use strength is not as good as that of low cement castables. The high alumina low cement castable refractory cement is added at 6%, with low calcium content and good later uses strength.

If used for chimney lining, it is better to use high alumina castable. Due to a large amount of refractory cement added, the chimney lining will be impacted by flue gas and water mist. Due to a large amount of cement, the fast setting speed of construction, and the smooth surface of the high-alumina castable surface, the high-alumina castable is more suitable in this case.

For high alumina low cement castables, the amount of refractory cement binder added is small, the amount of water added during construction is small, it is easy to bake, and it has good strength and high-temperature resistance. Moreover, the raw materials and binders of high-aluminum low-cement castables are better than the matrix of general high-aluminum castables, and the refractory cement are also relatively different in terms of labels. The price is also relatively higher than that of high-aluminum castables.

High alumina low cement castables are relatively used in high-temperature areas. Better than high aluminum castables. The material matrix used is also different than high alumina castables. So these two castables are different.

high alumina castable refractory in South Africa. The construction of high alumina castables is very important. Especially the amount of water added. Be sure to control the amount added according to the construction instructions, and do not add more. When stirring, the aggregate should be used first, then the fine powder should be added, the binder should be added, and the stirring time should not be less than 5 minutes.

After the initial setting and final setting of the high-alumina refractory castable after construction, the high-alumina castable must be cured before it can be demoulded, and then it can be put into use for baking after an appropriate period of natural curing.

The price of high-aluminum castables is determined according to the bulk density and aluminum content. The price of castables produced from high-aluminum materials with low bulk density will be relatively low. If it is castable with high bulk density and high aluminum content, the price will be relatively high.

Buy High Aluminium Castables Quickly

Rongsheng refractory material manufacturer has an advanced and environmentally friendly unshaped refractory castable production workshop. The main castable products of our factory are steel fiber castable, wear-resistant castable, high-alumina castable, non-stick alumina castable, explosion-proof quick-drying castable, alkali-resistant castable, and so on. high alumina castable refractory in South Africa. Quickly buy high alumina castables, just send us an email. We will get in touch with you as soon as possible and provide you with a free quotation and sample service.

Development of Low-Carbon Magnesia-Carbon Bricks

2021-07-25 by globalrefractory

The carbon content in traditional magnesia carbon bricks is relatively high, generally in the range of 10-20%. Due to the presence of carbon in magnesia-carbon bricks, the performance of magnesia-carbon bricks is greatly improved, making them superior to magnesia-chrome bricks and magnesia-dolomite bricks in certain properties. However, due to the progress of metallurgical technology and the demanding requirements for refractory materials, a series of problems have appeared in the use of traditional magnesia-carbon bricks. For example, the excellent thermal conductivity of graphite increases the heat loss in the steelmaking process and wastes energy. Too high graphite content will increase the carbon content in the molten steel during the refining process outside the furnace, affect the quality of the molten steel, and is not conducive to the reduction of the carbon content in the steel. In addition, graphite is a precious non-renewable resource, and traditional magnesia carbon bricks rely too much on graphite, which is detrimental to the sustainable use of resources.

Rongsheng High-Quality Magnesia Carbon Bricks

However, simply reducing the graphite content in the magnesia carbon brick will not only reduce the thermal conductivity of the magnesia carbon brick but also increase the elastic modulus of the magnesia carbon brick, which will reduce the thermal shock stability of the material. In addition, due to the low wettability of graphite with molten steel and molten slag, if the graphite content in the magnesia carbon brick is reduced, the magnesia carbon brick will be more easily corroded by molten steel and molten slag, resulting in a decrease in the corrosion resistance of the material. Therefore, research on magnesia carbon bricks with lower graphite content and excellent thermal shock stability, and slag erosion resistance has become the focus of current research and a new direction for the future development of magnesia carbon bricks.

Low Carbon Magnesia Carbon Brick with High Performance

In order to solve these contradictions and improve the performance of low-carbon magnesia-carbon bricks, we can start with improving the carbon structure of the combined carbon, optimizing the matrix, and using high-efficiency antioxidants. The specific improvement measures are as follows.

(1) Modified magnesia particles

In order to solve the poor thermal exfoliation of low-carbon magnesia-carbon bricks, a thin asphalt coating is prepared on the surface of the magnesia particles to reduce the thermal expansion of the magnesia particles during use. In this way, the thermal shock stability of low-carbon magnesia-carbon bricks can be improved.

(2) Change the type of carbon source and the particle size of graphite

By adding a small amount of carbon black (carbon black is a mixture of single spherical carbon black and polymeric carbon black), magnesia carbon bricks show outstanding excellent properties, such as reduction of elastic modulus, and relaxation of thermal stress between different particles. Improve the thermal shock stability and corrosion resistance of low-carbon magnesia-carbon bricks.

A small amount of nano-sized carbon is added to make the new magnesia carbon brick with a carbon content of about half of the ordinary magnesia carbon brick still have excellent performance. Adding different amounts of nano-sized carbon has different effects on performance. The practice has proved that adding 0.9wt% of nano-sized carbon and 3wt% of graphite as a mixed carbon source makes the material have the best performance.

(3) Modified binder

The magnesia-carbon bricks after adding the nano-sized matrix, on the one hand, reduce the carbon content and at the same time ensure the thermal shock stability of the material, on the other hand, reduce the heat loss of the converter. The composite bonding agent increases the degree of graphitization after carbonization of the bonding agent, forms micropores in the matrix, and improves the mechanical properties of the magnesia carbon brick at room temperature, high temperature, and other mechanical properties.

(4) Highly effective antioxidants

Low-carbon magnesia-carbon bricks with special additives have the same thermal shock stability as traditional magnesia-carbon bricks.

To purchase high-quality magnesia-carbon bricks and low-carbon magnesia-carbon bricks, please contact refractory manufacturers.

What are the High Alumina Refractory Mortar and High Alumina Phosphate Mortar?

2021-06-09 by globalrefractory

What are high alumina refractory mud and high alumina phosphate mud? Through searching, it is not difficult to find that most refractory material manufacturers provide refractory slurries for use with refractory bricks. The high-alumina refractory mud is used to fill the joints of high-alumina refractory bricks.

High Alumina Refractory Mortar

High-aluminum refractory mud, high-aluminum fire mud is also called high-aluminum mud. It selects high-aluminum clinker as raw material, mixes with the binder, and mixes and mixes uniformly according to a certain ratio. Its function is to cooperate with the masonry of high-alumina bricks, and sometimes also act as a joint filler.

The high alumina refractory mud determines the Al2O3 content and the particle size of the high alumina clinker according to the brick composition and use requirements of the masonry part, so as to better match the high alumina bricks and resist the erosion of gas and slag.

High Alumina Refractory Mortar - Rongsheng Company — High Alumina Refractory Mortar

Precautions for the Use of Alumina Refractory Mortar

According to the refractory bricks used, use the corresponding refractory mortar.

Add water or binder in proportion, not too thick.
Stir well after adding water or binder.
Apply the thickness according to the requirements during masonry, even and appropriate.
Use the prepared mud as soon as possible. If it hardens, it cannot be used again.
When storing, do a good job of waterproofing and damp proofing to avoid agglomeration of mud and affect the use effect.

High Alumina Phosphate Mortar

High-alumina phosphate mud is used as a joint material for masonry-shaped refractory products. It is composed of refractory powder, water or liquid binder, and additives (such as dispersant, plasticizer, stabilizer, or water-retaining agent). It is a kind of paste-like slurry with a high concentration of solid particles, which has the characteristics of Bingham fluid.

Generally speaking, the chemical properties of refractory mud should be similar to the chemical properties of refractory products. Therefore, it is the same as the classification of refractory products. There are siliceous, semi-silica, clay, high-aluminum, corundum, magnesia, magnesia, magnesia, chromium, carbon, or silicon carbide slurries. The high-strength phosphate refractory slurry is formulated with five raw materials, including phosphoric acid, aluminum chips, high-aluminum powder, aggregates, and additives in a certain proportion. Phosphoric acid reacts chemically with aluminum chips to form Al(H2PO4)3. Al(H2PO4)3 is the binder of the mud, high alumina powder increases the chemical activity of the mud, high alumina aggregate improves the thermal stability of the mud, and additives enhance the adhesion of Al(H2PO4)3 to refractory bricks.

The preparation process of high-strength phosphate refractory slurry. Put a certain proportion (weight) of phosphoric acid into a non-metallic container and heat it to 60°C. Then add aluminum scraps and additives in proportion, and remove unreacted aluminum scraps after the reaction stops. Then put the high-aluminum aggregate and high-aluminum powder into the container in batches, mix well and let stand for 1 hour. The adjusted mud should be dry and wet properly. Too dry mud reduces free Al (H2PO4) 3 and reduces bonding strength. Too thin mud has too much free water so that the porosity of the mud is too large after it dries, and the strength of the mud itself is reduced. It is advisable to blend it to flow, draw into silk, and have adhesive strength after use. The bonded refractory bricks can be dried immediately or after a period of time.

High-strength phosphate refractory mud can be used in heating furnaces for clay bricks, light clay bricks, high alumina bricks, silica bricks, mullite bricks, corundum bricks, etc. Especially it has a better effect when used in heat treatment furnaces.

Buy High-Quality Refractory Products from Manufacturers

What should I do if the refractory material cracks, falls off, and is easy to wear? To completely solve the problem, it is necessary to conduct a specific analysis from the consolidation of the refractory lining and the working conditions. Only in this way can the real cause be analyzed. Rongsheng refractory manufacturers have been engaged in refractory production and R&D services for many years, and have helped solve refractory lining problems in more than 60 countries, for example, Russia, South Africa, Kazakhstan, Philippines, Chile, Malaysia, Uzbekistan, Indonesia, Vietnam, Kuwait, Turkey, Zambia, Peru, Mexico, Qatar, etc. If you want to learn more about refractory materials, please follow our blog. To purchase high-quality refractory lining products, please contact us.

What are Aluminum-Carbon Refractories?

2021-05-28 by globalrefractory

What are aluminum carbon refractories? Special aluminum-carbon refractories refer to alumina and carbon as raw materials. In most cases, other raw materials such as SiC, metal Si, Al, etc. are also added. Carbon composite special refractory material bonded with organic binders such as asphalt or resin. Broadly speaking, refractories with alumina and carbon as the main components are called aluminum-carbon refractories. Aluminum-carbon refractories can be divided into two categories according to their different production processes. Non-burned aluminum carbonaceous refractories and fired aluminum carbonaceous refractories.

Introduction of Aluminum Carbon Refractories

Non-burning aluminum carbon refractories belong to carbon-bonded refractories. Because its oxidation resistance is obviously better than that of magnesia carbon bricks, and the corrosion resistance of Na2O series slag is excellent. Therefore, it is widely used in hot metal pretreatment equipment such as blast furnaces and hot metal ladle. The fired aluminum-carbon refractory is a ceramic-bonded refractory. Because of its high strength, corrosion resistance, and thermal shock resistance. Therefore, there are a large number of slide bricks suitable for continuous casting sliding nozzle systems and three continuous casting parts, namely, shroud, immersion nozzle, and integral stopper.

Alumina has high resistance to acid, alkaline slag, metal, and glass solutions. Whether it is used in an oxidizing atmosphere or a reducing atmosphere at a high temperature, it can be used well. The carbon raw materials, especially graphite, have high thermal conductivity and low linear expansion coefficient, and at the same time have non-wetting properties with slag and high-temperature solutions. Therefore, aluminum-carbon bricks have the following properties.

(1) Aluminum-carbon refractories have excellent slag resistance and thermal shock resistance. Compared with magnesium-carbon refractories, aluminum-carbon refractories have better resistance to alkali corrosion and TiO2 slag erosion.
(2) For fired aluminum-carbon bricks, silicon carbide is formed by the reaction of additive silicon and carbon at high temperature, so that it has a dual bonding system, namely carbon bonding and ceramic bonding. Therefore, the fired aluminum-carbon refractory has high mechanical properties. In continuous casting, it not only acts as a traditional refractory material but also a functional structural material.

At present, aluminum-carbon refractories mainly use fused corundum, sintered corundum, or sintered tabular corundum, super-grade or grade I high-quality bauxite clinker as the coarse-grained components of the products. Use corundum fine powder or fused mullite, sintered synthetic mullite fine powder, or synthetic high mullite fine powder. Adding a certain amount of carbon to the product is beneficial to improving the properties of the product and prolonging the service life. The melting point of carbon is very high, the coefficient of linear expansion is small, and the thermal conductivity is good.

Carbon can penetrate into the pores of the particles in the product or form a vein-like network carbon chain structure between the particles to form a “carbon bond”, thereby reducing the porosity of the product and improving the high-temperature strength of the product. Carbon can also form a surface that is not corroded by metals and slag, improving the corrosion resistance and thermal shock resistance of products. In addition, the presence of carbon creates conditions for the reduction of iron and silicon oxides, and the resulting metal does not react chemically with refractory materials. When the oxide is reduced by carbon, the generated gas can prevent the molten oxide from penetrating into the refractory material. Carbon can also improve the thermal conductivity of the product, so as to prevent individual parts of the product from peeling and breaking due to uneven temperature overheating. Therefore, the carbon raw materials in the aluminum-carbon bricks are mainly flake-like natural graphite, and pyrolytic high-purity graphite can also be used, and carbon black is usually added. Antioxidants include metal Al, Si powder and SiC, B4C powder. Adding a small number of antioxidants can delay the oxidation of the carbon-containing layer and increase the service life of the product.

Purchase High-Quality Aluminum Carbon Refractory Materials from Manufacturers

To purchase high-quality aluminum-carbon refractories, please choose a strong refractory manufacturer. Rongsheng refractory material manufacturer has rich experience in the production and sales of refractory materials. Its customer base covers more than 60 countries all over the world. For example, Russia, South Africa, Kazakhstan, Philippines, Chile, Malaysia, Uzbekistan, Indonesia, Vietnam, Kuwait, Turkey, Zambia, Peru, Mexico, Qatar, etc. Moreover, a number of turnkey projects for refractory lining materials have been completed. Annual output of 80,000 tons of monolithic refractories. For more detailed information, please contact us.