Configuration Scheme of Refractory Bricks for Melting Electric Arc Furnace

According to the needs of comprehensive utilization of vanadium-titanium magnetite, since the new process Melting Electric Arc Furnace was put into production, there have been many production and operation problems. Among them, the excessively high open arc temperature causes serious deformation of the furnace cover, and the mismatch between the furnace lining and the acid titanium slag leads to the rapid erosion of the furnace lining. According to the refractory bricks manufacturer, These have the greatest impact on production and test operations. What is the configuration scheme of Refractory Bricks for Melting Electric Arc Furnace? Which one is more resistant to erosion and more durable?

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Refractory Bricks for Melting Electric Arc Furnace

At present, medium-carbon magnesia-carbon bricks (C: 14% to 16%) are used as refractory bricks for Melting Electric Arc Furnace, which has a low service life and cannot meet the needs of field tests. For this reason, it is necessary to choose a refractory material suitable for smelting in an electric furnace. By carrying out the dynamic anti-slag erosion comparison test, calculation, analysis, and other methods of various refractory bricks, we can find refractory materials that can meet the working conditions of the Melting Electric Arc Furnace and can be produced for a long time. In particular, the refractory material needs to have good corrosion resistance to ferrous oxide and titanium dioxide acid slag, and excellent low-carbon hot metal scours resistance. Moreover, it has high refractoriness, suitable for high temperature and ultra-high temperature smelting of electric furnace.

Brief of Melting Electric Arc Furnace

The Melting Electric Arc Furnace is mainly composed of the furnace base, the furnace body, the furnace wall (furnace door), the furnace cover, the three-phase graphite electrode (A phase, B phase, C phase), refractory materials, iron tap, slag tap, operation platform, It is composed of electrode lifting device, feeding system, smoke exhaust system and other parts. The power is 12500kV·A, the furnace body diameter is 7.4m, the furnace diameter is 5.2m, and the depth is 2.1m. The molten pool is 3.8m in diameter and 0.8m in depth. The slag outlet is perpendicular to the tap hole at 90°, and the tap hole is directly aligned with the phase A electrode. After the slag and iron are separated at the end of smelting in the electric furnace, the slag will be discharged from the slag opening. After the slag is clean, the iron can be tapped. The slag is acidic with a basicity of about 0.2.

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Refractory Materials Used in the Melting Electric Arc Furnace

The initial design of the refractory masonry structure

In the design of the initial refractory material of the melting electric furnace, the main material of the masonry working layer is medium carbon magnesia carbon brick, and the permanent layer of the furnace lining uses magnesia brick. The permanent floor of the furnace bottom is comprehensively built with high alumina bricks and magnesia bricks. The iron tap and the slag tap are made of magnesium-carbon preforms.

The masonry situation of refractory materials in 1~5 furnaces

After the smelting electric furnace was put into production, due to rapid erosion, the refractory was overhauled and replaced, and 2 to 5 furnace campaigns were implemented before and after. details as following:

  1. The masonry structure of the second service refractory material is improved and optimized on the basis of the first service masonry structure. The thickness of the refractory material in the molten pool is reduced, and a converter is used at the tap hole and the slag tap. At present, tapping bricks are used instead of prefabricated parts.
  2. The masonry structure of refractory materials for the third furnace was further optimized. The thickness of the permanent lining of the magnesia brick is reduced, and the thickness of the magnesia carbon brick lining is increased. At the same time, the thickness of the refractory material above the slag line of the molten pool was increased on the basis of the second campaign. The tap hole and slag tap hole are still made of tap hole bricks, and the tap hole is reduced by about 50mm.
  3. The masonry structure of the refractory material of the fourth furnace is similar to that of the third furnace, with little change. The main reason is that the refractory material in the molten pool is slightly thickened and the diameter of the molten pool becomes smaller.
  4. The masonry structure of refractory materials in the early stage of the fifth battle is the same as that of the fourth battle. In the later stage of the test, the upper edge of the Melting Electric Arc Furnace was red, and the upper refractory bricks for Melting Electric Arc Furnace was improved. The thickness of the magnesia carbon brick on the upper edge is thickened, and the magnesia brick is built to protect the steel shell.
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Analysis of the corrosion of refractory materials in the 1~5 furnaces

The refractory linings of the 1 to 5 furnaces of the Melting Electric Arc Furnace were severely corroded and damaged in the middle and late tests. The location where the furnace lining is severely corroded is mainly near the slag line, especially the area behind the three-phase electrode, which presents an obvious three-phase plum petal-like contour. The corrosion and damage of the refractory materials on the iron wire and below and the upper part of the slag wire are not serious. It shows that slag has the most significant impact on the corrosion of refractory materials.

Causes of the Damage of the Melting Electric Arc Furnace Lining

According to the working conditions and smelting conditions of the Melting Electric Arc Furnace, there are four main reasons for the analysis of the corrosion and damage of the furnace lining:

  • (1) Acid slag (FeO, SiO2, and TiO2) corrodes refractory materials. The carbon in the magnesia carbon brick is oxidized and lost, forming holes. After the molten slag enters, it reacts with magnesium oxide to form low-melting substances such as magnesium ferrite, magnesium silicate, and magnesium titanate.
  • (2) Ultra-high temperature smelting conditions and arc irradiation and erosion cause corrosion and damage to refractory materials.
  • (3) The intermittent operation causes the refractory to be subjected to the thermal shock of alternating cold and heat, which is prone to cracks and lumps. Reduce the performance of refractory materials.
  • (4) The molten slag and low-carbon molten iron are stirred by the electric arc, which strongly scours the refractory. Causes the mechanical scouring damage of the furnace lining.
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Selection of Refractory Bricks for Melting Electric Arc Furnace

Comparative analysis of conventional physical properties

Choose magnesia carbon bricks (high carbon, medium carbon, low carbon), magnesia silicon carbide carbon bricks, magnesia bricks, alumina-silicon carbide carbon bricks, carbon bricks, Orr bricks (corundum composite bricks), magnesia chrome bricks, silicon carbide bricks, etc. Perform routine physical performance analysis. The bulk density, porosity, normal temperature compressive strength, and high-temperature flexural strength of magnesia carbon brick series all decrease with the increase of carbon content. Compared with the series of magnesia carbon bricks, magnesia bricks, carbon bricks, Orr bricks, magnesia-chrome bricks, and silicon carbide have higher porosity, indicating poor compactness. In addition, because these types of bricks are fired bricks, it shows that the high-temperature strength performance of this type of bricks is relatively poor. Combined with the smelting conditions of the Melting Electric Arc Furnace, it can be preliminarily determined that the series of magnesia carbon bricks are superior to other types of refractory bricks.

Analysis of dynamic slag erosion resistance

Divide into 3 groups to carry out the dynamic anti-slag erosion test.

  1. The first group is magnesia carbon bricks (high, medium, and low magnesia carbon bricks), carbon bricks, magnesia bricks, aluminum carbon bricks, Orr bricks (corundum composite bricks), magnesia chrome bricks, silicon carbide bricks.
  2. The second group is magnesia carbon bricks (high, medium, and low magnesia carbon bricks), magnesia silicon carbide carbon bricks, aluminum carbon bricks, alumina-silicon carbide carbon bricks, and aluminum magnesia carbon bricks.
  3. The third group is high magnesia carbon brick, alumina-silicon carbide carbon brick series, magnesia silicon carbide carbon brick series.

Through the comparison of the three sets of experiments, the type of refractory with the best resistance to corrosion by the slag of the Melting Electric Arc Furnace was finally found.

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High carbon magnesia carbon brick (GMT), medium carbon magnesia carbon brick (MT), low carbon magnesia carbon brick (DMT), magnesia silicon carbide carbon brick (MST), aluminum silicon carbide carbon brick (LST), aluminum carbon brick (LT) ), aluminum-magnesium-carbon brick (LMT), etc.

The following table shows the thickness of the decarburization reaction layer of refractory bricks. Among them, GMT, MST, and LST specimens were eroded the least deeply, and LT specimens were eroded the most.

GMT MT DMT MST LST LT LMT
0.3~0.5 0.5~0.8 1.2~1.4 0.3~0.4 0.3~0.4 1.5~2.2 1.0~1.5

In Conclusion

Through conventional physical performance analysis and dynamic anti-slag erosion test analysis, the following conclusions are drawn:

  • (1) Magnesia carbon brick series refractories have excellent high-temperature resistance. The matrix is dense, the porosity is low, and the dynamic resistance to the erosion of molten slag is good. And as the carbon content increases, the performance becomes better.
  • (2) Adding silicon carbide to magnesia-carbon bricks can further improve the brick’s corrosion resistance against molten slag. Improve the oxidation resistance of bricks at high temperatures.
  • (3) High carbon magnesia carbon bricks and magnesia silicon carbide carbon bricks are more suitable for the smelting requirements of the Melting Electric Arc Furnace.
  • (4) Experiments can be carried out to replace medium-carbon magnesia-carbon bricks with high-carbon magnesia-carbon bricks on Melting Electric Arc Furnaces.
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Rongsheng Refractory Bricks Manufacturer

Rongsheng refractory material manufacturer is an experienced refractory material manufacturer and sales company. Rongsheng’s refractory products have been sold to more than 60 countries and regions all over the world. For example, India, Pakistan, Kuwait, South Africa, Malaysia, Vietnam, Netherlands, Philippines, Singapore, Egypt, Russia, etc. Regarding Rongsheng’s product quality and customer service, in the same industry, customers are satisfied. For more information on the configuration of refractory bricks for melting electric arc furnace, please leave your specific needs on our message form. We will provide you with refractory products that best suit your production needs according to your actual working conditions.

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