A converter steelmaking slag system with low MgO content and ultra-high phosphorus distribution ratio

Abstract

The present application relates to a converter steelmaking slag system with low MgO content and ultra-high phosphorus distribution ratio, belonging to the technical field of steelmaking process. The slag-making materials of the slag system include the following components: 40-60 kg / t·steel of lime, 35-40 kg / t·steel of ore, and 0-5 kg / t·steel of light-burned dolomite. The activity coefficient of phosphorus in the steel slag is reduced and the activity coefficient of FeO is increased by reducing the MgO content in the steel slag.

Description

Technical Field

[0001] The present application relates to the technical field of steelmaking process, and in particular to a converter steelmaking slag system with low MgO content and ultra-high phosphorus distribution ratio. Background Art

[0002] At present, the smelting process and technology of low-phosphorus steel at home and abroad are relatively mature, and the most efficient method is generally to use the converter double-link method for smelting. The converter double-link method is a smelting method in which semi-steel is produced after the dephosphorization stage, the high-phosphorus slag is separated from the molten steel, and the pre-dephosphorized molten iron is returned to the converter or added to other converters. After the dephosphorization, the carbon content of the molten iron is generally about 3.0%, and the phosphorus content of the molten iron is about 0.030%; after the dephosphorization period, the molten steel and the slag are separated. The double-link method is widely used in Japan, South Korea, and China.

[0003] The steelmaking slag commonly used in converter low-phosphorus steel smelting is high-basicity (R≥4.0) and high iron oxide content (FeO: 20%-30%) steel slag. In order to protect the furnace lining, the magnesium oxide content in the steel slag is high, and the MgO content of the steel slag is between 6% and 12%. After the entire dephosphorization, the phosphorus content of the molten steel is controlled at 20-40ppm.

[0004] At present, there is no research or report on the use of low MgO (MgO%≤4.5%) converter steelmaking slag system in converter low-phosphorus steelmaking. Summary of the invention

[0005] In order to solve the above technical problems or at least partially solve the above technical problems, the present application provides a converter steelmaking slag system with low MgO content and ultra-high phosphorus distribution ratio.

[0006] In the first aspect, the present application provides a converter steelmaking slag system with a low MgO content and an ultra-high phosphorus distribution ratio, wherein the phosphorus content of molten iron is 0.075%-0.090%, and the slag-making materials of the slag system include the following components: 40-60 kg / t·steel of lime, 35-40 kg / t·steel of ore, and 0-5 kg / t·steel of light-burned dolomite.

[0007] Optionally, the phosphorus content of the molten iron is 0.080%, and the weight proportions of the slag-forming materials of the slag system are as follows: 58 kg / t·steel of lime, 35 kg / t·steel of ore, and 5 kg / t·steel of light-burned dolomite.

[0008] Optionally, the phosphorus content of the molten iron is 0.083%, and the weight proportions of the slag-forming materials of the slag system are as follows: 55 kg / t·steel of lime, 36 kg / t·steel of ore, and 4.5 kg / t·steel of light-burned dolomite.

[0009] Optionally, the ore is at least one of the following: iron ore, sintered ore, pelletized ore, and FeO-rich sludge balls.

[0010] In a second aspect, the present application provides a steelmaking method of a converter steelmaking slag system with a low MgO content and an ultra-high phosphorus distribution ratio, comprising:

[0011] The double slag method of top and bottom combined blowing converter is adopted for smelting, the phosphorus content of molten iron is controlled to be 0.075%-0.090%, and slag-making materials are added, and the weight content of MgO in the final slag is controlled to be lower than 4.5%, and the amount of the first batch of slag added accounts for 55-65% of the total amount of slag added; the slag-making materials include the following components: 40-60kg / t·steel of lime, 35-40kg / t·steel of ore, and 0-5kg / t·steel of light-burned dolomite;

[0012] After the smelting time is set, the slag is discharged, wherein the slag discharge speed is the set speed;

[0013] After the semi-steel slag is poured, continue smelting, add slag-making auxiliary materials, control the carbon content of the steel to be lower than 0.035%, and control the steel tapping temperature to the set temperature. Among them, the top blowing gas supply intensity is the first set intensity, and the gun position is 1.7m-2.3m and first high and then low;

[0014] The maximum gas supply intensity at the end of bottom blowing smelting is the second set intensity, and the composition of the slag at the converter end point is controlled.

[0015] Optionally, the setting time is 4-5 minutes, and the setting speed is 2-2.5° / S.

[0016] Optionally, the slag-making auxiliary material includes components: lime and / or ore, and the ore is at least one of the following: iron ore, sintered ore, pelletized ore, and FeO-rich sludge balls.

[0017] Optionally, the set temperature is 1600°C-1650°C, and the first set strength is 3.0-3.8Nm 3 / min / t, the second setting intensity is 0.1Nm 3 / min / t.

[0018] Optionally, the final slag composition of the converter includes: MgO≤4.5%, MnO≤1.5%, CaO: 40-50%, SiO 2 : 2-10%, FeO: 15%-30%, Al 2 O 3 , CaF 2 , S, P 2 O 5 .

[0019] Optionally, the slag basicity R = weight % CaO / weight % SiO 2 ≥6.

[0020] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0021] The present application provides a converter steelmaking slag system with a low MgO content and an ultra-high phosphorus distribution ratio and a steelmaking method, which reduces the activity coefficient of phosphorus in the steel slag and increases the activity coefficient of FeO by reducing the MgO content in the steel slag. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0023] In the first aspect, the present application provides a converter steelmaking slag system with a low MgO content and an ultra-high phosphorus distribution ratio, wherein the phosphorus content of molten iron is 0.075%-0.090%, and the slag-making materials of the slag system include the following components: 40-60 kg / t·steel of lime, 35-40 kg / t·steel of ore, and 0-5 kg / t·steel of light-burned dolomite.

[0024] The main component of lime is CaO, and the main component of ore is FeO, containing a small amount of SiO 2 ; Exemplarily, lime can be 40kg / t·steel, 41kg / t·steel, 42kg / t·steel, 43kg / t·steel, 44kg / t·steel, 45kg / t·steel, 46kg / t·steel, 47kg / t·steel, 48kg / t·steel, 49kg / t·steel, 50kg / t·steel, 51kg / t·steel, 52kg / t·steel, 53kg / t·steel, 54kg / t·steel, 55kg / t·steel, 56kg / t·steel, 57kg / t·steel, 58kg / t·steel, 59kg / t·steel, 60kg / t·steel, and ore can be 35kg / t·steel, 36kg / t·steel, 37kg / t·steel,

[0025] 38kg / t·steel, 39kg / t·steel, 40kg / t·steel, light-burned dolomite 0.5kg / t·steel, 1kg / t·steel,

[0026] 1.5kg / t·steel, 2kg / t·steel, 2.5kg / t·steel, 3kg / t·steel, 3.5kg / t·steel, 4kg / t·steel,

[0027] 4.5kg / t·steel, 5kg / t·steel.

[0028] The positive effects of lime are: increasing alkalinity, reducing the activity coefficient of phosphorus, which is beneficial to dephosphorization. The disadvantage of using too much lime is that the amount of slag is large, which is not conducive to the stirring of the molten pool and the slag is not easy to melt. The disadvantage of using too little lime is that the alkalinity is low and it is not conducive to dephosphorization.

[0029] The positive effect of ore is: increasing FeO in slag and improving oxidizability of slag. The disadvantage of too high dosage is low molten pool temperature, while the disadvantage of too low dosage is that slag is not easy to melt and has low oxidizability.

[0030] The positive effect of light-burned dolomite is that it is beneficial to the maintenance of the furnace lining. The disadvantage of using too much is that it increases the activity coefficient of phosphorus and the high viscosity of the slag is not conducive to slagging. The disadvantage of using too little is that it is not conducive to the maintenance of the furnace lining.

[0031] In some embodiments, the phosphorus content of molten iron is 0.080%, and the weight proportions of slag-forming materials of the slag system are as follows: 58 kg / t·steel of lime, 35 kg / t·steel of ore, and 5 kg / t·steel of light-burned dolomite.

[0032] In some embodiments, the phosphorus content of molten iron is 0.083%, and the weight proportions of slag-forming materials of the slag system are as follows: 55 kg / t·steel of lime, 36 kg / t·steel of ore, and 4.5 kg / t·steel of light-burned dolomite.

[0033] In some embodiments, the ore is at least one of the following: iron ore, sintered ore, pelletized ore, and FeO-rich sludge balls.

[0034] In a second aspect, the present application provides a steelmaking method of a converter steelmaking slag system with a low MgO content and an ultra-high phosphorus distribution ratio, comprising:

[0035] The double slag method of top and bottom combined blowing converter is adopted for smelting, the phosphorus content of molten iron is controlled to be 0.075%-0.090%, and slag-making materials are added, and the weight content of MgO in the final slag is controlled to be lower than 4.5%, and the amount of the first batch of slag added accounts for 55-65% of the total amount of slag added; the slag-making materials include the following components: 40-60kg / t·steel of lime, 35-40kg / t·steel of ore, and 0-5kg / t·steel of light-burned dolomite;

[0036] After the smelting time is set, the slag is discharged, wherein the slag discharge speed is the set speed;

[0037] After the semi-steel slag is poured, continue smelting, add slag-making auxiliary materials, control the carbon content of the steel to be lower than 0.035%, and control the steel tapping temperature to the set temperature. Among them, the top blowing gas supply intensity is the first set intensity, and the gun position is 1.7m-2.3m and first high and then low;

[0038] The maximum gas supply intensity at the end of bottom blowing smelting is the second set intensity, and the composition of the slag at the converter end point is controlled.

[0039] In some embodiments, the setting time is 4-5 minutes, and the setting speed is 2-2.5° / S.

[0040] In some embodiments, the slag-making auxiliary material includes the following components: lime and / or ore, and the ore is at least one of the following: iron ore, sintered ore, pelletized ore, and FeO-rich sludge balls.

[0041] In some embodiments, the set temperature is 1600°C-1650°C, and the first set strength is 3.0-3.8Nm 3 / min / t, the second setting intensity is 0.1Nm 3 / min / t.

[0042] In some embodiments, the final slag composition of the converter includes: MgO≤4.5%, MnO≤1.5%, CaO: 40-50%, SiO 2 : 2-10%, FeO: 15%-30%, Al 2 O 3 , CaF 2 , S, P 2 O 5 .

[0043] In some embodiments, the slag basicity R = (weight % CaO) / (weight % SiO 2 )≥6.

[0044] The present application will be further described below in conjunction with specific embodiments and experimental data. It should be understood that these embodiments are only intended to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for the unrecorded specific conditions in the following examples are usually measured according to national standards. If there is no corresponding national standard, then carry out according to general international standards, normal conditions, or according to the conditions recommended by the manufacturer.

[0045] Embodiment 1:

[0046] The double slag method of 200t top and bottom combined blown converter is used for smelting. The phosphorus content of molten iron is 0.080%, the amount of lime added is 58kg per ton of steel, the amount of ore added is 35kg per ton of steel, the amount of lightly burned dolomite and other materials added is 5kg / t, and the final slag MgO is controlled to be less than 4.5%. The amount of the first batch of slag added accounts for 60% of the total amount added. After smelting for 4.5 minutes, the slag is poured at a speed of 2.4° / S. The amount of slag poured is measured to be 7.25t. After the semi-steel slag is poured, smelting is continued, and the remaining slag-making auxiliary materials are added. The carbon content of the steel is controlled at about 0.030%, and the steel tapping temperature is controlled at 1605℃. The top blowing gas supply intensity is 3.0-3.8Nm 3 / min / t for blowing, the gun position is controlled in the conventional low carbon steel smelting method, the gun position is controlled at 1.7-2.3 meters, first high and then low. The maximum gas supply intensity at the end of bottom blowing smelting is 0.1Nm 3 / min / t.

[0047] Table 1 Converter endpoint composition and temperature control

[0048]

[0049] Table 2 Control of slag composition at converter end point

[0050]

[0051]

[0052] Embodiment 2:

[0053] The double slag method of 200t top and bottom combined blown converter is used for smelting. The phosphorus content of molten iron is 0.083%, the amount of lime added is 55kg per ton of steel, the amount of ore added is more than 36kg per ton of steel, the amount of lightly burned dolomite added is 4.5kg / t, and the final slag MgO is controlled to be less than 4.5%. The amount of the first batch of slag added accounts for 60% of the total amount added. After smelting for 4.3 minutes, the slag is poured at a speed of 2.25° / S. The amount of slag poured is measured to be 7.75t. After the semi-steel slag is poured, smelting is continued, and the remaining slag-making auxiliary materials are added. The carbon content of the steel is controlled at about 0.030%, and the steel tapping temperature is controlled at 1600℃. The top blowing gas supply intensity is 3.0-3.8Nm 3 / min / t for blowing, the gun position is controlled in the conventional low carbon steel smelting method, the gun position is controlled at 1.7-2.3 meters, first high and then low. The maximum gas supply intensity at the end of bottom blowing smelting is 0.1Nm 3 / min / t.

[0054] Table 3 Converter endpoint composition and temperature control

[0055]

[0056] Table 4 Control of slag composition at converter end point

[0057] Components FeO% CaO% <![CDATA[SiO 2 %]]> MnO% MgO% <![CDATA[P 2 THE 5 %]]> <![CDATA[Al 2 THE 3 %]]> other R Element 25.09 48.34 6.52 1.17 3.34 1.18 1.21 13.15 7.4

[0058] It should be noted that, in this article, relational terms such as "first" and "second" are only used 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. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0059] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be 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 the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A steelmaking method using a converter steelmaking slag system with a low MgO content and an ultra-high phosphorus distribution ratio, characterized in that: include: The double slag method of top and bottom combined blowing converter is adopted for smelting, the phosphorus content of molten iron is controlled to be 0.075%-0.090%, and slag-making materials are added, and the weight content of MgO in the final slag is controlled to be lower than 4.5%, and the amount of the first batch of slag added accounts for 55-65% of the total amount of slag added; the slag-making materials include the following components: lime 40-60kg / t·steel, ore 35-40kg / t·steel, and light-burned dolomite 0-5kg / t·steel; After smelting for 4-5 minutes, the slag is poured, wherein the slag pouring speed is 2-2.5° / S; After the semi-steel slag is finished, continue smelting, add the remaining slag-making auxiliary materials, control the carbon content of the steel to be less than 0.035%, and control the steel tapping temperature to be 1600℃-1650℃, among which the top blowing gas supply intensity is 3.0-3.8Nm 3 / min / t, the gun position is 1.7m-2.3m and first high and then low; The maximum gas supply intensity at the end of bottom blowing smelting is 0.1Nm 3 / min / t, and control the slag composition and slag basicity at the converter end point; The components of the converter final slag include: MgO≤4.5%, MnO≤1.5%, CaO: 40-50%, SiO2: 2-10%, FeO: 15%-30%, Al2O3, CaF2, S, P2O5.

2. The steelmaking method of the converter steelmaking slag system with low MgO content and ultra-high phosphorus distribution ratio according to claim 1, characterized in that: The phosphorus content of molten iron is controlled to be 0.080%, and the weight proportions of the slag-making materials are as follows: 58 kg / t·steel of lime, 35 kg / t·steel of ore, and 5 kg / t·steel of light-burned dolomite.

3. The steelmaking method of the converter steelmaking slag system with low MgO content and ultra-high phosphorus distribution ratio according to claim 1, characterized in that: The phosphorus content of molten iron is controlled to be 0.083%, and the weight proportions of the slag-making materials are as follows: 55 kg / t·steel of lime, 36 kg / t·steel of ore, and 4.5 kg / t·steel of light-burned dolomite.

4. The steelmaking method of the converter steelmaking slag system with low MgO content and ultra-high phosphorus distribution ratio according to claim 1, characterized in that: The slag-making auxiliary material comprises the following components: lime and / or ore, wherein the ore is at least one of the following: iron ore, sintered ore, pelletized ore, and FeO-rich sludge balls.

5. The steelmaking method of the converter steelmaking slag system with low MgO content and ultra-high phosphorus distribution ratio according to claim 1, characterized in that: The steel slag basicity R=weight %CaO / weight %SiO2≥6.

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