chinafirebrick,refractory products, fire brick ,refractory nozzle: 三月 2022

2022年3月30日星期三

What is the erosion process of magnesia carbon bricks in the process of electric furnace smelting

The basic process of magnesia carbon brick erosion is:

(1) After the EAF magnesia-carbon brick is reacted, it is divided into three layers: the original brick layer (the brick body that has not reacted), the decarburized layer (the internal MgO and carbon undergo a self-consumption reaction), and the dense layer (the part in contact with the steel slag).

(2) The MgO and carbon inside the magnesia-carbon brick undergo a self-consumption reaction at high temperature:

(3) The oxides in the slag react directly:

Magnesium oxide is reduced to become magnesium gas, which migrates along the pores of the refractory material to the surface and is secondary oxidized to MgO, and forms a high-viscosity lithofacies structure with other impurity elements in the middle of the brick body, that is, the so-called dense layer.?

The erosion process is as follows:

(1) Physical wear. During the blowing process of these lithofacies, the movement of the physical steel slag furnace gas causes its physical and mechanical wear and peeling into the slag.

(2) Chemical attack. The chemical action is that various components in the middle of the slag will react with the dense layer of the brick body, and FeO can promote the dissolution and transfer of magnesia to the middle of the slag, increasing the erosion of EAF magnesia carbon bricks.

(3) The effect of temperature on erosion. The higher the temperature, the lower the viscosity of the steel slag, the intensified physical erosion, and the deepening of the decarburized layer, resulting in intensified erosion.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality EAF magnesia-carbon brick 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:Why is the R.U.L of refractory materials a key indicator
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

Reasons for the erosion of EAF lining during normal use

During normal smelting, the furnace lining is in direct contact with high-temperature molten steel and molten slag, and the working conditions are very bad.?

The reasons for the damage to the furnace lining are:

(1) Thermal spalling and chemical attack at high temperature caused by the radiation of the arc.

(2) The scouring effect of molten slag, molten steel and furnace gas on the furnace lining.

(3) Chemical erosion of the furnace lining by the molten slag.

(4) Peeling caused by temperature changes.

(5) Spalling caused by the decomposition of the mineral composition of the lining brick itself.

(6) Mechanical impact and scouring of the furnace lining when adding scrap steel and adding molten iron.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality EAF gunning mix 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:Reasons for the erosion of EAF lining during normal use
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

2022年3月29日星期二

Why is the R.U.L of refractory materials a key indicator

The actual temperature that the refractory product can withstand is slightly higher than the load softening temperature, mainly for two reasons. First, in actual use, the load on the refractory product is generally lower than the load during the measurement; The second is the masonry in metallurgy. The refractory fire bricks in the furnace are only heated on one side.

Since the temperature experienced in actual use is higher than the load softening temperature, higher requirements are imposed on the refractory product. The softening temperature of the refractory product depends mainly on its chemical mineral composition and microstructure. The crystalline phase forms a network backbone, and the load softening temperature of the material is high. If the structure is dispersed in the liquid phase in an island shape, the load softening temperature is determined by the content of the liquid phase and its viscosity. For example, the more the liquid phase or the smaller the viscosity, the lower the load softening temperature. The interaction of both the crystalline phase and the liquid phase also changes the amount and nature of the liquid phase. The degree of compactness of the product also has a certain influence on the softening temperature of the load. The commonly used magnesium brick phase composition, mainly periclase crystals, is bonded together by the combination, so the load softening temperature of the magnesium bricks depends on the nature of the combination. The combination of magnesia bricks is generally a low-melting silicate phase such as calcium forsterite and magnesium rosewood. Due to the melting point phase of the periclase crystal, the viscosity at low temperature is low, and the magnesia brick exhibits a low load softening temperature. This is where the magnesia bricks need to be tackled.

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!

2022年3月28日星期一

Refractory materials for different furnaces

1) Refractory for BOF

At present, ladle magnesia carbon bricks are used for the furnace cap, tapping port, front and rear large faces, molten pool and furnace bottom of the converter; high-strength magnesia carbon bricks are used for the trunnion and slag line parts.

The MgO content in the magnesia carbon brick is generally 70% to 75%, the graphite content is 16% to 20%, the bulk density is 2.8g/cm3 to 2.9 g/cm3, and the compressive strength is 25 to 30 MPa.

High-strength magnesia carbon brick with the same composition as magnesia carbon brick, but the compressive strength is 30 ~ 42MPa.

2) Refractory for EAF

The furnace bottom, furnace slope and molten pool of the electric furnace are integrated with magnesia, or magnesia bricks combined with magnesia carbon brick and tar pitch; hot and slag line areas, using high-quality magnesia carbon bricks; Both sides of the furnace door and tapping El it is a magnesia brick and a chrome-magnesia brick; the electric furnace cover is a high-aluminum brick or a high-aluminum non-burned brick.

3) Refractory materials for ultra high power electric furnace

The permanent lining of the ultra-high power electric furnace is magnesia, the side column of the furnace door is magnesia chrome brick, the slag line is magnesia brick, the hot spot is magnesia carbon brick, the furnace wall is magnesia carbon brick, the eccentric bottom and the molten pool are magnesia brick, out the steel mouth is magnesia carbon brick, the electric furnace cover is high aluminum brick, and the tapping hole filler is high iron dolomite filler.

4) Refractory for open hearth furnace

It can be seen from the working conditions of various steelmaking furnaces that the working environment of the refractory material is very bad, therefore, no matter what refractory material is used, it must have the following properties:

(1) High temperature resistance and high refractoriness.

(2) Erosion and erosion of high temperature resistant steel and slag.

(3) The steelmaking furnace is intermittent operation, and the refractory material is required to have good thermal shock resistance and peeling resistance.

(4) It has high mechanical strength and can withstand the impact of the furnace body tilting and loading into the charge without damage.

Article Source:Refractory materials for different furnaces
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

2022年3月23日星期三

Top 10 countries by cumulative crude steel production in January 2022

January 2022, China's crude steel production is estimated at 81.7 million tons, down 11.2% year-on-year

India's crude steel output was 10.8 million tons, up 4.7% year-on-year

Japan's crude steel production was 7.8 million tons, down 2.1% year-on-year

U.S. crude steel production was 7.3 million tons, up 4.2% year-on-year

Russia's crude steel output is estimated at 6.6 million tons, up 3.3% year-on-year

South Korea's crude steel production is estimated at 6 million tons, down 1.0% year-on-year

German crude steel production was 3.3 million tons, down 1.4% year-on-year

Turkey's crude steel production was 3.2 million tons, down 7.8% year-on-year

Brazil's crude steel production was 2.9 million tons, down 4.8% year-on-year

Iran's crude steel production is estimated at 2.8 million tons, down 20.3% year-on-year.

Article Source:Applicable environment and performance characteristics of refractory fiber castables
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

Applicable environment and performance characteristics of refractory fiber castables

Refractory fiber castables can be divided into smearing materials, projecting materials and tundish spray coatings according to different construction methods. It is mainly made of fiber acupuncture blanket as refractory raw material, adding inorganic binder, expansion agent, inorganic curing agent and various additives. Its main properties are low thermal conductivity, extremely strong thermal stability, certain compressive strength, certain resistance to airflow erosion, certain resistance to mechanical vibration, strong integrity, simple and rapid construction and dust-free, maintenance is simple, the oven time is short and simple, and the service life is long.

1. Various fuel furnace linings with working temperature ≤1250℃, including furnace wall and furnace top. Different types of refractory fiber castables are used to make composite furnace lining, which is stable in structure, economical and reasonable, and convenient in construction.

2. Backing insulation layer (including furnace wall and furnace top) with interface temperature of various high temperature furnaces and kilns ≤1050℃.

3. The lining of industrial boilers is more effective for furnace roofs.

4. For resistance furnace lining with working temperature ≤1200℃, the electric heating element can be exposed or made into a buried structure.

5. For industrial furnaces using flat flame burners, the top of the furnace is sealed and insulated, and the sealing effect is better than any other material.

6. The flue and large-diameter metal chimney are insulated with heat insulation.

7. High temperature air (≤1200℃) heat insulation inside the pipeline.

8. The inner lining of various thermal equipment.

9. It is especially suitable for furnace linings with mechanical vibration and large temperature changes, such as bell-type furnaces, removable cover of aluminum melting furnaces, etc.

10. Various general and special-shaped prefabricated parts can meet the special requirements of users.

Advantages compared to refractory fiber linings:

①The lining has no joints, and the fibers are arranged in three-dimensional directions. Under high temperature use, the lining does not shrink in direction, and does not produce cracks. The integrity of the lining is good, the air tightness is good, the heat preservation effect is good, and the service life is long.

② The construction process is simple, the speed is fast, and the material consumption is small. The requirements for the position of the anchoring nails in the special-shaped parts of the furnace lining are not very strict, which simplifies the design and facilitates the construction. The construction of the backing insulation layer with the anchoring brick structure is particularly convenient.

③ It has good mechanical properties, has certain strength, has certain load-bearing capacity, and has strong resistance to airflow erosion. In the refractory fiber castable special-shaped products, the furnace lining plate with grooves can be directly arranged with electric furnace wires or resistance strips, or prefabricated embedded electric heating furnace lining plates. The burner brick made of refractory fiber castable can be used for a long time under the condition of ≤1200℃ furnace temperature.

④It has strong adaptability to the atmosphere in the furnace and can be used in various fuel furnaces, and the furnace lining is stable in long-term use in reducing atmosphere.

2022年3月9日星期三

Brief introduction of raw materials for production of magnesia carbon bricks

The main raw materials of magnesia-carbon bricks include fused magnesia or sintered magnesia, flake graphite, organic binders and antioxidants.

Magnesia

Magnesia is the main raw material for the production of MgO-C bricks, which can be divided into fused magnesia and sintered magnesia. Compared with sintered magnesia, fused magnesia has the advantages of coarse periclase crystal grains and large particle bulk density, and is the main raw material used in the production of ladle magnesia carbon bricks. The production of ordinary magnesia refractory materials mainly requires high temperature strength and corrosion resistance for magnesia raw materials. Therefore, attention is paid to the purity of magnesia and the C/S ratio and B2O3 content in the chemical composition. With the development of the metallurgical industry, the smelting conditions are becoming more and more severe. The magnesia used in the MgO-C bricks used in metallurgical equipment (converter, electric furnace, ladle, etc.) Large crystal.

Carbon Source

Whether in traditional MgO-C bricks or in widely used low-carbon MgO-C bricks, flake graphite is mainly used as its carbon source. Graphite, as the main raw material for the production of MgO-C bricks, mainly benefits from its excellent physical properties: ① Non-wetting to slag. ②High thermal conductivity. ③ Low thermal expansion. In addition, graphite and refractory do not eutectic at high temperature, and the refractoriness is high. The purity of graphite has a great influence on the performance of MgO-C bricks. Generally, graphite with a carbon content greater than 95%, preferably greater than 98%, should be used.

In addition to graphite, carbon black is also commonly used in the production of magnesia carbon bricks. Carbon black is a highly dispersed black powdery carbonaceous material obtained by thermal decomposition or incomplete combustion of hydrocarbon hydrocarbons. 99%, high purity, high powder resistivity, high thermal stability, low thermal conductivity, is a difficult graphitization carbon. The addition of carbon black can effectively improve the spalling resistance of MgO-C bricks, increase the amount of residual carbon, and increase the density of bricks.

Binding Agent

The commonly used binders for the production of MgO-C bricks are coal tar, coal pitch and petroleum pitch, as well as special carbonaceous resins, polyols, pitch-modified phenolic resins, synthetic resins, etc. The binders used are of the following types:

1) Bituminous substances. Tar pitch is a thermoplastic material with the characteristics of high affinity with graphite and magnesium oxide, high residual carbon rate after carbonization, and low cost. It has been widely used in the past; However, tar pitch contains carcinogenic aromatic hydrocarbons, especially benzoβ content. High; the use of tar pitch is now decreasing due to increased environmental awareness.

2) Resin substances. Synthetic resin is prepared by the reaction of phenol and formaldehyde. It can be well mixed with refractory particles at room temperature. After carbonization, the residual carbon rate is high. It is the main binder for the current production of MgO-C bricks. The glassy network structure is not ideal for thermal shock resistance and oxidation resistance of refractories.

3) Substances obtained by modification on the basis of asphalt and resin. If the binder can form a mosaic structure and in-situ carbon fiber material after carbonization, the binder will improve the high temperature performance of the refractory material.

Antioxidants

In order to improve the oxidation resistance of MgO-C bricks, a small amount of additives are often added. Common additives are Si, Al, Mg, Al-Si, Al-Mg, Al-Mg-Ca, Si-Mg-Ca, SiC, B4C , BN and recently reported additives such as Al-BC and Al-SiC-C [5–7]. The working principle of additives can be roughly divided into two aspects: one is from the point of view of thermodynamics, that is, at the working temperature, additives or additives react with carbon to form other substances, and their affinity with oxygen is greater than that of carbon and oxygen. , which is oxidized in preference to carbon to protect carbon; On the other hand, from a kinetic point of view, the compounds generated by the reaction of additives with O2, CO or carbon change the microstructure of carbon composite refractories, such as increasing the Density, blocking pores, hindering the diffusion of oxygen and reaction products, etc.

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 brick 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:Brief introduction of raw materials for production of magnesia carbon bricks
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

2022年3月8日星期二

How to do EAF repair

From the point of view of the furnace repair materials, there are dry repair and wet repair. The charging material is magnesia [w(MgO)>78%] or roasted dolomite, and tar (hydrocarbon) is used as a binder during dry repair. The binder used for wet repair is brine (MgCl2·xH2O) or water glass (Na2SiO4·yH2O), which is often used in the furnace lining where the damage is serious or the slope is large, and it is difficult to repair. The dosage ratio of asphalt and magnesia is about 1:10, and the dosage of brine, water glass or magnesia should be kneaded into a group and not loose.

Throw the furnace repair material to the eroded place, and sinter the furnace repair material and the furnace lining into a whole by the heat energy of the furnace lining. When the furnace is repaired with magnesia and asphalt mixture, the liquid asphalt is filled between the magnesia at high temperature, and decomposes and volatilizes, and what remains is fixed carbon, which is used as a skeleton to lock the magnesia particles into a whole. Carbon only volatilizes above 4000°C. When wet filling is used, the moisture of MgCl2·xH2O or Na2SiO4·yH2O is volatilized at high temperature, and MgO·MgCl2 compound is formed in the gap of magnesia, which plays the role of locking magnesia.

The principle of repairing furnace is high temperature, thin repair and quick repair. Minimize high-temperature radiation and heat dissipation, and operate quickly.

After tapping, immediately use a shovel to fill the two sides of the tapping hole and the furnace slope, so that the heat loss is less, and then use a large shovel to repair the two sides of the furnace door. Because the charging material depends on the residual temperature in the furnace for sintering, the faster the charging, the less heat loss in the furnace, and the higher the temperature, the better the sintering. After tapping, the door of the furnace and the tapping port are easily cooled by the cold air, and the slope of the tappin hole port is related to whether the molten steel can be fully poured (if the molten steel is not exhausted, the furnace bottom is easily damaged, and it is easy to use the next furnace. The chemical composition is unstable), so it is necessary to repair both sides of the furnace door and the steel outlet first. In order to avoid the residue sticking at the furnace slope, it is also possible to scrape it with an iron rake before repairing the furnace. The rest of the parts are relatively difficult to cool, and can be repaired after the two sides of the furnace door and the tapping hole brick are repaired. For the slag line and furnace slope near the three-phase electrode, due to the effect of the arc, there is more erosion, so pay attention to it. repair. It needs to be thinly filled, because it is too thick at once, and the inner layer of magnesia is poorly heated and cannot be sintered well, resulting in the floating of large pieces of magnesia during the smelting process and the viscosity of the slag, so the thickness of the furnace is generally not more than 25mm. When the amount of furnace repair is large, some lime can also be added to the dolomite magnesia to further protect the furnace body.

The time for repairing the furnace depends on the erosion situation and the capacity of the furnace, generally 3~5min.?We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality EBT taphole block 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:How to do EAF repair
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

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