CN-122012854-A - Direct-current arc furnace smelting method capable of effectively controlling nitrogen

CN122012854ACN 122012854 ACN122012854 ACN 122012854ACN-122012854-A

Abstract

The invention discloses a direct current arc furnace smelting method capable of effectively controlling nitrogen, which is characterized in that a side argon blowing device is arranged on a furnace wall of a molten pool, the smelting comprises the processes of scrap steel batching, blanking power transmission, slag making dephosphorization and oxygen blowing and carbon drawing, low-power transmission is carried out after oxygen blowing and carbon drawing operation, and the side argon blowing device is started to carry out argon blowing and stirring for 1-2 minutes, and tapping is carried out after the tapping temperature requirement is met. Compared with the technology without adopting a side argon blowing process, the method reduces the nitrogen content of molten steel by 5-15 ppm during tapping of the electric arc furnace, obviously improves the initial cleanliness of the molten steel, reduces the nitrogen content from 80-90 ppm to 65-75 ppm under the original process condition, and further inhibits the FeO% content of the terminal slag. According to the method, a side argon blowing device is additionally arranged to perform side blowing and combine the stirring effect of the bottom electrode anode, so that the stirring dead area of a molten pool is improved, the oxidability of terminal slag is reduced, and the original nitrogen content before tapping of molten steel is improved.

Inventors

LIU YONG
JIAO XUECHENG
PENG FEI
ZHANG YUNFEI
QI JIANJUN
ZHAO YINGLI
ZHANG HONGQI
FAN MINGQIANG
ZHAO ZHENGRONG
HUO YANPENG
XING LIYONG

Assignees

河北河钢材料技术研究院有限公司
河钢集团有限公司
河钢股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260305

Claims (9)

1. A direct-current arc furnace smelting method capable of effectively controlling nitrogen is characterized in that a side argon blowing device is arranged on a furnace wall of a molten pool of the direct-current arc furnace, smelting comprises the processes of scrap steel batching, blanking power transmission, slag making dephosphorization and oxygen blowing and carbon drawing, low-power transmission is carried out after oxygen blowing and carbon drawing operation, and the side argon blowing device is started to carry out argon blowing and stirring, so that tapping is carried out after tapping temperature requirements are met.
2. The method for smelting nitrogen-controlled direct current arc furnace according to claim 1, wherein argon blowing stirring is carried out for 1-2 minutes by the side argon blowing device.
3. The method for smelting nitrogen-controlled direct current arc furnace according to claim 1, wherein the voltage of the low-power transmission is 500-600V and the current is 85-95 KA.
4. The method for smelting nitrogen-controlled direct current arc furnace according to claim 1, wherein the side argon blowing device is provided with 2 argon blowing devices, and the flow rate of each argon blowing stirring device is 20-30 Nm 3 /h.
5. The direct current arc furnace smelting method for effectively controlling nitrogen according to claim 1, wherein the proportion of the scrap steel batching process is 15-20% of high-quality pig iron, 10-15% of self-produced crushed materials, 15-20% of small scrap steel, 25-35% of medium scrap steel and 10-20% of high-quality heavy scrap.
6. The direct current arc furnace smelting method capable of effectively controlling nitrogen according to claim 1, wherein the blanking and power transmission process comprises the steps of adopting twice charging, preheating waste steel of primary charging to the surface temperature of 600-800 ℃ at first, charging 55-60% of the total charging amount, charging secondary charging after the primary charging is conducted, and preheating waste steel of secondary charging to the surface temperature of 500-600 ℃ first.
7. The direct current arc furnace smelting method capable of effectively controlling nitrogen according to claim 1, wherein the blanking and power transmission process is characterized in that after blanking is completed, power transmission voltage is 900-1000V, current is 85-95 KA, and after a molten pool period state is reached, power transmission voltage is 600-700V, current is 85-95 KA.
8. The direct current arc furnace smelting method capable of effectively controlling nitrogen according to claim 1, wherein the slagging and dephosphorizing process is characterized in that the temperature of a molten pool is controlled to be less than 1530 ℃, lime is added to 15-20 kg/t and light burned dolomite is added to 5-10 kg/t, and the slagging, dephosphorizing and deslagging operation is carried out.
9. The method for smelting the direct current arc furnace with effective nitrogen control according to any one of claims 1 to 8, wherein the oxygen blowing and carbon drawing process is characterized in that carbon powder injection amount is 10-20 kg/t, deoxidization and carbon drawing operation is carried out at the same time, and oxygen blowing amount is 30-40 Nm 3 /h.

Description

Direct-current arc furnace smelting method capable of effectively controlling nitrogen Technical Field The invention relates to the technical field of electric arc furnace steelmaking, in particular to a direct current electric arc furnace smelting method which is suitable for steel grades with the end nitrogen content of an electric arc furnace to be effectively controlled. Background The domestic top-bottom combined blowing converter steelmaking has a complete bottom argon blowing process, and when an ultralow-carbon automobile plate requiring nitrogen control is produced, the whole argon blowing process or the proportional valve adjustment according to the need is adopted to perform the nitrogen-argon switching operation during blowing, so that the terminal nitrogen is controlled to be very low, and the level of less than 30ppm can be achieved. In addition to the factors of high liquid nitrogen content of steel caused by the self process (scrap steel and electric arc), the device of the AC or DC arc furnace has inferior nitrogen control capability as that of the converter smelting process. At present, a domestic three-phase alternating current arc furnace is provided with a bottom blowing process technology, a bottom blowing system can be utilized to perform nitrogen-argon switching operation similar to a converter to achieve the parent of optimizing economic and technical indexes, and a bottom blowing system is not designed and installed any more in the direct current arc furnace with single-phase electrodes because of adopting a bottom electrode anode if the bottom blowing system is arranged and has safety production risk. The operation mode is compared with converter steelmaking, the short plate is obvious in the aspect of controlling the end nitrogen content of molten steel, and the stirring radius of the bottom anode current magnetic field is smaller, and the stirring direction of the molten steel is not changed due to the fact that the current direction is not changed, so that a dead zone exists in a molten pool area beyond the stirring radius of the bottom anode current magnetic field. For example, the special steel, arc furnace bottom argon stirring process, 6 months 2000, developed an industrial test of one furnace service (80 ton furnace) by adopting the furnace bottom argon stirring process, and the bottom blowing system consists of an air brick, an air source, a flow and a pressure regulator, wherein 3 air bricks are arranged in a cold spot area between three-phase electrodes at the bottom of the electric furnace, and obviously the test is performed under the condition of the three-phase electrodes. The bottom blowing nitrogen and argon switching process developed in industrial heating, production process and metallurgical effect of electric furnace bottom blowing system in 2011, and the bottom blowing and furnace wall gun are matched for research, so that dead zone is reduced, and the technical and economic index of the electric arc furnace is optimized, and the method is suitable for an alternating current electric arc furnace for adding molten iron. Patent application CN202410668444.6, a method for producing ultra-low carbon steel by an electric furnace process, emphasizes that the synergism of an electric furnace system reduces the oxygen and nitrogen content, but more importantly emphasizes the deep denitrification after reaching an RH station, and is particularly suitable for the production field of ultra-low carbon steel. Patent application CN202410780242.0 relates to a production method of nitrogen-containing low-carbon aluminum killed molten steel, which is researched in the field of converter systems and is provided with a bottom blowing system for argon blowing control. Therefore, the control means of nitrogen content in the links of the direct current arc furnace is less, and is generally carried out by foam slag making submerged arc and raw material structure control, and mainly, the increase of the nitrogen content of molten steel is controlled by refining denitrification after the steel tapping of the arc furnace and the protection technical measures of each link, so that the research on how to reduce the end point nitrogen content of the initial arc furnace needs to be increased. Disclosure of Invention The invention aims to provide a method for smelting end point nitrogen of a direct current arc furnace, which can effectively control nitrogen. The technical scheme includes that a side argon blowing device is arranged on a furnace wall of a molten pool of the direct current arc furnace, smelting comprises the processes of scrap steel batching, blanking power transmission, slag making dephosphorization and oxygen blowing and carbon drawing, low-power transmission is carried out after oxygen blowing and carbon drawing operation, the side argon blowing device is started to carry out argon blowing stirring, and tapping is carried out after tapping temperature requirements are met.