Method for using hot-pressed iron blocks in converter steelmaking and molten steel
By adding hot-pressed iron blocks and limestone in stages and in precise quantities during the converter steelmaking process, combined with furnace shaking and oxygen flow control, the problem of uneven melting of hot-pressed iron blocks in converter steelmaking was solved, achieving a low oxygen consumption and high efficiency hot-pressed iron block melting effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING SHOUGANG CO LTD
- Filing Date
- 2026-03-16
- Publication Date
- 2026-05-29
AI Technical Summary
In the converter steelmaking process, the addition of hot-pressed iron blocks leads to phenomena such as surface slag, core refractory and floating debris, resulting in prolonged melting time, increased oxygen consumption and decreased metal yield. Moreover, existing technologies cannot effectively solve the problems of uncontrollable temperature gradient and reaction path.
The method of adding hot-pressed iron blocks in stages and in quantitative quantities is adopted. By adding limestone and hot-pressed iron blocks before the converter is charged with iron, combined with the front and rear shaking of the furnace, synchronous addition, and batch addition according to the changes in the furnace flame and CO concentration, the oxygen flow rate is controlled to achieve low oxygen consumption melting.
It reduces the TFe content in the final slag, increases the metal yield, reduces oxygen consumption, shortens the melting time, and achieves efficient and stable melting of hot-pressed iron blocks.
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Abstract
Description
Technical Field
[0001] This application belongs to the field of sintering technology in iron and steel metallurgy, and particularly relates to a method for utilizing hot-pressed iron blocks and molten steel in converter steelmaking. Background Technology
[0002] Hot-pressed iron blocks, due to their high metallization rate, low impurities, and ease of storage and transportation, have become an important supplementary metal material for converter steelmaking. Traditionally, hot-pressed iron blocks are added to the furnace along with the auxiliary raw materials after molten iron is added, relying on the latent heat of the high-temperature molten iron and the oxygen blowing process to complete melting. However, limited by the concentrated timing of addition, fixed oxygen flow rate, and fluctuations in slag basicity, hot-pressed iron blocks often exhibit surface slag adhesion, core refractory, and floating fragments, leading to prolonged melting time, ignition failure, increased splashing, a final slag TFe increase of over 3%, a decrease in metal yield of 0.5%–1.0%, and an additional oxygen consumption of over 200 m³. Existing technologies attempt to accelerate melting by increasing the lance position or oxygen flow rate, but this further exacerbates iron loss and refractory erosion, failing to resolve the core contradictions of large temperature gradients between batches of hot-pressed iron blocks and uncontrollable reaction pathways. Summary of the Invention
[0003] This application provides a method for utilizing hot-pressed iron blocks and molten steel in converter steelmaking to solve the following technical problem: how to add hot-pressed iron blocks in stages and quantitatively throughout the entire converter steelmaking process and melt them with low oxygen consumption.
[0004] In a first aspect, embodiments of this application provide a method for utilizing hot-pressed iron blocks in converter steelmaking, the method comprising: Before the converter is charged with iron, limestone and hot-pressed iron blocks are added to the empty furnace in sequence. The amount of limestone added is 4-7 wt% and it is added before the amount of hot-pressed iron blocks. Immediately pour molten iron into the converter and perform front and back shaking. The shaking angle of the front and back shaking is between -60° and 90° and the shaking number is not less than 2 times. In the first batch of material after the start of blowing, hot-pressed iron blocks and limestone are added simultaneously, with the amount of hot-pressed iron blocks being 2-4 wt% and the amount of limestone being 3-5 tons. Immediately after the first batch of material is added, hot-pressed iron blocks are added in an amount of 1-3 wt%. During the secondary blowing stage after the double slag removal is completed, hot-pressed iron blocks are added simultaneously with the auxiliary raw materials, and the amount of hot-pressed iron blocks added simultaneously is 1-3 wt%. During the secondary blowing stage, the hot-pressed iron blocks are added steadily in at least two batches according to the changes in the furnace flame and CO concentration in the furnace gas. The amount added in each batch is controlled at 1-2 wt%, and the total amount of hot-pressed iron blocks added in at least two batches is 4-7 wt%. Throughout the blowing process, the oxygen flow rate was set at 2.9-3.1 m³ / h. 3 / (min·t) and oxygen consumption increased by 200-300m compared to the conventional low-oxygen mode. 3 ; The total amount of hot-pressed iron blocks added is 15-20 wt% of the metal charge.
[0005] Optionally, all the hot-pressed iron blocks are added from the high-level silo.
[0006] Optionally, the shaking angle of the front and rear shaking furnaces is -70° to 80°.
[0007] Optionally, the amount of limestone added in the first batch is 5 tons.
[0008] Optionally, the additional hot-pressed iron block is added within 30 seconds after the first batch of material is added.
[0009] Optionally, the amount of hot-pressed iron block added simultaneously during the secondary blowing stage is 2.5 wt%.
[0010] Optionally, the total amount of the hot-pressed iron blocks added in at least two batches is 5 wt%.
[0011] Optionally, the oxygen flow rate is 2.95 m³ / h. 3 / (min·t).
[0012] In a second aspect, embodiments of this application provide molten steel obtained by any of the methods described in the first aspect, characterized in that the final slag TFe content of the molten steel is reduced by 3-5 wt% compared to that without the method described, and the metal yield is increased by 0.5-1.5 wt%.
[0013] Optionally, the total oxygen content of the molten steel is reduced by 20-30 wt% compared to when the method is not used.
[0014] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method for preparing sintered ore. This method is based on the three-coupling principle of "segmented time control - oxygen control - slag control". The total amount of hot-pressed iron block (HBI) is divided into 15-20% and precisely injected in 6 stages, corresponding to the three-stage thermodynamic window of "solid-state → molten pool → secondary reaction" in the converter.
[0015] Before charging the iron, the empty furnace is first laid with CaCO3+HBI. The heat absorption of limestone decomposition is used to pre-attach slag pads on the furnace lining surface, which reduces the peak heat release of Si / Mn oxidation in the early stage, so that HBI can slowly absorb heat in the low temperature zone without forming a crust. Then, the furnace is shaken twice at -60°~90° to mechanically embed solid HBI into the molten iron, expand the solid-liquid contact surface, and shorten the subsequent melting induction period.
[0016] The first batch of billet is fed with 2–4% HBI + 3–5 t CaCO3, and immediately followed by an additional 1–3% HBI. Utilizing the high FeO and low basicity conditions of the FeO-based primary slag, the "stepwise reduction" of Fe2O3→FeO→Fe is coupled with the "secondary combustion" of C→CO, transferring the heat load absorbed by the HBI melt to the slag-steel interface, achieving "slag-for-steel" heat storage; simultaneously, the oxygen flow rate is only 2.9–3.1 m³ / s. 3 / (min·t), 200–300m lower than conventional. 3 This suppresses excessive decarburization heat release and prevents the molten pool temperature from soaring, which would hinder the melting of the FeO shell on the HBI surface.
[0017] After the double slag is poured out, the molten pool temperature drops to ~1550℃. At this point, a second blowing is started and 1-3% HBI is added along with the auxiliary raw materials. Taking advantage of the low Si and Mn content in the molten pool, the entry of P into the slag system, and the high calorific value of CO secondary combustion, the heat absorption of HBI melting and the heat of CO secondary combustion are "instantly matched". Subsequently, 4-7% HBI is added steadily in 2-3 batches according to the flame at the furnace mouth and the CO concentration. The decarburization rate of the molten pool is fed back in real time by the CO signal, and the 1-2% HBI in each batch is dynamically adjusted so that "HBI heat absorption ≈ CO secondary combustion heat release + slag system heat storage", maintaining the molten pool temperature at 1560-1620℃ and achieving low oxygen consumption, low splashing, and full melting.
[0018] In summary, this method replaces the traditional "one-time heat compensation" with "segmented heat balance", using three heat sources: CaCO3 decomposition, CO secondary combustion, and slag heat storage to offset the heat absorption of HBI in stages; it uses low oxygen flow to suppress overheating and uses online CO signal closed-loop control to control the feeding rhythm, thereby achieving efficient and stable melting of 15-20% HBI under low oxygen consumption conditions throughout the process. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0020] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "including" and "contains" as used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.
[0021] In a first aspect, embodiments of this application provide a method for utilizing hot-pressed iron blocks in converter steelmaking, the method comprising: S1. Before the converter is charged with iron, limestone and hot-pressed iron blocks are added to the empty furnace in sequence. The amount of limestone added is 4-7 wt% and it is added before the amount of hot-pressed iron blocks. The amount of hot-pressed iron blocks added is 4-7 wt%. S2. Immediately pour molten iron into the converter and perform front and back shaking. The shaking angle of the front and back shaking is -60° to 90° and the shaking number is not less than 2 times. S3. In the first batch of material after the start of blowing, hot-pressed iron blocks and limestone are added simultaneously, with the amount of hot-pressed iron blocks being 2-4 wt% and the amount of limestone being 3-5 tons. S4. Immediately after the first batch of material is added, hot-pressed iron blocks are added in an amount of 1-3 wt%. S5. During the secondary blowing stage after the double slag removal is completed, hot-pressed iron blocks and auxiliary raw materials are added simultaneously, with the amount of hot-pressed iron blocks added simultaneously being 1-3 wt%. S6. During the secondary blowing stage, the hot-pressed iron blocks are added steadily in at least two batches according to the changes in the furnace flame and CO concentration in the furnace gas. The amount added in each batch is controlled at 1-2 wt%, and the total amount of hot-pressed iron blocks added steadily in at least two batches is 4-7 wt%. S7. Throughout the blowing process, the oxygen flow rate is set to 2.9-3.1 m³ / h. 3 / (min·t) and oxygen consumption increased by 200-300m compared to the conventional low-oxygen mode. 3 ; S8. The total amount of hot-pressed iron blocks added is 15-20 wt% of the metal loading amount.
[0022] S1. Before the converter is charged with iron, 4wt%, 5wt%, 6wt%, and 7wt% limestone are added to the empty furnace in sequence before 4wt%, 5wt%, 6wt%, and 7wt% hot-pressed iron blocks. This allows the CO2 bubbles generated by the decomposition of limestone to pre-fluff the free space of the furnace and form a liquid primary slag layer in advance. This causes the hot-pressed iron blocks that enter later to fall into the primary slag-molten iron interface instead of directly impacting the carbon-magnesia bricks, reducing the thickness of the condensation shell on the surface of the hot-pressed iron blocks and lowering the subsequent melting thermal resistance.
[0023] S2. Immediately pour molten iron into the converter and perform a series of shaking motions at different angles (-60°, -50°, -40°, -30°, -20°, -10°, 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°) 2, 3, 4, and 5 times respectively. This forces the molten iron to penetrate the initial slag layer and undergo initial mechanical mixing with the hot-pressed iron block, thereby instantly raising the surface temperature of the hot-pressed iron block to above 1450°C and peeling off the solid shell, shortening the melting induction period.
[0024] S3. In the first batch of material after the start of blowing, 2wt%, 2.5wt%, 3wt%, 3.5wt%, and 4wt% hot-pressed iron blocks are added simultaneously with 3t, 3.5t, 4t, 4.5t, and 5t of limestone. This allows the newly formed FeO and CaO to instantly generate a low-melting-point calcium-iron olivine slag phase, thereby maintaining the temperature of the hot-pressed iron blocks in the low melting zone of 1300-1350℃ and preventing large iron particles from settling to the bottom.
[0025] S4. Immediately after the first batch of material is added, add 1wt%, 1.5wt%, 2wt%, 2.5wt%, and 3wt% hot-pressed iron blocks. This utilizes the high heat capacity of the foamed slag already formed in the furnace to buffer the heat absorption impact brought by the additional hot-pressed iron blocks, thereby keeping the slag temperature drop below 30℃ and preventing the energy of the oxygen stream from being consumed by secondary heating, thus achieving low oxygen consumption.
[0026] S5. During the secondary blowing stage after the double slag pouring is completed, 1wt%, 1.5wt%, 2wt%, 2.5wt%, and 3wt% hot-pressed iron blocks are added simultaneously with the auxiliary raw materials. This allows the hot-pressed iron blocks to be directly heated by the high-temperature radiation field of the exposed molten iron surface in the furnace after the slag pouring, thereby reducing the heat of fusion that needs to be provided by oxygen in the subsequent process.
[0027] S6. During the secondary blowing stage, the hot-pressed iron blocks are added in at least two batches according to the changes in the furnace flame and CO concentration in the furnace gas. The amount added in each batch is 1wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, and 2wt%, with a total amount of 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, and 7wt%. This utilizes the heat released by the secondary combustion of CO to compensate for the heat absorbed by the melting of each batch of hot-pressed iron blocks, thereby keeping the furnace thermal balance fluctuation <20℃ and avoiding additional increase in oxygen flow.
[0028] S7. Throughout the blowing process, the oxygen flow rate is set to 2.9 m³ / (min·t), 2.95 m³ / (min·t), 3.0 m³ / (min·t), and 3.1 m³ / (min·t), and the oxygen consumption is increased by 200 m³, 210 m³, 220 m³, 230 m³, 240 m³, 250 m³, 260 m³, 270 m³, 280 m³, 290 m³, and 300 m³, respectively, compared to the conventional low-oxygen mode. This extends the residence time in the flame zone by maintaining a constant low-oxygen flow, thereby gradually reducing the FeO layer on the surface of the hot-pressed iron block without thickening it, reducing the melting thermal resistance, and minimizing oxygen waste.
[0029] S8. The total amount of hot-pressed iron blocks added is 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, and 20wt% of the metal loading, so that even under the condition of high proportion of hot-pressed iron blocks, the entire melting is still completed through the above-mentioned segmented-temperature-oxygen-control path, thereby achieving the goal of "adding hot-pressed iron blocks in segments and quantitatively throughout the entire process and melting with low oxygen consumption" proposed in the technical problem.
[0030] In some implementations, the hot-pressed iron blocks are all added from the high-level silo.
[0031] All hot-pressed iron blocks are added from the high-level silo, thereby avoiding fluctuations in the amount added due to adhesion of the belt or chute, thus ensuring that the addition ratio of each section in claim 1 is accurate and controllable, and maintaining the quantitative relationship of the causal chain unchanged.
[0032] In some embodiments, the shaking angle of the front and rear shaking furnaces is -70° to 80°.
[0033] The front and rear shaking angles are limited to -70°, -65°, -60°, -55°, -50°, -45°, -40°, -35°, -30°, -25°, -20°, -15°, -10°, -5°, 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, and 80°, thereby reducing the exposed area of molten iron and reducing the mechanical erosion of the furnace lining by the molten iron, thus extending the furnace lining life while ensuring the mixing intensity.
[0034] In some embodiments, the amount of limestone added in the first batch is 5 tons.
[0035] The amount of limestone added in the first batch is fixed at 5 tons, so as to provide sufficient CaO to quickly combine with the first batch of FeO to form CaO·FeO2 with a melting point of 1200℃, thereby stabilizing the height of the foam slag and reducing the probability of hot-pressed iron blocks floating.
[0036] In some embodiments, the additional hot-pressed iron block is added within 30 seconds after the first batch of material is added.
[0037] The additional hot-pressed iron blocks are added within 30 seconds after the first batch of material is added, so as to utilize the high heat capacity of the foam slag that has not yet broken in the furnace, thereby avoiding the slag temperature from dropping sharply by more than 30°C due to the addition of hot-pressed iron blocks.
[0038] In some embodiments, the amount of hot-pressed iron block added simultaneously during the secondary blowing stage is 2.5 wt%.
[0039] The amount of hot-pressed iron blocks added simultaneously during the secondary blowing stage is fixed at 2.5 wt%, thus forming a solid-liquid mass ratio of 1:40 with the weight of the exposed molten iron after slag removal, thereby maximizing the radiative heat transfer efficiency and shortening the first melting time by 1.5 min.
[0040] In some embodiments, the total amount of the hot-pressed iron blocks added in at least two batches is 5 wt%.
[0041] The hot-pressed iron blocks are added in at least two batches with a fixed total amount of 5 wt%, thereby forming a precise thermal balance with the heat provided by secondary combustion, and thus controlling the furnace temperature fluctuation within ±15℃.
[0042] In some embodiments, the oxygen flow rate is 2.95 m³ / h. 3 / (min·t).
[0043] Oxygen flow rate is fixed at 2.95m³. 3 / (min·t), thus forming a long flame zone in conjunction with the gun position being lowered by 200mm, thereby increasing the FeO reduction rate on the surface of the hot-pressed iron block by 10% and reducing excess oxygen.
[0044] In a second aspect, embodiments of this application provide molten steel obtained by any of the methods described in the first aspect, characterized in that the final slag TFe content of the molten steel is reduced by 3-5 wt% compared to that without the method described, and the metal yield is increased by 0.5-1.5 wt%.
[0045] The molten steel obtained by any of the methods in the first aspect has a final slag TFe content that is reduced by 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, and 5 wt% compared to the method not used, and the metal yield is increased by 0.5 wt%, 0.7 wt%, 0.9 wt%, 1.1 wt%, 1.3 wt%, and 1.5 wt%, respectively. This directly and quantitatively proves that the goal of "low oxygen consumption melting" has been achieved, thereby providing low inclusion molten steel for subsequent continuous casting.
[0046] In some embodiments, the total oxygen content of the molten steel is reduced by 20-30 wt% compared to when the method is not used.
[0047] The total oxygen content of the molten steel was reduced by 20wt%, 22wt%, 24wt%, 26wt%, 28wt%, and 30wt% compared to the method not used, thus proving that deoxidation is achieved simultaneously by adding hot-pressed iron blocks in segments and a low-oxygen-consumption melting path, thereby reducing the subsequent aluminum wire consumption.
[0048] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.
[0049] I. Implementation Examples Example 1 A method for utilizing hot-pressed iron blocks in converter steelmaking includes: Before the converter is charged with iron, 5 tons of limestone and 5 wt% hot-pressed iron blocks are added to the empty furnace in sequence. The amount of limestone added is 5 wt% and it is added before the hot-pressed iron blocks. Immediately pour 160t of molten iron into the converter and perform front and rear shaking. The shaking angle of the front and rear shaking is -60° to 90° and the shaking is performed twice. In the first batch of material after the start of blowing, 2wt% hot-pressed iron blocks and 5 tons of limestone are added simultaneously. Immediately after the first batch of material is added, add an additional 2 wt% hot-pressed iron blocks; During the secondary blowing stage after the double slag pouring is completed, 2.5 wt% hot-pressed iron blocks are added simultaneously with the auxiliary raw materials; During the secondary blowing stage, the hot-pressed iron blocks were added in two batches, with each batch containing 1 wt%, based on changes in the furnace flame and CO concentration in the furnace gas. The total amount of hot-pressed iron blocks added in the two batches was 4 wt%. Throughout the blowing process, the oxygen flow rate was set to 2.95 m3 / (min·t) and the oxygen consumption increased by 210 m3 compared to the conventional low oxygen mode; The total amount of hot-pressed iron blocks added is 15 wt% of the metal charge.
[0050] Example 2 A method for utilizing hot-pressed iron blocks in converter steelmaking includes: Before the converter is charged with iron, 5 tons of limestone and 7 wt% hot-pressed iron blocks are added to the empty furnace in sequence. The amount of limestone added is 5 wt% and it is added before the hot-pressed iron blocks. Immediately pour 160t of molten iron into the converter and perform front and rear shaking. The shaking angle of the front and rear shaking is -70° to 80° and the shaking is performed twice. In the first batch of material after the start of blowing, 3 wt% hot-pressed iron blocks and 5.5 tons of limestone were added simultaneously. Immediately after the first batch of material is added, add an additional 2 wt% hot-pressed iron blocks; During the secondary blowing stage after the double slag pouring is completed, 2.5 wt% hot-pressed iron blocks are added simultaneously with the auxiliary raw materials; During the secondary blowing stage, based on the changes in the furnace flame and CO concentration in the furnace gas, the hot-pressed iron blocks were added in two batches at a steady pace, with each batch containing 1.4 wt%, and the total amount of the hot-pressed iron blocks added in the two batches was 5 wt%. Throughout the blowing process, the oxygen flow rate was set to 2.9 m3 / (min·t) and the oxygen consumption increased by 200 m3 compared to the conventional low oxygen mode; The total amount of hot-pressed iron blocks added is 18 wt% of the metal charge.
[0051] Example 3 A method for utilizing hot-pressed iron blocks in converter steelmaking includes: Before the converter is charged with iron, 5 tons of limestone and 6 wt% hot-pressed iron blocks are added to the empty furnace in sequence. The amount of limestone added is 5 wt% and it is added before the hot-pressed iron blocks. Immediately pour 160t of molten iron into the converter and perform front and rear shaking. The shaking angle of the front and rear shaking is -65° to 85° and the shaking is performed 3 times. In the first batch of material after the start of blowing, 2.5 wt% hot-pressed iron blocks and 4 tons of limestone were added simultaneously. Immediately after the first batch of material is added, add an additional 1.5 wt% hot-pressed iron block; During the secondary blowing stage after the double slag pouring is completed, 2wt% hot-pressed iron blocks are added simultaneously with the auxiliary raw materials; During the secondary blowing stage, based on the changes in the furnace flame and CO concentration in the furnace gas, the hot-pressed iron blocks were added in three batches at a steady pace, with each batch containing 1.2 wt%, and the total amount of the hot-pressed iron blocks added in the three batches was 6 wt%. Throughout the blowing process, the oxygen flow rate was set to 3.0 m3 / (min·t) and the oxygen consumption increased by 250 m3 compared to the conventional low oxygen mode; The total amount of hot-pressed iron blocks added is 17 wt% of the metal charge.
[0052] Example 4 A method for utilizing hot-pressed iron blocks in converter steelmaking includes: Before the converter is charged with iron, 5 tons of limestone and 4 wt% hot-pressed iron blocks are added to the empty furnace in sequence. The amount of limestone added is 5 wt% and it is added before the hot-pressed iron blocks. Immediately pour 160t of molten iron into the converter and perform front and rear shaking. The shaking angle of the front and rear shaking is -60° to 90° and the shaking is performed twice. In the first batch of material after the start of blowing, 4 wt% hot-pressed iron blocks and 5 tons of limestone are added simultaneously. Immediately after the first batch of material is added, add an additional 3 wt% hot-pressed iron blocks; During the secondary blowing stage after the double slag pouring is completed, 3wt% hot-pressed iron blocks are added simultaneously with the auxiliary raw materials; During the secondary blowing stage, the hot-pressed iron blocks were added in two batches, each batch containing 2 wt%, based on changes in the furnace flame and CO concentration in the furnace gas. The total amount of hot-pressed iron blocks added in the two batches was 7 wt%. Throughout the blowing process, the oxygen flow rate was set to 3.1 m³ / (min·t) and the oxygen consumption increased by 300 m³ compared to the conventional low oxygen mode. The total amount of hot-pressed iron blocks added is 20 wt% of the metal charge.
[0053] II. Comparative Example Comparative Example 1 (Added all at once) A method for utilizing hot-pressed iron blocks in converter steelmaking includes: After the converter iron is added, 15 wt% hot-pressed iron blocks and 5 tons of limestone are added into the furnace at the same time. The oxygen flow rate was set to 3.5 m³ / (min·t) and the oxygen consumption increased by 400 m³ compared to the conventional mode; The furnace was not shaken before and after the start, the feed was not added in batches, and the lance position was not lowered.
[0054] Comparative Example 2 (without limestone pre-laying) A method for utilizing hot-pressed iron blocks in converter steelmaking includes: Before the converter iron is added, 7 wt% hot-pressed iron blocks are directly added to the empty furnace without limestone pre-padded. The remaining steps are the same as in Example 2.
[0055] Comparative Example 3 (Conventional Oxygen Levels) A method for utilizing hot-pressed iron blocks in converter steelmaking includes: The oxygen flow rate was set to 3.5 m3 / (min·t) and the oxygen consumption was increased by 0 m3. The remaining steps were the same as in Example 1.
[0056] III. Results Data Experimental methods for evaluating results: Final slag TFe: Take a slag sample with a stainless steel spoon within 3 minutes after lifting the lance at the end of the blowing process, and determine the total iron by titration method according to GB / T6730.65-2016.
[0057] Metal yield: Steel output / (molten iron input + hot-pressed iron block input) × 100%.
[0058] Total oxygen: Samples were taken from the tundish during the tapping process and determined using the LECOTC-436 infrared method.
[0059] Increased oxygen consumption: Cumulative oxygen consumption - consumption in the same furnace service under low oxygen mode.
[0060] Melting time: The time interval from the start of blowing to the first drop of the furnace acoustic curve to the splash critical value, recorded by the online acoustic system.
[0061] Table 1. Results data for both the examples and comparative examples.
[0062] As shown in Table 1, the technological advancements of this application's technical solution include: 1. The final slag TFe content in Examples 1–4 was 13.8wt%–14.5wt%, while that in Comparative Examples 1–3 was 17.5wt%–19.5wt%, thus demonstrating that the segmented quantitative addition of hot-pressed iron blocks and the low-oxygen-consumption melting path significantly reduced the iron carried in the slag.
[0063] 2. The metal recovery rates in Examples 1–4 were 95.7 wt%–96.2 wt%, and in Comparative Examples 1–3 they were 94.0 wt%–94.5 wt%, thus directly quantifying that the method of this application recovers more iron.
[0064] 3. The total oxygen content in Examples 1–4 was 350 ppm to 380 ppm, while that in Comparative Examples 1–3 was 440 ppm to 480 ppm, thus proving that the low oxygen consumption melting mode simultaneously improves the cleanliness of molten steel.
[0065] 4. For example, 0m needs to be added to Comparative Example 3. 3 However, the highest TFe content further proves that this application achieves a high proportion of hot-pressed iron block melting while reducing oxygen waste.
[0066] 5. The melting time of Examples 1–4 was 12 min to 14 min, and that of Comparative Examples 1–3 was 16 min to 18 min, thus proving that the segmented quantitative addition path significantly shortens the time required for the hot-pressed iron block to melt completely.
[0067] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.
Claims
1. A method for utilizing hot-pressed iron blocks in converter steelmaking, characterized in that, The method includes: Before the converter is charged with iron, limestone and hot-pressed iron blocks are added to the empty furnace in sequence. The amount of limestone added is 4-7 wt% and it is added before the amount of hot-pressed iron blocks. Immediately pour molten iron into the converter and perform front and back shaking. The shaking angle of the front and back shaking is between -60° and 90° and the shaking number is not less than 2 times. In the first batch of material after the start of blowing, hot-pressed iron blocks and limestone are added simultaneously, with the amount of hot-pressed iron blocks being 2-4 wt% and the amount of limestone being 3-5 tons. Immediately after the first batch of material is added, hot-pressed iron blocks are added in an amount of 1-3 wt%. During the secondary blowing stage after the double slag removal is completed, hot-pressed iron blocks are added simultaneously with the auxiliary raw materials, and the amount of hot-pressed iron blocks added simultaneously is 1-3 wt%. During the secondary blowing stage, the hot-pressed iron blocks are added steadily in at least two batches according to the changes in the furnace flame and CO concentration in the furnace gas. The amount added in each batch is controlled at 1-2 wt%, and the total amount of hot-pressed iron blocks added in at least two batches is 4-7 wt%. Throughout the blowing process, the oxygen flow rate was set at 2.9-3.1 m³ / h. 3 / (min·t) and oxygen consumption increased by 200-300m compared to the conventional low-oxygen mode. 3 ; The total amount of hot-pressed iron blocks added is 15-20 wt% of the metal charge.
2. The method according to claim 1, characterized in that, All the hot-pressed iron blocks were added from the high-level silo.
3. The method according to claim 1, characterized in that, The shaking angle of the front and rear shaking furnaces is -70° to 80°.
4. The method according to claim 1, characterized in that, The amount of limestone added in the first batch is 5 tons.
5. The method according to claim 1, characterized in that, The additional hot-pressed iron blocks were added within 30 seconds after the first batch of materials was added.
6. The method according to claim 1, characterized in that, The amount of hot-pressed iron block added simultaneously during the secondary blowing stage is 2.5 wt%.
7. The method according to claim 1, characterized in that, The total amount of hot-pressed iron blocks added in at least two batches is 5 wt%.
8. The method according to claim 1, characterized in that, The oxygen flow rate is 2.95 m³ / h. 3 / (min·t).
9. Molten steel obtained by the method according to any one of claims 1-8, characterized in that, The final slag TFe content of the molten steel is reduced by 3-5 wt% compared to that without the method described, and the metal yield is increased by 0.5-1.5 wt%.
10. The molten steel according to claim 9, characterized in that, The total oxygen content of the molten steel is reduced by 20-30 wt% compared to when the method was not used.