Slag regulating material for converter slag splash protection

 Slag splashing furnace protection is a new technology developed this year to increase converter age. The basic principle is that after the final molten steel is blown, the remaining MgO content reaches the saturated or supersaturated final slag, and a high-pressure nitrogen gas of 0.8-0.9 MPa is blown at 0.8-2.0 m at the theoretical level of the molten pool using a spray gun. , Spatter the slag and form a layer with a high melting point on the surface of the furnace lining. The slag-spattering layer adheres well to the furnace lining to protect the furnace lining.

The effect of slag splashing furnace protection is mainly determined by the MgO content in the slag before slag splashing. The addition of slag regulator can increase the MgO content in the slag. There are two ways to add it: adding slag adjuster after tapping to make the MgO content meet the requirements of slag splashing furnace protection; When the converter is blowing, add the slag adjuster and the slagging material into the furnace and control the final slag composition To make the MgO content meet the requirements. The commonly used slag conditioner and its chemical composition are shown in Table 1. When selecting a slag conditioner, the MgO content in the slag conditioner and its price should be comprehensively considered.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality refractory products are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Article Source:Slag regulating material for converter slag splash protection
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Table 1 Commonly used slag conditioner and its chemical composition（w）

Raw Material	CaO	SiO2	MgO	LOI	MgO
Metallurgical magnesia	8.0	5.0	83.0	0.8	75.8
Light burned magnesia ball	1.5	5.8	67.4	22.5	56.7
Light burned dolomite	51.0	5.5	37.9	5.6	55.5
Magnesium-containing lime	81.0	3.2	15.0	0.8	49.7
Raw dolomite	30.3	2.0	21.7	44.5	28.3
Magnesite slag grains	0.8	1.2	45.9	50.7	44.4

Comparison of four commonly used methods for improving the life of converter purging plug

 Ladle purging plug plays an important role in the refining process of molten steel. As a refractory product, there will be consumption damage during use. Therefore, how to effectively and easily lift the service life of the ladle purging plug is very important.?

In practical applications, there are four main methods:

1. Method of bottom blowing asymmetric gas supply
In the bottom blowing asymmetric gas supply method, the two sets of ladle purging plug are close to alternate work in production, and the size of ladle purging plug is increased, so that the single capillary eroded areas do not overlap, and the use and maintenance of ladle purging plug are adjusted to a good state. Both sets of ladle purging plug can fully play their role, and it is expected that the re-blowing furnace can be nearly doubled. The design of a large-flow ladle purging plug required for asymmetric gas supply has been technically solved. The added cost is small compared to the economic benefits achieved by increasing the metallurgical effect and extending the age of the re-blowing furnace. It is easy to operate and easy to grasp.

2. Method of pre-burying permeable bricks
In order to improve the re-blowing rate, steel used the method of pre-buried permeable bricks. When the permeable bricks were damaged to 600mm (the furnace age was 3000-3500 furnaces), the pre-buried permeable bricks began to work. The pre-buried permeable brick and the original brick are supplied with gas at the same time until the working layer of the bottom of the furnace is thinned to 250-300 mm and the furnace is finished. The furnace age can reach 4500-5500 furnace.
This method can make the blown air supply in the later stage of the furnace to maintain normal, has a stable metallurgical effect, and can extend the age of the re-blowing furnace, but the pre-buried brick can only function after the bottom of the furnace is damaged by 600mm. The effective working length of ladle purging plug is only about 400mm, which is equivalent to 43% of the effective working length of the normal ventilating brick, and its role in extending the furnace age is limited.

3. Method of replacing the permeable bricks
Iron and Steel Co., Ltd. adopts the method of replacing the ventilated bricks with the bottom of the furnace. After the furnace reaches 100 furnaces, 2-4 ventilating bricks are drilled in the predetermined position at the bottom of the furnace. The maximum air supply per permeable brick is 10m3/min. Each time you change 2, the ventilated brick can be used for 1000-1500 furnaces, and each furnace is replaced 2-3 times. The bottom blowing gas supply strength is 0.05% - 0.11%, and the carbon oxygen product is 0.0024.

The method of steelmaking in Iron and Steel Co., Ltd. can make the gas ladle purging plug at the bottom of the furnace have good gas permeability and maintain good metallurgical effect. The re-blowing life of 5000 furnaces is basically synchronized with the furnace age. The disadvantage is that each replacement of a breathable brick for 4h increases the inconvenience to tissue production. As the number of smelting furnaces in the furnace increases, the effective working length of the ventilated bricks that are thinned and replaced at the bottom of the furnace becomes shorter, increasing the frequency of replacement and the consumption of permeable bricks. Drilling method the safety of replacing the permeable brick is lower than that of the bottom laying method.

4. Control reasonable blowing parameters and maintenance
No. 3 Steel has carefully controlled the blowing parameters and carefully maintained it, so that the age of the re-blowing furnace reaches about 4500-5000 furnaces, which can also maintain good metallurgical effect and promote the large-scale converter re-blowing technology.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality ladle magnesia carbon bricks are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Article Source:Comparison of four commonly used methods for improving the life of converter purging plug
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The four most common damage mechanisms of magnesia carbon brick

 1. Slag causes melting and dissolution of magnesia

2. The oxidation of carbon
(1) Direct oxidation
The carbon in the MgO-C brick is directly oxidized by oxygen in the environment, generally occurring below 1400℃.
(2) Indirect oxidation
Indirect oxidation generally occurs above 1400℃, and indirect oxidation is divided into intrinsic oxidation and external oxidation.
3. Corrosion caused by molten steel flow
(1) The slag layer formed on the working surface of the magnesium carbon material could be washed away by the flow of the molten steel, or the slag is insufficient.
(2) Repeated heating and cooling during the production process and the stirring force of the molten steel may cause the structure of the material to relax.
4. Hot peeling and mechanical peeling.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality ladle magnesia carbon bricks are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Ladle Magnesia Carbon Brick:Magnesia carbon brick is made of fused magnesia and high carbon graphite, with antioxidant was added, and the phenolic resin was used as the binder for high pressure molding. MgO-C refractory bricks are widely used in steel industry.

Ladle Purging Plug:Ladle purging plug has been in the leading position in domestic and abroad over years. We have developed the series of corundum, chromium corundum, low silicon chromium corundum and corundum spinel one after another.

Ladle Slide Gate Plate:Slide gate plate is preferred products for big/medium ladle and continuous casting tundish. Alumina-carbon slide gate plates can meet the requirement of different steel grades.

Ladle Castable:Ladle castable has good workability, high strength, good volume stability, good abrasion resistance and thermal shock resistance, etc.

Article Source:The four most common damage mechanisms of magnesia carbon brick
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4 solutions for serious damage to refractory materials used in ladle lining

 Ladle turnover process: converter/electric furnace tapping once and twice refining process, continuous casting and pouring steel, ladle preparation work, and waiting for tapping. The normal turnaround time depends on the steel type and the continuous casting machine, and it takes 100 to 140 minutes. The tapping temperature of the ladle is 1680-1700℃, and the holding time is 100~120min. If the ultra-low carbon steel process such as silicon steel, bridge steel, automobile plate steel, etc must be vacuum treated, argon blowing and stirring at the bottom of the ladle and LF furnace are used at the same time. Arc heating, reducing atmosphere in the furnace, white slag refining, gas stirring, etc., strengthen the comprehensive refining effects of thermodynamics and kinetic conditions, desulfurization, alloying, and heating, so the slag alkalinity range is large, and the temperature of molten steel and slag is higher. The residence time of molten steel in the ladle is prolonged, the thermal shock is strong, the stirring force is large, and the damage to the inner lining of the ladle is aggravated.

The reasons for the damage of the ladle refractories are as follows:

First, the ladle is used to transport high-temperature molten steel. During transportation, high-temperature molten steel and molten slag at around 1680°C will erosively corrode it, especially at the slag line. The scouring erosion is more serious, which is an important factor in determining the service life of a tank.

Second, the refining treatment outside the furnace such as LF seriously damages the unburned bricks.

Third, the inner lining is subjected to severe temperature changes when the converter is tapped and molten steel flows out, which causes cracks and peeling of the inner lining material.

Fourth, when the ladle is filled with molten steel during the tapping of the converter, the high-temperature molten steel has strong mechanical erosion on the bottom of the ladle, which makes the lining material of this part prone to damage due to thermal shock. According to the above analysis, the ladle lining refractories should have the following characteristics: compact and uniform structure; high temperature micro-expansion, good volume stability; High strength, small ratio of medium temperature strength to high temperature strength.

In addition to the above-mentioned two chemical and physical reasons, there is another reason that cannot be ignored is man-made:

(1)Improper selection and collocation of refractory materials;

(2)Improper use of refractory materials, such as unreasonable masonry and baking methods;

(3)Too long ladle turnover period causes cold ladle;

(4)Improper unpacking will damage the permanent layer of the ladle;

(5)Failure to take repair measures in time. The method to reduce the structural spalling of refractory materials is to reduce the depth of slag penetration.

It is recommended to start from the following aspects: 

(1)Improve the slag penetration resistance of refractories;

(2)Reduce the porosity of refractory materials and reduce the erosion channel of slag;

(3)The slag reacts with the refractory material to form a high melting point compound retaining wall to prevent the penetration of the slag;

(4)Increase the viscosity of the slag. The greater the viscosity of the slag, the worse the corrosiveness to refractory materials;

(5)Understand the properties of the refractory materials used, and reasonably formulate the use conditions of the ladle;

(6)Speed up the use cycle of ladle as much as possible, and achieve "red envelope" work;

(7) The damaged parts of the lining refractories should be repaired or replaced in time.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality ladle magnesia carbon bricks are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Ladle Magnesia Carbon Brick:?Magnesia carbon brick is made of fused magnesia and high carbon graphite, with antioxidant was added, and the phenolic resin was used as the binder for high pressure molding. MgO-C refractory bricks are widely used in steel industry.

Ladle Purging Plug:Ladle purging plug has been in the leading position in domestic and abroad over years. We have developed the series of corundum, chromium corundum, low silicon chromium corundum and corundum spinel one after another.

Ladle Slide Gate Plate:Slide gate plate is preferred products for big/medium ladle and continuous casting tundish. Alumina-carbon slide gate plates can meet the requirement of different steel grades.

Ladle Castable:Ladle castable has good workability, high strength, good volume stability, good abrasion resistance and thermal shock resistance, etc.

Article Source:4 solutions for serious damage to refractory materials used in ladle lining
Company name: Henan Changxing Refractory Materials Co.,Ltd
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Several methods to improve the thermal shock resistance of low-carbon magnesia-carbon brick

 magnesia-carbon materials, magnesia-carbon brick, refractory material, refractory ram material,low-carbon magnesia-carbon materials,

Refractories with poor thermal shock resistance will cause cracks and crevices on the surface and inside of the material due to temperature changes, and will intensify crack expansion after being washed by molten steel. After many times of scouring, the refractory must be stopped for replacement if the refractory is damaged, which affects production. There are two causes of thermal stress in refractories: One is the large temperature gradient between the surface and the inside of the refractory; The other is that the thermal expansion coefficients of the various phases in the refractory are different.

The method to improve the thermal shock resistance of materials can be to create micro-cracks on the surface and inside of the material, and use micro-cracks to increase the toughness to neutralize thermal stress; or introduce ceramic phases to increase the overall strength of the material and reduce the overall thermal expansion rate; or introduce low-melting glass The glass phase melts at high temperatures to disperse the thermal stress, but the introduction of the glass phase will reduce the strength and compactness of the material, and it is generally rarely used.

The influence and reinforcement of carbon source?

Magnesium-carbon materials generally use flake graphite as the carbon source, which has the advantages of good thermal conductivity and low thermal expansion rate. Graphite plays a role in sealing pores and preventing corrosion of molten slag in?magnesia-carbon materials. In addition, graphite can also lubricate the surface of magnesia particles and reduce the damage of large particles during the pressing process.

After replacing flake graphite with artificial graphite particles or different nano-carbons, the thermal shock resistance is significantly improved. Graphite particle size also affects thermal shock resistance. When the amount of resin added is 4% (w), and nano graphite accounts for 5% of the resin mass, the high-temperature mechanical properties and thermal shock resistance of the magnesia-carbon material have been improved. Influence of raw materials and research progress.

The raw materials of low-carbon magnesia carbon materials are usually magnesia and flake graphite, of which magnesia is the main part of the magnesia carbon material. Magnesia can be divided into fused magnesia and sintered magnesia according to its treatment methods and equipment.

Fused magnesia and sintered magnesia are also divided into different grades according to their respective purity. Generally speaking, the higher the grade of magnesia used, the better the performance of the magnesia carbon material. The slag resistance and thermal shock resistance of the same grade fused magnesia are better than those of sintered magnesia, and as the grade of magnesia increases, the compressive strength increases and the linear expansion rate decreases. The compressive strength is related to the bulk density and porosity of the material.

Influence of additives and research progress.

Additives are an important part of magnesia-carbon materials. Although they do not occupy a high proportion in the ingredients, they can often play a decisive role. Al powder is a commonly used antioxidant in magnesia-carbon materials. It can not only improve the oxidation resistance of the material, but also form ceramic structures such as Al3C4 and AlN at high temperatures to increase the high temperature flexural strength of the material.

Thermal shock resistance is an important performance of low-carbon magnesia-carbon materials, but blindly improving the thermal shock resistance of low-carbon magnesia-carbon materials may affect other properties of the material, such as oxidation resistance and slag erosion resistance. Therefore, while studying the thermal shock resistance of low-carbon magnesia-carbon material, other properties of the materials must be considered.

Article Source：Several methods to improve the thermal shock resistance of low-carbon magnesia-carbon brick
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4 indicators that determine the high temperature performance of refractory materials

 During use, refractory materials are subject to physical, chemical, and mechanical effects at high temperatures (usually 1000~1800C), which are easy to melt and soften, or are corroded, abraded, or cracked and damaged, causing the operation to be interrupted and stained contaminated materials.

The following are 4 indicators that determine the high temperature performance of refractory materials:

(1)Refractoriness .

Refractoriness refers to the temperature at which a material reaches a certain degree of softening under the action of high temperature, which characterizes the performance of the material against high temperature. Refractoriness is the basis for judging whether a material can be used as a refractory material. The International Organization for Standardization stipulates that inorganic non-metallic materials with a refractoriness above 1500°C are refractory materials. It is different from the melting point of the material, and it is a comprehensive performance of a mixture of multiphase solids composed of various minerals.

(2) Deformation temperature under high temperature load.

It also known as the refractory softening point under load or the refractory deformation temperature under load, it means the resistance of the refractory to the combined action of high temperature and load under a constant load or the temperature range in which the refractory exhibits significant plastic deformation. The maximum use temperature of the refractory material can be inferred from its softening temperature under load.?

(3) High temperature volume stability of refractories.

Refractory materials produce volume expansion under the action of high temperature for a long time, which is called residual expansion. The size of the residual expansion (deformation) of refractory materials reflects the quality of high-temperature volume stability. The smaller the residual deformation, the better the volume stability; on the contrary, the worse the volume stability, the easier it is to cause deformation or damage to the masonry.

(4) Thermal shock stability.

The ability of refractory materials to resist sudden changes in temperature without being damaged is called thermal shock stability. This performance is also called thermal shock resistance or temperature sudden change resistance. Generally speaking, the greater the linear expansion rate of the material, the worse the thermal shock stability; The higher the thermal conductivity of the material, the better the thermal shock stability. In addition, the structure of the refractory material, the particle composition and the shape of the material all have an impact on the thermal shock stability.

Article Source：4 indicators that determine the high temperature performance of refractory materials
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What refractory material is used for the bottom of the electric furnace

 The bottom of the electric furnace and the bank slope together form a molten pool. The refractory materials directly bear high-temperature thermal load and erosion from molten slag. The erosion of molten steel, mechanical impact of scrap steel, and oxidation and reduction operations at high temperatures in the furnace make the molten slag penetrate into the furnace. Bottom, resulting in the thinning of the bottom of the furnace. The structure of the ultra-high-power electric furnace bottom is generally divided into three layers.

• 1. The insulation layer is the bottom layer of the furnace bottom. Its function is to reduce the heat loss of the electric furnace and to ensure that the temperature difference between the upper and lower sides of the molten pool is reduced. Generally, a layer of asbestos board is first laid on the furnace shell, and then diatomaceous earth powder. Lay insulation bricks on the flat surface.

• 2. The permanent layer is on top of the heat insulation layer, its function is to ensure the solidity of the molten pool, and play the role of supporting the bottom. Generally bricks are used, with about 3 layers of staggered joints, fired magnesia bricks containing Mg095%~96%, asphalt bonded magnesia bricks, magnesia dolomite bricks are used, and the brick joints are filled with magnesia or steel powder of the same material tightly compact.

• 3. The working layer is above the permanent layer. It is in direct contact with molten steel. It has high thermal load, severe chemical erosion, strong mechanical erosion, and is extremely easy to corrode. High-quality refractory materials should be used. The working layer of the bottom of the electric furnace in our country is combined with asphalt and built with magnesia carbon bricks. At present, ultra-high power electric furnaces generally use a mixture of 2CaOFe2O-rich magnesia and 2CaOFe2O-rich magnesia dolomite (without any binder). Ramming (actually the lower bunk) into a whole structure furnace bottom, its durability is high.

There are usually two types of ordinary power electric furnace bottoms:

① Knotted furnace bottom (or vibration compression furnace bottom). The working layer uses magnesia, and its bonding agent is tar and asphalt. When making the carbonless furnace lining, brine or water glass is used as the bonding agent.

② Brick furnace bottom. Generally, asphalt is used to combine magnesia brick, and carbon-free furnace lining is used to combine magnesia bricks with brine.

Article Source：What refractory material is used for the bottom of the electric furnace
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Magnesia refractory castable pouring method

 1. Vibration casting with 30~50mm vibrating rod.

2. Firstly, the bottom of the package is filled with the material, and the vibrating rod is used to level the vibration to ensure the thickness of the casting layer or slightly thickened.
3. After the bottom of the package, after placing for 2~4 hours, place the core, the core should be placed in the middle of the ladle, not offset, and should be leveled, the surface of the core should be cleaned, treated to be slippery and oiled.

(1) The vibrating bar must not touch the core and the heat insulating material, so it should be kept at a certain distance from the core and the heat insulating material, but it should not be larger than 50mm.
(2) The penetration depth of the vibrating bar shall not touch the underlying castable, but the distance from the lower layer shall not exceed 50 mm.
(3) The distance of the insertion point of the vibrating bar should not exceed 200mm, keep the uniform and dense vibration, and slowly lift the vibrating bar when it is pulled out. Do not pull out suddenly to avoid leaving holes.
(4) A special person should be in charge of mastering the vibrating rod. If it is found that there are unqualified quality requirements, it should be treated in time to continue construction.
(5) Pouring the wall of the package is usually two rounds of material vibration, each feeding thickness is about 250mm, to achieve uniform cloth, and pay attention to uniform vibration, avoid leakage vibration, vibration should be dense.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality refractory products are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Article Source：Magnesia refractory castable pouring method
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Three spraying methods of refractory spray coating material

 The spray coating construction shall be tested according to the construction manual provided by the manufacturer of the spray coating spleen number to determine the appropriate parameters, such as wind pressure, water pressure, etc.

Spraying is carried out by spraying machines and spray guns. The refractory spray paint is compressed air or mechanical pressure in the pipeline to obtain sufficient pressure and flow rate, and sprayed onto the sprayed surface through the nozzle to form a firm spray coating.

The spraying methods of refractory spray coatings are divided into three types: wet method, dry method and flame method.

(1) Wet spraying.

Wet spraying refers to the refractory spray paint sprayed onto the sprayed surface after adding water or liquid binder. Wet spraying is divided into four types: mud method, wet method, semi-dry method and pseudo-dry method. The latter three methods are suitable for spraying furnace construction or spraying furnace lining.

The mud method is to mix the refractory mixture into a slurry before spraying, and is mainly used for thermal gunning of furnace lining;?

The wet method is to stir the refractory mixture into pumping mud and then spray;

The semi-dry method is to add the refractory mixture first A small amount of water is stirred evenly.

When it is delivered to the nozzle, the remaining water is added and then sprayed; The false dry method is to stir the refractory mixture evenly through a mixer, and then send it to the nozzle to add water for spraying.

(2) Dry spraying.

Dry spraying refers to spraying the mixed refractory spray paint directly onto the sprayed surface through the nozzle, which is mainly used for repairing the furnace.

(3) Flame spraying.

Flame spraying means that the mixed refractory spray paint is transported to the nozzle by the high-speed flow of oxygen in the pipeline, and then sprayed out together with the combustible gas. The material advances during combustion and is sprayed onto the sprayed surface in a molten state. This method is mainly used to repair the furnace lining by thermal spraying, without damage to the original furnace lining, the spray coating is easy to sinter, and has a long service life.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality refractory products are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Article Source:Three spraying methods of refractory spray coating material
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Nanotechnology improves the thermal shock resistance of low-carbon magnesium-carbon refractory materials

 In addition to good slag resistance, low-carbon magnesia-carbon refractories also require products with a certain degree of thermal shock resistance. This is due to the sharp decline in thermal shock resistance due to the reduction of carbon content. Thermal shock resistance is not only an important index to measure refractory materials, but also a key research direction in the low-carbon use of magnesia-carbon bricks.

Nano powder particles have the characteristics of small size, large surface energy and large dispersion, which are conducive to the relative slip between particles and can improve their thermal shock resistance. Therefore, the use of nanotechnology to improve the thermal shock resistance of low-carbon magnesium-carbon refractories has attracted much attention. The use of nanotechnology to improve the thermal shock resistance of low-carbon magnesium-carbon refractories is essentially to increase the fracture toughness of the material. The microstructure of the material can be adjusted to further increase the crack propagation resistance of the material. There are two main toughening methods for low-carbon magnesium-carbon refractories.

(1) Crack deflection toughening, nano-powders are introduced in the form of refractory raw materials or additives, and the introduced nano-powders are dispersed and distributed in or between particles. A large number of sub-interfaces are formed and play a role in pinning dislocations, making the crack propagation path more tortuous, extending the crack propagation path, resulting in an increase in the ability of the crack to be consumed during the propagation process, and an increase in the fracture toughness of the material.

(2) Crack bridging and toughening, introducing nanoparticles into the refractory aggregates can form bridging components of fibers, whiskers and ceramic phases in situ. When larger bridging components are encountered in the process of crack propagation, their existence is relatively high. The bridge connecting element is equivalent to erecting a bridge between two opposing crack surfaces, which increases the resistance of crack propagation. If the cracks continue to expand further, the bridging component is destroyed by pulling out from the matrix. This pulling out process will consume a lot of energy and increase the fracture toughness of the product, thereby improving its thermal shock resistance.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality refractory products are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Article Source：Nanotechnology improves the thermal shock resistance of low-carbon magnesium-carbon refractory materials
Company name: Henan Changxing Refractory Materials Co.,Ltd
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Some measures to improve the life of ladle slag line bricks

 1. Optimize the refined slag system

In the refining process, light-burned dolomite is added to increase the MgO concentration in the slag, increase the alkalinity and viscosity of the slag, control the amount of slag in the converter, and reduce the FeO content in the slag. The basicity of refining slag is controlled within the range of 4.2 to 5.0, the FeO content in the slag is controlled at about 0.5%, and the viscosity of the slag is adjusted at the same time. The MgO content in the slag is controlled at about 12%, which can effectively reduce the erosion of magnesia carbon bricks by the slag.

2. Improve slag line brick material

Studies have found that the higher the purity of magnesia used in ladle magnesia-carbon bricks, the less B2O3 in impurities, and the higher the carbon-sulfur ratio, the better the corrosion resistance of the lining bricks. It shows the effect of carbon content on the depth of slag line magnesia carbon brick melting loss. The main principle is that the oxidation in magnesia-carbon bricks is the oxidation of graphite in the bricks, and graphite has no wettability to slag, so magnesia-carbon bricks with high carbon content have better resistance to slag erosion.

Improve the material of the slag line magnesia carbon brick, select high-purity fused magnesia as the raw material, and control the carbon content at about 14%, which can effectively improve the corrosion resistance of the slag line.

3. Control the argon blowing system and power-on system

The LF furnace adopts the argon blowing mode that combines intelligent argon blowing and manual control. By manually controlling the intermittent stirring of the large argon gas, it promotes the heat transfer of the steel slag near the electrode and avoids the damage of the slag temperature here to the magnesia carbon brick of Siji Song Sexual erosion. The VD furnace uses a staged argon control mode. At the same time, the refined energization system should be controlled. At the beginning of energization, high-voltage and low-current long-arc operation is adopted, and after the slag is completed, low-voltage, high-current submerged arc operation is used.

4. Strengthen ladle operation control system and maintenance

During the production process, it is necessary to strengthen the operation control of the ladle, strengthen the turnover of the hot ladle, and reduce the excessive internal thermal stress caused by the non-continuous use of the ladle, which causes the magnesia carbon brick to crack or peel off. The slag line is close to the ladle mouth, and the temperature of the empty ladle is large. The production organization must be coordinated to reduce the steel ladle pressing rate, and at the same time strengthen the baking and maintenance of the ladle.

Article Source：Some measures to improve the life of ladle slag line bricks
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Refractory materials for EAF working layer

 The key point to effect EAF service life is working layer. Working layer would touch melton steel directly, where is of high thermal load, heavy chemical mechanical erosion. So high quality refractory materials should be adapted in working layer.

Regular lining method for EAF working layer is namely gunning, vibrating and brick-construction. For brick-construction method, resin binder magnesia brick is widely used. For gunning and vibrating method, magnesia sand with tar as bonding agent are normally used. In nowever days, brick-construction and sintering method are gradually eliminated because of low service life and less applicability. For high power EAF, dry magnesia vibration mix is widely used. After powerful ramming and the density requirement, the mix can be sintered into overall under certain temperature, and a good service life can appear. In regular condition, service life of vibration mix can reach 300 heats. After one time hot-repairing, the service life can be as long as 500-600 heats. With this method, furnace stopping time would decrease, and steel unit cost would also low down by a large degree, then the steel plant profit would increase a lot.

Article Source：Refractory materials for EAF working layer
Company name: Henan Changxing Refractory Materials Co.,Ltd
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Website:https://www.cxrefractories.com