refractory

Fused cast AZS block is made of high pure raw materials in a special electric arc furnace by the casting process of long arc melting and oxidation treatment. There is almost no carbon contamination from the electrodes.

Due to the casting process and high pure materials, fused cast AZS block has super strong corrosion resistance to the glass liquid and low potential of pollution.

Fused cast AZS 33# block has great advantage in preventing the pollution from glass liquid. It can generate stones in glass and has low potential of glass precipitation and bubbling. It is suitable to the upper structure of the melting zone, the sidewall of the work tank, the paving blocks and the forehearth.

Fused cast AZS 36# block is the standard fused cast AZS block made by the oxidizing method. It has special high corrosion resistance to the glass liquid and has low potential of pollution. It is suitable for the areas that are in direct contact with the glass liquid, such as the sidewall of the melting zone, paving block and feed port.

Fused cast AZS 41# block is the highest grade fused cast AZS block. It has the best corrosion resistance to the glass liquid and low pollution potential. It is suitable for the parts that require super high resistance such as the electric melting furnace, throat, kiln dam, bubble block and the corner block of the feed port.

As their names imply, refractory brick is used to withstand high temperature and flame, while insulation brick is used to insulate and reduce heat loss. The insulation bricks seldom directly contact flame, while refractory bricks can directly contact flame. Both have their advantages and are used in different parts of furnaces.

Insulation bricks always have thermal conductivity between 0.2-0.4 w/m.k (350±25℃), while refractory bricks have thermal conductivity above 1.0w/m.k(350±25℃). So, insulation bricks have better insulation performance than refractory bricks. the refractoriness of insulation bricks is usually under 1400 degree, while that of refractory bricks is above 1400 degree. insulation bricks are generally lightweight materials with a density between 0.8-1.0g/cm3, while that of refractory bricks is above 2.0g/cm3.

Refractory bricks have better mechanical strength, long service life and better chemical stability. They do not react with batch materials. They have better high temperature performance and can withstand high temperature up to 1900℃.

Refractory bricks and insulation bricksa are quite different. Their applications and functions are quite different. It is important to select the right materials according to the actual conditions.

Compared to the traditional processing, modern glass making technology has undergone a qualitative change in efficiency, energy consumption and quality. Furnaces, as the core equipment of glass making, continue to be improved. The rapid development of glass making promotes the development of refractories.

Refractories used in the glass furnace are required to withstand higher temperature, sharper temperature changes, more serious chemical corrosion and severer stress damage. The common refractories used in the glass furnace are as followings:

1) fused cast AZS and fused cast high zircon block
For fused cast AZS block, it is important to improve its corrosion resistance and wear resistance. Besides the oxidizing melting method, reducing the carbon content to 0.005 and improving the exudation temperature of glass phase to 1450℃, the casting method and annealing method are also improved to improve the quality and properties of fused cast AZS.
Fused cast high zircon block with more than 90% ZrO2 has excellent thermal shock resistance and low potential of pollution to glass.

2) Chrome brick
Dense chrome bricks made by isostatic pressing are used in the walls, throat and other severely corroded areas in the E or C glass furnaces. Its service life can be as long as 6-7 years. Cr2O3 are added into fused cast AZS block to make fused cast AZSC block (Al2O3-ZrO2-SiO2-Cr2O3). At high temperature, Cr2O3 can from solid solution with Al2O3. Since Cr2O3 has a high melting point, it can improve the viscosity of glass phase and the exudation temperature of glass phase and improve the corrosion resistance to glass.

3) Basic brick
High pure direct bond basic bricks fired at 1800℃ are widely used in the walls of regerators and crown.

4) Olivine magnesia brick
Since olivine bonding phase has high corrosion resistance, increasing the olivine content in the bonding phase of magnesia can greatly improve the corrosion resistance of magnesia brick. Olivine magnesia brick is cheap and widely used in the middle part of the checker work.

5) Celsian olivine brick
Olivine has good corrosion resistance but insufficient thermal shock resistance. Celsian can significantly improve the thermal shock resistance. Celsian is formed in the firing process, and exists only in the binding matrix phase. Celsian can resist the corrosion of alkali and sulphate.

6) Monolithic materials
The application of monolithic materials in the glass industry can greatly reduce the joints of furnace structure and the cold repair time.

Recently, as a new refractory material, zircon refractory material has been developed. In the refractory industry, natural zircon minerals and artificial extracted or synthetic zircon oxides and composite oxides have been widely developed.

Zircon materials have been more widely used in the glass industry, metallurgical industry, cement industry, ceramics industry and refractory industry, due to high melting temperature, good chemical stability, good thermal shock, and good resistance to molten metals, slags or glass liquid.

Zircon materials are mainly used in the melting zone, superstructure, sidewall and throat. Zircon refractory materials mainly include dense zircon brick, fused cast AZS block, fused cast zircon mullite brick and rebounded AZS brick.

Zircon materials have a wide application in the metallurgical industry. According to the material, zircon materials can be divided into zircon brick, zirconite bricks, alumina zircon carbon products, zircon carbon products, zirconic acid calcium products, zirconium diboride products and zirconium oxide modified refractories.

Zirconite products have good high temperature resistance, good resistance to acid slags, low thermal expansion coefficient and good thermal shock resistance. It can be used in the ladle lining and critical parts such as the slag line and the outlet. It can also be used in the ladle nozzle, tundish nozzle and pocket block.

Semi-silica brick is an aluminosilicate refractory product containing 15-30% Al2O3. It is usually made of fire clay containing quartz, pyrophyllite (Al2O3 · 4SiO2 · H2O), refractory clay or tailings of kaolin.

According to the manufacturing method, semi-silica brick can be divided into fired brick and unfired brick. Unfired bricks are made with water glass as the binding agent. The manufacturing process of fired bricks is similar to that of fire clay brick.

Whether to add clinkers is up to the properties of raw materials and refractory bricks. Siliceous clay has small firing shrinkage and the clinker is not required. In order to improve the thermal shock resistance of semi-silica bricks, 10%-20% clinker is added.

If the raw materials contain a few fusible materials and coarse quartz grains, semi-silica bricks have low density and poor strength but good thermal shock resistance and high softening temperature under load. On the contrary, the refractory bricks have bad refractory performance and poor thermal shock resistance. Besides, according to the working conditions, fine or coarse quartz or silica clinker is added.

Under 1250℃, semi-silica brick has small volume shrinkage. At high temperature, with the increase of the liquid phase, the brick has large volume shrinkage. So, its firing temperature is higher than that of the fire clay brick, generally within 1350℃-1410℃ to obtain high density refractory bricks.

When pyrophyllite is used as the raw material of semi-silica brick, the manufacturing method is up to the chemical composition of pyrophyllite. The main chemical composition of pyrophyllite has small weight loss after dehydrated and can maintain its lattice structure. It can be directly used to manufacture bricks. In order to avoid firing expansion, it can also be calcined into clinker and added when batching.

Semi-silica brick has good volume stability at high temperature and can help to improve the integrity of the masonry and reduce the slag erosion to the masonry. When contacting hot slag, it can from a layer of glaze-like substances on the surface which can block pores, prevent the penetration of slags into the brick.

Semi-silica brick is mainly used in the ladle lining and the refractory layer of the lower steel casting system. In addition, it is also used in the roof of heating furnaces, regenerator checker bricks, the lining of Cupola furnaces, the hearth and flues of furnaces.

Bonded again fused cast alumina block is a type of bonded again sintered refractory brick made of fused corundum clinker as the granular material and fused corundum or sintered corundum powder as the matrix.

When using fused brown corundum or white corundum as raw materials, the frits should be smashed and then processed by removing the ferro-silicon alloy and other impurities. White corundum should be processed by removing the flaky sodium aluminate crystals and other low-melting substances. The impurities are easy to be identified since they have low density and float in the surface of corundum frits.

There are a few harmful ingredients in the corundum which will cause poor sintering or cracking, so corundum should be pre-calcined before use. The residual ferro-silicon alloy is oxidized and decomposed into Fe2O3 and SiO2 at 500-1000℃ and Ti in the minerals can be oxidized into TiO2 (rutile), which can cause large volume expansion. After pre-calcining, the stress caused by those decomposition reactions and oxidation reactions can be eliminated during the pre-calcining process and cracks caused by the volume expansion of those impurities can be avoided during the sintering process.

Fused corundum block has large volume, so it should be smashed with drop hammers and other ways and then pulverized. The pulverized fused corundum is stored by size after screened. Fused corundum is hard and difficult to grind. Therefore it is wet ground by ball mills or vibration ball mills. The grain size can be less than 40μm or even 10μm. The iron in the granular material can be removed with electromagnets and the iron in the fine powder can be washed with acids.

The batching of granular materials should be according to the principles of tightly packing, multilevel ratio, less intermediate particles and more fine powder. This can improve the density and sintering of the products. The additives include aluminum phosphate, phosphoric acid, aluminum chromium phosphate, cellulose and pulp waste solution. Among them, he most promising is active phosphate. Recently, ammonium phosphate is on the trial and achieves good results. The mud should be mixed evenly with a moisture content of 3-4%. After high pressure molding, high dense bricks are obtained.

The fused cast alumina block has high purity. It is difficult to sintere and should be sintered at 1800℃. The type of the kilns used depends on the production scale. For small batch production, high-temperature batch kiln is better. For batch stable production, the small high-temperature tunnel kiln is used.

Zhengzhou Sunrise Refractory is a refractory supplier from China. We provide various refractory materials such as fused cast AZS, fused cast alumina block, silica brick, zircon brick, etc..

The fuse cast alumina block is a kind of cast product with rough surface and big size tolerance. In actual use, in order to reduce the brick joints, factories machine it with diamond tools. This can save energy and prolong the service life of the furnace.

Fused cast alumina block can be divided into alpha-beta block, alpha block and beta block.

Alpha-beta fused cast Alumina Block is formed by the compact structure of alpha alumina and beta alumina crystals in a most ideal proportion which is approximately 50% and 50% respectively, where intertwined crystals of both materials result in a very dense structure. It has dense structure and no contamination to glass. It is the ideal refractory materials for channels, spouts and working ends of floating glass furnace.

Alpha fused cast alumina block is an ideal product for the lower temperature zones of the glass melting furnaces due to its high density, superior corrosion resistance and low blister potential. It is also an ideal material for Metallurgical Titanium Furnace because the superior thermal stability.

Beta fused cast alumina block comprises of a majority of beta alumina crystals and a slight portion of alpha alumina crystals in compact structure. Moreover, the intersected texture of large ß-alumina ensures great dimensional stability and great resistance against spalling. Its property of base saturation enables a higher resistance to alkali vapor, thus it has excellent thermal shock resistance and does not form molten droplets. It is the best material for molter crown, port crown, feeder channel, ect.

Recently, the mechanical processing technology of the refractory materials has seen development. The pre-assembling of the refractory materials has already been adopted aboard. After the products are processed, pre-assembled, numbered and accepted, it is transported from the factory. This can save the time of cold repair and hot repair.

Zhengzhou sunrise is a refractory supplier from China. We offers various refractory materials for glass furnaces, such as fused cast AZS, fused cast alumina block, fused cast high zircon block, etc..

The ceramic fiber lining is mainly made up with ceramic fiber products such as ceramic fiber blanket, ceramic fiber module or ceramic fiber board. There are mainly two structure types of ceramic fiber lining: layer structure and tile stacking composite structure.

The layer-structure lining is built by putting ceramic fiber products on the steel sheet of the furnace wall layer by layer and then fixing them with heat-resistant steel anchors or in other ways. According to the lining material, the layer structure can be divided into two types: layer structure with ceramic fiber blanket and layer structure with ceramic fiber felt or board.

The layer structure with ceramic fiber blanket can be classified into butt type and lap type, according to the installation method of the hot face of the blanket. The felt or board is mostly installed in the butt type. Both the two types of layer structure can be classified into anchoring-nail-exposed style and anchoring-nail-embedded style according to the fixed way of anchoring nails.

The anchoring-nail-exposed structure is built by tilting the blanket, felt or board on the wall and then fixing it with anchoring nails, fast cards, rotary cards or nuts. Different materials can be used in the lining according to the temperature along the direction of the lining thickness. This structure can greatly reduce the construction cost, improve the insulation performance and is easy to construct and repair. The drawback is its poor resistance to wind erosion. Since the anchors are exposed in the hot face, when the temperature is high, it puts higher requirements on the anchors. The anchor itself is a heat conductor and the ceramic fiber board (blanket or felt) can generate volume shrinkage when use, which may cause gaps in the butt joints and weaken its insulation performance. Therefore, this structure is suitable to low-temperature heat treatment furnace.

The anchoring-nail-embedded style can avoid the exposing of the hot face of the anchoring nails, reduce the heat loss and improve the insulation performance. But it is difficult to overcome the poor resistance to wind erosion. Meanwhile, if it adopts ceramic-cup structure, the ceramic cup is brittle and expansive, which increases the construction difficulty and the cost. If it adopts sinking-hole structure, when the temperature changes, the sinking hole may generate shrinkage and cracks and damage the anchors. Therefore, it is only suitable to the insulation of the low temperature furnace wall.

Currently the tile stacking composite structure can be categorized into ceramic fiber module + tile structure and polycrystalline bar + module + tile structure (from hot face to cold face). Given the actual conditions such as the speed of the burner flame and the composition of the fuel gas, a layer of coating with good resistance to erosion and high temperature may be brushed on the hot face of the ceramic fiber lining. This coating can form a dense protective layer with good resistance to erosion and high temperature.

The thickness of the ceramic fiber lining is up to the structure of the heating devices (flat wall or curved wall), the thermal conductivity of the materials, the average temperature of the cold and hot face and allowed unit heat loss. The material should be selected by taking into consideration many factors including the maximum temperature, the working conditions, the fuel, the atmosphere and the pressure. The selection of the anchor should be based on the temperature of its location and whether it is in direct contact with fuel gas.

The installation arrangement ways of the modules can be divided into parquet floor type and soldier row type. The parquet floor type is a traditional installation arrangement way and was very popular a few years ago. However, with the development of the development of the applied technology of ceramic fiber module, research and practice have proved that, the parquet floor type has some drawbacks. Therefore, it is only used in the bar pasted structure of the hot face. Currently, most programs adopt the soldier row type.

The ceramic fiber lining is mainly made up with ceramic fiber products such as ceramic fiber blanket, ceramic fiber module or ceramic fiber board. There are mainly two structure types of ceramic fiber lining: layer structure and tile stacking composite structure.

The layer-structure lining is built by putting ceramic fiber products on the steel sheet of the furnace wall layer by layer and then fixing them with heat-resistant steel anchors or in other ways. According to the lining material, the layer structure can be divided into two types: layer structure with ceramic fiber blanket and layer structure with ceramic fiber felt or board.

The layer structure with ceramic fiber blanket can be classified into butt type and lap type, according to the installation method of the hot face of the blanket. The felt or board is mostly installed in the butt type. Both the two types of layer structure can be classified into anchoring-nail-exposed style and anchoring-nail-embedded style according to the fixed way of anchoring nails.

The anchoring-nail-exposed structure is built by tilting the blanket, felt or board on the wall and then fixing it with anchoring nails, fast cards, rotary cards or nuts. Different materials can be used in the lining according to the temperature along the direction of the lining thickness. This structure can greatly reduce the construction cost, improve the insulation performance and is easy to construct and repair. The drawback is its poor resistance to wind erosion. Since the anchors are exposed in the hot face, when the temperature is high, it puts higher requirements on the anchors. The anchor itself is a heat conductor and the ceramic fiber board (blanket or felt) can generate volume shrinkage when use, which may cause gaps in the butt joints and weaken its insulation performance. Therefore, this structure is suitable to low-temperature heat treatment furnace.

The anchoring-nail-embedded style can avoid the exposing of the hot face of the anchoring nails, reduce the heat loss and improve the insulation performance. But it is difficult to overcome the poor resistance to wind erosion. Meanwhile, if it adopts ceramic-cup structure, the ceramic cup is brittle and expansive, which increases the construction difficulty and the cost. If it adopts sinking-hole structure, when the temperature changes, the sinking hole may generate shrinkage and cracks and damage the anchors. Therefore, it is only suitable to the insulation of the low temperature furnace wall.

Currently the tile stacking composite structure can be categorized into ceramic fiber module + tile structure and polycrystalline bar + module + tile structure (from hot face to cold face). Given the actual conditions such as the speed of the burner flame and the composition of the fuel gas, a layer of coating with good resistance to erosion and high temperature may be brushed on the hot face of the ceramic fiber lining. This coating can form a dense protective layer with good resistance to erosion and high temperature.

The thickness of the ceramic fiber lining is up to the structure of the heating devices (flat wall or curved wall), the thermal conductivity of the materials, the average temperature of the cold and hot face and allowed unit heat loss. The material should be selected by taking into consideration many factors including the maximum temperature, the working conditions, the fuel, the atmosphere and the pressure. The selection of the anchor should be based on the temperature of its location and whether it is in direct contact with fuel gas.

The installation arrangement ways of the modules can be divided into parquet floor type and soldier row type. The parquet floor type is a traditional installation arrangement way and was very popular a few years ago. However, with the development of the development of the applied technology of ceramic fiber module, research and practice have proved that, the parquet floor type has some drawbacks. Therefore, it is only used in the bar pasted structure of the hot face. Currently, most programs adopt the soldier row type.

There are three ways to install ceramic fiber lining: external thermal insulation, internal thermal insulation and intermediate thermal insulation. The intermediate thermal insulation, due to its drawbacks, is rarely used.

The ceramic fiber materials used to install the ceramic fiber linin include ceramic fiber board, ceramic fiber blanket and ceramic fiber module. The lining is generally 25-50mm, and 50-100mm is preferred.

1) External thermal insulation
The ceramic fiber board is pasted or anchored to the cold surface of the furnace walls. This structure simply needs low temperature fiber products or lightweight bricks.

2) Internal thermal insulation
Ceramic fiber board is pasted on the hot surface of the furnace walls. It has good thermal insulation performance in either batch or continuous furnaces. It can reduce the heat loss of the furnace wall and the regenerative loss.

3) Intermediate thermal insulation
The ceramic fiber layer is installed in the middle of the furnace wall.

The adhesives commonly used include agents made with Silica gel and water glass or mud formulated with Portland cement and sulphate.

Now most furnaces adopt the internal thermal insulation structure, since it has high thermal efficiency, good energy-saving effect and long service life. Of course, in some cases, the structure and construction method should be chosen based on the actual situation.

Zhengzhou sunrise refractory Co., Ltd. is a refractory supplier from China, specializing in various ceramic fiber materials for glass furnaces, such as ceramic fiber board, ceramic fiber blanket, ceramic fiber module, etc.