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CN-121975992-A - Converter slagging process with large scrap ratio and application thereof

CN121975992ACN 121975992 ACN121975992 ACN 121975992ACN-121975992-A

Abstract

The invention discloses a converter slagging process with a large scrap ratio and application thereof. The process is suitable for converter steelmaking with the scrap steel ratio of 15-30%, and sequentially comprises the following steps of S1, preprocessing, namely pouring out slag after slag splashing and furnace protection are finished, adding a solid carbonaceous heat generating agent in linear proportion to the scrap steel ratio into an empty furnace, S2, charging, namely, sequentially charging scrap steel and molten iron above the heat generating agent, S3, controlling blowing and slagging, namely, starting oxygen blowing smelting, controlling the position of an oxygen lance and the flow of oxygen according to a smelting model at different stages of total oxygen supply, and adding a slagging flux in at least four batches, and S4, performing end-point operation. According to the invention, through optimizing the adding position and time of the heating agent, the flux batch adding strategy and the cooperation with the oxygen supply system, the problems of insufficient heat, difficult slag formation, serious furnace mouth slag formation and the like in converter smelting under the condition of large scrap ratio are effectively solved, the stable and precise control of the blowing process and the terminal point are realized, and the utilization efficiency of scrap resources is improved.

Inventors

  • DAI ZHICAI
  • WANG SHIHUA
  • XIAO CHENGPENG
  • JIN XIANWEN
  • LONG XIONGFENG
  • LI ZHENGWU
  • QI JIANGHUA
  • XIANG WANG
  • LIANG LIANG
  • YIN ZHENZHI
  • XIE SENLIN
  • DENG ZHIXUN
  • LIU PENG
  • Tan Dajin

Assignees

  • 湖南华菱涟源钢铁有限公司

Dates

Publication Date
20260505
Application Date
20251220

Claims (10)

  1. 1. A large scrap ratio converter slag making process suitable for converter steelmaking with a scrap ratio of 15% to 30%, comprising the sequential steps of: S1, preprocessing, namely pouring out all residual slag in a furnace after slag splashing in the previous smelting period, and then adding a preset amount of solid carbonaceous heat generator into an empty furnace; s2, charging, namely charging scrap steel and molten iron above the solid carbonaceous exothermic agent; S3, blowing and slag forming control, namely starting oxygen blowing smelting, controlling the gun position and the oxygen flow of an oxygen gun at different stages of total oxygen supply according to a preset smelting model, and adding slag forming flux into the furnace in four batches; S4, performing end operation, namely tapping and alloying after the end of converting is reached.
  2. 2. The large scrap ratio converter slag forming process of claim 1 wherein in step S1, the solid carbonaceous heat generator comprises pyro-butyl; the addition amount of the solid carbonaceous heat generator and the scrap steel ratio satisfy the following linear relation that when R=15%, W=0, when R=30%, W=1000, when 15% < R <30%, W is calculated and determined according to the linear proportion between the two points, wherein W is the solid carbonaceous heat generator and is in kg/110t (scrap steel+molten iron), and R is the scrap steel ratio and is in%.
  3. 3. The large scrap ratio converter slag forming process according to claim 1, wherein the slag forming flux comprises a calcium-containing flux and a calcium-magnesium composite flux, and the mass ratio of the calcium-containing flux to the calcium-magnesium composite flux is 1-2:1; In step S3, the slag-forming flux is added in four batches, and the adding timing and ratio of each batch are as follows: The first batch is that after normal blowing ignition, a part accounting for one third of the total addition amount of the calcium-containing flux and the calcium-magnesium composite flux is added; The second batch, when the total oxygen supply reaches 25%, adding a part which accounts for one third of the total addition amount of the calcium-containing flux and the calcium-magnesium composite flux, and when the calcium-magnesium composite flux is added in the batch, adding the calcium-containing flux after the calcium-magnesium composite flux; The third batch, when the total oxygen supply reaches 40%, adding the rest calcium-magnesium composite flux; and in the fourth batch, when the total oxygen supply reaches 60%, adding the residual calcium-containing flux.
  4. 4. The slag forming process of a converter with large scrap ratio according to claim 3, wherein in the step S3, the gun position and the oxygen flow rate of the control oxygen gun are specifically: controlling the oxygen flow to be a first flow in the stage of 0 to 15 percent of total oxygen supply, and gradually reducing the gun position from the initial height; After the total oxygen supply exceeds 15%, raising the oxygen flow to a second flow until the blowing end point, and lowering the gun position to the end point gun height at the end point, wherein the second flow is higher than the first flow; the first flow rate is 19000-21000 M3/h, and the second flow rate is 24000-26000 M3/h.
  5. 5. The slag forming process of a large scrap ratio converter according to claim 4, wherein the initial height is 1.6-1.7m, and the gun position is reduced to 1.4-1.6m when the total oxygen supply is 10% -15%; in the case that the total oxygen supply is more than 15 percent and less than 60 percent, the oxygen supply gun position is 1.4-1.5m; under the condition that the total oxygen supply is 60% -92%, the gun position is controlled to be 1.6-1.8m; under the condition that the total oxygen supply is more than 92% and less than or equal to 100%, the gun position is controlled to be the final pressure gun height, and the final pressure gun height is 1.0-1.2m.
  6. 6. A large scrap ratio converter slag forming process according to claim 3, wherein the mass ratio of the calcium-containing flux to the calcium-magnesium composite flux is 1.55-1.7:1.
  7. 7. The slag forming process of the converter with large scrap ratio according to claim 6, wherein the calcium-containing flux comprises lime, the calcium-magnesium composite flux comprises light burned dolomite, the CaO content of the lime is more than or equal to 90%, the CaO content of the light burned dolomite is 40-60%, the MgO is 30-40%, and the balance is unavoidable impurities.
  8. 8. The large scrap ratio converter slag forming process of claim 1, further comprising adding ferrosilicon to the converter for auxiliary heating according to a thermal balance model calculation after the loading of step S2 and before the converting of step S3.
  9. 9. The large scrap ratio converter slag forming process of any one of claims 1 to 8, wherein in step S4, the terminal carbon content of the blowing terminal molten steel is 0.04% to 0.06%, the terminal oxygen content is 400 ppm to 500ppm, the terminal temperature is 1610 ℃ to 1625 ℃, and the terminal phosphorus content is 0.02% or less.
  10. 10. Use of a large scrap ratio converter slag forming process according to any one of claims 1 to 9 in converter smelting.

Description

Converter slagging process with large scrap ratio and application thereof Technical Field The invention belongs to the technical field of steel smelting, and particularly relates to a converter slag-forming process with a large scrap ratio and application thereof. Background With the continuous increase of steel accumulation in China, social steel scrap resources are increasingly abundant. Industry prediction shows that the total amount of domestic available scrap steel resources reaches 2.4-2.7 hundred million tons in 2025 and is further increased to 2.9-3.6 hundred million tons in 2030. The recycling of the scrap steel resources has important strategic significance for reducing the dependency on imported iron ores and guaranteeing the national ferrite resource safety, and the economic and environmental benefits are also more remarkable. At present, the steel production in China still takes long-flow converter steelmaking as a mainstream process. In the process, the heat required by the smelting process is mainly provided by physical heat and chemical heat of molten iron. Therefore, the conventional converter operation generally requires a high molten iron ratio, which is generally maintained at 85% or more, i.e., the scrap addition ratio is limited to 15% or less. When trying to improve the scrap steel ratio (for example, the scrap steel ratio is increased to 15% -30%), the material and heat balance of the whole smelting system are changed fundamentally, so that a series of serious technical challenges are caused, and the technical challenges mainly comprise serious heat shortage, low melting bath temperature and deterioration of smelting thermodynamic conditions, difficult slag formation, difficult quick melting of slag forming flux under low-temperature conditions, high slag viscosity and poor fluidity, influence on metallurgical reaction efficiency, and serious furnace mouth slagging, and unreasonable slag formation and oxygen supply system easily cause the flux to be splashed to a furnace mouth by airflow and solidify, and seriously influence equipment operation and maintenance. The slag and dephosphorization task is difficult due to the fact that the ratio of molten iron is reduced, the carbon content carried by the molten iron is reduced, the total oxygen supply time is shortened, the reaction time of slag steel is shortened, and the slag and dephosphorization task becomes difficult under the low-temperature and low-carbon condition in the smelting process. If the iron oxide material is used for slagging, the FeO reaction process is an endothermic reaction, so that the heat reduction in the smelting process is more insufficient, and the difficulties of molten steel peroxidation and furnace lining maintenance are aggravated. The adding of fluorite slag increases the peroxidation phenomenon of large scrap steel compared with molten steel, so that the corrosion of furnace conditions is increased, and fluorite is a scarce resource, has high price and is not suitable for large-scale use. The conventional slag melting material is unsuitable for slag melting under the condition of a large scrap steel process, and the slag melting process is the core of converter smelting. However, when the conventional slag-making process which is applicable to high molten iron ratio is used for coping with the condition of large scrap ratio, the core contradiction of insufficient heat, slag formation at the furnace mouth and slag formation difficulty cannot be solved, and the efficient and large-scale utilization of scrap steel resources is severely restricted. Therefore, there is an urgent need to develop a new converter slag-forming process suitable for conditions of large scrap ratio (15% -30%). Disclosure of Invention Aiming at solving the technical problems that the prior art cannot solve the core contradiction of insufficient heat, slag formation at the furnace mouth and difficult slag formation under the condition of large scrap ratio, the invention provides a slag-making process of a converter with large scrap ratio, which is suitable for converter steelmaking with scrap ratio of 15-30 percent and comprises the following sequential steps: S1, preprocessing, namely pouring out all residual slag in a furnace after slag splashing in the previous smelting period, and then adding a preset amount of solid carbonaceous heat generator into an empty furnace; s2, charging, namely charging scrap steel and molten iron above the solid carbonaceous exothermic agent; S3, blowing and slag forming control, namely starting oxygen blowing smelting, controlling the gun position and the oxygen flow of an oxygen gun at different stages of total oxygen supply according to a preset smelting model, and adding slag forming flux into the furnace in four batches; S4, performing end operation, namely tapping and alloying after the end of converting is reached. Further, in the step S1, the solid carbonaceous heat generator comprises self-produ