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The principle and function of electric furnace, AOD furnace, LF furnace and VD vacuum furnace

electric furnace:

The electric furnace steelmaking method mainly uses arc heat. In the arc action zone, the temperature is as high as 4000 ℃. The smelting process is generally divided into a melting period, an oxidation period and a reduction period. In the furnace, not only an oxidizing atmosphere but also a reducing atmosphere can be created, so the efficiency of dephosphorization and desulfurization is very high.

Compared with the blast furnace converter method, the electric furnace steelmaking with scrap steel as the raw material has less capital investment. At the same time, due to the development of direct reduction, the electric furnace provides metalized pellets to replace most of the scrap steel, so it greatly promotes the electric furnace steelmaking.

Function: At present, there are many intermediate frequency furnaces in China, which are mainly used for smelting high-quality steel, alloy steel and stainless steel molten steel. It is the first production process for smelting stainless steel.

AOD furnace:

AOD furnace method (ie argon oxygen decarburization method) is a more advanced technology for refining stainless steel. It has the advantages of simple equipment, convenient operation, strong adaptability, low investment and low production cost, and is widely used.

The blast furnace molten iron and molten steel melted on the electric furnace are injected into the AOD furnace through the ladle, and O2, Ar or N2 mixed gas is blown into the smelting process to decarburize the molten steel. The composition and temperature of molten steel can smelt out qualified stainless steel materials.

Principle: The delivery and adjustment of the mixed gas during refining is one of the main systems of the argon-oxygen furnace. The gas produced by the oxygen production workshop is separately transported into the gas storage tank near the workshop through the pipeline, after metering, decompression, adjustment, mixing, and finally the mixed gas according to the flow rate and proportion required by the process is sent into the furnace through the side gun.

At the beginning of smelting, oxygen is blown into the metal molten pool from the top furnace mouth through a double-layer water-cooled oxygen blowing pipe for decarburization. During refining, the mixed gas is fed into the side gun into the furnace (installed on the side wall opposite to the tapping port and near the bottom of the furnace). When charging and tapping, the furnace body is inclined forward at a certain angle, and the (side) tuyere is above the molten steel level. During normal blowing, the tuyere sinks into the deep part of the molten pool. A mixture of oxygen and argon or nitrogen is blown into the center tube of the tuyere, and the partial pressure of carbon monoxide can be reduced by adjusting the ratio of oxygen to argon to achieve the purpose of decarburization and chromium retention. The type of AOD furnace tuyere is unique, it is a gas-cooled consumable tuyere. The tuyere adopts a double-layer casing structure, the outer tube is only fed with argon or nitrogen to cool the tuyere, and the inner tube is fed with a mixture of oxygen and nitrogen, or argon. In order to achieve the best operation effect through the flow control of the air hood ring, the flow of the air hood ring central pipe and the air hood ring can be controlled in the main control room.

Adopt three side gun technology. It can enhance the strength of oxygen supply and improve the yield of metal materials, and this technology can shorten the time of AOD smelting. The stable and reliable control system can reduce the consumption of gas and various raw materials in smelting, and obtain stable product quality.

Function: The main function of AOD is to decarbonize and refine.

LF furnace:

LF furnace (LADLE FURNACE) is the ladle refining furnace, which is the main refining equipment outside the furnace in iron and steel production. LF furnace generally refers to the refining furnace in the steel industry. In fact, it is a special form of electric arc furnace.

LF furnace refining mainly relies on the white slag in the barrel. In a low oxygen atmosphere (oxygen content is 5%), argon gas is blown into the barrel for stirring, and the molten steel passing through the primary furnace is heated and refined by the graphite electrode. Since argon stirring accelerates the chemical reaction between the slag and the steel, arc heating for temperature compensation can ensure a longer refining time, thereby reducing the oxygen and sulfur content in the steel, and the inclusions are rated as O according to ASTM ~O. Level 1. The LF furnace can cooperate with the electric furnace to replace the reduction period of the electric furnace, and can also cooperate with the oxygen converter to produce high-quality alloy steel. In addition, the LF furnace is also an indispensable equipment for the continuous casting workshop, especially the alloy steel continuous casting production line to control the composition, temperature and preserve the molten steel. Therefore, the emergence of the LF furnace has formed a new combined production line of LD-LF-RH-CC (continuous casting) for the production of high-quality steel. The reduction refining of steel in this combined production line is mainly done by the LF furnace. The steel grades processed by the LF furnace involve almost all steel grades from special steel to general steel. Different process operation systems are adopted in production depending on the needs of quality control. Among various secondary refining equipment, the comprehensive cost performance of LF furnace is high.

 

  • LF has the following characteristics:

①Desulfurization

②Temperature adjustment

③ Precise fine-tuning of ingredients

④Improve the purity of molten steel

⑤ Slag making

 

  • It mainly has the following functions:

(1) The LF furnace is connected to the electric furnace, which speeds up the production cycle of the electric furnace and improves the quality of the electric furnace steel.

(2) The LF furnace is connected to the LD converter, which can reduce and refine the converter steel, so the quality of the steel can be improved and new steel grades can be produced.

(3) LF furnace can strictly adjust the composition and temperature of molten steel, which is beneficial to the hardenability of steel and the continuous casting of special steel.

After AOD refining, it is refined in LF furnace, which belongs to secondary refining, and the reduction of inclusions ensures the purity of molten steel;

VD vacuum furnace:

The electric furnace steelmaking method mainly uses arc heat. In the arc action zone, the temperature is as high as 4000 ℃. The smelting process is generally divided into a melting period, an oxidation period and a reduction period. In the furnace, not only an oxidizing atmosphere but also a reducing atmosphere can be created, so the efficiency of dephosphorization and desulfurization is very high.

EAF steelmaking with scrap as raw material requires less capital investment than the blast furnace converter method. At the same time, due to the development of direct reduction, EAF provides metalized pellets to replace most of the scrap, thus greatly promoting EAF steelmaking.

Function: At present, there are many intermediate frequency furnaces, which are mainly used for smelting high-quality steel, alloy steel and stainless steel molten steel. They belong to the first production process of smelting stainless steel.

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