Analises of LRF magnesia carbon bricks errossion

 About magnesia carbon brick damage mainly from two aspects of slag chemical attack and physical penetration to consider, and in different metallurgical reactors, because of the different operating process and slag composition, the erosion mechanism of magnesia carbon brick is not the same, because the steelmaking converter of furnace protection by slag splashing technology on the basic, so on the furnace life of converter are above all furnace, steel-making furnace and refining ladle lining erosion is in serious condition. For the erosion behavior of magnesia-carbon brick in slag, carbon oxidation and magnesium oxide dissolution are the main factors.

The damage process of magnesia-carbon brick can be summarized as oxidation, decarburization, loosening, erosion, scour, shedding and damage. First working face of magnesia carbon brick form graphite oxidation decarburization layer, the decarburized layer of magnesia in thermal stress (graphite and sintered at 1000 ℃, the thermal expansion rates were 1.4% and 0.2% respectively), chemical erosion and mechanical erosion conditions gradually eroded off, fall off suddenly and violently leak after graphite, continue to be oxidation decarburization layer formation, and then to the magnesia dissolution process, under the effect of repeated, cause the damage of magnesia carbon brick.

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Analysis of the causes of the fracture of the ladle nozzle

 The ladle nozzle is broken, and the specific reasons may have the following problems:

1. Reasons for sliding nozzle mechanism

1) The sliding mechanism is used for a long time at high temperature, or accidentally collided during operation, etc., which causes a large amount of deformation of the sliding gate mechanism, resulting in uneven force on the interface of the skateboard, and a small gap will be formed in the part with a small force surface, which may cause the skateboard. Infiltration steel.

2) The sliding trolley with the lower slide plate will slowly produce errors between the upper slide plate mechanism and the upper slide plate due to the long time loading and unloading of the slide plate, resulting in a small gap between the upper and lower slide plates.

3) Because the springs used in the mechanism have been used in high temperature environments for a long time, sometimes even though they are not in service, they may deform and fail. Under the static pressure of molten steel, there will be gaps between the skateboards, which may lead to steel seepage between the skateboards. It may be possible to wear steel into the entire body.

4) The deformation of the drain top sleeve makes the drain installation incorrect, or the pin buckle of the drain top sleeve sliding trolley is worn for a long time, so that the drain and the lower sliding plate cannot be tightly tightened. Steel infiltration.

2. Reasons for Skateboarding

1) The flatness of the skateboard surface does not meet the requirements, the flatness is low, and a microwave gap is formed between the skateboards.

2) There is a problem with the quality of the skateboard. When pouring, especially on the continuous sliding secondary skateboard, the surface scratches are serious, or a horseshoe-shaped melting loss is formed at the mouth of the skateboard. The molten steel will penetrate into the deeper scratches, where the temperature is relatively relative. If it is lower, the molten steel will condense to form steel clamping. If you continue to operate the slide plate, especially in continuous casting with large strokes, the gap between the slide plates may increase due to the steel clamping, which may cause a leakage accident.

3. Reasons for on-site operation

1) The refractory mortar is not working well, and the thickness is inappropriate. If the fire mortar in the installation nozzle is too thin, it will be squeezed out, and it will not provide good support. If it is too thick, it will not spread well. Moreover, when the residual mud in the nozzle eye is blown with high-pressure compressed air, the too thin refractory mud will be blown out of the gap, which lays a hidden danger for the sewer seepage.

2) The dry refractory mud in the upper nozzle mechanism is not cleaned up, or there is steel slag, there is a little refractory mud on the surface of the skateboard, and it is not cleaned up due to negligence during use. When the fire mud is applied to the drain, the fire mud is mixed with particles The dry refractory sludge of the steel, which brings many hidden dangers to the production.

3) Problems in the operation of the continuous casting machine. When the ladle is opened for pouring, a large ladle nozzle is hung on the nozzle for protective pouring. At this time, you should try to avoid pulling the slide plate with the ladle nozzle with a large stroke. This may cause the nozzle to become loose due to improper operation. It may cause steel seepage in the drain. The flow rate can be adjusted by inching mode instead.

Article Source:Slag regulating material for converter slag splash protection
Company name: Henan Changxing Refractory Materials Co.,Ltd
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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
Company name: Henan Changxing Refractory Materials Co.,Ltd
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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
Company name: Henan Changxing Refractory Materials Co.,Ltd
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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
Company name: Henan Changxing Refractory Materials Co.,Ltd
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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
More refractory products:https://www.cxrefractories.com/en-product-solution
Email:info@cxrefractories.com
Website:https://www.cxrefractories.com

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
Company name: Henan Changxing Refractory Materials Co.,Ltd
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Email:info@cxrefractories.com
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