A low-ash-consumption converter smelting method

Abstract

The application discloses a low-ash-consumption converter smelting method, adopts single-slag smelting, controls the converter scrap steel ratio in 8% to 26%, controls the top blowing oxygen supply flow in 3.0 to 4.0 Nm 3 / (min·t), controls the bottom blowing argon flow in 0.03 to 0.10 Nm 3 / (min·t); the smelting process is improved by the cooperation of the gun position and the charging; the solid waste slag is added in the converter blowing process, the content of CaO in the slag is controlled in 45% to 55%, and the content of MgO is controlled in 5.5% to 7.5%; meanwhile, the dust removal pressure ball is added to improve the activity of FeO in the slag, and the terminal carbon content of the converter is controlled to be less than or equal to 0.05%. By adding the solid waste slag in the smelting process, the slag needed to oxidize a large amount of iron elements to generate FeO is reduced, so that the total iron content of the slag is reduced; by adding the synthetic slag, the liquidity of the slag is ensured, and the carbon-oxygen reaction is promoted; the total iron content of the low-carbon steel converter terminal slag is stably controlled to be less than 14.5%, the metal yield is provided; the lime addition amount can be reduced, the lime addition amount is controlled to be less than or equal to 10 kg / t, and the cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of converter steelmaking technology, and particularly relates to a low-ash-consumption converter smelting method. Background Technology

[0002] The converter steelmaking process is essentially an oxidation process to remove impurities. Oxygen is blown from the top of the oxygen lance to oxidize elements such as C, Si, Mn, and P in the molten steel, forming gases or oxides that enter the slag for removal. To remove these impurities, a large amount of lime is added. Simultaneously, a large amount of iron in the molten pool needs to be oxidized to melt the lime, resulting in iron loss, especially in the smelting of low-carbon steel. Because the carbon content of the molten steel at the end of the process is low, the oxidizing properties of the steel are enhanced, leading to more significant iron loss. To reduce the oxidation of large amounts of iron in the converter, less lime needs to be added to reduce the total iron content of the slag at the end. High-carbon tapping is commonly used to reduce the iron oxide content in the slag and thus reduce iron loss. However, for low-carbon steel grades, reducing slag oxidizing properties through high-carbon tapping is difficult to achieve.

[0003] A Chinese patent with publication number CN116622939A discloses a smelting method for reducing converter steelmaking material consumption. This method, through the coordination of oxygen supply and charging, adds a calcium ferrite dephosphorizing agent containing CaO·SiO2 and a calcium ferrite slagging agent based on the silicon content of the molten iron. This improves the slagging effect and enhances the slag dephosphorization capacity, achieving low-slag smelting in the converter. Simultaneously, by controlling the final slag basicity within the range of 2.5 to 3.0, the final carbon content is ensured to be greater than 0.05%, thereby increasing metal recovery. This method primarily achieves low-slag smelting by improving dephosphorization capacity and reduces the total iron content of the slag through high-carbon tapping at the final stage, ultimately increasing metal recovery.

[0004] However, the above methods are difficult to apply to steel grades requiring a final carbon content of ≤0.05% in the converter, making it difficult to control the lime addition below 10 kg / t, resulting in high steelmaking costs. Therefore, the technical problem this invention aims to solve is how to design a technology that can reduce lime consumption during converter steelmaking to lower steelmaking costs. Summary of the Invention

[0005] The purpose of this invention is to provide a low-ash-consumption converter smelting method that can reduce the amount of lime consumed during converter steelmaking and thus lower steelmaking costs.

[0006] To solve the above-mentioned technical problems, the present invention is mainly achieved through the following technical solutions: In the first aspect, the present invention provides a low-ash-consumption converter smelting method, employing a single-slag method, controlling the converter scrap ratio at 8%~26%, and controlling the top-blown oxygen supply flow rate at 3.0~4.0 Nm³. 3 / (min·t), the bottom-blown argon flow rate is controlled at 0.03~0.10 Nm³. 3 / (min·t); The smelting process improves the slag-forming effect by coordinating the lance position and the feeding. Solid waste slag is added during the converter blowing process to control the CaO content in the slag to be 45%~55% and the MgO content to be 5.5%~7.5% respectively; at the same time, dust removal briquettes are added during the process to increase the activity of FeO in the slag and control the carbon content at the converter endpoint to be ≤0.05%.

[0007] This invention reduces the need for slag formation to oxidize large amounts of iron to generate FeO by adding solid waste slag during the smelting process, thereby lowering the total iron content of the slag. The addition of synthetic slag ensures slag fluidity and promotes the carbon-oxygen reaction. This stabilizes the total iron content in the final slag of low-carbon steel converters below 14.5%, improving metal yield. The solid waste slag can replace some lime and magnesium oxide, reducing their consumption. The lime addition is controlled to within 10 kg / t, while fully utilizing the solid waste slag produced in steelmaking, which helps reduce environmental pollution and lower costs. Controlling the CaO content in the slag to 45%–55% facilitates phosphorus removal. The converter lining material is mainly magnesia-carbon bricks; controlling the MgO content to 5.5%–7.5% helps protect the converter's service life. Adding dust removal briquettes increases the activity of FeO in the slag.

[0008] In some embodiments of this application, the smelting process includes, through the coordination of the lance position and the feeding, the following: When the oxygen supply reaches 15% to 20% of the total amount of oxygen blowing, add 80% to 100% of the total amount of solid waste residue at one time, add all the lightly calcined dolomite, and add 5 to 15 kg / t of dust removal briquettes to help with slag formation; When the oxygen supply reaches 50% to 70% of the total oxygen supply, add 10 kg / t of lime and the remaining solid waste residue in small batches and multiple batches. When the oxygen supply reaches 70% to 80% of the total oxygen supply during blowing, dust removal briquettes are added to adjust the activity of FeO in the slag.

[0009] In this invention, the lightly calcined dolomite mainly consists of calcium oxide and magnesium oxide. By adding corresponding materials under different oxygen supply blowing conditions, it is beneficial to control the total iron content of the final slag.

[0010] In some embodiments of this application, the final slag composition of converter smelting, by mass percentage, includes: CaO: 40%~55%, SiO2: 18%~22%, MnO: 2%~4.5%, MgO: 6%~10%, P2O5: 2%~4%, Al2O3: 2%~6%, total iron: 8%~14.5%, and some unavoidable impurities.

[0011] In some embodiments of this application, the smelting process further includes, through the coordination of the lance position and the feeding, the following: From the start of oxygen blowing to 85% oxygen blowing, the oxygen lance position is controlled at 1.7~1.5m; from 85% oxygen blowing to the end of blowing, the oxygen lance position is controlled at 1.5~0.9m.

[0012] In this invention, the slag-forming effect and the reaction intensity of the molten pool can be adjusted by controlling the oxygen lance position. Improper oxygen lance position control in the converter can cause splashing, resulting in a high total iron content in the final slag and affecting the dephosphorization effect. If the oxygen lance position is too low, excessive stirring power accelerates the reaction, leading to splashing and affecting the dephosphorization effect. If the oxygen lance position is too high, insufficient stirring in the molten pool results in a slow chemical reaction rate, making slag formation difficult and reducing dephosphorization efficiency, and may also cause slag overflow. From the start of oxygen blowing to 85% oxygen blowing, the oxygen lance position is controlled at 1.7~1.5m, gradually decreasing in height. In the initial stage, soft blowing is formed, which is beneficial for melting the added materials. Simultaneously, the molten iron has a high carbon content, and bubbles are formed through the reaction of carbon and oxygen. In the later stage, from 85% oxygen blowing to the end of blowing, the oxygen lance position is controlled at 1.5~0.9m. The molten iron forms molten steel, the carbon content decreases, and splashing is avoided.

[0013] In some embodiments of this application, the bottom-blown argon gas comprises oxygen blowing from the start to 85% oxygen blowing, and the bottom-blown argon gas flow rate is 0.10~0.05 Nm³. 3 / (min·t); Oxygen blowing to 85% until the lance is lifted, bottom blowing argon flow rate is 0.05~0.10Nm 3 / (min·t). In this invention, in the early stage of the converter, the furnace temperature is not high and the carbon-oxygen reaction is weak. The bottom-blown argon flow rate should be large to make the stirring stronger and improve the dephosphorization rate. In the middle stage of the converter, the carbon-oxygen reaction is intense. The bottom-blown argon flow rate should be small to make the stirring slow, maintain deep dephosphorization, and suppress splashing. In the later stage of the converter, the carbon in the furnace is too low and the carbon-oxygen reaction is weakened. It is necessary to increase the bottom-blown gas flow rate again to strengthen the stirring in the furnace and ensure the uniformity of the composition in the furnace.

[0014] In some embodiments of this application, the timing of adding solid waste slag is as follows: when the silicon content of molten iron is ≤0.2%, all solid waste slag is added in the early stage, and 0~500kg of lime is added during the process; when the silicon content of molten iron is 0.2%~0.5%, 80%~100% of solid waste slag is added in the early stage, and 0~500kg of lime is added during the process; when the silicon content of molten iron is >0.5%, all solid waste slag is added in the early stage, and 800~1000kg of lime is added during the process.

[0015] In this invention, solid waste slag and lime are added in stages according to the silicon content of molten iron. When the silicon content of molten iron is ≤0.2%, the silicon content is low. All solid waste slag is added in the early stage, which can advance slag formation and utilize the residual heat of the waste slag, avoiding excessively low temperature and difficulty in slag formation in the early stage. 0~500kg of lime is added in the process to reduce the heat absorption of lime and prevent excessive temperature drop in the early stage. The heat brought by the waste slag is used to make up for the insufficient heat of low silicon molten steel. When the silicon content of molten iron is 0.2%~0.5%, the silicon content is moderate and the heat is sufficient. Adding 80%~100% solid waste slag in the early stage can ensure rapid slag removal in the early stage and avoid excessive instantaneous temperature drop and splashing caused by a large amount of waste slag at one time. Adding 0~500kg of lime in the process can make the silicon content low, the alkalinity easy to control, and avoid waste of lime. When the silicon content of molten iron is >0.5%, the silicon content is high and the oxidation of high silicon is violently exothermic. By adding all solid waste slag in the early stage, a large amount of heat can be absorbed, suppressing the temperature rise in the early stage and preventing splashing and over-oxidation. Adding 800~1000kg of lime in the process can ensure high alkalinity, stable dephosphorization throughout the process, and controllable final composition; otherwise, the slag will become acidic, dephosphorization will fail, and phosphorus reversion will be serious.

[0016] In some embodiments of this application, the solid waste residue comprises, by mass percentage: CaO: 40%~50%, SiO2: 10%~15%, Al2O3: 1.0%~5.0%, TFe: 8%~12%, and some unavoidable impurities.

[0017] In some embodiments of this application, the amount of dust collector briquettes added is 10~40 kg / t. In this invention, the dust collector briquettes are pellets made from dust collected by the primary flue gas dust removal system of the converter through a briquetting process. The dust collector briquettes contain 50%~60% iron oxide. By adding dust collector briquettes to molten iron, solid waste resource utilization, cost reduction and efficiency improvement can be achieved, which is beneficial to environmental protection.

[0018] Compared with the prior art, the advantages and positive effects of the present invention are as follows: by adding solid waste slag during the smelting process, the need for slag to oxidize a large amount of iron to generate FeO is reduced, thereby reducing the total iron content of the slag; by adding synthetic slag, the fluidity of the slag is ensured, and the carbon-oxygen reaction is promoted; the total iron content in the final slag of the low-carbon steel converter is stabilized below 14.5%, improving the metal yield; and the amount of lime added can be reduced, controlling the amount of lime added to within 10 kg / t, which is beneficial to reducing costs. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that in the description of this invention, terms such as "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating directional or positional relationships, are based on the directional or positional relationships shown in the specification. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0024] In the first aspect, embodiments of this disclosure provide a low-ash-consumption converter smelting method, employing a single-slag method, controlling the converter scrap ratio at 8%~26%, and controlling the top-blown oxygen supply flow rate at 3.0~4.0 Nm³. 3 / (min·t), the bottom-blown argon flow rate is controlled at 0.03~0.10 Nm³. 3 / (min·t); The smelting process improves the slag-forming effect by coordinating the lance position and the feeding. Solid waste slag is added during the converter blowing process to control the CaO content in the slag to be 45%~55% and the MgO content to be 5.5%~7.5% respectively; at the same time, dust removal briquettes are added during the process to increase the activity of FeO in the slag and control the carbon content at the converter endpoint to be ≤0.05%.

[0025] In some embodiments of this application, the smelting process includes, through the coordination of the lance position and the feeding, the following: When the oxygen supply reaches 15% to 20% of the total amount of oxygen blowing, add 80% to 100% of the total amount of solid waste residue at one time, add all the lightly calcined dolomite, and add 5 to 15 kg / t of dust removal briquettes to help with slag formation; When the oxygen supply reaches 50% to 70% of the total oxygen supply, add 10 kg / t of lime and the remaining solid waste residue in small batches and multiple batches. When the oxygen supply reaches 70% to 80% of the total oxygen supply during blowing, dust removal briquettes are added to adjust the activity of FeO in the slag.

[0026] In some embodiments of this application, the final slag composition of converter smelting, by mass percentage, includes: CaO: 40%~55%, SiO2: 18%~22%, MnO: 2%~4.5%, MgO: 6%~10%, P2O5: 2%~4%, Al2O3: 2%~6%, total iron: 8%~14.5%, and some unavoidable impurities.

[0027] In some embodiments of this application, the smelting process further includes, through the coordination of the lance position and the feeding, the following: From the start of oxygen blowing to 85% oxygen blowing, the oxygen lance position is controlled at 1.7~1.5m; from 85% oxygen blowing to the end of blowing, the oxygen lance position is controlled at 1.5~0.9m.

[0028] In some embodiments of this application, the bottom-blown argon gas comprises oxygen blowing from the start to 85% oxygen blowing, and the bottom-blown argon gas flow rate is 0.10~0.05 Nm³. 3 / (min·t); Oxygen blowing to 85% until the lance is lifted, bottom blowing argon flow rate is 0.05~0.10Nm 3 / (min·t).

[0029] In some embodiments of this application, the timing of adding solid waste slag is as follows: when the silicon content of molten iron is ≤0.2%, all solid waste slag is added in the early stage, and 0~500kg of lime is added during the process; when the silicon content of molten iron is 0.2%~0.5%, 80%~100% of solid waste slag is added in the early stage, and 0~500kg of lime is added during the process; when the silicon content of molten iron is >0.5%, all solid waste slag is added in the early stage, and 800~1000kg of lime is added during the process.

[0030] In some embodiments of this application, the solid waste residue comprises, by mass percentage: CaO: 40%~50%, SiO2: 10%~15%, Al2O3: 1.0%~5.0%, TFe: 8%~12%, and some unavoidable impurities.

[0031] In some embodiments of this application, the amount of dust removal briquettes added is 10~40 kg / t.

[0032] Example 1: When smelting low-carbon steel in a 100t converter, the raw materials used include 115t of molten iron, molten iron temperature of 1380℃, molten iron silicon content of 0.31%, and 10t of scrap steel.

[0033] During the smelting process, a constant flow operation mode is adopted, and the oxygen supply flow rate is set to 23000 Nm³. 3 / h. The top-blown oxygen supply system is as follows: during the oxygen supply period of 0-85%, the smelting lance position is maintained at 1.7-1.5m; when the oxygen supply reaches 85% or higher, the smelting lance position is gradually reduced to 0.9m. Regarding the bottom-blown argon system: when the oxygen supply is 0-85%, the bottom-blowing flow rate is 345 Nm³. 3 / h; when the oxygen supply reaches 85% or above, the bottom blowing flow rate is increased to 600 Nm³. 3 / h.

[0034] The feeding system is as follows: When the oxygen supply reaches 15%~20%, add 3000 kg of solid waste residue, whose composition includes CaO: 50%, SiO2: 15%, Al2O3: 4.2%, MgO: 7.2%, TFe: 11.3%, and some unavoidable impurities. The particle size range is 10~50 mm. Add 1500 kg of lightly calcined dolomite and 1500 kg of iron oxides. When the oxygen supply reaches 50%~70%, add 300 kg of lime at 50%, 55%, and 60% oxygen supply respectively, and add 300 kg and 350 kg of solid waste residue at 55% and 60% oxygen supply respectively. When the oxygen supply reaches 75%, add 200 kg of lime. After the oxygen supply reaches 75%, no more slag-forming materials are added.

[0035] The final slag composition of converter smelting includes: CaO: 50%, SiO2: 18%, MnO: 2%, MgO: 6%, P2O5: 4%, Al2O3: 2.8%, total iron: 13.5%, and some unavoidable impurities.

[0036] Using the above smelting method, the converter final temperature reached 1622℃, the final carbon content was 0.028%, the slag SiO2 content was 19.2%, the lime addition was 1100kg, and the final slag total iron content was 13.5%.

[0037] Example 2: Low-carbon steel was smelted in a 100t converter. The raw materials used included 123t of molten iron, 1350℃ of molten iron, 0.23% silicon content of molten iron, and 19t of scrap steel.

[0038] The smelting process adopts a constant flow operation mode, with the oxygen supply flow rate set at 26000 Nm³. 3 / h. The top-blown oxygen supply system is as follows: during the oxygen supply range of 0-85%, the smelting lance position is maintained at 1.7-1.5m; when the oxygen supply reaches 85% or higher, the smelting lance position is adjusted to 1.2m. The bottom-blown argon system is as follows: during the oxygen supply range of 0-85%, the bottom-blown flow rate is 300 Nm³. 3 / h; when the oxygen supply reaches 85% or above, the bottom blowing flow rate is increased to 560 Nm. 3 / h.

[0039] The specific feeding system is as follows: During the oxygen supply phase of 15%–20%, 3500 kg of solid waste slag is added, comprising CaO: 41.9%, SiO2: 15.0%, Al2O3: 5%, MgO: 6.7%, TFe: 12%, and some unavoidable impurities. The particle size range is 10–50 mm, and 1000 kg of lightly calcined dolomite is added. During the oxygen supply phase of 50%–70%, 200 kg of dolomite ash is added at 50%, 55%, and 60% oxygen supply, and 200 kg and 300 kg of iron oxides are added at 55% and 60% oxygen supply, respectively. When the oxygen supply reaches 75%, 200 kg of dolomite is added. After the oxygen supply reaches 75%, no more slag-forming materials are added.

[0040] The slag composition analysis results at the end of converter smelting were as follows: CaO content 40%, SiO2 content 22%, MnO content 4.5%, MgO content 6.5%, P2O5 content 3.2%, Al2O3 content 2.6%, total iron content 14.0%, and some unavoidable impurities.

[0041] Using the above smelting method, the converter final temperature reached 1610℃, the final carbon content was 0.04%, the amount of lime added was 0kg, and the total iron content of the final slag was 14.2%.

[0042] Example 3: Low-carbon steel was smelted in a 100t converter. The raw materials used included 109t of molten iron, 1328℃ of molten iron, 0.18% silicon content of molten iron, and 15t of scrap steel.

[0043] The smelting process adopts a constant flow operation mode, with the oxygen supply flow rate set at 26160 Nm³. 3 / h. The top-blown oxygen supply system is as follows: during the oxygen supply range of 0-85%, the smelting lance position is maintained at 1.7-1.5m; when the oxygen supply reaches 85%, the smelting lance position is adjusted to 1.3m. The bottom-blown argon system is as follows: during the oxygen supply range of 0-85%, the bottom-blown flow rate is 196.2 Nm³. 3 / h; when the oxygen supply reaches 85% or above, the bottom blowing flow rate is increased to 600 Nm³. 3 / h.

[0044] The specific feeding procedure is as follows: During the oxygen supply phase of 15-20%, 2800 kg of solid waste slag is added, comprising CaO: 40%, SiO2: 10%, Al2O3: 1.0%, MgO: 7.2%, TFe: 8%, and some unavoidable impurities. The particle size range is 10-50 mm, and 1200 kg of lightly calcined dolomite is added. During the oxygen supply phase of 50-70%, 150 kg of dolomite is added at 52% and 55% oxygen supply, respectively, and 350 kg and 400 kg of dust removal balls are added at 55% and 60% oxygen supply, respectively. After the oxygen supply reaches 75%, no more slag-forming materials are added.

[0045] The composition analysis results of the slag at the end of the converter smelting were as follows: CaO: 55%, SiO2: 18%, MnO: 4.5%, MgO: 10%, P2O5: 2%, Al2O3: 2.0%, total iron content 8%, and some unavoidable impurities.

[0046] Using the above smelting method, the converter final temperature reached 1613℃, the final carbon content was 0.048%, the slag SiO2 content was 15.6%, the lime addition was 0kg, and the final slag total iron content was 14.3%.

[0047] Example 4: Low-carbon steel was smelted in a 100t converter. The raw materials used included 109t of molten iron, 1380℃ of molten iron, 0.20% silicon content of molten iron, and 38.3t of scrap steel.

[0048] The smelting process adopts a constant flow operation mode, with the oxygen supply flow rate set at 19620 Nm³. 3 / h. The top-blown oxygen supply system is as follows: during the oxygen supply range of 0-85%, the smelting lance position is maintained at 1.7-1.5m; when the oxygen supply reaches 85% or higher, the smelting lance position is adjusted to 1.2m. The bottom-blown argon system is as follows: during the oxygen supply range of 0-85%, the bottom-blown flow rate is 300 Nm³. 3 / h; when the oxygen supply reaches 85% or above, the bottom blowing flow rate is increased to 654 Nm. 3 / h.

[0049] The specific feeding procedure is as follows: During the oxygen supply phase of 15-20%, 2500 kg of solid waste slag is added, comprising CaO: 41.9%, SiO2: 15.0%, Al2O3: 5.0%, MgO: 6.7%, TFe: 10.7%, and some unavoidable impurities. The particle size range is 10-50 mm. 1500 kg of dust collector balls and 1000 kg of lightly calcined dolomite are also added. During the oxygen supply phase of 50-70%, 200 kg of limestone is added at 50%, 55%, and 60% oxygen supply, and 300 kg and 300 kg of dust collector balls are added at 55% and 60% oxygen supply, respectively. When the oxygen supply reaches 75%, 300 kg of dolomite and 300 kg of limestone are added. After the oxygen supply reaches 75%, no further slag-forming materials are added.

[0050] The composition analysis results of the slag at the end of the converter smelting were as follows: CaO: 40.8%, SiO2: 18%, MnO: 3.7%, MgO: 7.7%, P2O5: 2.3%, Al2O3: 6%, total iron: 14.5%, and some unavoidable impurities.

[0051] Using the above smelting method, the converter final temperature reached 1623℃, the final carbon content was 0.05%, the amount of lime added was 700kg, and the total iron content of the final slag was 13.8%.

[0052] Comparative Example 1: Low-carbon steel was smelted in a 100t converter. The raw materials used included 109t of molten iron, 1380℃ of molten iron, 0.26% silicon content of molten iron, and 15t of scrap steel.

[0053] The smelting process adopts a constant flow operation mode, with the oxygen supply flow rate set at 23000 Nm³. 3 / h. The top-blown oxygen supply system is as follows: during the oxygen supply range of 0-85%, the smelting lance position is maintained at 1.8-1.5m; when the oxygen supply reaches 85% or higher, the smelting lance position is adjusted to 1.4m. The bottom-blown argon system is as follows: during the oxygen supply range of 0-85%, the bottom-blown flow rate is 300 Nm³. 3 / h; when the oxygen supply reaches 85% or above, the bottom blowing flow rate is increased to 600 Nm³. 3 / h.

[0054] The specific feeding system is as follows: During the oxygen supply stage of 15%~20%, add 2500 kg of lime, 2000 kg of dust removal balls, and 1000 kg of lightly calcined dolomite; during the oxygen supply stage of 50%~70%, add 200 kg of lime at 50%, 55%, and 60% oxygen supply, and add 200 kg and 300 kg of dust removal balls at 55% and 60% oxygen supply, respectively; when the oxygen supply reaches 75%, add 300 kg of dolomite and 300 kg of limestone; after the oxygen supply reaches 75%, add 200 kg of lime.

[0055] The slag composition analysis results at the end of converter smelting were as follows: CaO content 49.0%, SiO2 content 13.1%, MnO content 3.8%, MgO content 9.9%, P2O5 content 2.7%, Al2O3 content 1.3%, total iron content 16.8%, and some unavoidable impurities.

[0056] Using the above smelting method, the converter final temperature reached 1618℃, the final carbon content was 0.03%, the amount of lime added was 3300kg, and the total iron content of the final slag was 16.8%.

[0057] Comparative Example 2: Low-carbon steel was smelted in a 100t converter. The raw materials used included 109t of molten iron, 1380℃ of molten iron, 0.36% silicon content of molten iron, and 15t of scrap steel.

[0058] The smelting process adopts a constant flow operation mode, with the oxygen supply flow rate set at 23000 Nm³. 3 / h. The top-blown oxygen supply system is as follows: during the oxygen supply range of 0-85%, the smelting lance position is maintained at 1.8-1.5m; when the oxygen supply reaches 85% or higher, the smelting lance position is adjusted to 1.3m. The bottom-blown argon system is as follows: during the oxygen supply range of 0-85%, the bottom-blown flow rate is 300 Nm³. 3 / h; when the oxygen supply reaches 85% or above, the bottom blowing flow rate is increased to 660 Nm. 3 / h.

[0059] The specific feeding system is as follows: During the oxygen supply stage of 15%~20%, add 3000 kg of lime, 1800 kg of dust removal balls, 1200 kg of lightly calcined dolomite, and 500 kg of magnesium balls; during the oxygen supply stage of 50%~70%, add 200 kg of lime at 50%, 55%, and 60% oxygen supply respectively, and add 300 kg and 300 kg of dust removal balls at 55% and 60% oxygen supply respectively; when the oxygen supply reaches 75%, add 320 kg of dolomite and 350 kg of limestone; after the oxygen supply reaches 75%, add 350 kg of lime.

[0060] The slag composition analysis results at the end of converter smelting were as follows: CaO content 49.2%, SiO2 content 12.6%, MnO content 4.1%, MgO content 11.7%, P2O5 content 2.3%, Al2O3 content 1.2%, total iron content 14.8%, and some unavoidable impurities.

[0061] Using the above smelting method, the converter final temperature reached 1626℃, the final carbon content was 0.05%, the amount of lime added was 3950kg, and the total iron content of the final slag was 14.8%.

[0062] Therefore, compared with the prior art, the embodiments of this disclosure reduce the need for slag to oxidize a large amount of iron to generate FeO by adding solid waste slag during the smelting process, thereby reducing the total iron content of the slag; the addition of synthetic slag ensures the fluidity of the slag and promotes the carbon-oxygen reaction; the total iron content in the final slag of the low-carbon steel converter is kept stable below 14.5%, improving the metal yield; and the amount of lime added can be reduced, controlling the amount of lime added to within 10 kg / t, which is beneficial to reducing costs.

[0063] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-ash-consumption converter smelting method, characterized in that, The single-slag process is used for smelting, with the converter scrap ratio controlled at 8%~26% and the top-blown oxygen supply flow rate controlled at 3.0~4.0 Nm³. 3 / (min·t), the bottom-blown argon flow rate is controlled at 0.03~0.10 Nm³. 3 / (min·t); The smelting process improves the slag-forming effect by coordinating the lance position and the feeding. Solid waste slag is added during the converter blowing process to control the CaO content in the slag to be 45%~55% and the MgO content to be 5.5%~7.5% respectively; at the same time, dust removal briquettes are added during the process to increase the activity of FeO in the slag and control the carbon content at the converter endpoint to be ≤0.05%.

2. The low-ash-consumption converter smelting method according to claim 1, characterized in that, The smelting process, through the coordination of lance position and charging, includes: When the oxygen supply reaches 15% to 20% of the total amount of oxygen blowing, add 80% to 100% of the total amount of solid waste residue at one time, add all the lightly calcined dolomite, and add 5 to 15 kg / t of dust removal briquettes to help with slag formation; When the oxygen supply reaches 50% to 70% of the total oxygen supply, add 10 kg / t of lime and the remaining solid waste residue in small batches and multiple batches. When the oxygen supply reaches 70% to 80% of the total oxygen supply during blowing, dust removal briquettes are added to adjust the activity of FeO in the slag.

3. The low-ash-consumption converter smelting method according to claim 2, characterized in that, By mass percentage, the final slag composition of converter smelting includes: CaO: 40%~55%, SiO2: 18%~22%, MnO: 2%~4.5%, MgO: 6%~10%, P2O5: 2%~4%, Al2O3: 2%~6%, total iron: 8%~14.5%, and some unavoidable impurities.

4. The low-ash-consumption converter smelting method according to claim 2, characterized in that, The smelting process, through the coordination of lance position and charging, also includes: From the start of oxygen blowing to 85% oxygen blowing, the oxygen lance position is controlled at 1.7~1.5m; from 85% oxygen blowing to the end of blowing, the oxygen lance position is controlled at 1.5~0.9m.

5. The low-ash-consumption converter smelting method according to claim 1, characterized in that, Bottom-blown argon gas includes the process from the start of oxygen blowing to 85% oxygen blowing, with a flow rate of 0.10~0.05 Nm³. 3 / (min·t); Oxygen blowing to 85% until the lance is lifted, bottom blowing argon flow rate is 0.05~0.10Nm 3 / (min·t).

6. The low-ash-consumption converter smelting method according to claim 1, characterized in that, The timing for adding solid waste slag is as follows: when the silicon content of molten iron is ≤0.2%, all solid waste slag is added in the early stage, and 0~500kg of lime is added during the process; when the silicon content of molten iron is 0.2%~0.5%, 80%~100% solid waste slag is added in the early stage, and 0~500kg of lime is added during the process; when the silicon content of molten iron is >0.5%, all solid waste slag is added in the early stage, and 800~1000kg of lime is added during the process.

7. The low-ash-consumption converter smelting method according to claim 6, characterized in that, The solid waste residue comprises, by mass percentage: CaO: 40%~50%, SiO2: 10%~15%, Al2O3: 1.0%~5.0%, TFe: 8%~12%, and some unavoidable impurities.

8. The low-ash-consumption converter smelting method according to claim 1, characterized in that, The amount of dust collector briquettes added is 10~40kg / t.