CN115011752A - Method for controlling slag alkalinity by adopting limestone for steelmaking of converter - Google Patents

Method for controlling slag alkalinity by adopting limestone for steelmaking of converter Download PDF

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Publication number
CN115011752A
CN115011752A CN202210568960.2A CN202210568960A CN115011752A CN 115011752 A CN115011752 A CN 115011752A CN 202210568960 A CN202210568960 A CN 202210568960A CN 115011752 A CN115011752 A CN 115011752A
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limestone
lime
converter
molten iron
weight
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CN115011752B (en
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陈国�
杨锋功
李荣祥
秦影
周惠芳
卫广运
刘健
焦雪城
王雷雷
董朝阳
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Shijiazhuang Iron and Steel Co Ltd
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Shijiazhuang Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/36—Processes yielding slags of special composition
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/40—Production or processing of lime, e.g. limestone regeneration of lime in pulp and sugar mills

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)

Abstract

A method for controlling slag alkalinity of a converter by adopting limestone for steelmaking belongs to the technical field of converter steelmaking. Firstly, the total weight S of pure lime to be added is calculated according to a formula S = C multiplied by W multiplied by 60/28 multiplied by 1- [ B + (W-D)/0.1% × N ] }multipliedby R, the weight ratio of the lime to be added to the limestone is based on 2/3, the base weight of the lime to be added to the lime and the limestone is calculated according to the content of CaO in the lime and the limestone, and then the actual weight of the lime to be added to the lime and the limestone is determined according to the temperature of molten iron to be added to the furnace and the weight content of silicon in the molten iron. The invention controls the slag alkalinity within the range of the target value R +/-0.15 to reach more than 92 percent, and has the advantages of reducing the carbon dioxide emission, reducing the cost and accurately controlling the slag alkalinity.

Description

Method for controlling slag alkalinity of converter by adopting limestone for steelmaking
Technical Field
The invention belongs to the technical field of converter steelmaking, and particularly relates to a method for controlling slag alkalinity in converter steelmaking by adopting limestone.
Background
Converter steelmaking is the mainstream production technology of steel metallurgy in the world at present, molten iron is the main raw material for converter smelting, and the temperature and the components of the molten iron have important influence on the production operation of the converter. Due to the change of the ore raw materials of the steel enterprises and the difference of the production operation of the blast furnace at present, the fluctuation of the temperature, the silicon content and the like of the molten iron produced by the blast furnace is large, and the instability of the silicon content of the molten iron can bring adverse effects to the process control and the smelting effect of the converter.
Lime used for converter steelmaking is generated by calcining limestone, and in the production process of a lime kiln, heat is provided by burning gas in the kiln, so that the temperature of the limestone is raised to be higher than the decomposition temperature, and a large amount of dust and carbon dioxide gas can be generated in the calcining process. Cooling the burnt lime to room temperature, and conveying the lime to a storage bin at the top of the converter through a belt for later use. Therefore, some steel enterprises begin to use limestone for steelmaking, the limestone is directly added into the converter for steelmaking, the limestone decomposes and absorbs the excessive heat in the early smelting stage of the converter, and calcium oxide generated by the limestone heated and decomposed participates in slagging and dephosphorization. Therefore, the use efficiency of limestone is improved, the energy waste is reduced, the generation of carbon dioxide gas and dust is reduced, and the environment protection is facilitated.
In the converter smelting process, silicon in molten iron is oxidized to release heat and is a main heat source of chemical reaction. The proper silicon content in the molten iron is beneficial to control the converter temperature, the slag alkalinity and the slag amount, but if the silicon content of the smelted molten iron is higher, a large amount of silicon elements are oxidized and released to increase the molten steel temperature in the earlier stage of converter smelting, and simultaneously silicon dioxide is generated, so that the initial slag alkalinity of the converter is reduced. The low alkalinity and the higher temperature in the earlier stage of converter blowing are very unfavorable for molten steel dephosphorization, in order to achieve the proper dephosphorization effect, proper lime needs to be added, and the alkalinity of the slag is controlled to be about 3.5, so that the adding amount of the lime is difficult to accurately control, and the converter operation is difficult.
The converter adopts limestone as a slag agent for steelmaking, and the limestone can generate a decomposition reaction in the converter to produce carbon dioxide gas, so that the amount of the carbon dioxide gas in the converter is increased. The silicon has the capability of reduction and migration under the high-temperature reduction condition, which has important significance on the control of the basicity of the converter slag. The main reaction of silicon in molten iron in the furnace is shown as follows:
[Si] +O 2 （g）=SiO 2 （s） （1）
CaCO 3 =CaO+CO 2 （g） （2）
C+CO 2 (g)=2CO(g) （3）
SiO 2 +CO=SiO（g）+CO 2 （g） （4）
SiO 2 +2C+ CO 2 (g)=SiO（g）+3CO（g） （5）
through the reaction, carbon dioxide generated by limestone decomposition reacts with carbon in the molten steel to form carbon monoxide, the carbon monoxide reduces silicon dioxide in the slag to generate silicon monoxide gas, and the silicon monoxide gas is discharged along with flue gas, so that the silicon content in the slag is reduced, the alkalinity of final slag is increased, the slag condition is unstable, the viscosity of the slag is increased, and the slag is seriously splashed. Therefore, when the converter adopts limestone for smelting, the proper final slag alkalinity needs to be ensured by adjusting the adding amount of the limestone and the lime.
Disclosure of Invention
In order to solve the technical problem, the invention provides a method for controlling the slag alkalinity of a converter by adopting limestone for steelmaking. The invention adopts the following technical scheme:
a method for controlling the slag alkalinity of a converter in the process of steelmaking by adopting limestone comprises the following steps:
(1) calculating the reduced lime amount S in kg according to the formula S = C × W × 60/28 × {1- [ B + (W-D)/0.1% × N ] } × R;
the converted lime amount S in the furnace refers to the total weight of pure lime which needs to be added after the limestone and lime are converted into the pure lime;
c is the nominal capacity of the converter, unit kg;
w is the weight content of silicon in molten iron, unit%;
b is the desilication base number, and the fixed value is 15 percent;
d is the reference weight content of silicon in the molten iron, and the fixed value is 0.3%;
n is a desiliconization coefficient, and a fixed value is 2.2%;
r is a target value of the slag alkalinity;
(2) the weight ratio of the lime to the limestone in the furnace is based on 2/3, and the reference weight of the lime to the limestone is calculated according to the content of CaO in the lime and the limestone; determining the actual weight of lime and limestone in the furnace according to the temperature of molten iron in the furnace and the weight content of silicon in the molten iron:
on the basis of the reference weight content of silicon in molten iron being 0.30 percent and the reference temperature of molten iron entering a furnace being 1300 ℃, the actual weight of limestone entering the furnace is increased by 20kg on the basis of the reference weight to replace the corresponding lime amount when the weight content of silicon in the molten iron is increased by 0.01 percent or the temperature of molten iron entering the furnace is increased by 1 ℃; when the weight content of silicon in the molten iron is reduced by 0.01 percent or the temperature of the molten iron entering the furnace is reduced by 1 ℃, the actual weight of limestone entering the furnace is reduced by 20kg on the basis of the reference weight and the corresponding lime amount is increased;
(3) adding limestone in batches within 2-6 min of blowing, wherein the converter is operated at a high lance position during blowing, and the limestone is not used for adjusting the alkalinity of the slag in the middle and later smelting periods.
The weight content of silicon in the molten iron used for smelting in the converter is 0.30-0.65%.
In the step (3), limestone is added in batches after the temperature in the converter is more than or equal to 1350 ℃, and the addition amount of each batch of limestone is 10-100% of the total weight of the limestone; the converter is opened and blown by high lance position operation, and the oxygen supply intensity is 3-4 Nm 3 Steel/min. t.
The method controls the slag alkalinity within the range of a target value R +/-0.15 to be more than or equal to 92 percent.
The method comprises the step of intensively adding limestone in batches within 2-6 min of blowing so as to avoid a silicomanganese oxidation period at the beginning of blowing and a slag drying stage in the middle stage of blowing. The limestone is ensured to react rapidly through the high-temperature environment in the furnace, the weight of carbon dioxide generated by decomposing the limestone is more than or equal to 8kg/t, and a stable high-concentration carbon dioxide atmosphere is formed in the furnace, so that reaction conditions are created for desilication reaction and escape in the furnace.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: (1) the limestone is adopted for direct steelmaking, so that the calcination of the limestone is reduced, the emission of dust and greenhouse gas carbon dioxide is reduced, the energy is saved, the environment is protected, and the cost of steel per ton can be reduced by 2-6 yuan due to the limestone steelmaking. (2) The method can adapt to the silicon component of the molten iron with wide variation range, can accurately control the alkalinity of the slag, and ensures the stability of the desulphurization and dephosphorization of the slag. (3) Because of the gasification of SiO, when the alkalinity is fixed, the total amount of lime needed by the slag is reduced, the method can be better applied to high-silicon molten iron, and on the premise of ensuring the stability of the alkalinity of the slag, the total amount of the lime needed by conversion is reduced, and the total weight of the slag is reduced.
Detailed Description
The technical index requirements of the limestone and lime used in the method are as follows:
CaO in the limestone is more than or equal to 51wt%, SiO 2 Less than or equal to 2.5wt% and the granularity is 20-40 mm;
CaO in the lime is more than or equal to 85wt%, SiO 2 Less than or equal to 3.5wt%, less than or equal to 5wt% of MgO, less than or equal to 0.1wt% of S, and the granularity of 30-70 mm.
Example 1
In the embodiment, a converter with a nominal capacity of 60t is adopted for smelting, the weight content of silicon in molten iron used for smelting is 0.3%, and the temperature of the molten iron is 1300 ℃. The specific process steps are as follows:
(1) the target value R of the slag alkalinity is 3.3, B is the desilication base number, and the fixed value is 15 percent; d is the reference weight content of silicon in the molten iron, and the fixed value is 0.3%; n is a desilication coefficient, and the constant value is 2.2%. The reduced lime feed (i.e. the total weight of pure lime to be added) S to the furnace was calculated to be 1082kg according to the formula S = C × W × 60/28 × {1- [ B + (W-D)/0.1% × N ] } × R.
(2) The weight ratio of the lime to the limestone is 2/3, the CaO content in the lime is 85%, the CaO content in the limestone is 51%, and the basis weight of the lime to the limestone is 670kg and 1005kg respectively. Because the weight content of silicon in the molten iron is 0.3 percent, the temperature of the molten iron is 1300 ℃, and the reference weight of the lime and the limestone entering the furnace is the actual weight.
(3) After the converter is charged, the converter is opened and blown by adopting high lance position operation, and the oxygen supply intensity is 4Nm 3 And (2) min. t steel, after blowing for 2min, observing that the temperature in the flame furnace reaches 1350 ℃, adding limestone into the furnace in 3 batches, wherein the adding weight of each batch of limestone is 50%, 30% and 20% of the total weight of the limestone, completely adding the limestone within 6min, adding certain lime into the limestone in 2 nd and 3 rd batches, and adding the rest lime into the furnace in the middle and later smelting periods.
After smelting, taking a converter slag sample for fluorescence detection, wherein the components are as follows: TFe: 18.39% of SiO 2 ：12.47%，CaO：41.94%，MgO：5.67%，Al 2 O 3 ：2.42%，TiO 2 ：0.71%，MnO：5.3%，P 2 O 5 ：3.056%，CaF 2 : 1.41 percent; actual basicity R 2 : 3.36, the requirement of the target value of 3.3 +/-0.15 is met, and the method is proved to be effective in controlling the slag alkalinity.
Example 2
In this example, a converter with a nominal capacity of 100t is used for smelting, the weight content of silicon in molten iron used for smelting is 0.4%, and the temperature of the molten iron is 1310 ℃. The specific process steps are as follows:
(1) the target value R of the slag alkalinity is 3.5, B is the desilication base number, and the fixed value is 15 percent; d is the reference weight content of silicon in the molten iron, and the fixed value is 0.3%; n is a desiliconization coefficient, and the fixed value is 2.2%. The reduced lime feed (i.e. the total weight of pure lime to be added) S to the furnace was calculated to be 2484kg according to the formula S = C × W × 60/28 × {1- [ B + (W-D)/0.1% × N ] } × R.
(2) The weight ratio of the lime to the limestone is 2/3, the CaO content in the lime is 87%, the CaO content in the limestone is 53%, and the weight of the lime to the limestone is 1492kg and 2238 kg. The temperature of the molten iron entering the furnace is 10 ℃ higher than the reference temperature, and the weight content of silicon in the molten iron is 0.1% higher than the reference weight content, so that the actual weight of the limestone entering the furnace is increased by 400kg on the basis of the reference weight, and the corresponding actual weight of the lime is reduced by 240 kg. Therefore, the adding amount of lime is 1252kg, the adding amount of limestone is 2638kg, and the charging ratio of lime to limestone is 0.47.
(3) After the converter is charged, the converter is opened and blown by adopting high lance position operation, and the oxygen supply intensity is 3.5Nm 3 And (2) blowing for 2min, observing that the temperature in the flame furnace reaches 1350 ℃, adding limestone into the furnace in 3 batches, wherein the adding weight of limestone in each batch accounts for 40%, 40% and 20% of the total weight of the limestone respectively, completely adding limestone within 6min, adding certain lime into limestone in each batch, and adding the rest lime into the furnace in the middle and later smelting periods.
After smelting, taking a converter slag sample for fluorescence detection, wherein the components are as follows: TFe: 17.09% of SiO 2 ：12.91%，CaO：44.29%，MgO：4.67%，Al 2 O 3 ：2.24%，TiO 2 ：0.76%，MnO：5.46%，P 2 O 5 ：3.51%，CaF 2 : 1.53 percent; actual basicity R 2 : 3.43, the requirement of the target value of 3.5 +/-0.15 is met, and the method is proved to be effective in controlling the slag alkalinity.
Example 3
In the embodiment, a converter with a nominal capacity of 120t is adopted for smelting, the weight content of silicon in molten iron used for smelting is 0.5%, and the temperature of the molten iron is 1305 ℃. The specific process steps are as follows:
(1) the target value R of the slag alkalinity is 3.2, B is the desilication base number, and the fixed value is 15 percent; d is the reference weight content of silicon in the molten iron, and the fixed value is 0.3%; n is a desiliconization coefficient, and the fixed value is 2.2%. The reduced lime feed (i.e. the total weight of pure lime to be added) S to the furnace is calculated according to the formula S = C × W × 60/28 × {1- [ B + (W-D)/0.1% × N ] } × R to 3316 kg.
(2) The weight ratio of the lime to the limestone is 2/3, the CaO content in the lime is 85%, the CaO content in the limestone is 51%, and the basis weight of the lime to the limestone is 2053kg and 3080 kg. The temperature of the molten iron entering the furnace is 5 ℃ higher than the reference temperature, and the weight content of silicon in the molten iron is 0.2% higher than the reference weight content, so that the actual weight of the limestone entering the furnace is increased by 500kg on the basis of the reference weight, and the corresponding actual weight of the lime is reduced by 300 kg. Therefore, the adding amount of lime is 1753kg, the adding amount of limestone is 3580kg, and the charging ratio of the lime to the limestone is 0.49.
(3) After the converter is charged, the converter is opened and blown by adopting high lance position operation, and the oxygen supply intensity is 3.3Nm 3 And (2) blowing for 2min, observing that the temperature in the flame furnace reaches 1350 ℃, adding limestone into the furnace in 3 batches, wherein the adding weight of limestone in each batch accounts for 30%, 50% and 20% of the total weight of limestone respectively, completely adding limestone within 6min, adding certain lime into 1 st and 3 rd batches of limestone, and adding the rest lime into the furnace in the middle and later smelting periods.
After smelting, taking a converter slag sample for fluorescence detection, wherein the components are as follows: TFe: 13.74% of SiO 2 ：14.98%，CaO：47.62%，MgO：6.02%，Al 2 O 3 ：3.02%，TiO 2 ：0.85%，MnO：5.51%，P 2 O 5 ：4.19%，CaF 2 : 1.33 percent; actual basicity R 2 : 3.18, the requirement of the target value of 3.2 +/-0.15 is met, and the method is proved to be effective in controlling the alkalinity of the slag.
Example 4
In the embodiment, a converter with a nominal capacity of 100t is adopted for smelting, the weight content of silicon in molten iron used for smelting is 0.65%, and the temperature of the molten iron is 1325 ℃. The specific process steps are as follows:
(1) the target value R of the slag alkalinity is 3.3, B is the desilication base number, and the fixed value is 15 percent; d is the reference weight content of silicon in the molten iron, and the fixed value is 0.3%; n is a desiliconization coefficient, and the fixed value is 2.2%. The reduced lime feed (i.e. the total weight of pure lime to be added) S to the furnace was calculated to be 3553kg according to the formula S = C × W × 60/28 × {1- [ B + (W-D)/0.1% × N ] } × R.
(2) The weight ratio of the lime to the limestone is 2/3, the CaO content in the lime is 85%, the CaO content in the limestone is 51%, and the basis weight of the lime to the lime is 2200kg and the basis weight of the limestone is 3300 kg. The temperature of the molten iron entering the furnace is 25 ℃ higher than the reference temperature, and the weight content of silicon in the molten iron is 0.35% higher than the reference weight content, so that the actual weight of the limestone entering the furnace is increased by 1200kg on the basis of the reference weight, and the corresponding actual weight of the lime is reduced by 720 kg. Therefore, the lime addition is 1480kg, the limestone addition is 4500kg, and the charging ratio of lime to limestone is 0.33.
(3) After the converter is charged, the converter is opened and blown by adopting high lance position operation, and the oxygen supply intensity is 3.8Nm 3 And (2) blowing for 3min, observing that the temperature in the flame furnace reaches 1350 ℃, adding limestone into the furnace in 3 batches, wherein the adding weight of limestone in each batch accounts for 50%, 25% and 25% of the total weight of limestone respectively, completely adding limestone within 6min, adding certain lime into limestone in the last two batches, and adding the rest lime into the furnace in the middle and later smelting periods.
After smelting, taking a converter slag sample for fluorescence detection, wherein the components are as follows: TFe: 19.77% of SiO 2 ：12.7%，CaO：41.03%，MgO：4.23%，Al 2 O 3 ：1.97%，TiO 2 ：0.76%，MnO：4.82%，P 2 O 5 ：2.09%，CaF 2 : 1.36 percent; actual basicity R 2 : 3.23, the requirement of the target value of 3.3 +/-0.15 is met, and the method is proved to be effective in controlling the alkalinity of the slag.
Example 5
In this example, a converter with a nominal capacity of 100t is used for smelting, the weight content of silicon in molten iron used for smelting is 0.45%, and the temperature of the molten iron is 1310 ℃. The specific process steps are as follows:
(1) the target value R of the slag alkalinity is 3.2, B is the desilication base number, and the fixed value is 15 percent; d is the reference weight content of silicon in the molten iron, and the fixed value is 0.3%; n is a desiliconization coefficient, and the fixed value is 2.2%. The converted lime amount (i.e. the total weight of pure lime to be added) S to the furnace is calculated according to the formula S = C × W × 60/28 × {1- [ B + (W-D)/0.1% × N ] } × R to be 2521 kg.
(2) The weight ratio of the lime to the limestone is 2/3, the CaO content in the lime is 85%, the CaO content in the limestone is 51%, and the weight of the lime to the limestone is 1561kg and 2341kg respectively. The temperature of the molten iron entering the furnace is 10 ℃ higher than the reference temperature, and the weight content of silicon in the molten iron is 0.15% higher than the reference weight content, so that the actual weight of the limestone entering the furnace is increased by 500kg on the basis of the reference weight, and the corresponding actual weight of the lime is reduced by 300 kg. Therefore, the lime adding amount is 1261kg, the limestone adding amount is 2841kg, and the charging ratio of lime to limestone is 0.44.
(3) After the converter is charged, the converter is opened and blown by adopting high lance position operation, and the oxygen supply intensity is 3.2Nm 3 And (2) blowing for 2min, observing that the temperature in the flame furnace reaches 1350 ℃, adding limestone into the furnace in 3 batches, wherein the adding weight of limestone in each batch accounts for 40%, 50% and 10% of the total weight of limestone respectively, completely adding limestone within 6min, adding certain lime into the limestone in the first two batches, and adding the rest lime into the furnace in the middle and later smelting periods.
After smelting, taking a converter slag sample for fluorescence detection, wherein the components are as follows: TFe: 18.9% of SiO 2 ：12.4%，CaO：41.04%，MgO：5.4%，Al 2 O 3 ：2.51%，TiO 2 ：0.75%，MnO：5.32%，P 2 O 5 ：2.92%，CaF 2 : 1.41 percent; actual basicity R 2 : 3.31, the requirement of the target value of 3.2 +/-0.15 is met, and the method is proved to be effective in controlling the alkalinity of the slag.
Example 6
In the embodiment, a converter with a nominal capacity of 100t is adopted for smelting, the weight content of silicon in molten iron used for smelting is 0.65%, and the temperature of the molten iron is 1325 ℃. The specific process steps are as follows:
(1) the target value R of the slag alkalinity is 3.5, B is the desilication base number, and the fixed value is 15 percent; d is the reference weight content of silicon in the molten iron, and the fixed value is 0.3%; n is a desiliconization coefficient, and the fixed value is 2.2%. The reduced lime feed (i.e. the total weight of pure lime to be added) S to the furnace was calculated according to the formula S = C × W × 60/28 × {1- [ B + (W-D)/0.1% × N ] } × R to be 3768 kg.
(2) The weight ratio of the lime to the limestone is 2/3, the CaO content in the lime is 85%, the CaO content in the limestone is 51%, and accordingly, the weight of the lime to be smelted is 2333kg, and the weight of the limestone is 3500 kg. The temperature of the molten iron entering the furnace is 25 ℃ higher than the reference temperature, and the weight content of silicon in the molten iron is 0.35% higher than the reference weight content, so that the actual weight of the limestone entering the furnace is increased by 1200kg on the basis of the reference weight, and the corresponding actual weight of the lime is reduced by 720 kg. Therefore, the adding amount of lime is 1613kg, the adding amount of limestone is 4700kg, and the charging ratio of lime and limestone is 0.34.
(3) After the converter is charged, the converter is opened and blown by adopting high lance position operation, and the oxygen supply intensity is 3.8Nm 3 And (3) blowing for 3min, observing that the temperature in the flame furnace reaches 1350 ℃, adding 1 batch of limestone into the furnace, adding a certain amount of lime subsequently after the limestone is added, and adding the rest lime into the furnace in the middle and later smelting periods.
After smelting, taking a converter slag sample for fluorescence detection, wherein the components are as follows: TFe: 19.77% of SiO 2 ：12.7%，CaO：41.03%，MgO：4.23%，Al 2 O 3 ：1.97%，TiO 2 ：0.76%，MnO：4.82%，P 2 O 5 ：2.09%，CaF 2 : 1.36 percent; actual basicity R 2 : 3.23, the requirement of the target value of 3.3 +/-0.15 is met, and the method is proved to be effective in controlling the alkalinity of the slag.
According to statistics, the proportion of controlling the slag alkalinity within the range of the target value R +/-0.15 to 92.26% according to the data of 500 heats of a certain steel mill.

Claims (6)

1. A method for controlling slag alkalinity in converter steelmaking by adopting limestone is characterized by comprising the following steps:
(1) calculating the converted lime amount S in kg into the furnace according to the formula S = C × W × 60/28 × {1- [ B + (W-D)/0.1% × N ] } × R;
the converted lime amount S in the furnace refers to the total weight of pure lime which needs to be added after the limestone and lime are converted into the pure lime;
c is the nominal capacity of the converter in kg;
w is the weight content of silicon in molten iron, unit%;
b is the desilication base number, and the fixed value is 15 percent;
d is the reference weight content of silicon in the molten iron, and the fixed value is 0.3%;
n is a desiliconization coefficient, and a fixed value is 2.2%;
r is a target value of slag alkalinity;
(2) the weight ratio of the lime to the limestone in the furnace is based on 2/3, the reference weight of the lime to the limestone is calculated according to the content of CaO in the lime and the limestone, and the actual weight of the lime to the limestone is determined according to the temperature of molten iron in the furnace and the weight content of silicon in the molten iron:
on the basis of the reference weight content of silicon in molten iron being 0.30 percent and the reference temperature of molten iron entering a furnace being 1300 ℃, the actual weight of limestone entering the furnace is increased by 20kg on the basis of the reference weight to replace the corresponding lime amount when the weight content of silicon in the molten iron is increased by 0.01 percent or the temperature of molten iron entering the furnace is increased by 1 ℃; when the weight content of silicon in the molten iron is reduced by 0.01 percent or the temperature of the molten iron fed into the furnace is reduced by 1 ℃, the actual weight of limestone fed into the furnace is reduced by 20kg on the basis of the reference weight and the corresponding lime amount is increased;
(3) adding limestone in batches within 2-6 min of blowing, wherein the converter is operated at a high lance position during blowing, and the limestone is not used for adjusting the alkalinity of the slag in the middle and later smelting periods.
2. The method for controlling the basicity of slag in the steelmaking of limestone in a converter according to claim 1, wherein: the weight content of silicon in the molten iron used for smelting in the converter is 0.30-0.65%.
3. The method for controlling the basicity of slag in the steelmaking of limestone in a converter according to claim 2, wherein: in the step (3), the addition amount of each batch of limestone is 10-100% of the total weight of limestone.
4. The method for controlling the basicity of slag in the steelmaking of limestone in a converter according to claim 3, wherein: in the step (3), limestone is added in batches after the temperature in the converter is more than or equal to 1350 ℃.
5. The method for controlling the basicity of slag in the steelmaking of limestone in a converter according to claim 4, wherein: in the step (3), the converter is started and blown by adopting high lance position operation, and the oxygen supply intensity is 3-4 Nm 3 The steel is/min t.
6. The method for controlling the basicity of slag in the steelmaking of limestone in a converter according to any one of claims 1 to 5, wherein: the method controls the slag alkalinity within the range of a target value R +/-0.15 to be more than or equal to 92 percent.
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WO2014112432A1 (en) * 2013-01-18 2014-07-24 Ｊｆｅスチール株式会社 Converter steelmaking process
CN109136456A (en) * 2018-11-08 2019-01-04 宝钢湛江钢铁有限公司 A kind of method of converter application lime stone steel-making
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5743919A (en) * 1980-08-30 1982-03-12 Kawasaki Steel Corp Method for blow refining in top and/or bottom-blown converter
JPS60230932A (en) * 1984-04-28 1985-11-16 Toshin Seikou Kk Method for operating electric furnace for manufacturing steel
JP2001262214A (en) * 2000-03-16 2001-09-26 Kawasaki Steel Corp Method for refining molten iron alloy
JP2002047508A (en) * 2000-07-31 2002-02-15 Kobe Steel Ltd Blowing method in converter
CN101117651A (en) * 2006-07-31 2008-02-06 宝山钢铁股份有限公司 Converting process for converter low-silicon molten iron
EP2213753A1 (en) * 2009-02-02 2010-08-04 AKADEMIA GORNICZO-HUTNICZA im. Stanislawa Staszica Method of production of a slag-forming compound for secondary steel refining in a ladle or ladle furnace
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CN109136456A (en) * 2018-11-08 2019-01-04 宝钢湛江钢铁有限公司 A kind of method of converter application lime stone steel-making
CN110373511A (en) * 2019-07-17 2019-10-25 邯郸钢铁集团有限责任公司 A kind of converter smelting process of low lime consumption

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