Development of VOD ladle lining refractories

 Magnesia-chrome brick was first used in VOD ladle lining because of its excellent slag resistance. However, under intermittent operation of VOD ladle, magnesia-Chrome brick is easy to produce spalling damage and poor thermal shock resistance. Because of the environmental protection of hexavalent chromium, the use of chromium-containing refractories is more and more restricted. At present, domestic stainless steel steel mills have rarely used magnesia-chrome brick.

In Europe, VOD ladle lining is mostly made of (magnesium) dolomite bricks. Compared with magnesia-Chrome brick, dolomite brick has good thermal shock resistance due to its high temperature flexibility. Most VOD ladles in China use magnesium-calcium bricks fired at high temperature. Although magnesium-calcium brick has the function of purifying molten steel and has better thermal shock resistance than magnesium-chromium brick, the content of CaO in the brick reduces slag erosion resistance under the condition that the slag composition of VOD ladle varies greatly and is mainly acidic slag. Due to the hydration problem, magnesium-calcium brick is not suitable for intermittent production, and the management of storage, use and other aspects puts forward very high requirements.

In the smelting of low carbon and ultra-low carbon stainless steel, stainless steel plants are reluctant to use magnesium carbon brick for fear that the liquid steel may be carburized by using magnesium carbon bricks in VOD ladle. In fact, these problems can be minimized by using low-carbon magnesium-carbon bricks. Although low carbonization tends to reduce the thermal shock resistance, the bricks with excellent thermal shock resistance can be developed by selecting the best amount of special asphalt and antioxidant.

Article Source：Development of VOD ladle lining refractories
Company name: Henan Changxing Refractory Materials Co.,Ltd
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Lining method of EAF bottom ramming material

 Lining preparation

Clean up the permanent layer residue, dust, iron wire, plastic cloth and other foreign objects. Calculate the knot size, the actual knot thickness is equal to the required knot thickness multiplied by 1.09, and a sufficient amount of ramming material should be prepared according to the construction furnace slope and furnace bottom size requirements. After receiving the material, check whether the ramming material has debris and damp. The debris should be cleaned up. The damp material should not be used, and knotting equipment such as rammers and pneumatic picks should be prepared.

Lining method
After shoveling the material flat with a shovel, step on it with your feet to remove the air, insert the steel drill into the material and shake it repeatedly, and then use your feet to further solidify. The construction thickness of each layer of ramming material is 150~200mm. Appropriate, and then use a knotting implement to repeatedly beat it 3 times in a spiral from the periphery to the center.

The method to check the quality of knotting is usually to put a round steel with a diameter of 5mm on the ramming layer and press it down with a pressure of 10kg, and its depth does not exceed 30mm. Steel drills can be inserted forcefully during site construction, and the depth should not exceed 30mm.

The method of knotting the furnace slope is the same as that of the furnace bottom. First, use your feet firmly, and then use the knotting appliance to ram, the maximum angle between the furnace slope and the furnace bottom does not exceed 40°. Prevent rolling or collapse due to the furnace slope is too large.

Place bricks at the tapping mouth, furnace door and other places where molten steel is agitated and scour severely should be beaten vigorously and appropriately thickened to extend the service life of refractory materials in these damaged parts as much as possible.

After the ramming is finished, cover the 5~10mm thick steel plate on the ramming material to prevent the shape of the furnace bottom being damaged or the waste steel penetrates the ramming material layer when loading the scrap steel, which may cause the hidden danger of steel leakage. If steel cannot be made in time, 100~200mm thick lime is added to the iron plate to prevent the ramming material from hydrating.

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.?

Article Source：Lining method of EAF bottom ramming material
Company name: Henan Changxing Refractory Materials Co.,Ltd
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Measures to solve the problems of tundish refractory

 Some of the problems that occur during the use of tundish refractory materials are the quality of the material itself, and some are related to the on-site construction and need to be carefully observed and analyzed.

(1) Dry material has no strength

Before the tundish is put into use, the dry material of the working layer needs to have a certain low temperature strength, which is mainly obtained by vibration and baking. After the dry material is demolded by vibration and baking, there will often be local lack of strength or low strength, which is very easy to cause collapse and affect the production of continuous casting cases.

After long-term observation and analysis, the main reasons for the lack of strength or low strength of the dry material are:

①Baking problem: The tundish baking device used in the steel plant is a gas baking device, which will cause a large number of pipelines to focus after long-term use. The tar or the burner is damaged, causing the partial baking effect to be poor and leading to no strength or low strength.

②The dry material is damp: The dry material is composed of 70% particles and 30% fine powder. The fine powder contains magnesia and binder. Because of its high specific surface area, the fine powder is easy to absorb water and become damp. The magnesia and the binder absorb water after they absorb water. Chemical deterioration causes the bonding agent to fail and cannot produce bonding strength during baking;

③Uneven mixing of binder: When producing dry materials, various particles, fine powders and binders need to be put together and mixed uniformly. Sometimes, the mixing is uneven due to human factors or mixing equipment. Some dry materials do not have binder or the content of bonding agent is rarely resulting in partial loss of strength after baking and demoulding.

Solution: First of all, it is necessary to ensure the baking effect of the roaster, regularly purge the gas pipe, remove tar and dust, and replace the damaged burner in time. Secondly, it is necessary to ensure that the dry material is dry and mixed evenly.

(2) Nozzle cracking steel infiltrating the tundish nozzle with zirconium core in the pouring process is easy to crack and lead to steel infiltration, often forcing continuous casting to block production or abnormal shutdown. The analysis believes that the nozzle cracking is mainly due to the poor thermal shock resistance of the zirconium core.

Solution: The bulk density of the zirconium core should not be too high. The higher the bulk density, the worse the thermal shock resistance. Appropriately thickening the nozzle body can prevent molten steel from seeping out.

(3) Ladle casing fracture. The ladle casing is located between the ladle nozzle and the tundish. Its metallurgical function is to prevent the molten steel from splashing and being oxidized during the process of the molten steel flowing from the ladle into the tundish. The most common problem in the use of large-clad casing is fracture. There are two reasons for the fracture. One is the poor thermal shock resistance of the large-clad casing, and the other is that the large-clad casing and the steel ladle need to be replaced when replacing the ladle. The nozzle is separated. When the casing and the ladle upper nozzle are tightly adhered, the steelworker applies an external force to the ladle casing, causing the casing to break.

Solution: First, use materials with small thermal expansion coefficient and elastic mold to produce the casing to improve thermal shock resistance; Second, when the casing and the water outlet cannot be shared, no external force can be applied to the lower part of the casing, and the upper part of the casing can be steel external force is applied to the shell to separate it.

Article Source：Measures to solve the problems of tundish refractory
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Precautions for ladle filler sand and factors affecting automatic pouring

 Precautions for Ladle Nozzle Filling Sand:

The following points should be paid attention to during the use of the product in the links that affect the pouring process or each operation section:

1.Ladle preparation

The residual steel around the wall of the bag and the bricks of the nozzle block when the empty bag is turned back from the casting machine. If the residual steel around the cladding wall is not cleaned up. When the converter is tapped out, the base tank will be shaken off, and it will not be able to add sand when it falls into the nozzle. The residual steel at the nozzle of the runner block slide plate must be completely burned clean, and the parts that cannot be burned or whose service life has expired need to be replaced in time.

When burning residual steel, it should be done bidirectionally from the top of the ladle mouth and the direction of the drain to ensure that the nozzle is transparent. The air outlet of the ventilating brick must be burned out. If the air outlet is not exposed, it will affect the argon blowing effect in the future. If the argon blowing is not good, it will cause the bottom of the tank to crust in the future. There is a pot at the bottom of the tank, The skateboarder closes the skateboard after all the burn-in work and should try the skateboard several times, so as to omit the test of the flexibility of the skateboard and the hydraulic mechanism by the caster ladle worker in the future, so as to gain time on the casting machine. Finally, turn over the ladle to pour out all residual steel in the ladle.

2. Sand feeding work

Sanding workers should carefully observe the nozzle conditions before adding sand. Anyone with foreign objects will require the aerial crane to flip the ladle and dump it, because the residual steel in the nozzle is the deadliest. Once there is residual steel in the nozzle, it is difficult for the ladle of the casting machine to burn oxygen. If the situation is serious, the casting machine will stop pouring due to the failure to open pouring for a long time, and the accident will be seriously responsible.

The sanding of the casting machine is the last process to check the nozzle, which is of great significance. The amount of addition depends on the size of the seat bricks, and the shape of the sand pile should be 5-10cm higher than the ladle bottom brick.

3. Converter tapping

a.?The alloy should be placed away from the nozzle, especially the aluminum alloy. Aluminum is extremely replaceable. Aluminum and the oxides in the drainage sand are the easiest to react. The formation of aluminum oxide with extremely poor fluidity affects the pouring. Many domestic steel mills have a headache in making high-aluminum steel.

b.?When the converter is tapping, the tapping direction should avoid the position of the nozzle drainage agent to prevent the molten steel from being washed into the sand.

Factors affecting automatic pouring include:

①Steel grade, molten steel viscosity, tapping temperature, timing, etc.

②Material of nozzle block brick. High-aluminum materials are better than magnesium-carbon materials. Carbon materials have strong thermal conductivity, and the sand is heated more, which affects the fluidity of the sand.

③Permeable brick performance. Poor argon blowing will form a crust on the bottom of the tank.

④Skateboard and mechanism performance.

Article Source：Tundish lining construction and refractory material composition
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The difference between fireclay and firebrick

 Firebrick is a mixture of stone powder and clay fired in a kiln at 1300 degrees Celsius. Firebrick is a refractory material with a certain shape and size.

According to the preparation process, it can be divided into fired brick, unfired brick, electric fused brick and fire-resistant and heat-insulating brick. Refractory?fire brick?It can divide for standard brick, common brick, unusual brick to wait by shape and dimension.?Firebrick?can be used as high temperature building materials and structural materials for building kilns and various thermal equipment, and can withstand various physical and chemical changes and mechanical action at high temperature. For example, refractory clay brick, high aluminum brick, silicon brick, magnesium brick and so on.

Fire-clay usually refers to a kind of clay refractory used in civil furnace and furnace chamber.

Clay refractory brick is a weak acid refractory material, its thermal stability is good, suitable for hot furnace, various boiler lining and flue, smoke chamber, etc. Under atmospheric pressure 1500 degrees or so the dosage is larger with silicon brick and clay brick. Silica brick is a siliceous product containing more than 93% SiO2. The raw materials used are silica, waste silicon brick, etc. Silica brick has a strong ability to resist acid slag erosion, but it is easily eroded by alkaline slag. Its softening temperature under load is high, which is close to its refractoriness, but its thermal shock stability is poor. Silica brick is mainly used in coke oven, glass melting furnace, acid steelmaking furnace and other thermal equipment.

The main crystal phases in the high alumina products of neutral refractory materials are mullite and corundum, the content of corundum increases with the increase of alumina content, corundum products containing more than 95% alumina are a kind of high-quality refractory with wide use. Chromium brick is mainly made of chromite and its main crystalline phase is chromite. It has good corrosion resistance to steel slag, but poor thermal shock resistance and low deformation temperature under high temperature.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality 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：Tundish lining construction and refractory material composition
Company name: Henan Changxing Refractory Materials Co.,Ltd
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The effect of continuous casting long nozzle

 In the continuous casting operation, the long nozzle is located at the sliding nozzle of the ladle, and its main function is to prevent the molten steel from contacting the atmosphere and oxidizing when it flows to the tundish.?

Compared with the submerged entry nozzle, the long nozzle has a higher probability of cracks or breakage during use, so in the process of material selection, more attention should be paid to its crack resistance. Because in terms of appearance, the long nozzle is larger and heavier, and the mechanical shock is much greater whether it is during installation or use. Moreover, compared with the submerged entry nozzle, the long nozzle does not have a special preheating device, so it needs to withstand more severe heat during use.

For the corrosion resistance of the long nozzle, these parts are mainly emphasized.

1. The position in contact with molten steel;
2. The position where it is immersed in the inner hole and the slag line.

Since the joint between the long nozzle and the ladle is easy to enter air, the molten steel at this location is prone to oxidation and corrosion.

Article Source:The effect of continuous casting long nozzle
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The main refractory wear mechanism at the bottom of the ladle

 The damage to the bottom of the ladle, especially the impact area, may be the second reason why the ladle cannot be used and needs to be repaired or relined. The typical feature is: the higher the height of the ladle, the worse the wear of the refractory in the bottom area. Other relevant factors may include tapping temperature and furnace height.

There are three main stages:

1. Thermal spalling-temperature gradient and tapping cause the formation of cobweb-like vertical cracks on the bottom hot surface at the early stage of the furnace age;
2. The penetration of molten steel and slag—the penetration of molten steel and slag into the bottom hot surface , Especially through those vertical cracks formed on the surface;
3. Structural cracking-the subsequent thermal cycle causes the structural cracking of the alternating hot surface area, and then a new refractory surface is formed. Once the newly formed refractory surface is exposed to molten steel and slag, the second and third stages will be repeated.

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：The main refractory wear mechanism at the bottom of the ladle
Company name: Henan Changxing Refractory Materials Co.,Ltd
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Five main functions of tundish

 The continuous casting tundish was originally used for the heat preservation of molten steel, and its main purpose was to distribute and rectify molten steel. With the successful development of technologies such as slow cooling of molten steel, molten steel reheating technology, argon gas sealing technology, gas stirring technology, and removal of non-metallic inclusions in molten steel,?continuous casting tundish has become the most important part in the final stage of the steel smelting process. The main refining vessel is developing to a large scale.

1 Purification function

To produce high-purity clean steel, install porous ladle purging plug at the bottom of the tundish or embed a porous tubular gas distributor between the working layer and the permanent layer, or install porous bricks on the slag retaining wall to blow argon to make argon bubbles. Float evenly from the bottom to promote the removal of inclusions. These devices can eliminate the increase of argon in the molten steel and the reduction of oxide inclusions in the molten steel at the initial stage of pouring, and reduce the defects caused by Al203 inclusions on the tin plate.

2 Temperature adjustment function

In order to make the temperature difference of the molten steel before, during and after the tundish be less than 5℃ and close to the liquidus temperature during the pouring process, expand the equiaxed crystal area of the slab and reduce the center segregation, small scrap steel and iron injection can be adopted to the tundish. Powder and other measures to adjust the temperature of molten steel.

3 fine-tuning of ingredients

The center hole of the tundish stopper rod feeds cored wires such as aluminum, titanium, boron, etc. To the mold to realize the fine adjustment of the microalloy composition in the steel, which not only improves the yield of easily oxidized elements, but also avoids nozzle blockage.

4 Refining function

Add double-layer slag to the surface of the tundish molten steel to absorb the floating inclusions in the molten steel, or feed the calcium line to the tundish to change the form of AL2O3 inclusions to prevent clogging of the nozzle.

5 Heating function

In the tundish, induction heating and plasma heating are used to accurately control the molten steel pouring temperature within ±.3-5°C. In the initial stage of continuous casting, the tundish heating is used at the end of ladle pouring to compensate for the decrease in molten steel temperature and keep the molten steel temperature near the target. This is conducive to the stability of the pouring operation and improves the quality of the cast slab. During the pouring period, proper heating can compensate for the natural cooling of molten steel. The heating method uses induction heating and plasma heating.

Article Source：Five main functions of tundish
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The main tasks of continuous casting tundish

 1. Divert molten steel. For the multi-strand continuous casting machine, the molten steel is distributed to each mold through the tundish.

2. Steady flow. Reduce the static pressure of the molten steel, maintain a stable liquid level in the tundish, and smoothly inject the molten steel into the mold.
3. Store molten steel. When replacing ladle with multiple furnace continuous casting, the drawing speed is not reduced, creating conditions for multiple furnace continuous casting.
4. Purify molten steel. In a long pouring time, the temperature of the molten steel is basically unchanged, and the inclusions in the molten steel are further raised to prevent the molten steel from contacting air and avoid oxygen and nitrogen absorption.
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:The main tasks of continuous casting tundish
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The importance of porosity to refractory castables

 The ratio of the volume of pores in a material to the total volume of the material can be divided into true porosity, closed porosity and apparent porosity. It is usually called apparent porosity in the refractory industry in my country. The pores in refractory materials can be roughly divided into three categories: closed pores, open pores, and through pores. Generally, the above three types of pores are combined into two types, namely, open pores (including through pores) and closed pores. The apparent porosity refers to the volume density of all open pores in the material, which is the ratio of the dry mass of the refractory material to its total volume (the sum of the volume of solid, open pores and closed pores), that is, the mass per unit volume of the material use g/cm3 or kg/m3 said.

The bulk density of dense shaped refractory products should be determined according to the national standard GB/T2997-2000. The bulk density of shaped heat-insulating refractory products shall be determined according to the national standard GB/T2998-2001. The bulk density of dense refractory castables should be measured according to YB/T5200-1993.

Porosity is the basic technical index of most refractory materials. It almost affects all properties of refractory products, especially strength, thermal conductivity, corrosion resistance, and thermal shock resistance. Generally speaking, the porosity increases, the strength decreases, the thermal conductivity decreases, and the corrosion resistance decreases. Refractory castable is an unshaped refractory made of granular and powdered refractory materials according to a certain composition, plus a certain amount of binder and water, and formed by stirring and vibration casting. It is widely used in metallurgy, glass, cement, petrochemical, High-temperature industries such as energy.

Refractory castables will inevitably produce pores in the dehydration and sintering stages of the molding and heat treatment process. According to statistics, in the dense refractory castable, the matrix accounts for 25% of the total volume of the castable, and the pores account for about 10% of the total volume of the matrix. It can be seen that the pores are an important part of the matrix microstructure. The pore structure parameters include a very rich content, such as porosity, pore shape and distribution, pore size and pore size distribution, pore volume, etc. They all determine the mechanical and thermal properties of refractory castables to a large extent.

Article Source：The importance of porosity to refractory castables
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Tundish lining construction and refractory material composition

 The tundish is a transition device for molten steel between the ladle and the mold.

The main tasks of the intermediate package are:

(1) Diversion of molten steel. For the multi-stream continuous casting machine, the molten steel is distributed to each mold through the tundish;
(2) Steady flow. Reduce the static pressure of the molten steel, maintain a stable liquid level in the tundish, and smoothly inject the molten steel into the mold;
(3) Store molten steel. When replacing the ladle with multiple furnace continuous casting, the drawing speed is not reduced, creating conditions for multiple furnace continuous casting;
(4) Purify molten steel. In a long pouring time, the temperature of the molten steel is basically unchanged, and the inclusions in the molten steel are further raised to prevent the molten steel from contacting air and avoid oxygen and nitrogen absorption.?

The tundish is lined with refractory materials, and generally includes the following parts:

(1) Insulation layer (10~30mm), this layer is next to the steel shell of the tundish, usually using asbestos board, insulation brick or lightweight castable. The best effect is aluminum silicate fiber felt, which has low thermal conductivity and is easy to build.
(2) Permanent layer (100 ~ 200mm), this layer is in contact with the insulation layer, and its material is generally clay brick. The overall permanent lining is the most common, and the castable is generally high-alumina or mullite self-flowing castable.
(3) Working layer (20-50mm), which is in contact with molten steel and is the key part. Nowadays, insulation boards or coatings are commonly used. Insulation panels are generally siliceous, magnesia, and forsterite; Coatings are magnesia, magnesia chromium, and magnesia calcium. The paint is sprayed mechanically or applied manually.
(4) Tundish well block is inlaid at the bottom of the tundish and used to install the tundish nozzle. The material is usually high aluminum.
(5) The material of the bottom of the package is basically the same as that of the working layer. The working layer of the tundish bottom is easily damaged by the impact of molten steel and requires corrosion resistance and wear resistance. Generally, high alumina bricks or dense high alumina bricks and aluminum chrome bricks are used. Special large high-strength tar magnesia bricks are also used. The impact part of molten steel is reinforced by stony bricks or prefabricated blocks.
(6) The cover is covered on the tundish, which can play the role of heat preservation and splashing of molten steel. The material is made of clay or high-aluminum castable.
(7) Slag retaining wall (weir), which is built in the tundish and can be a single wall or a double wall. The material of the slag retaining wall weir is usually high-alumina bricks, but can also be made into prefabricated blocks, and its purpose is to block. In order to improve the cleanliness of molten steel, a molten steel filter can be installed on the slag retaining wall.
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：Tundish lining construction and refractory material composition
Company name: Henan Changxing Refractory Materials Co.,Ltd
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Lining method of dry ramming material for EAF bottom

 

Lining preparation

Clean up the permanent layer residue, dust, iron wire, plastic cloth and other foreign objects. Calculate the knot size, the actual knot thickness is equal to the required knot thickness multiplied by 1.09, and a sufficient amount of ramming material should be prepared according to the construction furnace slope and furnace bottom size requirements. After receiving the material, check whether the ramming material has debris and damp. The debris should be cleaned up. The damp material should not be used, and knotting equipment such as rammers, pneumatic picks, etc should be prepared.

Lining method

After shoveling the material flat with a shovel, step on it with your foot to remove the air, insert the steel drill into the material and shake it repeatedly, and then use your foot to further solidify. The construction thickness of each layer of the ramming material is 150~200mm. Appropriate, and then use a knotting implement to repeatedly beat it 3 times in a spiral shape from the periphery to the center.

The method to check the quality of knotting is usually to put a round steel with a diameter of 5mm on the ramming layer and press it down with a pressure of 10kg, and its depth does not exceed 30mm. Steel drills can be inserted forcefully during on-site construction, and the depth should not exceed 30mm.

The method of knotting the furnace slope is the same as that of the furnace bottom. First, use your feet firmly, and then use the knotting device to ramming. The maximum angle between the furnace slope and the furnace bottom does not exceed 40°. Prevent rolling or collapse due to the furnace slope is too large.

In places where steel tapping bricks, furnace doors and other places where molten steel is agitated and scoured severely, it should be beaten vigorously and the size should be appropriately thickened to extend the service life of the refractory materials in these damaged parts as much as possible.

After beating, cover the ramming material with 5~10mm thick thin steel plate to prevent the shape of the furnace bottom from being damaged or the waste steel penetrating the ramming material layer when loading the scrap steel, which will cause the hidden danger of steel leakage. If steel cannot be made in time, 100~200mm thick lime should be placed on the iron plate to prevent hydration of the ramming material.

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：Lining method of dry ramming material for EAF bottom
Company name: Henan Changxing Refractory Materials Co.,Ltd
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The purpose and features of neutral ramming mass

 Neutral ramming mass have a wider range of applications, such as the smelting of stainless steel, high-alloy steel and high-speed tool steel. Neutral ramming mass is usually rammed with an air hammer or a ramming machine, and the thickness of the ramming material is about 50~150mm at one time.

Refractory ramming materials can be constructed at room temperature, such as using thermoplastic organic materials that can form carbon bonds as binders, most of which are heated and mixed evenly and then constructed immediately. After molding, different heating methods are used to promote hardening according to the hardening characteristics of the mixture or sintering. For ramming materials containing inorganic chemical binders, they can be demolded and baked after they harden to a certain strength; Materials containing thermoplastic carbon binders can be demolded after cooling to have appropriate strength. After demolding it should be quickly heated to carbonize before use. The sintering of the refractory ramming material furnace lining can be carried out in advance before use, or can be completed by heat treatment with a suitable thermal system during the first use. The baking and heating system of the ramming material varies according to the material.

The main purpose of the ramming material is to cast the lining of the smelting furnace in direct contact with the melt, such as the blast furnace tap hook, the bottom of the steelmaking furnace, the inner lining of the induction furnace, the top of the electric furnace, and the blanking part of the rotary kiln. In addition to the furnace lining, large prefabricated components can also be manufactured.
We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality 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：The purpose and features of neutral ramming mass
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Destructive factors of refractory materials in electric furnace

 In general, the main destructive factors of electric furnace refractories are: erosion, oxidation, erosion, melting, spalling and hydration. Among them, the area occupied is targeted at oxidation, chemical erosion and erosion.

(1) Chemical attack

Iron oxide (FeO) or acidic components in the slag, such as SiO 2 chemically react with CaO and MgO, as shown below:

Exceeding the reaction can turn the furnace lining into slag, resulting in damage to the refractory material.

(2) Oxidation

Oxidation is one of the leading causes of corrosion of refractory materials in electric furnace linings. In this process, the carbonaceous oxygen fraction (such as iron oxide, oxygen, and magnesium oxide) in the refractory material is oxidized, resulting in decarburization and damage of the material.

The iron oxide in the slag reacts with the graphite or tar/resin in the hot surface of the brick lining, or oxygen erodes the graphite or the binder on the cold surface of the brick lining. In both cases, the strength of the brick is reduced and the slag may be erosion of molten steel.
Under actual electric furnace atmosphere conditions, starting from above 1700°C, reaction (6) is particularly prone to occur. The generated Mg vapor is easily diffused and tissue destruction occurs. This is one of the main factors that cause high-temperature damage to magnesia carbon bricks.

(3) Scour or mechanical shock

Physical damage is caused by molten steel or molten slag flowing over the surface of the refractory material and physically abrading or scouring the furnace lining. Erosion and erosion are the most common at the tap hole, slag line, electrode hole or exhaust platform of the electric furnace.
Spalling is an intricate damage mechanism of refractory materials. This is caused by the rapid heating and cooling of the lining refractory material, which causes the refractory material to produce stress. This stress often exceeds the strength of the refractory material, resulting in the intersecting and penetrating cracks, and the fragments of the furnace lining will peel off or fall off completely. This situation generally occurs on the roof of the electric furnace.

(4) Hydration

Hydration is also a factor in the destruction of refractory materials in electric furnaces. During use, water easily penetrates into the furnace cover or furnace wall, and water or steam can corrode the refractory furnace lining. Magnesium oxide (or other alkaline oxides) and water (or steam) react as follows to be hydrated.

Reaction will cause the performance of refractories to be greatly weakened, and the permeability of slag and molten steel will be deteriorated.
We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality 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：Destructive factors of refractory materials in electric furnace
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

Seamless ladle lining can reduce the unit consumption of refractory materials by 50%

 Magnesia carbon brick (MgO-C) has been used for many years as a refractory lining for ladle. In the 1980s, Japan developed a magnesia-aluminum spinel castable amorphous lining containing prefabricated spinel for use in ladle. In the 1990s, an in-situ spinel composition was formed in the second generation lining with fine magnesia and activated alumina added to the matrix. Different spinel castables are used in different ladle areas. At the bottom of the ladle, especially the ladle purging plug and wall bricks, the volume stability under high temperature and high pressure is the most important. High corrosion resistance and thermal shock resistance are also important in the process of high-speed molten steel production and when blowing in low-temperature stirring gas. Castables containing prefabricated spinel have become the standard for this application and provide optimal performance. The requirements for the side wall of the ladle vary. Since each steel cladding shell has some deformation after transportation, storage and processing, and because the inner lining is not absolutely rigid, one of the advantages is that stress relaxation can be used to avoid stress peaks causing cracks. Adding silicon powder to the castable formed by spinel to form a liquid phase will cause the castable to soften (a sharp drop in the RUL curve) to release thermal stress. The volume expansion caused by the in-situ spinel formation can close the seams on the surface. Therefore, the castable formed by spinel brings some advantages to the side wall of the ladle. This article believes that the combination of spinel and spinel is the best solution. This article provides a quick review of the ladle unshaped lining and innovative installation technology.

Advantages of unshaped lining for ladle:

(1) The replacement of magnesia carbon bricks with amorphous linings at the bottom and side walls of the ladle brings many advantages to the steelmaking process, mainly as follows:
(1) The use time of ladle is extended;
(2) The total number of ladle operations is reduced by 20%;
(3) Compared with MgO-C bricks containing toxic and carcinogenic substances (phenolic resin, coal tar pitch, etc.), the castable does not have any harmful materials;
(4) Reduce the unit cost of steel production;
(5) Produce ultra-low carbon steel in a better operating environment, because there is no carbon increase in the ladle refractories;
(6) The unit consumption of refractory materials is reduced by more than 50%.

Compared with other amorphous linings, the last advantage is the most important. Technically, the unit consumption of refractory materials is reduced by more than 50%, which is based on the concept of seamless lining. When magnesia-carbon bricks are used as the lining of the ladle and the service life of the bricks is reached, it will be replaced by a new set of MgO-C bricks. However, for amorphous linings, the situation is completely different. In the first installation, the amount of castable is the same as that of bricks. Subsequent replacement of the lining at the bottom and side walls, if brick lining is used, all need to be replaced. If unshaped refractory is used, only the part of the lining (about 40% to 60%) in contact with molten steel needs to be replaced, and the undamaged the lining will remain in place. Until the end of the ladle operation and before the complete renewal of all the inner?linings of the ladle, including the necessary safe working layer, refractory materials can be saved by using the unshaped inner lining.

Article Source:Seamless ladle lining can reduce the unit consumption of refractory materials by 50%
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