#eaffurnace

The AC EAF has a long history of steelmaking, so its refractory materials for the bottom of the furnace have also undergone changes. The bottom of the furnace is rammed with asphalt tar magnesia or brine magnesia. Because brine magnesia is eroded quickly at the bottom of the furnace, it cannot meet the requirements for use. Although asphalt tar magnesia has better durability, it is troublesome to construct and has environmental pollution. Therefore, more magnesia bricks and low-grade magnesia-carbon bricks are used to build the bottom of the furnace. The durability of the brick-built furnace bottom is very good, but the masonry is labor-intensive and time-consuming.

By the 1990s, my country began to use the furnace bottom dry ramming material. It is simple and convenient to construct, and does not need to be baked. After the construction is completed, it can be directly used for steelmaking. The material is magnesium calcium iron dry vibrating ramming material. Using the low melting point calcium ferrite it contains, when the temperature rises above 1200 °C, it can quickly sinter to produce strength. Under the hydraulic pressure of molten steel, it can rapidly sinter and shrink, the shrinkage reaches 4% to 5%, and the bulk density increases to more than 3.0 g/cm3. Has particularly good corrosion resistance and good use results. The consumption of steel per ton of refractory materials is reduced from 4 to 8 kg of asphalt magnesia bricks to less than 2 kg. Some modern EAF bottom dry materials consume as little as 0.3 kg per ton of steel, which is mainly corresponding to the steelmaking process technology; In the process of use, the material is sintered layer by layer, sintered and densified near the molten steel, resisting The erosion and scouring of molten steel, the transition layer is under the sintered layer, and the loose non-sintered layer is under it. This loose layer has low density and low thermal conductivity, which play an important role in the insulation of the EAF. After years of promotion and development, the vast majority of electric furnace bottoms in my country use this kind of ramming material.

The construction and use of the furnace bottom dry material are the key factors affecting the use effect. The bottom material should be called dry vibratory castable more appropriately. Because the vibration densification density of the material is more than 0.2g/cm3 higher than that of ramming, the erosion resistance will be significantly improved. Kairuid kiln believes that the dry material should be vibrated for construction, especially for the DC EAF bottom that is not easy to be repaired. When repairing, the slag and scrap steel at the bottom of the furnace must be cleaned up, otherwise the steel slag under the repairing material may melt when used to a certain extent, and the furnace bottom material will float up under the impact of the steel block. When tapping, the floating bottom block may block the tapping hole and affect the tapping. In the process of use, the furnace bottom should be observed at any time. When there is a floating, it should be repaired in time (generally, the same kind of material can be filled to the pit) to prevent the floating from further expansion and prevent the occurrence of steel breakout. It is worth noting that when using in the first few furnaces, due to the thin sintered layer, the ability to withstand the impact of scrap steel is weak, so light and thin materials should be added, and the feeding basket should be lowered to prevent the scrap steel from having a large impact on the bottom of the furnace.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality EAF dry ramming 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:What are the refractory materials for the bottom of the AC EAF Company name: Henan Changxing Refractory Materials Co.,Ltd More refractory products:https://www.cxrefractories.com/en-product-solution Email:[email protected] Website:https://www.cxrefractories.com

Electric furnace oxidation period

The oxidation period of electric furnace is the main process of oxidation smelting, which can remove phosphorus, gas and inclusions in steel. When the scrap steel material is completely melted and reaches the oxidation temperature, more than 70% to 80% of phosphorus is removed and enters the oxidation period. In order to ensure the progress of the metallurgical reaction, the oxidation starting temperature is 50-80°C higher than the melting point of the molten steel. The main tasks during the oxidation period of the electric furnace: Continue dephosphorization to the requirement-dephosphorization; Decarburization to the lower limit of specification-decarburization; Get rid of gas, get rid of inclusions-go two;

Increase the temperature of molten steel-heating up.

Electric furnace reduction period

In the traditional electric furnace smelting process, the existence of the reduction period shows the characteristics of electric furnace steelmaking. The main difference of modern electric furnace smelting process is that the reduction period is moved outside the furnace. The main tasks during the reduction period of the electric furnace: Deoxygenation to the requirement-deoxygenation; Desulfurization to a certain value-desulfurization; Adjust the composition-alloying; Adjust the temperature-adjust the temperature. Among them: deoxidation is the core, temperature is the condition, and slagging is the guarantee.

Wanhao is a manufacturer who is specialized in designing various kinds of furnace and making refractory products for electric furnace, ladle, tundish, blast furnace, AOD furnace, IF furnace, etc.

Article Source:Main tasks of the electric furnace during the oxidation period and reduction period

More Refractory Products:https://www.wanhaorefractory.com/en/product.html

Website:https://www.wanhaorefractory.com/

In the production process of electric furnace steelmaking, it is a very common method to improve the service life of electric furnace refractory linings by optimizing gunning repair materials. Generally, the aggregate material in the EAF gunning material is the same as the material of the gunning furnace lining.?

With the development of metallurgical furnace lining quality, the material of gunning material has also changed from silicon, high aluminum, and magnesium to high aluminum silicon carbide, magnesium dolomite, aluminum-magnesium, magnesium-carbon, aluminum-magnesium-carbon, Magnesium calcium carbonaceous development. Both at home and abroad are committed to the development of new materials and varieties to meet the needs of the development of gunning technology for different metallurgical furnaces.

The gunning materials for electric furnaces include magnesia, magnesia-dolomite, magnesia-chromite, magnesia-carbon, magnesia-dolomite-carbon, etc., and part of the high-activity seawater magnesia is used in the aggregate. To promote sintering and improve the density and strength of the gunning layer. In order to make the gunning material solidify quickly during the gunning operation, and at the same time adhere to the furnace lining, a small amount of additives are often added to the aggregate.

1. When adding Al, Mg and other low-melting metal powders for gunning, the metal powder's oxidation heat will increase the temperature, and harmless oxides will be formed in the gunning material to improve the adhesion between the gunning layer and the furnace lining.

2.Add spinel Cr2O3, SiC, B4C, etc. to improve the oxidation resistance and corrosion resistance of the material.

3.Add a small amount of organic fiber with a length of 1~5mm, which will melt at low temperature to form an air duct, which is conducive to the evaporation of water in the binder and prevents bursting.

4.Add 0.1~2mm, 10~40mm long metal fiber, used in the tap hole and other parts to improve the corrosion resistance of the gunning layer.

5.Add part of the slag of the metallurgical furnace to improve the adhesion and corrosion resistance of the gunning material.

Article Source:How to choose gunning material for electric furnace lining Company name: Henan Changxing Refractory Materials Co.,Ltd More refractory products:https://www.cxrefractories.com/en-product-solution Email:[email protected] Website:https://www.cxrefractories.com

Electric furnaces mainly use scrap steel as the main raw material for steelmaking. Put scrap steel, lime, etc. into the furnace. When the electricity is turned on, an electric arc is generated between the electrode and the scrap to heat the charge. The metallurgical spare parts undergo a series of chemical reactions, and the scrap is made into steel. Electric furnaces mainly include DC electric arc furnace, AC electric arc furnace and induction furnace.? A.Refractories for DC electric arc furnace There are three types of DC electric arc furnaces, namely ABB, Clecim and GHH. Different types of DC electric arc furnaces are classified according to the structure of the bottom electrode, which illustrates the importance of the bottom electrode. The bottom electrode of the ABB type DC electric arc furnace is electrically conductive with a conductive refractory material, and the bottom surface is cooled; while GHH has many small steel needles (thin steel rods with a diameter of 20-50mm) buried in the bottom, and the bottom surface of metallurgical spare parts is also cooled by wind ; The bottom electrode of Clecim is 1-4 thick steel rods, and the lower end is cooled with a copper water cooling jacket. On the basis of these three types, various forms have been developed, such as the steel sheet type, the water-cooled bottom electrode rod type, and the steel rod and copper rod composite bottom electrode type.? The life of the bottom electrode of the DC electric arc furnace is essentially the life of the refractory material. For the Clecim bottom electrode, the electrode cover bricks are made of iron, magnesia-carbon, magnesia-aluminum, and iron-based refractories. The repair materials currently used are mainly magnesium dry ramming materials. For DC arc furnaces with conductive steel needles or steel sheet bottom electrodes, dry materials are often used between the steel needles or steel sheets, and some are made into preforms, mainly magnesium refractories. In order to improve the life span, NMe0-C materials are now available. It is impossible to greatly increase the life of the bottom electrode by improving the performance of refractory materials. Therefore, metallurgical spare parts have carried out hot repair work abroad in recent years. The hot repair materials used are required to be conductive refractory materials (the conductive steel needles and steel sheets are arranged), mainly including magnesium-iron conductive ramming materials, magnesium-carbon conductive ramming materials, magnesium-calcium carbon conductive ramming material.? B.Refractories for AC arc furnace The refractory used for the AC arc furnace bottom was rammed into the furnace bottom with asphalt tar iron sand or brucite knotting material in the early days, and then more iron bricks and low-grade magnesia carbon bricks were used to build the furnace bottom. By the 1990s In the 1940s, my country began to use dry vibrating ramming materials of furnace bottom magnesium-calcium-iron series. The construction of various metallurgical parts is simple and convenient, without baking, after the construction is completed, it can be directly used in steelmaking. Refractory materials for small electric arc furnace walls mainly use asphalt magnesia bricks, iron-carbon bricks, and iron sand to fill the furnace charge. For ultra-high-power large electric furnaces, high-quality magnesia-carbon bricks are used for electric furnace walls, especially high-quality magnesia-carbon bricks with very high performance for slag lines and hot spots. Magnesium gunning materials are mainly used for furnace wall repair.? Small electric arc furnace roofs generally use high alumina bricks, high power and ultra-high power electric arc furnace top electrode triangles with corundum, metallurgical spare parts, chromium steel jade and corundum magnesia castables and preforms. The outer roof generally uses fired high alumina brick or unfired high alumina brick, magnesia brick and magnesia chrome brick. The tapping tip generally adopts side tapping troughs.? In our country, we generally use high-aluminum, magnesium and other non-shaped ramming materials or castables prefabricated integral tapping troughs. The taphole bricks are magnesia bricks, magnesia carbon bricks, and coarse sand with forsterite as the matrix is often used as drainage sand.

Article Source: Refractory products used in electric arc furnaces Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd Email: [email protected] Website:http://www.cxrefractories.com