At the very beginning, clay brick is used for building ladle. However, as the ton steel consumption is high, it has been taken place by unshaped ramming mass. The integral ladle built with ramming mass was characterized with longer service life and lower ton steel consumption, and labor amount is also less.
However, some small steel plants cannot melting molten steel continuously, and with integral ladle it is neither convenient to handle nor convenient to replace well block. So if we still insisting on using ramming mass to build ladle, then energy waste will be huge. What is worse that the service life of a ladle will be only 8-10 heats, and bleed-out will happen frequently.
In order to solve those problems, Henan Xinmi Changxing Refractory Material Co., Ltd. started to do some researches and then successfully manufactured magnesia carbon bricks. The magnesia carbon brick made by Changxing Refractory has the following characteristics.
Using fused magnesite, high purity magnesium sand and graphite as raw refractory material, and then through high-pressure molding and low temperature treatment finally we made the magnesia carbon brick. The bricks can be used for both ladle and EAF, and whose service life is not less than 100 heats for ladle, and 120 heats for EAF.
What is more, Changxing Refractory not only provides products, but also dispatches engineers to help clients build furnace to guarantee our magnesia carbon bricks reach the service life we just stated.
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.
In recent years, silica ramming mass is widely used in induction furnace. Compared with traditional refractory lining material, this product is of lower cost, shorter sintering time and better working condition.
To offer clients better refractory products, we have successfully developed our 25+ heats silica ramming mass. As per actual working, we summed up the material consumption as following.
1. First heat: 10-15mm
2. Rest heat: 3-5mm
As per our experience, we should leave 70mm as save level. So if the
lining thickness is 180/300/450mm, we could promise the least service life of our refractory material to be 25 heats. If the working condition is convenient, 30-40 heats is no problem.
Furthermore, our silica ramming mass can also be applied in tundish and ladle. Service life can namely be 48-60 hours/ 200+ heats.
Because of the great advantages as above, our silica ramming mass is very welcomed by our clients all over the world say Bangladesh, Ghana, South Africa, and Indonesia, etc. If more interests, please feel free to make us informed, our professional teams are ready to give you our reliable service. For new clients, we would offer more preferential as following.
1. Lower price trial order
2. Professional refractory technicians overseas service
Therefore, what are you waiting for? Take your phone and call us!
Intermediate frequency furnace ramming material has many names, including dry ramming material vibration of intermediate frequency furnace, medium frequency furnace lining materials, intermediate frequency furnace refractory material, and intermediate frequency furnace dry vibration material. All those names are saying the same refractory product, and the properties and usage of all of them are the same. Intermediate frequency furnace ramming material refers to a kind of unshaped refractory products which are applied in the method of ramming (by human or machine), and then becomes hard in heating.
According to chemical properties, ramming material can be divided into acidic, neutral and alkaline ramming material. Acid intermediate frequency furnace ramming material is mainly made from high purity quartz and fused silica. During composite period, sintering agent uses composite additive as main material. Neutral intermediate frequency furnace ramming material uses alumina, high alumina material as main raw materials, it also uses composite additive as sintering agent. What makes alkaline ramming material different from the above two kinds of ramming materials is that its main raw materials are high purity fused corundum, high purity fused magnesia and high purity spinel. And also it uses composite additive as sintering agent. The above three kinds of ramming materials which are acidic, neutral and alkaline intermediate frequency furnace ramming materials are widely used for coreless intermediate frequency furnace and cored induction furnace.
There are two types of AOD furnace bottom shape to choose: Dish and flat base.
Flat base furnace bottom is easy to be constructed, and it needs less refractory brick types than dish furnace bottom, so the flat base furnace bottom is very widely used in
Dish furnace bottom needs more types of refractory brick than flat base furnace, and it costs more time to be made than the flat base one, while it has two important advantages as follows.
1. The dish furnace bottom is designed according to furnace casing size and spherical radius of furnace bottom shell, thus finally improving the quality of ton loading by increasing the furnace bottom volume.
2. The structure of dish furnace bottom will keep the original shape even after most of the bottom refractory bricks have been worn down.
For more knowledge about refractory AOD furnace design, go to the Industry News in www.yilongrefractory.com
Among all kinds of refractory furnace, for the design of AOD molten pool, it is better to choose flat molten pool. The flat kind has been proved to be the best one according to the past experience.
One special feature of the flat molten pool is that its furnace bottom conic section is short and its ratio of molten pool diameter to height is big, D/H is not less than 2.2, while in conventional AOD design, D/H is always no more than 2. It is also proved that relatively flatter molten pool has great effect on metallurgical properties of the furnace, especially for its decarbonization function. What’s more, it has the following four refractory advantages for using flat molten pool.
1. It can reduce CO partial pressure in bubble surface, speed up decarbonization and improve the efficiency by 15%.
2. Shorter blowing and converting time.
3. Lessen consumption of reductive silicon.
4. Lower refractories cost due to no backpack.
A good construction method can help to save refractories, but many many people don’t know how to do it exactly, here are the construction methods of castable for ladle bottom and ladle wall.
Casting of Backing Layer for Ladle Bottom (construction time: 1 day)
Firstly, fix Refractory Permeable Brick and Well Block, and then plug the inner hole with some resilient staff.
Secondly, weld some anchoring nails in the middle area of ladle bottom between one well block and another, the vertical and horizontal distances between every two anchoring nails are
25 mm and 30 mm.
Thirdly, mix backing layer castable for ladle with about 5% of water, and then stir it for about 20 minutes till smooth.
At last, pave the mixed backing layer refractory castable at the bottom of ladle, and then vibrate it to
in thickness by flat vibrator.
Casting of Backing Layer for Refractory Ladle Wall (construction time: 1 day)
After maintenance of bottom permanent layer, stick a layer of high alumina fiber mat which is
10 mm in thickness with the ladle shell. Then
place the mould right in the middle, flat, no deviation. The mould surface
should be clean, smooth and greased for easy demould.
Lay the mould properly to ensure that the gaps between mould and sidewall are the same, then pour the mixed backing layer refractory castable into the gaps, vibrate it by vibration bar till no bubble emerges (If mould is unavailable, cast working layer first and then permanent backing layer). The bottom of permanent backing layer is
in height; vibrate 300 -400 mm
per time, and its 90 -100 mm
in thickness, then one circle by one circle till to the top.
After vibration of permanent backing layer, lift the refractory ladle to an area at higher temperature, so that it is convenient for water evaporation and drying of cast body. The time of demould should be more than 12 hours, usually 24 hours, specific time depends on lining harden situation.
In a word: Recycle the refractory materials by decomposing them.
The type of refractory materials used in a furnace differs by the position. All kinds of used refractories mixed together make it hard to keep good quality, so it is necessary to classify refractories before reusing them. They can be classified by magnesia, alumina, carbon-based, non-carbon-based.
In addition, for the dissimilar materials or iron mixed in, we can use some ways to pick them out, such as the method of magnetic separation. First, the used refractory materials should be crushed to
400mm, and then reduce to smaller than 20mm after impacting, compression or
snipping, so as to be easy used.
For the refractories mixed with iron, we can use the way of electromagnetic separation, on the effect of magnetic strength higher than 12000 GS, making the content of iron in the used refractories with the size of 5~
less than 2%. While reusing the slit after crushing and after removal of iron
powder as raw materials, we should classify them by particle size. The classification
is generally done by using some metal mesh sieves, put the large mesh screen in
the above and the small mesh screen under the large ones, keep continuously
screening. In the process of crushing, grinding and classification, we should notice
that not let the dust spread, sealing the device and recycling refractories in duster. The left
dust also can be added to raw materials of landscape bricks.
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