A method for heat compensation of a converter in a low iron consumption production mode
By using coal blocks for heat compensation in the low iron consumption production mode, the problem of insufficient final temperature in the converter steelmaking process was solved, achieving efficient temperature control and equipment protection, and reducing production costs.
Patent Information
- Application Number
- CN202311150061.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-07
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2043-09-07
AI Technical Summary
In the low iron consumption production mode, the heat compensation method when the final temperature is insufficient in the converter steelmaking process has problems such as steel over-oxidation, aggravated furnace lining erosion, and high cost. The existing heat compensation method is not ideal.
Coal blocks are used for thermal compensation. Based on the molten iron temperature and scrap steel ratio, coal blocks are added after the converter starts blowing. After the semi-oxidation period, slag formation is carried out. The amount and timing of coal block addition are controlled to avoid over-oxidation and furnace lining erosion, and to increase the final temperature.
It improves the accuracy of the final temperature, reduces steel over-oxidation, extends the service life of the furnace lining, reduces costs, increases steel yield, and avoids equipment damage and explosion risks.
Smart Images
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of steelmaking production, and in particular to a method for heat compensation of a converter under a low iron consumption production mode. BACKGROUND
[0002] Under the condition of a certain blast furnace ironmaking capacity, the converter needs to improve the steelmaking capacity, and the low iron consumption and high scrap steel ratio production mode is an important way. The steelmaking plant of Shandong Iron and Steel Group Yongfeng Lingang Co., Ltd. adopts a long process route of "converter-LF refining furnace-continuous casting", in order to improve the steelmaking capacity, an ultra-low iron consumption production mode with iron consumption of less than or equal to 720 kg / t is adopted.
[0003] Under the ultra-low iron consumption production mode, the biggest problem is the problem of heat balance. When the end temperature is insufficient, it is necessary to supplement and raise the temperature by blowing, so as to increase the tapping temperature to the process requirement temperature of the steel grade, and to ensure the normal production order.
[0004] In order to avoid the end temperature from being insufficient to supplement and raise the temperature by blowing, the company also adopts the method of adding low-silicon iron from the scrap steel bucket and adding coke from the bin after blowing to perform heat compensation, but the effect is not ideal. The following problems are caused:
[0005] 1. The method of directly supplementing and raising the temperature by blowing causes the steel to be over-oxidized due to the low carbon content in the steel at the end, and the heat source mainly comes from the heat released by the oxidation reaction of the blown oxygen and the metal iron. The method of directly supplementing and raising the temperature by blowing will cause the molten steel to be over-oxidized, reduce the molten steel yield, and aggravate the erosion of the furnace lining, thereby shortening the service life of the furnace lining.
[0006] 2. The method of directly supplementing and raising the temperature by blowing causes the slag to be over-oxidized, and the slag foams during the tapping and steel tapping process, which is easy to scald the lower equipment, increase the consumption of the pressure slag material, and the decrease of the slag amount will also affect the effect of slag splashing and furnace protection.
[0007] 3. The method of adding low-silicon iron into the scrap steel bucket to perform heat compensation has a high alloy price and cost. In order to ensure the dephosphorization efficiency, lime needs to be added to maintain the basicity, which causes the slag amount to increase, the slag takes away part of the FeO, and affects the molten steel yield.
[0008] 4. The method of using coke to perform heat compensation has a slow combustion speed of coke, and after the smelting medium period, the temperature of the molten pool rises rapidly, the carbon-oxygen reaction speed is fast, and the metal spatter caused by dryness is easy to appear, and there is a risk of explosion caused by the leakage of the oxygen lance into the furnace due to the sticking of the oxygen lance to the steel. Therefore, a method for heat compensation of a converter under a low iron consumption production mode needs to be designed to solve the above problems. SUMMARY
[0009] In view of the problems in the prior art, the purpose of the present application is to provide a method for heat compensation of a converter under a low iron consumption production mode.
[0010] The technical scheme adopted by the present application to solve its technical problems is: a method for heat compensation of a converter in a low-iron-consumption production mode, comprising the following steps:
[0011] S1. In the low-iron-consumption production mode, when the end point temperature is insufficient, the converter uses coal blocks for heat compensation;
[0012] S2. According to the molten iron temperature and the molten iron scrap ratio, coal blocks are added after the converter is blown and ignited;
[0013] S3. 500-800 kg of coal blocks are added after the semi-oxygen point ignition is normal;
[0014] S4. If coal blocks need to be added again, the added coal blocks need to be added at the same time as the first batch of materials, and the addition point is immediately after the semi-oxygen ends;
[0015] S5. The process is well predicted and controlled during smelting, and the slag is returned to dry and the poor slag is timely relieved;
[0016] S6. For poor ignition, first treat the ignition problem, add coal blocks and magnesium balls with the first batch of materials, and perform slagging operation.
[0017] Specifically, when the end point temperature in step S1 is lower than 1380℃, coal blocks are added.
[0018] Specifically, in step S2, the mass percentage of the molten iron scrap ratio is C: 4.31%-4.45%, Si: 0.33%-0.45%, Mn: 0.27%, P: 0.126%-0.13%, and S: 0.017%-0.018%.
[0019] Specifically, in step S3, each 100 kg of coal blocks increases the temperature by 2-4℃, the maximum addition of a single furnace is ≤1500 kg, and each 100 kg of coal blocks increases the oxygen consumption by 60-80 m 3 .
[0020] Specifically, the semi-oxygen time in step S4 is 60 seconds.
[0021] Specifically, the upper limit of the amount of coal blocks added in step S6 cannot exceed 800 kg.
[0022] The present application has the following beneficial effects:
[0023] The method for heat compensation of a converter in a low-iron-consumption production mode designed by the present application can improve the first hit rate of the end point temperature and reduce the frequency of post-blowing temperature raising. Using coal blocks for heat compensation can effectively avoid over-oxidation of the end point molten steel, slow down the erosion speed of the furnace lining, prolong the service life of the furnace lining, and improve the molten steel yield. DETAILED DESCRIPTION
[0024] The technical solutions in the embodiments of the present application will be further clearly and completely explained below. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of the present application.
[0025] A method for heat compensation of a converter in a low-iron-consumption production mode. In the low-iron-consumption production mode, when the estimated endpoint temperature is insufficient, the converter uses coal blocks for heat compensation. According to the composition of the molten iron temperature and the molten iron scrap ratio, coal blocks are added after the converter is blown and ignited, and slag is added for slagging operation after the end of the semi-oxygen period.
[0026] I. Key points of coal block usage process control.
[0027] 1. Considering the impact of coal block addition timing on environmental protection and ensuring efficient utilization, 500-800 kg of coal blocks are added after normal ignition at the semi-oxygen point. The pre-melting effect of coal blocks and the pre-temperature raising effect are improved by taking advantage of the minimum slag amount and air blowing characteristics during this period, to avoid poor furnace mouth smoke.
[0028] If additional coal blocks are needed, they should be added at the same time as the first batch of material, and the addition node is immediately after the end of the semi-oxygen period (the semi-oxygen period is 60 seconds), to avoid excessive concentrated addition leading to "69" flying guns.
[0029] 2. The temperature raising effect of 100 kg of coal blocks is considered to be 2-4°C. The best melting and temperature raising effect of coal blocks and utilization rate are considered, and the maximum addition per furnace is ≤1500 kg.
[0030] 3. 100 kg of coal blocks increases oxygen consumption by 60-80 m 3 Therefore, the blowing time needs to be estimated based on the actual addition amount (throat diameter 42 mm, blowing time extended by 6-8 s).
[0031] 4. The smelting process of coal block addition furnace is prone to increased dry return, poor slag inversion, and other phenomena. Process prediction and control should be done during smelting to timely alleviate the conditions of slag dry return and poor slag inversion, to meet the endpoint control requirements. Secondly, the addition of coal blocks in the smelting process of the furnace has a low molten iron materialization heat, and the slag condition and scrap steel sticking phenomenon are verified as much as possible.
[0032] 5. The relationship between the amount of coal blocks added and the molten iron materialization index (reference molten iron materialization index, charging amount, and endpoint temperature, refer to the table below for flexible adjustment but the upper limit of the addition amount should be controlled, the basic charging amount is 108+50 t).
[0033] 6. For poor ignition furnace, first treat the ignition problem. After missing the "69" stage, the coal blocks and magnesium balls of the first batch of material are added together, and the upper limit cannot exceed 800 kg.
[0034] II. Lump coal feeding table
[0035] Temperature of molten iron (°C) Si content (%) Coal block addition amount 1370-1380 ＜0.40 800 kg 1350-1370 1000 kg 1330-1350 1300 kg ＜1330 1500 kg
[0036] III. Lump coal composition table
[0037]
[0038]
[0039] IV. Application examples
[0040] Example 1: 1# converter G00543 on July 12, 2023
[0041] 1. Basic information
[0042]
[0043] 2. Process control situation
[0044]
[0045] 3. End point situation
[0046]
[0047] Example 2: 2# converter G00390 on July 8, 2023
[0048] 1. Basic information
[0049]
[0050] 2. Process control situation
[0051]
[0052] 3. End point situation
[0053]
[0054] 1. The price of lump coal is relatively low compared to low-silicon iron and coke, and the temperature-raising effect is close to that of coke. Through testing, the temperature-raising range of each 100 kg of lump coal is about 3°C, reducing the frequency of converter blow temperature-raising, which is beneficial to improve the yield of molten steel.
[0055] 2. Reducing the frequency of end-point molten steel over-oxidation, reducing the frequency of slag foaming during tapping, reducing the slag tapping at the large furnace mouth during converter tapping, which is beneficial to slag splashing and furnace protection operation, prolonging the service life of the furnace lining.
[0056] 3. After reducing the frequency of end-point over-oxidation, the erosion of the furnace lining is slowed down, which is beneficial to prolong the service life of the furnace lining.
[0057] 4. The combustion speed is faster than that of coke, which is beneficial to slow down the intensity of the medium-term carbon-oxygen reaction, and avoid explosion caused by water leakage into the furnace.
[0058] 5. The coal blocks are added at the initial smelting stage to increase the temperature, which is beneficial to the temperature increasing speed of the molten pool before the converter under the ultra-low iron consumption production mode, promotes early slagging of the converter at the initial stage, improves the dephosphorization efficiency of the converter, and promotes the improvement of the molten steel quality.
[0059] The present application is not limited to the above-mentioned embodiments, and any person should know that the structural changes made under the inspiration of the present application fall within the protection scope of the present application.
[0060] The technical, shape and structure parts not described in detail in the present application are all known technologies.
Claims
1. A method for thermal compensation in a low iron consumption production mode in a converter, characterized in that, The method comprises the following steps: S1, in a low iron consumption production mode, when the end point temperature is insufficient, the end point temperature is lower than 1380 DEG C, and coal blocks are added for heat compensation of the converter; S2, according to the molten iron temperature and the molten iron scrap ratio, coal blocks are added after the converter is blown and ignited; S3, after the normal ignition of the semi-oxygen point, 500-800 kg of coal blocks are added; the temperature is increased by 2-4 ℃ for every 100 kg of coal blocks added, the maximum addition of a single furnace is ≤1500 kg, and the oxygen consumption is increased by 60-80 m 3 3 for every 100 kg of coal blocks added; S4, if coal blocks need to be added again, the added coal blocks are added simultaneously with the first batch of materials, and the added node is immediately added after the half oxygen is completed; S5, process prediction and control are well done in the smelting process, and the conditions of slag returning to dry and poor slag pouring are timely relieved; S6, for a poor ignition furnace, firstly, the ignition problem is handled, the coal blocks and the magnesium balls of the first batch of materials are added together, and slagging operation is performed.
2. The method of claim 1, wherein the hot compensation of the low iron loss production mode of the converter is characterized by, The mass percentage of the molten iron scrap ratio in the step S2 is C: 4.31%-4.45%, Si: 0.33%-0.45%, Mn: 0.27%, P: 0.126%-0.13%, and S: 0.017%-0.018%.
3. The method of claim 1, wherein the hot compensation of the low iron loss production mode of the converter is characterized by, The half oxygen time in the step S4 is 60 seconds.
4. The method of claim 1, wherein the hot compensation of the low iron loss production mode of the converter is characterized by, The upper limit of the coal block addition amount in the step S6 cannot exceed 800 kg.