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Aluminate Cement and Aluminate Refractory Castable

KilnRefractory

Aluminate cement and aluminate refractory castables. aluminate cement (Al2O3 65～70%, CaO 21～24% low iron type). RS Kiln Refractory Manufacturer is a refractory material manufacturer with rich production and sales experience. RS manufacturer is committed to providing high-quality and long-life refractory lining materials for high-temperature industrial furnaces. Contact Rongsheng for a free quote.

Rongsheng Calcium Aluminate Cement - High Alumina Cement
Rongsheng Calcium Aluminate Cement – High Alumina Cement

Aluminate Cement

Aluminate cement is a refractory cement, which has many names: refractory cement, 625 cement, high alumina cement, CA-50 cement, etc. It has a wide range of applications. In many refractory concretes, aluminate cement is an indispensable refractory binder.

Aluminate cement is a special cement with weak alkaline calcium aluminate as the main component. It is a hydraulic cementitious material made of bauxite and limestone as raw materials, calcined and made of clinker with calcium aluminate as the main component and about 50% alumina content.

The use temperature of aluminate cement can reach 1350℃. If it is mixed with high-alumina aggregate and other refractory materials in proportion to form a refractory castable, the refractory temperature can reach 1700℃.

Aluminate cement can be divided into CA-50 and CA-70 (also called calcium aluminate cement, white) according to the aluminum content. It is a hydraulic cementitious material with fast hardening, early strength, corrosion resistance and high temperature resistance. Aluminate cement is yellow-brown or gray and is widely used in metallurgy, machinery, building materials, petrochemicals, electricity, food and other industries.

Introduction to the uses of aluminate cement

  1. Used to prepare refractory castables and kiln linings.
  2. Suitable for projects that resist sulfate erosion.
  3. Suitable for concrete projects that require rapid hardening and emergency repair projects.
  4. Suitable for winter construction and special projects that require early strength.
  5. Used as raw material for making water purifiers (calcium aluminate powder).
  6. Used as the best raw material for making decorative materials (such as artificial marble, colored road tiles, colored corrugated tiles, etc.).
  7. It is an important component for preparing expansive cement, self-stressed cement and other special cements.
Rongsheng High Alumina Castables Refractory
Rongsheng High Alumina Castables Refractory

Aluminate Refractory Castables

Aluminate Refractory Castables are an important amorphous refractory material, widely used in industrial kilns such as metallurgy, building materials, petrochemicals, and electric power. It consists of refractory aggregate, powder and binder (such as aluminate cement), which is mixed by adding water or other liquids and has good construction performance and high temperature performance.

Aluminate Refractory Castables Aluminate cement is the key binder in aluminate refractory castables. The type and amount of aluminate cement have a significant effect on the performance of the castable. For example, an increase in the amount of CA-50 cement will increase the compressive strength at room temperature, but the compressive strength will decrease after burning at 1200℃, the refractoriness and load softening temperature will also decrease, and the linear shrinkage after burning will also increase. When preparing aluminate refractory castables, in addition to the amount of cement, the amount of water is also a key factor. An increase in the amount of water will lead to a decrease in performance, so the amount of water in the mixture should be minimized to ensure construction and workability. The selection of refractory powder and aggregate will also have an important impact on the performance of castables. Refractory powder can improve the refractory performance of castables, while the type, grade, maximum particle size and particle grading of aggregates are the main factors affecting the performance.

The use of aluminate castable admixtures is also an important means to improve the performance of aluminate refractory castables. Water reducers can improve the fluidity of castables and reduce water consumption, and coagulants and retarders can adjust the setting time of castables. Sintering agents and expansion agents can improve the medium-temperature strength of castables and compensate for shrinkage at high temperatures.

Refractories for Carbon Baking Furnaces

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The Carbon Baking Furnaces adopt silicon-alumina refractory materials as a whole. Refractories for Carbon Baking Furnaces. The furnace body of the Carbon Baking Furnace is made of high-quality fire clay bricks or high alumina bricks, and the furnace cover is integrally prefabricated with high-alumina refractory castables.

The brick piers and pit-faced masonry at the bottom of the closed Carbon Baking Furnaces bear the weight of the upper masonry and calcined products. The masonry of the upper electrode box’s heating wall, firebox and burner are subjected to a high temperature of 1400 ° C. At the same time, during each Furnace’s cycle, it is also affected by temperature changes. Therefore, fire clay bricks with high mechanical strength, high load softening temperature, and good thermal stability are used for masonry. The removable furnace cover can be built with heat-resistant refractory materials.

Low Creep Low porosity fire clay bricks
Low Creep Low Porosity Fire Clay Bricks

Refractories for Carbon Baking Furnaces

In the construction of a Carbon Baking Furnace, the following refractory materials are required. For example, fire clay bricks, fire clay insulation refractory bricks, special-shaped fire clay bricks, clay refractory mortar, fire clay insulation refractory particles, refractory fiber felt, asbestos rope, fire hole, burner bricks, etc. Among them, the amount of fire clay bricks are the largest.

Fire clay bricks are one of the main varieties of aluminum silicate products. It is made of clay clinker as aggregate and refractory soft clay as a binder with Al2O3 content of 30% ~ 48%. Clay refractory bricks have the following characteristics:

  • The properties of clay refractory bricks products can fluctuate in a large range, which is due to the large fluctuation range of the chemical composition of the product and the difference in the production process. (AL2O3 content fluctuates between 30% and 48%).
  • The refractoriness fluctuates between 1580 ~ 1700 ° C;
  • Its products have good thermal shock resistance and a large fluctuation range, generally more than 10 times (1100 ° C water cooling);
  • Coefficient of linear expansion of fire clay products. The average linear expansion coefficient from 20 to 1300 ° C is (4.5 to 5.8) * 10-6 ° C-1.

Fire clay products are kinds of weakly acidic refractory products, which increase their acidity as the SiO2 content increases. It has a certain erosion resistance to acidic slag, but a poor erosion resistance to alkaline slag. Therefore, clay products are suitable for the refractory lining of the acid slag furnace.

Refractories for Carbon Baking Furnaces
Refractories for Carbon Baking Furnaces

Construction of Refractories for the Carbon Baking Furnaces

When the Carbon Baking Furnace is constructed, the furnace body is built first. The flue and “Π” shaped regulators on both sides are built together. As for the bricklaying of the furnace cover and the outer flue (or flue pipe), it will be carried out after the furnace body is completed, and they can also be constructed along with the furnace body under the conditions allowed by the site.

The masonry construction of refractory materials for Carbon Baking Furnaces is often the key to the safe operation of the entire kiln. Therefore, in the masonry construction of the Carbon Baking Furnaces, it is necessary for the construction personnel to carry out the construction in an orderly, and high-quality manner.

RS Refractory Manufacturer
RS Refractory Manufacturer

Rongsheng Refractory Bricks Manufacturer

Rongsheng is an experienced refractory bricks manufacturer, Rongsheng’s customers have more than 60 countries and regions around the world. Our technical engineers can customize refractory materials for customers according to their production conditions. For refractory bricks that are used in large quantities, such as fire clay bricks, high alumina bricks, and silica bricks, Rongsheng competes with its peers by quality. For thermal furnaces with harsh production conditions, Rongsheng can customize refractory materials for customers. Last year, RS have customized fused silica bricks for a customer. This is also the first time of us to use such refractory, said by the customer. If you need to buy refractory bricks to build refractory lining. Please contact us and we will reply to you as soon as possible, and perfectly solve the refractory linings’ problems.  by RS Kiln Refractories Blog.

The Difference Between Refractory Mortar and Refractory Cement

KilnRefractory

In the process of building refractory bricks lining, for those who do not know much about refractory materials, the difference between refractory mortar and refractory cement is difficult to distinguish. When should I choose refractory cement and refractory mortar? The technical staff of Rongsheng refractory manufacturer gave the following explanation.

Refractory Mortar for Sale in RS Manufacturer
Refractory Mortar for Sale in RS Manufacturer

The furnace lining material can be made of refractory bricks or directly cast by refractory castables.

When building refractory brick lining, the special joint material or bonding material needed is refractory mortar.

Because the refractory bricks are piece by piece, the complete refractory lining material requires that the refractory bricks are to be tightly linked together and not fall off. Therefore, a kind of binder is used when refractory bricks are used for kiln linings building. This kind of binder is called refractory mortar or seam material. They are refractory slurries reconciled with refractory mortar and water. It is the main auxiliary material for refractory brick masonry and the seam filler for the bonding of refractory bricks.

The choice of refractory mortar material needs to be selected strictly in accordance with the material of the refractory brick used in the construction of the refractory lining. Do not mix! There are as many types of refractory bricks as there are refractory mortar materials. Commonly, high alumina refractory mortar is used for masonry high alumina bricks, magnesium refractory mortar is sampled for masonry magnesiate bricks, and silica refractory mortar is used for masonry silicon bricks.

Refractory Brick Lining Building
Refractory Brick Lining Building

How to use refractory mortar

The supply method of refractory mortar is supplied as dry powder. When used, it is mixed with liquid gelling agent to form a viscous slurry. This kind of mortar is collectively called high temperature refractory mortar, high temperature refractory mud or high temperature binder. According to the combination method of liquid gelling agent, it is divided into: water glass combined refractory mortar, phosphoric acid combined refractory mortar, aluminum phosphate combined refractory mortar, etc. In addition to being used as a bonding material, refractory mortar can also be used as a protective coating for furnace linings by smearing or spraying.

The refractory lining material can also be completed by painting, spraying and pouring.

When the refractory castable is casting, a binder is needed to bond the refractory feedstock together. So that the refractory lining material can be firmly fixed on the lining of thermal equipment. The binder used here is generally refractory cement.

Refractory cement, also called aluminate cement or high alumina cement. Aluminate cement is often yellow or brown, and sometimes gray. The main mineral composition of aluminate cement is calcium aluminate (CaO · Al2O3, CA), other aluminates, and a small amount of dicalcium silicate (2CaO · SiO2). Refractory cement forms eutectics under the action of high temperature. When configuring refractory castables, excessive addition will reduce the high-temperature performance of the castables, usually using silica powder to replace part of the refractory cement.

Furnace Lining Castable Refractory
Furnace Lining Castable Refractory 

In Conclusion

The biggest difference between refractory mortar and refractory cement is that refractory mortar is used for refractory bricks (mixed with water or other liquids). The refractory cement is used as a binder material for various refractory aggregates, and the refractory castables made of it are used as lining materials for kilns.

Characteristics and Application of Mullite Bricks

KilnRefractory

Mullite Bricks and corundum mullite bricks have the advantages of high load softening temperature, low high-temperature creep rate, and good thermal shock resistance. Widely used in industrial furnaces such as blast furnace, hot blast furnace, glass melting furnace, dry quenching and heating furnace. Mullite Bricks are easily eroded by alkaline refractory bricks at high temperatures. In addition, at high temperatures, mullite can react with water vapor to form Al2O3 and be damaged. Contact RS Refractory Supplier for more.

mullite brick

Therefore, mullite refractory bricks are not suitable for long-term use in environments with high alkaline slag and high water vapor content.

In addition to mullite and its composite refractory bricks composed of corundum, mullite can also be used to form refractory bricks with other materials to improve its performance. Such as zircon mullite refractory brick, mullite-silicon carbide refractory brick and so on. Zircon mullite refractory brick is mullite-zirconia composite material. However, because zirconia is expensive, in actual production, zircon mullite clinker or refractory bricks are often prepared by reacting Al2O3 or alumina with zircon.

The manufacturing methods of such refractory bricks and raw materials include electric melting method and sintering method. Aluminum fused zirconium silicon (AZS) refractory bricks made by electrofusion have been discussed in fused zirconium corundum bricks. Zircon mullite clinker is prepared by calcining Al2O3 and ZrSiO4 ingredients, and then crushing, kneading, molding and firing to obtain zircon mullite refractory bricks, that is, sintered AZS brick.

corundum mullite bricks

 

Refractory bricks made with sintered or fused mullite as the main raw material can be all mullite, some can be mullite, and some are corundum. The former is called mullite refractory brick, and the latter is called corundum-mullite refractory brick or corundum mullite brick. The production process of mullite refractory bricks is the same as that of high-alumina bricks, and the ingredients are subjected to several processes such as mixing, forming, drying and firing. The firing temperature is related to the composition of ingredients, the purity of the raw materials and the requirements for the performance of the refractory bricks, which is usually 1500 to 1700 ° C.

The Mullite Bricks are mainly used for hot blast stove top, blast furnace body and bottom, glass melting furnace heat storage chamber, ceramic sintering kiln, dead angle lining of petroleum cracking system, etc.  More info at website: https://kilnrefractory.com/.