Method for improving stability of converter smelting based on flue gas information

Abstract

This invention provides a method for improving the stability of converter smelting based on flue gas information, belonging to the field of converter smelting. The method includes: sequentially mixing scrap steel, first ore, and molten iron to obtain steelmaking raw materials; smelting the steelmaking raw materials in a converter and obtaining the CO content of the output flue gas from the converter smelting; when the oxygen blowing rate of the converter smelting is within a set oxygen blowing rate range, adjusting the oxygen lance height according to the CO content; the set oxygen blowing rate range is >65% and ≤85%. When the oxygen blowing rate reaches the range of >65% and ≤85%, smelting instability is prone to occur, such as slag overflow or back-drying. The CO mass fraction in the flue gas information directly reflects the degree of physical and chemical reactions in the furnace. By dynamically controlling the oxygen lance height in stages, the reaction process can be controlled, thereby improving the stability of converter smelting and reducing the occurrence of slag overflow or back-drying.

Description

Technical Field

[0001] This application relates to the field of converter smelting technology, and in particular to a method for improving the stability of converter smelting based on flue gas information. Background Technology

[0002] Based on previous research on the impact of scrap ratio on the efficiency per ton of steel, while increasing the scrap ratio can reduce environmental pollution, decrease overall energy consumption, and improve productivity, when scrap prices are high, a significant increase in the scrap ratio not only increases converter smelting costs but also leads to problems such as low converter endpoint temperature hit rate, long smelting cycle, large slag volume, and high post-blowing rate. Therefore, from the perspective of low-cost converter smelting, the optimal scrap ratio is often no more than 20%, meaning the converter needs to adopt a high-iron-consumption smelting mode. When the converter adopts a high-iron-consumption smelting mode, due to the relatively small amount of scrap added, the excess heat in the furnace needs to be balanced with slagging agents. This results in a faster heating rate of the molten pool, ultimately leading to an uneven development of the carbon-oxygen reaction in the furnace, eventually causing slag overflow or splashing.

[0003] A converter is a high-temperature, high-pressure, multi-phase reaction vessel. During normal smelting, splashing occurs only to a certain extent within the furnace, usually without causing significant metal loss or dangerous accidents. However, when this splashing of molten slag or molten metal droplets exceeds the controllable range within the furnace, it violently impacts the furnace lining and flies out of the furnace opening. In severe cases, large quantities may gush out of the furnace opening, causing dangerous accidents, commonly known as converter splashing. Slag overflow and splashing during the blowing process are the most frequent types of accidents. This phenomenon is caused by the combined impact of the oxygen stream during the blowing process and the escape of gases from the decarburization reaction, resulting in the overflow of molten slag and molten metal from the furnace. It has a significant impact on the safety and economy of converter smelting. In traditional converter steelmaking, operators typically judge the occurrence of slag overflow or splashing by observing the flame at the furnace opening or using sonar slag treatment. However, observation is highly subjective, and sonar slag treatment not only has a certain lag but its monitoring signal is also greatly affected by the stability of the smelting process within the furnace. Therefore, the probability of slag overflow or splashing is relatively high. Against this backdrop, the stable operation of the high-iron-consumption smelting mode in converters has become a technical challenge, seriously affecting the efficient production of converters. Summary of the Invention

[0004] This application provides a method for improving the stability of converter smelting based on flue gas information, in order to solve the following technical problem: how to improve the stability of converter smelting in order to reduce the occurrence of slag overflow, splashing or re-drying during the smelting process.

[0005] This application provides a method for improving converter smelting stability based on flue gas information, the method comprising:

[0006] Scrap steel, first ore, and molten iron are mixed sequentially to obtain steelmaking raw materials;

[0007] The steelmaking raw materials are smelted in a converter, and the CO content of the flue gas output from the converter is obtained.

[0008] When the oxygen blowing rate in the converter smelting is within the set oxygen blowing rate range, the oxygen lance height is adjusted according to the CO content; the set oxygen blowing rate range is >65% and ≤85%.

[0009] Optionally, adjusting the oxygen lance height according to the CO content includes:

[0010] Adjust the oxygen lance height according to the CO content; wherein,

[0011] If, by mass fraction, 48% < the CO content < 55%, then adjust the oxygen lance height to the reference height.

[0012] If the CO content is ≤48% by mass fraction, the oxygen lance height should be adjusted to decrease by 0.15m to 0.25m from the reference height.

[0013] If, by mass fraction, the CO content is 55% ≤ 60%, then the oxygen lance height should be increased by 0.15m to 0.25m above the reference height.

[0014] If the CO content is ≥60% by mass fraction, the oxygen lance height should be increased by 0.25m to 0.35m above the reference height.

[0015] Optionally, the reference height satisfies the following relationship:

[0016] When 65% < oxygen blowing rate ≤ 70%, the reference height is 2.0m;

[0017] When 70% < oxygen blowing rate ≤ 78%, the reference height is 2.25m;

[0018] When 78% < oxygen blowing rate ≤ 85%, the reference height is 2.1m.

[0019] Optionally, the scrap steel in the steelmaking raw materials accounts for 10% to 20% by mass; the temperature of the molten iron is ≥1360℃; and the Si content of the molten iron is ≥0.25% by mass fraction.

[0020] Optionally, the method further includes: controlling the oxygen lance height in stages during the converter smelting process; wherein,

[0021] When 0 ≤ oxygen blowing rate ≤ 6%, the height of the oxygen lance is 2.2m;

[0022] When 6% < oxygen blowing rate ≤ 28%, the height of the oxygen lance is 2.0m;

[0023] When 28% < oxygen blowing rate ≤ 65%, the height of the oxygen lance is 1.8m;

[0024] When 85% < oxygen blowing rate ≤ 100%, the oxygen lance height is 1.9m.

[0025] Optionally, the method further includes: controlling the oxygen supply intensity in stages during the converter smelting process; wherein,

[0026] When 0 ≤ oxygen blowing rate ≤ 40%, the oxygen supply intensity slowly increases to 2.7 Nm. 3 / (t·min)~2.9Nm 3 / (t·min);

[0027] When the oxygen blowing rate is >40%, the oxygen supply intensity slowly increases to 3.0 Nm. 3 / (t·min)~3.2Nm 3 / (t·min).

[0028] Optionally, the method further includes: during the converter smelting process, when the oxygen blowing rate is 4% to 6%, adding a second ore; the feeding rate of the second ore is 0.8 t / min to 1.2 t / min, the total amount of the first ore and the second ore added is 26 kg / t steel to 40 kg / t steel, and the ratio of the amount of the first ore added to the total amount added is 40% to 50%.

[0029] Optionally, the method further includes: adding limestone, lime, and lightly calcined dolomite into the furnace in stages during the converter smelting process; wherein,

[0030] When the oxygen blowing rate is 4% ≤ oxygen blowing rate ≤ 6%, limestone, lime, and lightly calcined dolomite with the first-stage addition amount are added to the furnace; the first-stage addition amount of limestone is 11 kg / t·steel to 12 kg / t·steel; the first-stage addition amount of lime is 12.5 kg / t·steel to 15 kg / t·steel; and the first-stage addition amount of lightly calcined dolomite is 8.5 kg / t·steel to 9.5 kg / t·steel.

[0031] When the oxygen blowing rate is 20% ≤ oxygen blowing rate ≤ 23%, limestone, lime, and lightly calcined dolomite with a second-stage addition amount are added to the furnace; the second-stage addition amount of limestone is 6 kg / t·steel to 8 kg / t·steel; the second-stage addition amount of lime is 12.5 kg / t·steel to 15 kg / t·steel; and the second-stage addition amount of lightly calcined dolomite is 8.5 kg / t·steel to 9.5 kg / t·steel.

[0032] Optionally, the bottom-blown gas supply intensity for the converter smelting is 0.03 Nm. 3 / (t·min)~0.09Nm 3 / (t·min).

[0033] Optionally, the final molten steel from the converter smelting has a P content ≤0.0080% and an O content ≤0.06% by mass fraction; the final molten steel temperature from the converter smelting is 1620℃~1660℃; the final slag basicity from the converter smelting is 3.2~3.8, and the final slag TFe content is 14%~18% and the final slag MgO content is 8%~12% by mass fraction.

[0034] The technical solutions provided in this application have the following advantages compared with the prior art:

[0035] This application provides a method for improving the stability of converter smelting based on flue gas information, comprising: sequentially mixing scrap steel, first ore, and molten iron to obtain steelmaking raw materials; smelting the steelmaking raw materials in a converter and obtaining the CO content of the output flue gas from the converter smelting; when the oxygen blowing rate of the converter smelting is within a set oxygen blowing rate range, adjusting the oxygen lance height according to the CO content; the set oxygen blowing rate range is >65% and ≤85%. By adding ore to the smelting raw materials, the molten pool temperature in the early stage of smelting is reduced, which is beneficial to the dephosphorization reaction and promotes the early slag formation; when the oxygen blowing rate reaches the range of >65% and ≤85%, smelting instability is likely to occur, such as slag overflow, splashing, or back-drying. The mass fraction of CO in the flue gas information can directly reflect the degree of decarburization reaction in the furnace. By dynamically controlling the oxygen lance height in stages, the reaction process can be controlled, thereby improving the stability of converter smelting and reducing the occurrence of slag overflow or splashing. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a flowchart illustrating a method for improving converter smelting stability based on flue gas information, provided as an embodiment of this application. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0041] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0042] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0043] Figure 1This is a flowchart illustrating a method for improving converter smelting stability based on flue gas information, provided as an embodiment of this application.

[0044] Please see Figure 1 This application provides a method for improving the stability of converter smelting based on flue gas information, applicable to 180-ton to 300-ton converters, the method comprising:

[0045] S1. The scrap steel, the first ore, and the molten iron are mixed sequentially to obtain the steelmaking raw materials;

[0046] In some embodiments, the scrap steel accounts for 10% to 20% of the mass of the steelmaking raw materials; the temperature of the molten iron is ≥1360℃; and the Si content of the molten iron is ≥0.25% by mass fraction.

[0047] In some implementations, step S1 can specifically be: adding scrap steel and first ore into the converter, and then filling the converter with molten iron to obtain steelmaking raw materials.

[0048] The mass percentage of scrap steel in steelmaking raw materials is 10%–20%, meaning that scrap steel accounts for 10%–20% of the total charge into the furnace. This charging system is adopted because: currently, scrap steel prices are high, and a larger scrap steel charge would be detrimental to the efficiency per ton of steel; the reason for adding ore to the converter before adding iron is to lower the molten pool temperature in the early stages of smelting, which is beneficial for dephosphorization and promotes early slag formation. For example, the mass percentage of scrap steel in steelmaking raw materials can be 10%, 12%, 14%, 16%, 18%, 20%, etc.; the temperature of molten iron can be 1360℃, 1365℃, 1370℃, 1375℃, 1380℃, etc.; and the Si content of molten iron, by mass fraction, can be 0.25%, 0.26%, 0.27%, 0.28%, 0.30%, etc.

[0049] S2. The steelmaking raw materials are smelted in a converter, and the CO content of the flue gas output from the converter is obtained;

[0050] In recent years, with the continuous improvement of computer computing power and the monitoring capabilities of detection equipment, the development of flue gas steelmaking models has become increasingly helpful. The application of these models in production not only allows for the prediction and dynamic adjustment of reactions and slag conditions within the furnace, but also enables closed-loop dynamic control throughout the entire process. This characteristic has become a key area for improving the stability of converter smelting. During the converter smelting process, information on the output flue gas from the converter is acquired in real time.

[0051] S3. When the oxygen blowing rate in the converter smelting is within the set oxygen blowing rate range, adjust the oxygen lance height according to the CO content; the set oxygen blowing rate range is >65% and ≤85%.

[0052] It should be noted that the oxygen blowing volume in this application is the volume fraction of the top-blown oxygen supply to the total oxygen supply.

[0053] Based on flue gas analysis, this invention enables efficient and stable converter blowing processes. It not only avoids human error introduced by experience in steelmaking but also mitigates the long delay effect of sonar slag formation. Furthermore, it allows for the prediction of slag overflow or splashing within the furnace, reducing these issues during blowing. Under these charging conditions, dynamic lance position control effectively prevents slag overflow or splashing during blowing and promotes dephosphorization within the converter, achieving a dephosphorization rate of up to 95.2% and a final phosphorus content of 0.0044%, thus enabling efficient and stable converter production.

[0054] When the oxygen blowing rate reaches a range of >65% and ≤85%, smelting instability is likely to occur, such as slag overflow or splashing. Extensive research has found that the oxygen lance height can be dynamically controlled in stages based on flue gas information, thereby reducing the occurrence of slag overflow or splashing.

[0055] In some embodiments, adjusting the oxygen lance height according to the CO content includes: adjusting the oxygen lance height according to the CO content; wherein, based on mass fraction, if 48% < CO content < 55%, the oxygen lance height is adjusted to a reference height; based on mass fraction, if the CO content ≤ 48%, the oxygen lance height is adjusted to decrease by 0.15m to 0.25m from the reference height; based on mass fraction, if 55% ≤ CO content < 60%, the oxygen lance height is adjusted to increase by 0.15m to 0.25m from the reference height; and based on mass fraction, if the CO content ≥ 60%, the oxygen lance height is adjusted to increase by 0.25m to 0.35m from the reference height.

[0056] In some embodiments, the reference height satisfies the following relationship: when 65% < oxygen blowing rate ≤ 70%, the reference height is 2.0m; when 70% < oxygen blowing rate ≤ 78%, the reference height is 2.25m; when 78% < oxygen blowing rate ≤ 85%, the reference height is 2.1m.

[0057] During the converter blowing process, the oxygen lance height is controlled based on the CO mass fraction in the flue gas information. The reason for adopting this lance position control strategy is that the CO mass fraction in the flue gas information directly reflects the degree of decarburization reaction in the furnace. Therefore, after determining the standard value range of CO mass fraction, adjusting the lance height based on the benchmark lance position is more instructive for controlling the degree of reaction in the furnace.

[0058] The CO mass fraction in the flue gas directly reflects the progress of the decarburization reaction in the furnace. The oxygen lance height is dynamically adjusted based on the baseline oxygen lance height. If the CO mass fraction is within the standard range (48%–55%), no intervention is needed; otherwise, intervention is required. Intervention continues until the CO mass fraction returns to the standard range, and the dynamic oxygen lance height returns to the baseline height.

[0059] For example, when the oxygen blowing rate is >65% and <70%, the CO mass fraction in the flue gas information is within the standard range, and the oxygen lance height is 2.0m. When the oxygen blowing rate reaches 70%, the CO mass fraction in the flue gas information increases to 58%, so the oxygen lance height is adjusted to 2.45m, and the CO mass fraction in the flue gas information decreases. When the oxygen blowing rate reaches 75%, the CO mass fraction in the flue gas information returns to the standard range, so the oxygen lance height is adjusted to 2.25m. When the oxygen blowing rate is between 75% and 78%, the oxygen lance height is fixed at 2.25m. When the oxygen blowing rate is >78% and ≤85%, the CO mass fraction in the flue gas information is within the standard range, so the oxygen lance height is fixed at 2.1m.

[0060] In some embodiments, the method further includes: controlling the oxygen lance height in stages during the converter smelting process; wherein, when 0 ≤ oxygen blowing rate ≤ 6%, the oxygen lance height is 2.2m; when 6% < oxygen blowing rate ≤ 28%, the oxygen lance height is 2.0m; when 28% < oxygen blowing rate ≤ 65%, the oxygen lance height is 1.8m; and when 85% < oxygen blowing rate ≤ 100%, the oxygen lance height is 1.9m.

[0061] The oxygen lance height control in this application is specifically as follows: the oxygen lance height is controlled in stages. When the oxygen blowing volume is [0-65]% and (85-100]%, the oxygen lance height is fixed. When the oxygen blowing volume is (65-85]%, the oxygen lance height is dynamically controlled in stages. That is, the oxygen lance height is dynamically adjusted based on the flue gas information and the reference oxygen lance height.

[0062] In some embodiments, the method further includes: controlling the oxygen supply intensity in stages during the converter smelting process; wherein, when 0 ≤ oxygen blowing rate ≤ 40%, the oxygen supply intensity is slowly increased to 2.7 Nm³. 3 / (t·min)~2.9Nm 3 / (t·min); When the oxygen blowing rate is >40%, the oxygen supply intensity slowly increases to 3.0 Nm. 3 / (t·min)~3.2Nm 3 / (t·min).

[0063] The phased control of oxygen supply intensity is as follows: when the oxygen blowing rate is 0-40%, the oxygen flow rate is increased slowly; when the oxygen blowing rate is 40%, the oxygen supply intensity is controlled at 2.7 Nm.3 / (t·min)~2.9Nm 3 / (t·min), when the oxygen supply is >40%, slowly increase the oxygen supply intensity to 3.0 Nm 3 / (t·min)~3.2Nm 3 / (t·min). During the converter blowing process, the top-blown oxygen supply intensity is controlled according to the oxygen supply volume. The reason for adopting this oxygen supply system is that since a certain amount of ore is added before iron addition, there are more iron oxides in the molten pool, which is conducive to the early slag formation. Therefore, the oxygen supply intensity does not need to be too high in the early stage of smelting. If the oxygen supply intensity is too high at this time, it will lead to the molten pool heating rate being too fast, which will eventually lead to incomplete dephosphorization, slag overflow, or splashing. When 0 ≤ oxygen blowing volume ≤ 40%, the oxygen supply intensity can be slowly increased to 2.7 Nm. 3 / (t·min), 2.75m 3 / (t·min), 2.8m 3 / (t·min), 2.85m 3 / (t·min), 2.9Nm 3 / (t·min), etc.; when the oxygen blowing rate is >40%, the oxygen supply intensity can be slowly increased to 3.0 Nm. 3 / (t·min), 3.05m 3 / (t·min), 3.1m 3 / (t·min), 3.15m 3 / (t·min), 3.2Nm 3 / (t·min), etc.

[0064] In some embodiments, the method further includes: during the converter smelting process, when the oxygen blowing rate is 4% to 6%, adding a second ore; the feeding rate of the second ore is 0.8 t / min to 1.2 t / min, the total amount of the first ore and the second ore added is 26 kg / t steel to 40 kg / t steel, and the ratio of the amount of the first ore added to the total amount added is 40% to 50%.

[0065] During the converter blowing process, the iron ore feeding rate is controlled. The reason for using this feeding rate is twofold: firstly, it suppresses the rate of molten pool heating; secondly, it ensures that the molten pool temperature is maintained within a certain range, without adversely affecting the reaction rate within the furnace. For example, the feeding rate of the second ore is 0.8 t / min, 0.9 t / min, 1.0 t / min, 1.1 t / min, 1.2 t / min, etc., and the total amount of the first and second ore added is 26 kg / t steel, 30 kg / t steel, 32 kg / t steel, 35 kg / t steel, 40 kg / t steel, etc., and the ratio of the first ore added to the total added amount can be 40%, 42%, 44%, 46%, 48%, 50%, etc.

[0066] In some embodiments, the method further includes: adding limestone, lime, and lightly calcined dolomite into the furnace in stages during the converter smelting process; wherein, when 4% ≤ oxygen blowing rate ≤ 6%, limestone, lime, and lightly calcined dolomite of a first-stage addition amount are added into the furnace; the first-stage addition amount of limestone is 11 kg / t·steel to 12 kg / t·steel; the first-stage addition amount of lime is 12.5 kg / t·steel to 15 kg / t·steel; the first-stage addition amount of lightly calcined dolomite is... The initial addition amount is 8.5 kg / t·steel to 9.5 kg / t·steel; when 20% ≤ oxygen blowing amount ≤ 23%, limestone, lime, and lightly calcined dolomite with the second-stage addition amount are added to the furnace; the second-stage addition amount of limestone is 6 kg / t·steel to 8 kg / t·steel; the second-stage addition amount of lime is 12.5 kg / t·steel to 15 kg / t·steel; and the second-stage addition amount of lightly calcined dolomite is 8.5 kg / t·steel to 9.5 kg / t·steel.

[0067] The reason for adding limestone, lime and lightly calcined dolomite to the furnace in stages during the converter blowing process is that the thermal state inside the converter is different at different blowing stages. Adding limestone, lime and lightly calcined dolomite in stages not only helps with slag formation, but also helps control the thermal state inside the furnace and improve the blowing stability.

[0068] In some embodiments, the bottom-blown gas supply intensity of the converter smelting is 0.03 Nm. 3 / (t·min)~0.09Nm 3 / (t·min).

[0069] In converter smelting, controlling the bottom-blown gas supply intensity can ensure favorable kinetic conditions in the molten pool and promote chemical reactions within the pool. For example, the bottom-blown gas supply intensity in this converter smelting process can be 0.03 Nm³. 3 / (t·min), 0.04Nm 3 / (t·min), 0.05Nm 3 / (t·min), 0.06Nm 3 / (t·min), 0.08Nm 3 / (t·min), 0.09Nm 3 / (t·min), etc.

[0070] In some embodiments, the final molten steel from the converter smelting has a P content ≤0.0080% and an O content ≤0.06% by mass fraction; the final molten steel temperature from the converter smelting is 1620℃~1660℃; the final slag basicity from the converter smelting is 3.2~3.8, and the final slag TFe content is 18%~24% and the final slag MgO content is 8%~12% by mass fraction.

[0071] Controlling the molten steel temperature after tapping to 1620–1660℃ helps control the final phosphorus content in the molten steel; controlling the oxygen content after tapping to ≤0.06% ensures the furnace reaction proceeds and helps reduce alloy consumption and inclusion control in subsequent processes; controlling the final slag basicity to 3.2–3.8 ensures the final phosphorus content in the molten steel and helps slow down slag erosion of the furnace lining; controlling the final slag TFe to 14%–18% ensures the furnace chemical reaction proceeds and helps reduce metal consumption; controlling the final slag MgO to 8%–12% helps adjust slag viscosity and facilitates the implementation of subsequent slag splashing and furnace protection processes.

[0072] 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 common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0073] The following examples and comparative examples all use a 210-ton top-and-bottom blown converter for smelting.

[0074] Example 1

[0075] This embodiment provides a method for improving the stability of converter smelting based on flue gas information, including the following steps:

[0076] S11. Scrap steel, first ore, and molten iron are mixed sequentially to obtain steelmaking raw materials; the scrap steel ratio in the furnace is 11.7% of the total charge, the molten iron temperature is 1375℃, and the silicon content of the molten iron is 0.342%; the amount of first ore added is 15 kg / t steel.

[0077] S21. The steelmaking raw materials are smelted in a converter, and the CO content of the output flue gas from the converter is obtained. During the converter smelting process, when the oxygen blowing rate is 4-6%, the addition amounts of lime, limestone, and light-burned dolomite are 15 kg / t·steel, 11.5 kg / t·steel, and 8.5 kg / t·steel, respectively; when the oxygen blowing rate is 20-23%, the addition amounts of lime, limestone, and light-burned dolomite are 14.8 kg / t·steel, 6.5 kg / t·steel, and 9 kg / t·steel, respectively; when the oxygen blowing rate is 4-6%, a second ore is added at a feeding rate of 1 t / min, and the addition amount of the second ore is 18.4 kg / t·steel.

[0078] S31. When the oxygen blowing rate in the converter smelting is within the set oxygen blowing rate range, the oxygen lance height is adjusted according to the CO content; the set oxygen blowing rate range is >65% and ≤85%. When 65 < oxygen blowing rate ≤70, the CO content is 52%, and the corresponding lance position is 2.0m; when 70 < oxygen blowing rate ≤78, the CO content is 58%, and the corresponding lance position is 2.4m; when 78 < oxygen blowing rate ≤85, the CO content is 51%, and the corresponding lance position is 2.1m.

[0079] The molten steel temperature after tapping was 1626℃; the oxygen mass fraction after tapping was 0.041%; the final slag basicity was 3.76; the final slag TFe content was 19.0%; the final slag MgO content was 10.1%; there was no overflow or splashing during the entire smelting process; the dephosphorization rate and the final phosphorus content were 95.2% and 0.0044%, respectively.

[0080] Example 2

[0081] This embodiment provides a method for improving the stability of converter smelting based on flue gas information, including the following steps:

[0082] S11. Scrap steel, first ore, and molten iron are mixed sequentially to obtain steelmaking raw materials; the scrap steel ratio in the furnace is 10.3% of the total charge, the molten iron temperature is 1366℃, and the silicon content of the molten iron is 0.286%; the amount of first ore added is 17.5 kg / t steel.

[0083] S21. The steelmaking raw materials are smelted in a converter, and the CO content of the output flue gas from the converter is obtained. During the converter smelting process, when the oxygen blowing rate is 4-6%, the addition amounts of lime, limestone, and lightly calcined dolomite are 14 kg / t·steel, 11.5 kg / t·steel, and 9 kg / t·steel, respectively; when the oxygen blowing rate is 20-23%, the addition amounts of lime, limestone, and lightly calcined dolomite are 16 kg / t·steel, 6.7 kg / t·steel, and 9.5 kg / t·steel, respectively; when the oxygen blowing rate is 4-6%, a second ore is added at a feeding rate of 1 t / min, and the addition amount of the second ore is 18 kg / t·steel.

[0084] S31. When the oxygen blowing rate in the converter smelting is within the set oxygen blowing rate range, the oxygen lance height is adjusted according to the CO content; the set oxygen blowing rate range is >65% and ≤85%. When 65 < oxygen blowing rate ≤70, the CO content is 57%, and the corresponding lance position is 2.15m; when 70 < oxygen blowing rate ≤78, the CO content is 56%, and the corresponding lance position is 2.45m; when 78 < oxygen blowing rate ≤85, the CO content is 50%, and the corresponding lance position is 2.1m.

[0085] The molten steel temperature after tapping was 1638℃; the oxygen mass fraction after tapping was 0.0524%; the final slag basicity was 3.51; the final slag TFe content was 20.3%; and the final slag MgO content was 8.04%. No slag overflow or splashing occurred during the entire smelting process. The dephosphorization rate and the final phosphorus content were 94.0% and 0.0057%, respectively.

[0086] Example 3

[0087] This embodiment provides a method for improving the stability of converter smelting based on flue gas information, including the following steps:

[0088] S11. Scrap steel, first ore, and molten iron are mixed sequentially to obtain steelmaking raw materials; the scrap steel ratio in the furnace is 11% of the total charge, the molten iron temperature is 1367℃, and the silicon content of the molten iron is 0.259%; the amount of first ore added is 12.5 kg / t steel.

[0089] S21. The steelmaking raw materials are smelted in a converter, and the CO content of the output flue gas from the converter is obtained. During the converter smelting process, when the oxygen blowing rate is 4-6%, the addition amounts of lime, limestone, and lightly calcined dolomite are 13 kg / t·steel, 11.3 kg / t·steel, and 8.6 kg / t·steel, respectively; when the oxygen blowing rate is 20-23%, the addition amounts of lime, limestone, and lightly calcined dolomite are 12.2 kg / t·steel, 8.3 kg / t·steel, and 8.6 kg / t·steel, respectively; when the oxygen blowing rate is 4-6%, a second ore is added at a feeding rate of 1 t / min, and the addition amount of the second ore is 14.2 kg / t·steel.

[0090] S31. When the oxygen blowing rate in the converter smelting is within the set oxygen blowing rate range, the oxygen lance height is adjusted according to the CO content; the set oxygen blowing rate range is >65% and ≤85%. When 65 < oxygen blowing rate ≤70, the CO content is 52%, and the corresponding lance position is 2.0m; when 70 < oxygen blowing rate ≤78, the CO content is 62%, and the corresponding lance position is 2.55m; when 78 < oxygen blowing rate ≤85, the CO content is 56%, and the corresponding lance position is 2.25m.

[0091] The molten steel temperature after tapping was 1640℃; the oxygen mass fraction after tapping was 0.0575%; the final slag basicity was 3.44; the final slag TFe content was 19.1%; the final slag MgO content was 9.51%; there was no overflow or splashing during the entire smelting process; the dephosphorization rate and the final phosphorus content were 94.0% and 0.0065%, respectively.

[0092] Comparative Example 1

[0093] This comparative example provides a method for improving the stability of converter smelting, including the following steps:

[0094] S11. The scrap steel and molten iron are mixed to obtain steelmaking raw materials; the scrap steel ratio in the furnace accounts for 10.6% of the total charge, the molten iron temperature is 1375℃, and the silicon content of the molten iron is 0.198%.

[0095] S21. The steelmaking raw materials are smelted in a converter. During the converter smelting process, when the oxygen blowing rate is 4-6%, the addition amounts of lime, limestone, light-burned dolomite, and cooling slag-forming agent are 17.3 kg / t steel, 10.6 kg / t steel, 8.3 kg / t steel, and 6.4 kg / t steel, respectively. When the oxygen blowing rate is 20-23%, the addition amounts of lime, limestone, light-burned dolomite, and cooling slag-forming agent are 15.2 kg / t steel, 6.6 kg / t steel, 8 kg / t steel, and 3.4 kg / t steel, respectively. When the oxygen blowing rate is 4-6%, ore is added at a feeding rate of 1 t / min, and the amount of ore added is 15.4 kg / t steel.

[0096] The molten steel temperature after tapping was 1688℃; the oxygen mass fraction after tapping was 0.0450%; the final slag basicity was 3.09; the final slag TFe content was 16.4%; the final slag MgO content was 11.1%; some degree of slag overflow occurred in the early stage of smelting, lasting for 1.2 minutes, and slight splashing occurred in the later stage; the dephosphorization rate and the final phosphorus content were 82.1% and 0.0175%, respectively.

[0097] Furthermore, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0098] In this embodiment of the invention, the occurrence of slag overflow or splashing during the high iron consumption production process of converters can be solved.

[0099] In this embodiment of the invention, based on flue gas analysis, the converter blowing process is made efficient and stable. This invention not only avoids the human error introduced by experience in steelmaking, but also avoids the long delay effect of sonar slag formation, and can predict slag overflow or splashing in the furnace, reducing the occurrence of slag overflow and splashing during the blowing process. Under this charging condition, by controlling the dynamic lance position, not only can the occurrence of slag overflow or splashing during the blowing process be effectively avoided, but the dephosphorization reaction in the converter can also be promoted, with a dephosphorization rate of up to 95.2% and a final phosphorus content of 0.0044%, achieving efficient and stable converter production.

[0100] 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 improving stability of converter smelting based on fume information, characterized by, The method includes: Scrap steel, first ore, and molten iron are mixed sequentially to obtain steelmaking raw materials, wherein the mass percentage of scrap steel in the steelmaking raw materials is 10% to 20%. The steelmaking raw materials are smelted in a converter, and the CO content of the flue gas output from the converter is obtained. When the oxygen blowing rate in the converter smelting is within the set oxygen blowing rate range, the oxygen lance height is adjusted according to the CO content; the set oxygen blowing rate range is >65% and ≤85%. Adjusting the oxygen lance height according to the CO content includes: If, by mass fraction, 48% < the CO content < 55%, then adjust the oxygen lance height to the baseline height. If the CO content is ≤48% by mass fraction, the oxygen lance height should be adjusted to decrease by 0.15m~0.25m from the reference height. If, by mass fraction, the CO content is 55% ≤ 60%, then the oxygen lance height should be increased by 0.15m to 0.25m above the reference height. If the CO content is ≥60% by mass fraction, the oxygen lance height should be increased by 0.25m to 0.35m above the reference height. The reference height satisfies the following relationship: When 65% < oxygen blowing rate ≤ 70%, the reference height is 2.0m; When 70% < oxygen blowing rate ≤ 78%, the reference height is 2.25m; When 78% < oxygen blowing rate ≤ 85%, the reference height is 2.1m.

2. The method according to claim 1, characterized in that, The temperature of the molten iron is ≥1360℃; the Si content of the molten iron is ≥0.25% by mass fraction.

3. The method according to claim 1, characterized in that, The method further includes: controlling the oxygen lance height in stages during the converter smelting process; wherein... When 0 ≤ oxygen blowing rate ≤ 6%, the height of the oxygen lance is 2.2m; When 6% < oxygen blowing rate ≤ 28%, the height of the oxygen lance is 2.0m; When 28% < oxygen blowing rate ≤ 65%, the height of the oxygen lance is 1.8m; When 85% < oxygen blowing rate ≤ 100%, the height of the oxygen lance is 1.9m.

4. The method according to claim 1, characterized in that, The method further includes: controlling the oxygen supply intensity in stages during the converter smelting process; wherein... When 0 ≤ oxygen blowing rate ≤ 40%, the oxygen supply intensity slowly increases to 2.7 Nm. 3 / (t·min)~2.9Nm 3 / (t·min); When the oxygen blowing rate is >40%, the oxygen supply intensity slowly increases to 3.0 Nm. 3 / (t·min)~3.2Nm 3 / (t·min).

5. The method according to claim 1, characterized in that, The method further includes: during the converter smelting process, when the oxygen blowing rate is 4% to 6%, a second ore is added; the feeding rate of the second ore is 0.8 t / min to 1.2 t / min, the total amount of the first ore and the second ore added is 26 kg / t steel to 40 kg / t steel, and the ratio of the amount of the first ore added to the total amount added is 40% to 50%.

6. The method according to claim 1, characterized in that, The method further includes: adding limestone, lime, and lightly calcined dolomite into the furnace in stages during the converter smelting process; wherein... When the oxygen blowing rate is 4% ≤ oxygen blowing rate ≤ 6%, limestone, lime, and lightly calcined dolomite with the first-stage addition amount are added to the furnace; the first-stage addition amount of limestone is 11 kg / t·steel to 12 kg / t·steel; the first-stage addition amount of lime is 12.5 kg / t·steel to 15 kg / t·steel; and the first-stage addition amount of lightly calcined dolomite is 8.5 kg / t·steel to 9.5 kg / t·steel. When the oxygen blowing rate is 20% ≤ oxygen blowing rate ≤ 23%, limestone, lime, and lightly calcined dolomite with a second-stage addition amount are added to the furnace; the second-stage addition amount of limestone is 6 kg / t·steel to 8 kg / t·steel; the second-stage addition amount of lime is 12.5 kg / t·steel to 15 kg / t·steel; and the second-stage addition amount of lightly calcined dolomite is 8.5 kg / t·steel to 9.5 kg / t·steel.

7. The method of claim 1, wherein, The bottom-blown gas supply intensity for the converter smelting is 0.03 Nm. 3 / (t·min)~0.09Nm 3 / (t·min).

8. The method according to claim 1, characterized in that, By mass fraction, the final molten steel produced by the converter smelting has a P content ≤0.0080% and an O content ≤0.06%; the final molten steel temperature is 1620℃~1660℃; the final slag basicity is 3.2~3.8, and by mass fraction, the final slag TFe content is 14%~18% and the final slag MgO content is 8%~12%.

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