Control method for reducing steel material consumption of converter by using refined steel powder

Abstract

The invention relates to a control method for reducing converter steel material consumption by using refined steel powder, which is characterized in that the refined steel powder obtained by slag treatment of converter slag is utilized, and the consumption of converter steel materials is effectively reduced. The refined steel powder has the specific particle size of 1-5 mm and strict component requirements of 55%-65% of TFe, 5%-6% of SiO2, 14%-16% of CaO, 4%-5% of MgO and Slt. 0.03%). In the smelting process of the converter, the stability and high efficiency of the smelting process are ensured by accurately controlling the key steps of raw material preparation, scrap steel adding and distribution, oxygen pressure and flow, lance position adjustment, auxiliary material types, adding time and the like. Especially, due to the uniform distribution of the scrap steel and the effective utilization of the refined steel powder, the splashing phenomenon during iron mixing is avoided. And the smelting final temperature and components are strictly controlled, so that the quality of molten steel is ensured. The method not only improves the production efficiency of converter steelmaking, but also remarkably reduces the consumption of steel and iron materials, and has remarkable economic benefits and environmental friendliness.

Description

Technical Field

[0001] The invention belongs to the technical field of steel smelting, and in particular relates to a control method for reducing the consumption of converter steel materials by utilizing refined steel powder. Background Art

[0002] In the steel smelting industry, converter steelmaking is one of the mainstream processes, and its production cost and efficiency are directly related to the economic benefits and market competitiveness of steel companies. Traditionally, converter steelmaking is highly dependent on scrap steel as one of the raw materials to adjust the charge structure and optimize the smelting process. However, in recent years, the price of scrap steel has continued to rise, which has gradually weakened the marginal benefit of scrap steel as a steelmaking raw material, and steel companies are facing the pressure of rising costs. Therefore, finding new steelmaking raw materials to replace or supplement scrap steel has become the key to reducing production costs and improving competitiveness.

[0003] As a by-product of the steelmaking process, the potential value of converter slag has not been fully explored for a long time. After the slag is processed by magnetic separation, rod grinding and other processes, iron-containing substances of different particle sizes can be separated. Among them, the larger screened material is called fine steel grains, which have a high iron content and good magnetic properties; while the smaller screened material forms high-grade fine steel powder, which is also rich in iron. These slag by-products, especially fine steel powder, are easily sucked away by the dust removal system when they are directly added from the converter high-level silo due to their fine particle size, resulting in resource waste and environmental pollution.

[0004] At present, some steel mills choose to export refined steel grains and refined steel powder to professional processing plants, which process them into iron-containing pressed cakes and then repurchase them as scrap steel. This practice not only increases intermediate links and costs, but also fails to effectively utilize the steel mills' own resources, reducing resource utilization efficiency.

[0005] In view of the above situation, the present invention proposes an innovative converter steelmaking method, that is, using the refined steel powder produced by the steelmaking plant as a substitute or supplement for scrap steel, and directly adding it into the converter for smelting. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a control method for reducing the consumption of converter steel material by using refined steel powder. The method aims to reduce the amount of scrap steel added by effectively utilizing refined steel powder, thereby reducing the smelting cost; at the same time, the addition of refined steel powder can also adjust the furnace temperature and optimize the smelting process, further reducing the difficulty of operation, and increasing steel production and economic benefits. In addition, the implementation of this method can also help reduce resource waste and environmental pollution, and promote the sustainable development of steel enterprises.

[0007] The present invention is achieved by a control method for reducing the consumption of converter steel material by using refined steel powder, characterized in that the refined steel powder is a sieve undersize with a particle size of 1-5 mm obtained after slag treatment of converter slag, and the composition of the refined steel powder meets the following requirements: TFe content is 55-65%, SiO2 content is 5-6%, CaO content is 14-16%, MgO content is 4-5%, and S content is less than 0.03%; the method specifically comprises the following steps:

[0008] Prepare raw materials, wherein the molten iron conditions are: weight 110t, temperature 1350-1400℃, composition includes C: 4.4-4.8%, Si: 0.20-0.35%, Mn: 0.25-0.35%, P: 0.100-0.140%, S less than 0.025%; scrap steel includes 3-5t of washed bean briquettes, 2-4t of iron pin briquettes, 6-8t of steel bar briquettes and 3-4t of refined steel powder;

[0009] During the converter smelting process, the scrap steel in the scrap steel bucket is first added to the converter, and then the converter is repeatedly shaken to a tilting angle of -60° and 110° to ensure that the scrap steel is evenly distributed and to prevent the fine steel powder from agglomerating to avoid splashing when adding iron;

[0010] Control the oxygen pressure at the early stage of converter smelting to 0.80MPa and the oxygen flow rate to 24000-26000m 3 / h, in the middle and late stages of smelting, the oxygen pressure was adjusted to 0.85MPa to even out the temperature and composition of the molten steel; the gun position adopted the "low-high-low" mode, with the gun position at about 1600mm in the early stage, increased to 1700mm in the middle stage, and reduced to 1300mm in the late stage;

[0011] Add auxiliary materials in the early stage of converter smelting, including 0.8-1 ton of lime, 1-1.5 tons of limestone, 1-1.5 tons of raw dolomite, and 1.5-2 tons of sintered ore, and add all of the above auxiliary materials within 60 seconds after the start of blowing. The remaining auxiliary materials are added after the carbon-oxygen reaction starts. The amount of auxiliary materials added in each batch is 200-400kg. All auxiliary materials are aggregated 3 minutes before the end of blowing;

[0012] The smelting endpoint temperature is controlled in the range of 1640-1660°C, and the composition control range is C: ≥0.08%, P: ≤0.025%.

[0013] The invention has the advantages and technical effects: through the implementation of the method of the invention, the use of refined steel powder, a byproduct of converter steel slag, during converter smelting can be achieved, which can not only reduce the temperature of molten steel in the furnace, but also avoid the high temperature of molten steel caused by high iron consumption, high physical heat and chemical heat of molten iron. At the same time, due to the high iron content in refined steel powder, the use of refined steel powder in the converter steelmaking process can also increase the output of converter steel, thereby reducing the consumption of converter steel. The use of refined steel powder in converter smelting can reduce the consumption of converter steel by about 2.5kg / ton of steel; after adding refined steel powder, the amount of some auxiliary materials added can be reduced, thereby reducing the consumption of converter slag, and the slag consumption is reduced by about 10kg / t. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0015] A control method for reducing the consumption of converter steel materials by using refined steel powder aims to effectively reduce the consumption of converter steel materials by using refined steel powder obtained by slag treatment of converter slag. As the core raw material of this method, the refined steel powder has a particle size controlled at 1-5mm, and its composition strictly meets the requirements of TFe content of 55-65%, SiO2 content of 5-6%, CaO content of 14-16%, MgO content of 4-5%, and S content of less than 0.03%, ensuring its efficient use in converter smelting. Step 1: Raw material preparation and technical effect Hot metal conditions: Select hot metal with a weight of 110t, a temperature of 1350-1400℃, and a composition that meets a specific range (C: 4.4-4.8%, Si: 0.20-0.35%, Mn: 0.25-0.35%, P: 0.100-0.140%, S less than 0.025%) as raw material, which provides a stable heat source and chemical composition basis for converter smelting. Scrap steel combination: 3-5t of washed bean briquettes, 2-4t of iron pin cakes, 6-8t of steel bar briquettes and 3-4t of refined steel powder. This not only ensures the diversity of scrap steel, but also effectively reduces the amount of traditional scrap steel through the addition of refined steel powder, thereby directly reducing the consumption of steel materials. Technical effect: The high iron content and suitable particle size distribution of refined steel powder enable it to melt quickly in the converter and participate in the smelting reaction, improving the smelting efficiency and reducing the cost of scrap steel, thereby significantly reducing the consumption of converter steel materials.

[0016] Step 2: Operation control and technical effects during converter smelting Scrap steel addition and converter shaking: By repeatedly shaking the converter to a tilting angle of -60° and 110° respectively, the scrap steel (including refined steel powder) is ensured to be evenly distributed in the converter, avoiding splashing during iron addition caused by the aggregation of refined steel powder, thereby improving the safety and stability of the smelting process. Technical effect: Uniform distribution of scrap steel contributes to the uniform transfer of heat in the converter and the full progress of chemical reactions, further improving smelting efficiency, while reducing iron loss and energy consumption caused by splashing. Oxygen pressure and flow control: In the early stage of smelting, the oxygen pressure is controlled to be 0.80MPa and the flow rate is 24000-26000m 3 / h, and adjust the oxygen pressure to 0.85MPa in the middle and late stages to make the temperature and composition of the molten steel uniform. The gun position adopts the "low-high-low" mode and is flexibly adjusted according to the smelting stage. Technical effect: Reasonable oxygen pressure and flow control, as well as flexible adjustment of the gun position, help optimize the oxidation reaction in the converter, improve the utilization rate of oxygen, and ensure the uniformity of the temperature and composition of the molten steel, laying a good foundation for the subsequent smelting process.

[0017] Step 3: Addition of auxiliary materials and their technical effects Types and amounts of auxiliary materials: Add 0.8-1 ton of lime, 1-1.5 tons of limestone, 1-1.5 tons of raw dolomite, and 1.5-2 tons of sintered ore in the early stage of converter smelting, and add all of the above auxiliary materials within 60 seconds after the start of blowing (the remaining auxiliary materials are added after the start of carbon-oxygen reaction). The amount of auxiliary materials added to each batch is 200-400kg. Technical effect: Timely and appropriate addition of auxiliary materials helps to adjust the chemical composition of molten steel and the properties of slag, and improve the controllability of the smelting process. At the same time, the rapid addition of auxiliary materials reduces heat loss and improves smelting efficiency. Material setting time control: The material is set 3 minutes before the end of blowing to ensure that the auxiliary materials are fully reacted and integrated into the molten steel. Technical effect: Accurate material setting time control avoids waste of auxiliary materials and excessive oxidation of molten steel, and ensures the quality of molten steel and the stability of the smelting process.

[0018] Step 4: Smelting endpoint control and its technical effect Temperature and composition control: Control the smelting endpoint temperature range to 1640-1660℃, and the composition control range to C: ≥0.08%, P: ≤0.025%. Technical effect: Strict endpoint temperature and composition control ensure that the quality and performance of the molten steel meet the needs of subsequent processing and use. At the same time, through precise control, the scrap rate caused by unqualified temperature or composition is reduced, and the consumption of steel materials is further reduced. In summary, the present invention achieves the goal of reducing the consumption of converter steel materials by using refined steel powder by precisely controlling key links such as raw material preparation, operation during converter smelting, addition of auxiliary materials, and smelting endpoint control. This method not only improves smelting efficiency and reduces production costs, but also provides strong technical support for the sustainable development of steel enterprises.

[0019] Application Example This example describes in detail the specific application process of the control method for reducing the consumption of converter steel material by using refined steel powder, aiming to achieve high-efficiency and low-consumption converter steelmaking production by accurately controlling the raw material composition, smelting parameters and the amount of auxiliary materials added. 1. Requirements for the composition of refined steel powder The refined steel powder used in this example is the sieve undersize with a particle size of 1-5 mm obtained after slag treatment of converter slag, and its composition strictly meets the following requirements: TFe content is 55-65% (58% in this example), SiO2 content is 5-6% (5.5% in this example), CaO content is 14-16% (15% in this example), MgO content is 4-5% (4.5% in this example), and S content is less than 0.03% (0.028% in this example). 2. Requirements for converter smelting control (1) Molten iron conditions Molten iron weight: 110t (meets the design requirements). Molten iron temperature: 1385℃ (within the appropriate range of 1350-1400℃). Molten iron composition: C: 4.51%, Si: 0.26%, Mn: 0.30%, P: 0.122%, S: 0.023% (all meet the requirements of molten iron composition). (2) Scrap steel added to the ladle Scrap steel type: steel bar briquettes. Added weight: 5.3t (added as additional scrap steel in the ladle). (3) Scrap steel bucket plus scrap steel and fine steel powder washed beans briquettes: 4.1t. Iron pin cakes: 3.5t. Steel bar briquettes: 7.4t. Fine steel powder: 3.2t (meets the addition requirement of 3-4t). (4) Auxiliary materials added to the high-level silo Types and amounts of auxiliary materials: 2.1 t of lime (of which 0.9 t was added in the early stage, which is within the appropriate range of 0.8-1 t. ​​The actual amount of lime added is adjusted according to the furnace conditions. The amount of lime added in the middle and late stages is controlled according to the amount of auxiliary materials added per batch of 200-400 kg), 2.3 t of raw dolomite (of which 1.2 t was added in the early stage, which is within the appropriate range of 1-1.5 t. The actual amount of raw dolomite added is adjusted according to the actual smelting conditions. The amount of raw dolomite added in the middle and late stages is controlled at 200-400kg per batch of auxiliary materials), limestone 1.2t (in line with the requirement of 1-1.5 tons, but adjusted according to the furnace conditions), sintered ore 2.4t (of which, the amount added in the early stage is 1.7 tons, in line with the requirement of 1.5-2 tons); and all the above auxiliary materials are added within 60 seconds after the start of blowing. The remaining auxiliary materials except the above are added after the carbon-oxygen reaction starts, and the amount of auxiliary materials added in each batch is 200-400kg. (5) Oxygen pressure and flow in the early stage of converter smelting Oxygen pressure: 0.80MPa (in line with the early control requirements). Oxygen flow: 25500m 3 / h(24000-26000m 3 / h within the appropriate range). (6) End point control of molten steel: PQ355B (determined according to customer needs). End point temperature: 1648℃ (within the appropriate range of 1640-1660℃). End point composition: C: 0.08%, Mn: 0.14%, P: 0.022%, S: 0.020% (all meet the composition control requirements). Steel material consumption: 1067kg / ton steel.

[0020] This embodiment successfully achieves the goal of reducing converter steel consumption by using fine steel powder by strictly controlling the composition of fine steel powder, molten iron conditions, the amount of scrap steel and auxiliary materials added, and key parameters such as oxygen pressure and flow rate during the smelting process. At the same time, by accurately controlling the terminal temperature and composition of molten steel, the quality and performance of steel products are guaranteed, providing strong support for the sustainable development of steel enterprises.

[0021] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A control method for reducing the consumption of converter steel material by using refined steel powder, characterized in that: The refined steel powder is a sieve undersize with a particle size of 1-5 mm obtained by slag treatment of converter slag, and the composition of the refined steel powder meets the following requirements: TFe content is 55-65%, SiO2 content is 5-6%, CaO content is 14-16%, MgO content is 4-5%, and S content is less than 0.03%. The method specifically comprises the following steps: Prepare raw materials, wherein the molten iron conditions are: weight 110t, temperature 1350-1400℃, composition includes C: 4.4-4.8%, Si: 0.20-0.35%, Mn: 0.25-0.35%, P: 0.100-0.140%, S less than 0.025%; scrap steel includes 3-5t of washed bean briquettes, 2-4t of iron pin briquettes, 6-8t of steel bar briquettes and 3-4t of refined steel powder; During the converter smelting process, the scrap steel in the scrap steel bucket is first added to the converter, and then the converter is repeatedly shaken to a tilting angle of -60° and 110° to ensure that the scrap steel is evenly distributed and to prevent the fine steel powder from agglomerating to avoid splashing when adding iron; Control the oxygen pressure at the early stage of converter smelting to 0.80MPa and the oxygen flow rate to 24000-26000m 3 / h, in the middle and late stages of smelting, the oxygen pressure was adjusted to 0.85MPa to even out the temperature and composition of the molten steel; the gun position adopted the "low-high-low" mode, with the gun position at about 1600mm in the early stage, increased to 1700mm in the middle stage, and reduced to 1300mm in the late stage; Add auxiliary materials in the early stage of converter smelting, including 0.8-1 ton of lime, 1-1.5 tons of limestone, 1-1.5 tons of raw dolomite, and 1.5-2 tons of sintered ore, and add all of the above auxiliary materials within 60 seconds after the start of blowing. The remaining auxiliary materials are added after the carbon-oxygen reaction starts. The amount of auxiliary materials added in each batch is 200-400kg. All auxiliary materials are aggregated 3 minutes before the end of blowing; The smelting endpoint temperature is controlled in the range of 1640-1660°C, and the composition control range is C: ≥0.08%, P: ≤0.025%.