Technical Innovation of Carbon Brick for Blast Furnace Hearths

Carbon Brick for Blast Furnace Hearths

Possessing with the excellent corrosion resistance and high thermal conductivity which can lead to easily form a protective layer for blast furnace hearth, refractory brick carbon bricks have been used as refractory material for hearths for more than half century.

To further improve its performance, the refractory experts have carried out many investigations recently. Finally, they find out some main reasons which caused the damage. They are including as below:
1) The penetration of molten iron into pores.
2) Erosion due to direct contact with molten iron (dis-solution by carburizing).
3) Embrittlement of the material on hot side (loss of cooling capacity).

In order to enhance its corrosion resistance, the experts have developed new technology to get new magnesia carbon brick through numerous experiments.
1) Add the aluminum oxide which has a good resistance to molten steel.
2) Reduce the pore diameter to prevent the penetration of molten steel and other impurity items.
3) Enhance the high thermal conductivity to reduce the surface temperature.
4) Add the TiC to improve the corrosion against molten steel, increase its viscosity and slow down the flow which could effectively reduce the damage on the MgO-C bricks.

Article sources:

http://www.yilongrefractory.com/news/Technical%20Innovation%20of%20Carbon%20Brick%20for%20Blast%20Furnace%20Hearths.html

On the light burning magnesium ball structure

Application of regenerator in gas burning industrial furnace combustion system

There are between light burning magnesium powder crystal molecule and a molecule force there, this force is called intermolecular forces. Intermolecular forces and the polarity of the molecules magnesia carbon brick related to the whole molecule is electrically neutral. Because the molecular positive charge and negative charge of electricity power is equal. But molecules

Both internal charge distribution situation, the molecule can be divided into polar molecules and non-polar molecules categories.

Each charge, there is a "charge centers", such as positive and negative charge relative position of the center of refractory brick the "+" or "one" is represented, the positive and negative charges coincide with the center of the molecule is called the non-polar molecules, the molecules do not coincide called a polar molecule. CKS molecules, the negative charge carried by the central power

As q, the distance l, called the product of the two dipole moment p - P.

Forming a light refractory material burning magnesium ball intensity light burning magnesium ball size depends on the structural strength of the internal structure of the organization's role in the size of the force. Theoretically, the process of forming a light burning magnesium ball castable refractory material strength, mainly two physical and chemical processes. Physical process of light magnesium burning ball burning magnesium powder and water are mixed by the light

After extrusion. Light burning magnesium powder diameter of about 0.074mm, molecules or crystal structure was physics.

According to a large number of experimental and theoretical results show that there is interaction between the charge and the charge, the same charge repel each other, dissimilar charges attract each other. Show that the interaction force between two point charges, whose size is proportional to the product of two charges of electricity, with two

It is inversely proportional to the square of the distance from the charge. Light burning magnesium powder crystal unit there are also an equal amount of positive and negative charges.

In a moment there will always be a dipole exists, this is called an instantaneous dipole-dipole. Intermolecular forces and the polarity of the molecules related to the whole refractory company molecule is electrically neutral. Because the molecular positive charge and negative charge of electricity power is equal.

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Influence of LF Refining Slag Adjustment on Ladle Refractories and Refining Effect

In order to take with the problem of serious erosion of ladle lining during the desulfrization of LF refining, LFrefining slag was adjusted and calcium aluminate system substituted fluorine free refining slag with fluorine. After the adjustment of the slag, the erosion conditions on ladle were improved greatly and refining number, refining ratio and remaining lining thickness after demolishing all increased substantially. 
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Molding methods of refractories and widely used refractories

There are many refractory material molding methods, such as common molding method, vibration extrusion method, extrusion method, pounding method and so on.

At present, when it comes to the production of refractory materials, the most frequent way of molding refractory material is machine pressure molding method which is a way using brick molding machine and mold to compress the clay material into body. because the clay contains 5% water it is called semi-dry molding method. Machine molding is with compact structure, high strength, narrow drying and firing way, and size is also easy to control. It can be divided into the single side pressure, and double sides pressure which can reduce the phenomenon of layer density.

The common refractory material are AZS brick, corundum brick, magnesite chrome brick, directly silica carbide, silicon carborundum brick, nitrides, silicides, sulfide, boride, carbide and other non oxide refractories materials; Calcium oxide, chromium oxide, aluminum oxide, magnesium oxide and so on.

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How to Choose Refractory Bricks Used for Different Parts of Blast Furnace

1. Good corrosion/erosion resistance 2. High temperature performance 3. Longer service life 4. Stable structure 5. Thermal shock resistance

How to choose refractory brick used for different parts of blast furnace?

When choosing refractory brick used for different lining parts of blast furnace, we should follow some principles. The refractory lining of every part should fit the parts thermal current intensity, so that the lining can maintain previous vertebral shape and stability under the impact of strong heat flux. 

Here are some methods of selectingrefractory brick for sale for every part of furnace lining.
(1) Furnace throat. It mainly needs to withstand impact and abrasion of burden, so generally we use steel brick or water cooling steel brick for the furnace throat.

(2) The upper shaft. Plus the burden descent and ascending gas flow of scour and wear. Therefore, we should choose resistance to chemical erosion and abrasion resistance of refractory material, the most appropriate is high relative density brick, high density, high aluminum brick or phosphoric acid impregnated clay brick.

(3) The middle and lower part of nozzle refractory furnace and furnace bosh. The main mechanism of damage is thermal shock, high temperature gas scouring, and impact of alkali metals, zinc and carbon deposition, as well as chemical erosion of the initial slag. For those three parts, we should choose refractory materials with properties of thermal shock resistance, slag erosion resistance and erosion prevention. For blast furnace whose volume is smaller than 1000m3, we can use aluminum carbon brick. 

(4) Furnace bosh. Hot gas erosion and iron slag erosion are the main reasons for furnace bosh damage, this part of the heat flux intensity, refractory material refractory fiber felt life not long (as long as 1 to 2 months, as short as 2 to 3 weeks), generally used in refractory degree is high, load softening temperature is high and the volume density of refractory material, such as the high aluminum brick, alumina carbon brick. 

(5) Hearth tuber. This site is only in blast furnace of oxidation reaction area, high temperature from 1900 to 2400 DEG C, lining by damage caused by high temperature thermal stress. Composite brick masonry hearth tuyere zone is adopted by the modern blast furnace, material for high alumina, corundum Mo mullite; corundum and silicon nitride combined silicon carbide, useful also hot pressed carbon block. 

(6) The lower part and bottom of hearth. For those two parts, we use hot pressing small carbon brick, micro porous carbon brick, and hot semi graphite carbon brick with high thermal conductivity, good resistance to penetration, good resistance to chemical erosion, low porosity and micro aperture, as well as brown corundum or gray corundum brick used for ceramic cup.

Technical Innovation of Carbon Brick for Blast Furnace Hearths--Changxing Refractory

    Possessing with the excellent corrosion resistance and high thermal conductivity which can lead to easily form a protective layer for blast furnace hearth, carbon bricks have been used as refractory material for hearths for more than half century.

    To further improve its performance, the refractory experts have carried out many investigations recently. Finally, they find out some main reasons which caused the damage. They are including as below.

1) The penetration of molten iron into pores.

2) Erosion due to direct contact with molten iron (dis-solution by carburizing).

3) Embrittlement of the material on hot side (loss of cooling capacity).

    In order to enhance its corrosion resistance, the experts have developed new technology to get new refractory carbon brick through numerous experiments.

1)      Add the aluminum oxide which has a good resistance to molten steel.

2)      Reduce the pore diameter to prevent the penetration of molten steel and other impurity items.

3)      Enhance the high thermal conductivity to reduce the surface temperature.

4)      Add the TiC to improve the corrosion against molten steel, increase its viscosity and slow down the flow which could effectively reduce the damage on carbon brick.