CN115927783A

CN115927783A - Steelmaking method for reducing comprehensive lime consumption by rapidly slagging in converter under high iron loss

Info

Publication number: CN115927783A
Application number: CN202211422001.6A
Authority: CN
Inventors: 吴伟; 杨利彬; 苑一波; 汪成义; 卫国强
Original assignee: Central Iron and Steel Research Institute
Current assignee: Central Iron and Steel Research Institute
Priority date: 2022-11-14
Filing date: 2022-11-14
Publication date: 2023-04-07

Abstract

The invention discloses a steelmaking method for reducing comprehensive lime consumption by rapidly slagging in a converter under high iron loss, belongs to the technical field of converter steelmaking, and solves the technical problems of realizing converter less-slag smelting and improving the cleanliness level of molten steel under the condition of high iron loss. The steelmaking method of the invention comprises the following steps: s1, slag splashing and furnace protection are carried out; s2, adding limestone and sinter as a bedding material; s3, adding molten iron and scrap steel into a converter; s4, adding lime, sinter and magnesium balls in batches when BT is more than or equal to 0min and less than or equal to 6min in blowing; s5, when blowing is carried out for 6min and BT is less than or equal to 10min, adding sinter to control the temperature of molten steel; s6, when converting is carried out for 10min and BT is less than BT, adding sintered ore to control the temperature of molten steel; s7, operating the oxygen lance at the high oxygen pressure and the low lance position for 40-60 seconds; s8, reversing the furnace and tapping, and stopping slag at the end of tapping. By the method, the basicity of the slag is between 1.8 and 2.3 when the converter blows for 6 minutes, the dephosphorization rate is between 40 and 60 percent, and the early-stage dephosphorization effect of the converter is obvious.

Description

Steelmaking method for reducing comprehensive lime consumption by rapidly slagging in converter under high iron loss

Technical Field

The invention belongs to the technical field of converter steelmaking, and particularly relates to a steelmaking method for reducing comprehensive lime consumption by rapidly slagging in a converter with high iron loss.

Background

Like other substances, the cleanliness of steel is also an important index of steel, and the improvement of the cleanliness of steel and the improvement of the performance of steel are important technical directions for the development of steel production. Further reducing the production cost of the pure steel and improving the production stability and the production efficiency of the pure steel are the historical trends of the development of the steelmaking technology.

The clean steel is not specific to a specific steel type, but represents the process level which can be achieved by controlling the cleanliness of molten steel in the actual production process, and reflects the specific production process and manufacturing level of the clean steel. The traditional steelmaking process is a production system with low efficiency, high energy consumption and high pollution, for example, the reaction efficiency of slag steel is low, and the slag quantity is large; the production rhythm is slow, the auxiliary time is long, and the heat loss of steel making is large; severe oxidation of molten steel, etc., which all result in a sudden increase of inclusions in the steel, a reduction in efficiency and an increase in cost.

Therefore, how to improve the reaction efficiency of the slag steel, reduce the slag quantity, reduce the heat loss in the steel making process and prevent the molten steel from being oxidized by the oxygen is an important subject for the clean steel production.

Disclosure of Invention

In view of the above analysis, the invention provides a steelmaking method for reducing comprehensive lime consumption by fast slagging in a converter with high iron loss, so as to solve the technical problems of how to utilize surplus heat to realize converter slag-less smelting and improve the cleanliness level of molten steel under the condition of high iron loss with small addition of scrap steel and surplus molten iron temperature. The invention can at least solve one of the following technical problems: (1) Under the condition of high iron loss, the addition amount of lime is large, and the converter slagging speed is slow; (2) Under the condition of high iron consumption, the decarburization speed is accelerated, and the dephosphorization effect of the converter end point is influenced; (3) The reaction degree of carbon and oxygen at the end point of the converter is greatly different from the balance and is not closer to the balance, so that the molten steel is seriously oxidized.

The purpose of the invention is mainly realized by the following technical scheme:

the invention provides a steelmaking method for reducing comprehensive lime consumption by rapidly slagging in a converter with high iron loss, which comprises the following steps:

s1, keeping slag after tapping of a previous furnace in a converter, and performing slag splashing furnace protection operation;

s2, adding limestone and sinter as a bedding material according to the weight of molten iron to be added into the converter and the contents of Si and Mn in the molten iron, wherein the molten iron comprises, by mass, less than 1.2% of Mn, less than 1.2% of Si, more than 0.1% and less than 0.15% of P, and more than 0.002% and less than 0.035% of S;

s3, adding the molten iron in the step S2 and the scrap steel into a converter, wherein the weight ratio of the scrap steel to the molten iron is less than or equal to 5%; the temperature of molten iron is more than or equal to 1240 ℃;

s4, when BT is not less than 0min and not more than 6min during blowing, lime, sinter and magnesium balls are added in batches according to the Si content in the molten iron added into the converter in S3, wherein the total weight of the sinter is equal to that of the sinter added in S2, the oxygen supply flow of the oxygen lance is controlled to be the lower limit of the designed oxygen pressure, and the bottom blowing gas supply intensity is 0.05-0.08 Nm ³ /t·min；

S5, when BT is more than 6min and less than or equal to 10min after converting, adding sinter to control the temperature of molten steel, controlling the oxygen supply flow of the oxygen lance to exceed 5% of the designed oxygen pressure and controlling the bottom blowing gas supply intensity to be 0.04-0.06 Nm ³ /t·min；

S6, when converting is carried out for 10min and BT is less than BT, adding sintered ore to control the temperature of molten steel, controlling the oxygen supply flow of the oxygen lance to exceed 10% of the designed oxygen pressure and controlling the bottom blowing gas supply intensity to be 0.04-0.06 Nm ³ /t·min；

S7, in the final stage of smelting, operating the oxygen lance with high oxygen pressure and low lance position for 40-60 seconds;

s8, measuring temperature, sampling and measuring components, pouring steel out of the converter, deoxidizing and alloying in the tapping process, and stopping slag at the end of tapping.

Furthermore, in S1, when the tapping temperature of the last furnace is more than 1670 ℃, or molten steel is over oxidized, 1/2 of slag of the furnace is left.

Further, when Mn of the molten iron in S2 is less than 0.6% and Si is less than 0.20%, in S2:

adding amount of limestone: m _Limestone ＝0.0108M _{Molten iron} +0.0694，

Addition amount of sinter: m _{Sintered ore} ＝0.00815M _{Molten iron} +0.0487；

When the Mn of molten iron in S2 is less than 0.6 percent and Si is more than or equal to 0.2 percent and less than 0.5 percent, in S2:

adding amount of limestone: m is a group of _Limestone ＝(0.0161～0.0267)M _{Molten iron} +(0.1165～0.1969)，

Addition amount of sinter: m _{Sintered ore} ＝(0.01085～0.01355)M _{Molten iron} +(0.06625～0.08255)；

When Mn in the molten iron in S2 is less than 0.6 percent and Si in the range of 0.5 percent to 0.8 percent, in S2:

adding amount of limestone: m _Limestone ＝(0.0457～0.0571)M _{Molten iron} +(0.548～0.8898)，

Adding amount of sinter: m _{Sintered ore} ＝0.01625M _{Molten iron} +0.1010；

When the Mn of the molten iron in S2 is less than 0.6 percent, si is more than 0.8 percent and less than or equal to 1.2 percent, in S2:

adding amount of limestone: m _Limestone ＝(0.0611～0.0663)M _{Molten iron} +(0.2351～0.3047)，

Adding amount of sinter: m _{Sintered ore} ＝0.01375M _{Molten iron} +0.06095；

Wherein M is _Limestone Is the added weight of limestone, M _{Sintered ore} For the added weight of sinter, M _{Molten iron} Is the weight of the molten iron added into the converter.

Further, when 0.6% or more of Mn and less than 1.2% of Si in the molten iron in S2 are less than 0.20%, in S2:

adding amount of limestone: m _Limestone ＝0.0108M _{Molten iron} +0.0694+(0.5～1.0)，

Adding amount of sinter: m _{Sintered ore} ＝0.00815M _{Molten iron} +0.0487；

When the molten iron in S2 is more than or equal to 0.6 percent and less than 1.2 percent of Mn and more than or equal to 0.2 percent and less than 0.5 percent of Si, in S2:

adding amount of limestone: m _Limestone ＝(0.0161～0.0267)M _{Molten iron} +(0.1165～0.1969)+(0.5～1.0)，

When Mn is more than or equal to 0.6 percent and less than 1.2 percent and Si is more than or equal to 0.5 percent and less than or equal to 0.8 percent in the molten iron in S2, in S2:

adding amount of limestone: m is a group of _Limestone ＝(0.0457～0.0571)M _{Molten iron} +(0.548～0.8898)+(0.5～1.0)，

When the molten iron in S2 is more than or equal to 0.6 percent and less than 1.2 percent of Mn and more than or equal to 0.8 percent and more than or equal to 0.2 percent of Si, in S2:

adding amount of limestone: m _Limestone ＝(0.0611～0.0663)M _{Molten iron} +(0.2351～0.3047)+(0.5～1.0)，

Furthermore, in S2, the CaO content of the limestone is 52-55% by mass.

Further, when the Si content of the molten iron in S2 is less than 0.20%, in S4:

lime addition: m _Lime ＝0.0108M _{Molten iron} +0.0694，

Adding amount of magnesium balls: m _{Magnesium ball} ＝0.0043M _{Molten iron} +0.0273；

When Si is more than or equal to 0.2% and less than 0.5% in the molten iron in S2, in S4:

adding amount of lime: m is a group of _Lime ＝0.0163M _{Molten iron} +0.0974，

Adding amount of magnesium balls: m _{Magnesium ball} ＝(0.0066～0.011)M _{Molten iron} +(0.0271～0.0503)；

When Si is more than or equal to 0.5% and less than or equal to 0.8% in the molten iron in S2, in S4:

lime addition: m is a group of _Lime ＝0.0108M _{Molten iron} +0.0694，

Adding amount of magnesium balls: m _{Magnesium ball} ＝(0.0123～0.0133)M _{Molten iron} +(0.0187～0.0249)；

When the molten iron in S2 is more than 0.8% and less than or equal to 1.2% of Si, in S4:

adding amount of lime: m is a group of _Lime ＝0.0108M _{Molten iron} +0.0694，

Adding amount of magnesium balls: m is a group of _{Magnesium ball} ＝0.0108M _{Molten iron} +0.0694；

M _Lime Is the weight of lime added, M _{Magnesium ball} Weight of added magnesium balls, M _{Molten iron} Is the weight of the molten iron added into the converter.

Further, the sintered ore comprises the following components in percentage by mass: TFe not less than 54%, feO<10％，9％＜CaO＜13％，5.5％＜SiO ₂ < 8%, basicity R = CaO/SiO ₂ ≥1.6，S<0.04％。

Further, in S4, the slag alkalinity at 6 minutes of converter blowing is between 1.8 and 2.3.

Further, when the Mn of the molten iron in S2 is less than 0.6 percent, the lance position of the oxygen lance is controlled to be 1.8-2.4 m in S4, 0.9-1.2 m in S5 and 1.2-1.6 m in S6.

Further, when the Mn in the molten iron in S2 is more than or equal to 0.6 percent and less than 1.2 percent, oxygen lances in S4, S5 and S6 are operated at a constant lance position of 1.2-1.8 meters.

Compared with the prior art, the invention has the following beneficial effects:

(1) The invention adopts the converter slag retention and slag splashing protection operation, is beneficial to early formation of initial slag, can improve the efficiency of removing P and S in the earlier stage of smelting, is beneficial to protecting the furnace lining and saves the lime consumption.

(2) According to the invention, the limestone and the sintered ore are added as the bedding material before the molten iron is added in the converter, so that the phenomenon of molten iron splashing caused by slag remaining is avoided, the temperature of the molten iron is reduced, the limestone in the bedding material is decomposed into calcium oxide and is combined with the sintered ore at the same time, the low-melting-point calcium ferrite slag is formed, and the melting of the slag at the early stage of the converter is promoted. Compared with the traditional mode of adding slag in the early stage of the converter, the method can lead the formation of the slag in the early stage of the converter to be earlier by 3-4 minutes.

(3) The invention achieves the aim of forming calcium ferrite slag as soon as possible by adding the converter lime and the sinter at the early stage of blowing at the same time. The basicity of the slag is between 1.8 and 2.3 when the converter blows for 6 minutes, the dephosphorization rate is between 40 and 60 percent, and the early-stage dephosphorization effect of the converter is obvious.

(4) The invention utilizes FeO and Fe mainly contained in the sinter by adding the sinter ₂ O ₃ 、SiO ₂ CaO, mgO and Al ₂ O ₃ When the steel-making slag contains components, the slag is rapidly formed, the balance of the steel slag is established, the early dephosphorization is facilitated, the lime consumption is saved, and a furnace lining is protected.

(5) The contents of P and S at the end point are in a controllable range, the carbon content of the steel tapping is controlled to be more than 0.07 percent, the carbon-oxygen reaction is balanced, and the peroxidation of the molten steel is effectively reduced.

(6) The method provided by the invention can save more than 30% of the comprehensive lime on average, and obtain better economic benefit.

Drawings

FIG. 1 shows CaO-FeO _x A binary phase diagram;

FIG. 2 shows CaO-Fe ₂ O ₃ A binary phase diagram.

Detailed Description

The following is a more detailed description of a steelmaking process with rapid slagging at high iron loss and reduced combined lime consumption, taken in conjunction with the specific examples which are provided for illustrative purposes only and to which the present invention is not limited. It should be noted that the contents of the components in the present specification are all by mass.

A large number of production practices show that if converter less-slag smelting is to be realized, the cleanliness level of molten steel needs to be improved under the following conditions, and firstly, slag is formed in the early stage of the converter as a precondition; and secondly, the carbon-oxygen reaction at the end point of the converter is closer to balance, and the peroxidation trend of molten steel is reduced.

s1, remaining slag after tapping of the last furnace in a converter, and performing slag splashing furnace protection operation;

s2, adding limestone and sinter as a bedding material according to the weight of molten iron to be added into the converter and the contents of Si and Mn in the molten iron;

s3, adding the molten iron and the scrap steel in the step S2 into a converter, wherein the weight ratio of the scrap steel to the molten iron is less than or equal to 5%;

s4, when BT is more than or equal to 0min and less than or equal to 6min in blowing, according to the Si content in the molten iron added into the converter in the step S3, lime, sinter and magnesium balls are added in batches, the oxygen supply flow of the oxygen lance is controlled to be the lower limit of the designed oxygen pressure, and the bottom blowing gas supply strength is 0.05-0.08 Nm ³ /t·min；

S7, in the final stage of smelting, operating the high-oxygen-pressure low-lance-position oxygen lance for 40-60 seconds.

S8, measuring temperature, sampling and measuring components, pouring steel out of the converter, performing deoxidation and alloying operation in the steel-out process, and stopping slag at the end of steel-out.

In step S1, during the normal production rhythm, the slag of the previous furnace is completely left, and then nitrogen gas is blown to splash the slag for furnace protection. The slag splashing layer has the function of protecting the furnace, and meanwhile, because the end-point slag has high alkalinity, high temperature and certain TFe content, low-melting-point substances such as ferric oxide exist in the slag layer, and the low-melting-point substances are melted into the furnace along with molten iron when molten iron is added, so that the melting of initial-stage slag can be effectively ensured in the early stage of blowing, and the function of helping to melt slag is achieved.

For abnormal ladles with lower ladle temperature, such as black ladles, the tapping temperature is high and is more than 1670 ℃, or the molten steel is seriously oxidized (TFe is high), so that the converter has bad furnace conditions, and 1/2 of the slag of the converter is reserved for slag splashing protection.

For the furnace number needing to be added with iron and then measured, or the furnace is repaired after tapping, such as small and large surfaces, slag is not left, and slag splashing protection is not carried out.

In step S2, the content of CaO in the limestone is about 52 to 55% by mass; the main components of the sinter comprise the following components in percentage by mass: TFe not less than 54%, feO<10％，9％＜CaO＜13％，5.5％＜SiO ₂ < 8%, basicity R = CaO/SiO ₂ ≥1.6，S<0.04 percent; according to the mass percentage, the content of Mn is less than 0.6 percent, the content of Si is less than 1.2 percent, the content of P is more than 0.1 percent and less than 0.15 percent, and the content of S is more than 0.002 percent and less than 0.035 percent. The adding amount of the limestone and the sinter has a certain relation with the Si content in the molten iron, and the concrete steps are as follows:

when the Si is <0.20%,

adding amount of limestone: m _Limestone ＝0.0108M _{Molten iron} +0.0694 (1)

Addition amount of sinter: m _{Sintered ore} ＝0.00815M _{Molten iron} +0.0487 (2)

When Si is more than or equal to 0.2 percent and less than 0.5 percent,

adding amount of limestone: m _Limestone ＝(0.0161～0.0267)M _{Molten iron} +(0.1165～0.1969)(3)

Adding amount of sinter:

M _{sintered ore} ＝(0.01085～0.01355)M _{Molten iron} +(0.06625～0.08255) (4)

When Si is more than or equal to 0.5 percent and less than or equal to 0.8 percent,

adding amount of limestone: m _Limestone ＝(0.0457～0.0571)M _{Molten iron} +(0.548～0.8898)(5)

Adding amount of sinter: m _{Sintered ore} ＝0.01625M _{Molten iron} +0.1010(6)

When Si is more than 0.8 percent and less than or equal to 1.2 percent,

adding amount of limestone: m _Limestone ＝(0.0611～0.0663)M _{Molten iron} +(0.2351～0.3047)(7)

Adding amount of sinter: m is a group of _{Sintered ore} ＝0.01375M _{Molten iron} +0.06095(8)

M _Limestone Is the added weight of limestone, M _{Sintered ore} For the added weight of sinter, M _{Molten iron} The capacity of the converter is 30 to 300 tons based on the weight of molten iron charged into the converter.

When Mn in the molten iron is more than or equal to 0.6 percent and less than 1.2 percent, paving the base material on the basis, and adding 0.5 to 1.0t of limestone.

Specifically, in step S3, in the charging amount of the present invention, the weight ratio of the scrap steel to the molten iron is less than or equal to 5%, which is a specific requirement of the present invention for high iron consumption, and the weight ratio of the conventional scrap steel to the molten iron is about 10%, and in most cases is more than 10%. The temperature of the molten iron is more than or equal to 1240 ℃.

In steps S4, S5, and S6, BT is an abbreviation of air time and indicates the blowing time.

In step S4, lime, sinter and magnesium balls are added according to the principle of small quantity and multiple batches according to the furnace condition in the converting process. Because of the surplus heat under the condition of high iron consumption, the slag is not required to be heated and melted through carbon-oxygen reaction, the high lance position is adopted for blowing, the lance position is properly reduced after the primary slag is melted to avoid splashing, and the lance position is generally controlled to be 1.8-2.4 m. The oxygen supplying design pressure of oxygen lances of converters with different tonnages is different, for example, the oxygen supplying design pressure is between 0.60 and 1.3MPa, and the bottom blowing gas of the converter is nitrogen or argon.

The adding amount of lime, sinter and magnesium balls has a certain relation with the Si content in the molten iron, and particularly, when the Si content is less than 0.20 percent,

adding amount of lime: m _Lime ＝0.0108M _{Molten iron} +0.0694 (9)

Adding amount of sinter: m' _{Sintered ore} ＝0.00815M _{Molten iron} +0.0487 (10)

Adding amount of magnesium balls: m _{Magnesium ball} ＝0.0043M _{Molten iron} +0.0273 (11)

When Si is more than or equal to 0.2 percent and less than 0.5 percent,

adding amount of lime: m _Lime ＝0.0163M _{Molten iron} +0.0974(12)

Adding amount of sinter:

M’ _{sintered ore} ＝(0.01085～0.01355)M _{Molten iron} +(0.06625～0.08255) (13)

Adding amount of magnesium balls: m _{Magnesium ball} ＝(0.0066～0.011)M _{Molten iron} +(0.0271～0.0503)(14)

adding amount of lime: m _Lime ＝0.0108M _{Molten iron} +0.0694 (15)

Adding amount of sinter: m' _{Sintered ore} ＝0.01625M _{Molten iron} +0.1010 (16)

Adding amount of magnesium balls: m _{Magnesium ball} ＝(0.0123～0.0133)M _{Molten iron} +(0.0187～0.0249)(17)

When Si is more than 0.8 percent and less than or equal to 1.2 percent,

lime addition: m is a group of _Lime ＝0.0108M _{Molten iron} +0.0694 (18)

Adding amount of sinter: m' _{Sintered ore} ＝0.01375M _{Molten iron} +0.06095 (19)

Adding amount of magnesium balls: m _{Magnesium ball} ＝0.0108M _{Molten iron} +0.0694 (20)M _Lime Is the weight of lime added, M _{Magnesium ball} Is the weight of magnesium balls added, M' _{Sintered ore} For the weight of the sinter, M _{Molten iron} The capacity of the converter is 30 to 300 tons based on the weight of molten iron charged into the converter.

When slag splashing protection is carried out on the last furnace without slag, lime can be properly increased by 0.5-1.0 t in the blowing process of the step S4 in the furnace.

It should be noted that, under the influence of the content of Si in the molten iron, the weight M of limestone added to the base material in the step S2 is _Limestone And step S2 and step S4 are addedThere is a certain proportional relationship between the total amount of the sintering ore added, specifically, when Si is added<When the concentration is 0.20%, TFe in the sintered ore added in the step S2 and the step S4 is completely converted into Fe ₂ O ₃ Is about 2.1, i.e., (M) to the total amount of CaO in the limestone charged in step S2 _{Sintered ore} +M’ _{Sintered ore} )×54％÷70％】/【M _Limestone X 55% ] is approximately equal to 2.1; when Si is more than or equal to 0.2 percent and less than or equal to Si<When the concentration is 0.5%, TFe in the sintered ore added in the step S2 and the step S4 is completely converted into Fe ₂ O ₃ The ratio of the total amount of (A) to the total amount of CaO in the limestone added in step S2 is about 1.12 to 2.34, i.e., [ M ] (M) _{Sintered ore} +M’ _{Sintered ore} )×54％÷70％】/【M _Limestone X 55% ] is approximately equal to 1.12-2.34; when Si is more than or equal to 0.5% and less than or equal to 0.8%, TFe in the sinter ore added in the step S2 and the step S4 is completely converted into Fe ₂ O ₃ The ratio of the total amount of (A) to the total amount of CaO in the limestone added in step S2 is about 0.72 to 0.94, i.e., [ M ] _{Sintered ore} +M’ _{Sintered ore} )×54％÷70％】/【M _Limestone X 55% ] is approximately equal to 0.72-0.94; when Si is more than 0.8% and less than or equal to 1.2%, TFe in the sinter ore added in the step S2 and the step S4 is completely converted into Fe ₂ O ₃ The ratio of the total amount of (A) to the total amount of CaO in the limestone added in the step S2 is about 0.62 to 0.80, i.e., (M) _{Sintered ore} +M’ _{Sintered ore} )×54％÷70％】/【M _Limestone ×55％】≈0.62～0.80。

FIG. 1 shows CaO-FeO _x Binary phase diagram, FIG. 2 is CaO-Fe ₂ O ₃ A binary phase diagram. As can be seen from the figure, caO is present in combination with FeO _x The calcium ferrite formed has three compounds, namely C ₂ F(2CaO·Fe ₂ O ₃ )、CF(CaO·Fe ₂ O ₃ ) And CF2 (CaO.2Fe) ₂ O ₃ ) The melting temperatures of the three are 1448 ℃, 1228 ℃ and 1205 ℃ respectively.

In the invention, the calcium ferrite slag with a lower melting point is firstly generated by adjusting the proportion of limestone, lime and sinter and uniformly mixing molten iron.

Limestone reacts with iron oxide as follows:

2CaCO _3(s) +Fe ₂ O _3(s) ＝2CaO·Fe ₂ O _3(s) +CO _2(g) (21)

ΔG ⁰ ＝269500-276.97T

CaCO _3(s) +Fe ₂ O _3(s) ＝CaO·Fe ₂ O _3(s) +CO _2(g) (22)

ΔG ⁰ ＝131600-142.04T

by the calculation of the formulas (21) and (22), when the temperature is more than 700 ℃, Δ G <0 of the formulas (21) and (22), calcium ferrite and dicalcium ferrite can be generated. The slag with low melting point is formed, which is beneficial to the dissolution of lime, and the slag with high alkalinity is formed at the earlier stage of the converter, which is beneficial to the dephosphorization of the converter.

2CaO _(s) +Fe ₂ O _3(s) ＝2CaO·Fe ₂ O _3(s) (23)

ΔG ⁰ ＝-53100-2.51T

CaO _(s) +Fe ₂ O _3(s) ＝CaO·Fe ₂ O _3(s) (24)

ΔG ⁰ ＝-29700-4.81T

By the calculation of the equations (23) and (24), when the temperature is more than 25 ℃, Δ G <0 of the equations (23) and (24), calcium ferrite and dicalcium ferrite can be generated. The slag with low melting point is formed, which is beneficial to the dissolution of lime, and the slag with high alkalinity is formed at the earlier stage of the converter, which is beneficial to the dephosphorization of the converter.

Note that CaO and Fe ₂ O ₃ The mass ratio of the calcium ferrite completely formed by the reaction to the dicalcium ferrite should be M _Fe2O3 /M _CaO Not less than 1.41 but not more than 2.85, but SiO is contained in the steel-making slag system ₂ In the presence of SiO ₂ Calcium silicate is formed with CaO, and SiO ₂ 、CaO、Fe ₂ O ₃ Ternary and even quaternary oxide combinations are formed among FeO and MgO, so that in addition to calcium ferrite and dicalcium ferrite, other calcium oxides are generated in the initial slag. And SiO with the increase of Si content in the molten iron ₂ And CaOThe combination probability is increased, the consumption of CaO is increased, and the content of CaO is increased to ensure the alkalinity, so that M is increased along with the increase of the content of Si in the molten iron _Fe2O3 /M _CaO Will gradually go low. When Si is more than or equal to 0.5 percent, M _Fe2O3 /M _CaO Less than 1.0, less than the range of 1.41 to 2.85, but due to the presence of other phases, in particular SiO ₂ In a large amount, when M is present _Fe2O3 /M _CaO The ratio does not react with CaO and Fe ₂ O ₃ The actual conditions of the two-phase reaction, together with the lower melting points of the calcium ferrite and the dicalcium ferrite, far below the melting points of the other oxide combinations in the slag system, are more favourable for the formation of calcium ferrite and dicalcium ferrite, depending on the metallurgical and physicochemical reaction kinetics, and moreover some calcium ferrite compounds are also present in the sinter, which, after first melting, promote the further progress of the reaction.

In addition, if the addition amount of the bedding material is too large, the phenomenon that the sintering ore is not fired after blowing is caused, so that half of the calculated amount of the sintering ore is added into the bedding material, and the rest half of the sintering ore is added in batches according to the slag melting condition at the stage of blowing for 0min to 6min, namely the total weight of the sintering ore added in the step S2 is equal to that of the sintering ore added in the step S4. And with the progress of converting oxidation, fe element in the molten iron enters slag, and lime and magnesium balls are required to be added to further maintain the component balance of the slag system.

P generally belongs to harmful elements in steel, dephosphorization is an important task in steel making, oxidation dephosphorization reaction occurs at a steel slag interface, and the chemical reaction equation can be expressed as follows:

2[P]+5(FeO)+4(CaO)＝(4CaO·P ₂ O ₅ )+5[Fe] (25)

2[P]+5(FeO)+3(CaO)＝(3CaO·P ₂ O ₅ )+5[Fe] (26)

from the above two formulae, it is found that high (FeO), high (CaO) (high basicity) and large amount of slag in the slag are advantageous for the progress of dephosphorization reaction, and further, since the dephosphorization reaction is a strongly exothermic reaction, dephosphorization is also advantageous at a low temperature.

The limestone and the sinter are added simultaneously in the bedding material to promoteThe formation of low-temperature liquid phase calcium ferrite and dicalcium ferrite in the slag system is realized, the dynamic condition of dephosphorization reaction is met in a micro area of a steel slag interface, and the dephosphorization reaction is promoted to be carried out. Firstly, steel making is an oxidation exothermic process, the furnace temperature gradually rises along with the reaction, and the dephosphorization efficiency is lower in the later period, so that initial slag is formed as early as possible at relatively low temperature to facilitate dephosphorization. Secondly, the sintered ore contains CaO and SiO which are necessary in the slag ₂ Etc., and basicity R (CaO/SiO) ₂ ) More than or equal to 1.6, partial low-melting point calcium ferrite compounds exist, and the surplus heat of high iron consumption is favorable for the formation of primary slag. Again, liquid phase reactions are more efficient than solid phase reactions, or liquid-solid reactions. Finally, the calcium ferrite and the dicalcium ferrite provide simultaneous, simultaneous Ca ²⁺ 、Fe ₂ O ₅ ^4- 、Fe ₂ O ₄ ^4- State of ion of [ P ]]The chance of meeting satisfies the material condition of combining the three reactants, and naturally increases the reaction probability.

It should be noted that the calculation mode of the comprehensive lime consumption is M _Limestone ×55％+M _Lime 。

Compared with the invention, the existing converter slagging material is added after the converter is added with molten iron for blowing, the lime is slowly melted in the early stage of the converter, and the dephosphorization effect in the early stage of the converter is poor. The dephosphorization of the converter is mainly completed after lime is melted to form high-alkalinity slag at the later stage. Therefore, the burden of later dephosphorization is heavy, and the proportion of the one-time hit rate at the end point is low, thereby causing serious peroxidation of molten steel at the end point of the converter, reducing the yield of metal and lowering the production efficiency of the converter.

Specifically, after the slag is melted in step S4, the lance position is properly reduced in step S5 to avoid splashing, but the lance position is too low and is easy to return to dry, and the lance position is generally controlled to be 0.9-1.2 meters. Meanwhile, in order to control the temperature of the molten steel to rise too fast, a proper amount of sinter is added to regulate the temperature of the molten steel.

Specifically, through the blowing of the two steps, the preliminary dephosphorization task is basically completed, the carbon content and the temperature of the molten steel are controlled in the step S6 to meet the tapping requirement, the decarburization and the temperature control are main tasks at this stage, 1.2-1.6 m is generally controlled according to the carbon content in the steel, and a proper amount of sinter is added according to the requirement to control the temperature of the molten steel.

In step S7, the oxygen lance operation at a high oxygen pressure and a low lance height is performed to homogenize the composition and temperature and to reduce the oxidizing property of the slag, and the oxygen lance operation at a lance height of 0.82 to 0.95MPa and 0.8 to 1.0m is performed, for example.

It should be noted that when Mn is between 0.6% and 1.2% in the molten iron, a constant gun position operation is adopted in steps S4, S5 and S6, for example, the gun position is 1.2 to 1.8 meters.

Compared with the traditional charging mode in the blowing period of the converter, the operation of paving the bottom material provided by the invention can lead the formation of the primary slag of the converter to be advanced by 3-4 minutes. The lime and the sinter are added simultaneously, so that the aim of forming calcium ferrite slag as soon as possible is achieved, the basicity of the slag is between 1.8 and 2.3 when the converter blows for 6 minutes, the dephosphorization rate is between 40 and 60 percent, and the early-stage dephosphorization effect of the converter is obvious. In addition, the method provided by the invention can save more than 30% of comprehensive lime on average, and obtain better economic benefit.

Example 1

S1, keeping slag after tapping of the previous furnace in the converter, and performing slag splashing furnace protection operation; the slag amount is 25kg/t, and the slag components are CaO 45.34% and SiO ₂ 18.12％、FeO 10.32％、MnO 1.24％、MgO 6.98％、P ₂ O ₅ 2.24％。

the molten iron amount is 85t, and the chemical components of the molten iron are 4.53 percent of C, 0.25 percent of Si, 0.22 percent of Mn, 0.13 percent of P and 0.025 percent of S.

Adding amount of limestone:

M _limestone =0.018 × 85+0.1370=1.667 ton

Adding amount of sinter:

M _{sintered ore} =0.011 × 85+0.07=1.005 ton

S3, adding molten iron and scrap steel; the temperature of the molten iron is 1247 ℃, the weight ratio of scrap steel to the molten iron is 3.53 percent, and the weight ratio of scrap steel to the molten iron is 3 t.

S4, when BT is more than or equal to 0min and less than or equal to 6min in blowing, lime, sinter and magnesium balls are added in batches according to the Si content in molten iron added into the converter, the lance position is 2.0m, and the oxygen supply flow of the oxygen lance is controlled to be 18000Nm ³ The nitrogen supply intensity of bottom blowing is 0.05Nm ³ /t·min；

Adding amount of lime: m _Lime =0.0163 × 85+0.0974=1.483 ton

Addition amount of sinter: m' _{Sintered ore} =0.011 × 85+0.07=1.005 ton

Adding amount of magnesium balls: m is a group of _{Magnesium ball} =0.008 × 85+0.03=0.71 ton

The slag basicity at 6 minutes in converter blowing was 2.0.

S5, when BT is more than 6min and less than or equal to 10min during blowing, adding sinter to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to be 19000Nm ³ The gun position was 0.9m, and the intensity of nitrogen gas supplied by bottom blowing was 0.04Nm ³ /t·min；

S6, when converting is carried out for 10min and BT is less than BT, adding sintered ore to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to 21000Nm ³ The gun position is 1.2m, and the intensity of nitrogen supplied by bottom blowing is 0.06Nm ³ /t·min；

S7, at the final stage of smelting, performing high-oxygen-pressure and low-lance-position oxygen lance operation for 40 seconds, wherein the oxygen pressure of the oxygen lance is 0.9MPa, and the oxygen supply flow is 22000Nm ³ The oxygen lance position is 1.0m.

The end point [ P ] of the converter is 0.015 percent, which meets the control requirement that the [ P ] is less than or equal to 0.035 percent, the C is 0.14 percent, the steel tapping amount is 80.72t, the temperature is 1655 ℃, the early dephosphorization rate is 60 percent, and the total dephosphorization rate is 88 percent. The consumption of slagging materials is 17.45kg/t of lime, 19.61kg/t of limestone, 9.46kg/t of magnesium balls and 23.65kg/t of sinter.

The method realizes the reduction of lime under the condition of high iron consumption, and can reduce the lime consumption to 28.2kg/t from 55kg/t of the comprehensive lime of the original process, thereby greatly saving the lime consumption.

Example 2

S1、Keeping the slag tapped from the previous furnace in the converter, and performing slag splashing furnace protection operation; the slag amount is 28kg/t, and the slag components are CaO 44.15% and SiO ₂ 18.5％、FeO 11.82％、MnO 1.84％、MgO 8.01％、P ₂ O ₅ 2.65％。

the molten iron amount is 93t, and the chemical components of the molten iron are 4.34 percent of C, 0.43 percent of Si, 0.25 percent of Mn, 0.13 percent of P and 0.03 percent of S.

Adding amount of limestone:

M _limestone =0.0267 × 93+0.1969=2.68 tons

Adding amount of sinter:

M _{sintered ore} =0.01085 × 93+0.06625=1.075 ton

S3, adding molten iron and scrap steel; the temperature of the molten iron is 1324 ℃, the scrap steel is 4t, and the weight ratio of the scrap steel to the molten iron is 4.3%.

S4, when BT is not less than 0min and not more than 6min during blowing, lime, sinter and magnesium balls are added in batches according to the content of Si in molten iron added into the converter, the lance position is 2.4m, and the oxygen supply flow of the oxygen lance is controlled to be 18000Nm ³ The intensity of argon supplied by bottom blowing is 0.06Nm ³ /t·min；

Adding amount of lime: m _Lime =0.0163 × 93+0.0974=1.613 tons

Adding amount of sinter: m' _{Sintered ore} =0.01085 × 93+0.06625=1.075 ton

Adding amount of magnesium balls: m is a group of _{Magnesium ball} =0.0082 x 93+0.0374 t 0.8 t

The slag basicity at 6 minutes of converter blowing was 1.8.

S5, when blowing is carried out for 6min and BT is less than or equal to 10min, adding sinter to control the temperature of molten steel, and controlling the oxygen supply flow of an oxygen lance to be 19000 Nm/m ³ The gun position is 1.1m, and the intensity of argon supplied by bottom blowing is 0.05Nm ³ /t·min；

S6, when converting is carried out for 10min and BT is less than BT, adding sintered ore to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to 21000Nm ³ The position of a gun is 1.6m, and argon is supplied by bottom blowingStrength of 0.06Nm ³ /t·min；

S7, at the final stage of smelting, operating the oxygen lance at the high oxygen pressure and the low lance position for 50 seconds, wherein the oxygen pressure of the oxygen lance is 0.9MPa, and the oxygen supply flow of the oxygen lance is 22000Nm ³ The oxygen lance position is 0.9m.

The end point P of the converter is 0.029 percent, which meets the control requirement that the P is less than or equal to 0.035 percent, the C is 0.13 percent, the steel tapping amount is 88.92t, the temperature is 1660 ℃, the early-stage dephosphorization rate is 40 percent, and the total dephosphorization rate is 77.7 percent. The consumption of slagging materials is 17.34kg/t of lime, 28.82kg/t of limestone, 8.6kg/t of magnesium balls and 23.12kg/t of sinter.

The method realizes the reduction of lime under the condition of high iron consumption, and can reduce the lime consumption to 33.19kg/t from 55kg/t of the comprehensive lime of the original process, thereby greatly saving the lime consumption.

Example 3

S1, keeping slag after tapping of the previous furnace in the converter, and performing slag splashing furnace protection operation; the slag amount is 30kg/t, and the slag components comprise CaO 45.65% and SiO ₂ 14.98％、FeO 13.24％、MnO 1.12％、MgO 8.21％、P ₂ O ₅ 2.12％。

the molten iron amount is 91t, and the chemical components of the molten iron are C5.12%, si 0.60%, mn 0.23%, P0.12% and S0.028%.

Adding amount of limestone:

M _limestone =0.05 × 91+0.55=5.1 ton

Adding amount of sinter: m _{Sintered ore} =0.01625 × 91+0.1010=1.580 ton;

s3, adding molten iron and scrap steel; the temperature of the molten iron is 1334 ℃, the weight ratio of the scrap steel to the molten iron is 4.4 percent, and the weight of the scrap steel is 4 t.

S4, when BT is more than or equal to 0min and less than or equal to 6min in blowing, according to the Si content in molten iron added into the converter, adding lime, sinter and magnesium in batchesThe position of the lance is 2.0m, and the oxygen supply flow of the oxygen lance is controlled to be 18000Nm ³ Per hour, the intensity of nitrogen supplied by bottom blowing is 0.07Nm ³ /t·min；

Adding amount of lime: m _Lime =0.0108 × 91+0.0694=1.052 ton

Adding amount of sinter: m' _{Sintered ore} =0.01625 x 91+0.1010=1.580 ton

Adding amount of magnesium balls: m _{Magnesium ball} =0.0123 x 91+0.0187 t 1.138 t

The slag basicity at 6 minutes of converter blowing was 2.3.

S5, when BT is more than 6min and less than or equal to 10min during blowing, adding sinter to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to be 19000Nm ³ The gun position is 1.2m, and the intensity of nitrogen supplied by bottom blowing is 0.06Nm ³ /t·min；

S6, after converting for 10min and BT less, adding sinter to control the temperature of molten steel and the oxygen supply flow of oxygen lance to 21000Nm ³ The gun position is 1.4m, and the intensity of nitrogen supplied by bottom blowing is 0.06Nm ³ /t·min；

S7, at the final stage of smelting, operating the high-oxygen-pressure low-lance-position oxygen lance for 60 seconds, wherein the oxygen pressure of the oxygen lance is 0.9MPa, and the oxygen supply flow of the oxygen lance is 22000Nm ³ The oxygen lance position is 0.8m.

The end point [ P ] of the converter is 0.029 percent, the control requirement that the [ P ] is less than or equal to 0.035 percent is met, the [ C ] is 0.07 percent, the steel tapping amount is 89.84t, the temperature is 1669 ℃, the early dephosphorization rate is 50 percent, and the total dephosphorization rate is 76 percent. The consumption of slagging materials is 11.56kg/t of lime, 56.04kg/t of limestone, 12.51kg/t of magnesium balls and 34.73kg/t of sintered ore.

The method realizes the reduction of lime under the condition of high iron consumption, and can reduce the lime consumption to 42.38kg/t from 55kg/t of the comprehensive lime of the original process, thereby greatly saving the lime consumption.

Example 4

S1, keeping slag after tapping of the previous furnace in the converter, and performing slag splashing furnace protection operation; the slag amount is 23kg/t, and the slag components are CaO 40.5% and SiO ₂ 17.4％、FeO 13.6％、MnO 1.2％、MgO 8.2％、P ₂ O ₅ 2.5％。

the molten iron has the molten iron content of 89t, and the chemical components of the molten iron comprise 5.3% of C, 0.22% of Si, 0.67% of Mn, 0.10% of P and 0.023% of S.

Adding amount of limestone:

M _limestone =0.0267 × 89+0.1969+0.5=3.073 ton

Addition amount of sinter: m _{Sintered ore} =0.0119 × 89+0.0669=1.126 ton;

s3, adding molten iron and scrap steel; the temperature of molten iron is 1390 ℃, the scrap steel is 4.45t, and the weight ratio of the scrap steel to the molten iron is 5 percent.

S4, when BT is more than or equal to 0min and less than or equal to 6min in blowing, lime, sinter and magnesium balls are added in batches according to the Si content in molten iron added into the converter, the lance position is 1.5m, and the oxygen supply flow of the oxygen lance is controlled to be 18000Nm ³ The nitrogen supply strength by bottom blowing is 0.08Nm ³ /t·min；

Adding amount of lime: m _Lime =0.0163 × 89+0.0974=1.548 ton

Adding amount of sinter: m' _{Sintered ore} =0.0119 × 89+0.0669=1.126 ton;

adding amount of magnesium balls: m is a group of _{Magnesium ball} =0.0085 × 89+0.0355=0.792 ton

The slag basicity at 6 minutes of converter blowing was 1.95.

S5, when BT is more than 6min and less than or equal to 10min during blowing, adding sinter to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to be 19000Nm ³ The gun position is 1.5m, and the intensity of nitrogen supplied by bottom blowing is 0.04Nm ³ /t·min；

S6, when converting is carried out for 10min and BT is less than BT, adding sintered ore to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to 21000Nm ³ The gun position is 1.5m, and the intensity of nitrogen supplied by bottom blowing is 0.04Nm ³ /t·min；

S7, at the final stage of smelting, performing high-oxygen-pressure and low-lance-position oxygen lance operation for 50 seconds, wherein the oxygen pressure of the oxygen lance is 0.95MPa, and oxygen is generatedThe oxygen supply flow of the gun is 22000Nm ³ The oxygen lance position is 0.85m.

The end point [ P ] of the converter is 0.021 percent, which meets the control requirement that the [ P ] is less than or equal to 0.035 percent, the [ C ] is 0.14 percent, the steel tapping amount is 88t, the temperature is 1660 ℃, the early-stage dephosphorization rate is 58 percent, and the total dephosphorization rate is 79 percent. The consumption of slagging materials is 17.39kg/t of lime, 34.53kg/t of limestone, 8.9kg/t of magnesium balls and 25.3kg/t of sinter.

The method realizes the reduction of lime under the condition of high iron consumption, and can reduce the lime consumption to 36.38kg/t from 55kg/t of the comprehensive lime of the original process, thereby greatly saving the lime consumption.

Example 5

S1, keeping slag after tapping of the previous furnace in the converter, and performing slag splashing furnace protection operation; the slag amount is 25kg/t, and the slag components are CaO 42.1% and SiO ₂ 15.4％、FeO 12.5％、MnO 1.3％、MgO 9.3％、P ₂ O ₅ 2.2％；

the molten iron amount is 97t, and the chemical components of the molten iron are C4.9%, si 0.52%, mn 0.82%, P0.11% and S0.022%;

adding amount of limestone:

M _limestone =0.046 × 97+0.6 =5.662 ton

Adding amount of sinter: m _{Sintered ore} =0.01625 × 97+0.1010=1.677 ton;

s3, adding molten iron and scrap steel; the temperature of molten iron is 1380 ℃, the weight ratio of scrap steel to molten iron is 4.12 percent, and the weight of scrap steel is 4 t.

S4, when BT is not less than 0min and not more than 6min during blowing, lime, sinter and magnesium balls are added in batches according to the content of Si in molten iron added into the converter, the gun position is 1.3m, and the oxygen supply flow of the oxygen lance is controlled to be 18000Nm ³ The nitrogen supply intensity of bottom blowing is 0.07Nm ³ /t·min；

Lime additionQuantity: m is a group of _Lime =0.0108 × 97+0.0694=1.117 ton

Addition amount of sinter: m' _{Sintered ore} =0.01625 × 97+0.1010=1.677 ton;

adding amount of magnesium balls: m _{Magnesium ball} = 0.013X 97+0.02=1.281 ton

The slag basicity at 6 minutes of converter blowing was 2.1.

S5, when blowing is carried out for 6min and BT is less than or equal to 10min, adding sinter to control the temperature of molten steel, and controlling the oxygen supply flow of an oxygen lance to be 19000 Nm/m ³ The gun position is 1.3m, and the intensity of nitrogen supplied by bottom blowing is 0.05Nm ³ /t·min；

S6, when converting is carried out for 10min and BT is less than BT, adding sintered ore to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to 21000Nm ³ The gun position is 1.3m, and the intensity of nitrogen supplied by bottom blowing is 0.05Nm ³ /t·min；

S7, at the final stage of smelting, operating the high-oxygen-pressure low-lance-position oxygen lance for 40 seconds, wherein the oxygen pressure of the oxygen lance is 0.82MPa, and the oxygen supply flow of the oxygen lance is 22000Nm ³ The oxygen lance position is 0.9m.

The end point P of the converter is 0.027 percent and meets the control requirement that the P is less than or equal to 0.035 percent, the C is 0.20 percent, the steel tapping amount is 97t, the temperature is 1640 ℃, the early dephosphorization rate is 55 percent and the total dephosphorization rate is 75.5 percent. The consumption of slagging materials is 11.52kg/t of lime, 58.37kg/t of limestone, 13.21kg/t of magnesium balls and 34.58kg/t of sintered ore.

The method realizes the reduction of lime under the condition of high iron consumption, can reduce the lime consumption to 43.62kg/t from 55kg/t of the comprehensive lime of the original process, and greatly saves the lime consumption.

Example 6

S1, keeping slag after tapping of the previous furnace in the converter, and performing slag splashing furnace protection operation; the residual slag amount is 22kg/t, and the slag components comprise CaO 45.2% and SiO ₂ 17.3％、FeO 10.2％、MnO 1.1％、MgO 7.9％、P ₂ O ₅ 2.1％。

the molten iron amount is 86t, and the chemical components of the molten iron are C5.1%, si 0.16%, mn 0.22%, P0.124% and S0.021%.

Adding amount of limestone: m _Limestone =0.0108 × 86+0.0694=0.998 ton

Adding amount of sinter: m _{Sintered ore} =0.00815 × 86+0.0487=0.750 ton;

s3, adding molten iron and scrap steel; the temperature of the molten iron is 1334 ℃, the weight ratio of the scrap steel to the molten iron is 3.5 percent, and the weight of the scrap steel is 3 t.

S4, when BT is not less than 0min and not more than 6min during blowing, lime, sinter and magnesium balls are added in batches according to the content of Si in molten iron added into the converter, the gun position is 1.9m, and the oxygen supply flow of the oxygen lance is controlled to be 18000Nm ³ The nitrogen supply intensity of bottom blowing is 0.07Nm ³ /t·min；

Lime addition: m _Lime =0.0108 × 86+0.0694=0.998 ton

Adding amount of sinter: m' _{Sintered ore} = 0.00815X 86+0.0487 t 0.750 ton

Adding amount of magnesium balls: m _{Magnesium ball} = 0.0043X 86+0.0273=0.397 ton

The slag basicity at 6 minutes of converter blowing was 2.3.

S5, when BT is more than 6min and less than or equal to 10min during blowing, adding sinter to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to be 19000Nm ³ The gun position is 1.1m, and the intensity of nitrogen supplied by bottom blowing is 0.06Nm ³ /t·min；

S6, when converting is carried out for 10min and BT is less than BT, adding sintered ore to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to 21000Nm ³ The gun position was 1.6m, and the intensity of nitrogen gas supplied by bottom blowing was 0.04Nm ³ /t·min；

S7, at the final stage of smelting, operating the oxygen lance with high oxygen pressure and low lance position for 40 seconds, wherein the oxygen pressure of the oxygen lance is 0.9MPa, and the oxygen supply flow of the oxygen lance is 22000Nm ³ The oxygen lance position is 1.0m.

The end point [ P ] of the converter is 0.021 percent, which meets the control requirement that the [ P ] is less than or equal to 0.035 percent, the [ C ] is 0.08 percent, the steel tapping amount is 86t, the temperature is 1645 ℃, the early-stage dephosphorization rate is 60 percent, and the total dephosphorization rate is 83 percent. The consumption of slagging materials is 11.6kg/t of lime, 11.6kg/t of limestone, 4.62kg/t of magnesium balls and 17.44kg/t of sinter.

The method realizes the reduction of lime under the condition of high iron loss, can reduce the lime consumption to 17.98kg/t from 55kg/t of the comprehensive lime of the original process, and greatly saves the lime consumption.

Example 7

S1, keeping slag after tapping of the previous furnace in the converter, and performing slag splashing furnace protection operation; the slag amount remained is 23kg/t, the slag components are CaO 41.6 percent and SiO ₂ 13.7％、FeO 11.6％、MnO 1.34％、MgO 8.21％、P ₂ O ₅ 2.23％。

the molten iron amount is 92.5t, and the chemical components of the molten iron are C5.2%, si 0.85%, mn 0.21%, P0.114% and S0.022%.

Adding amount of limestone: m _Limestone =0.063 × 92.5+0.24=6.068 ton

Adding amount of sinter: m is a group of _{Sintered ore} =0.01375 × 92.5+0.06095=1.333 ton;

s3, adding molten iron and scrap steel; the temperature of the molten iron is 1376 ℃, the weight ratio of the scrap steel to the molten iron is 4.8%, and the weight ratio of the scrap steel to the molten iron is 4.5 t.

S4, when BT is not less than 0min and not more than 6min during blowing, lime, sinter and magnesium balls are added in batches according to the content of Si in molten iron added into the converter, the lance position is 2.2m, and the oxygen supply flow of the oxygen lance is controlled to be 18000Nm ³ The nitrogen supply intensity of bottom blowing is 0.07Nm ³ /t·min；

Adding amount of lime: m is a group of _Lime =0.0108 × 92.5+0.0694=1.068 ton

Adding amount of sinter: m' _{Sintered ore} =0.01375 x 92.5+0.06095=1.333 ton

Adding amount of magnesium balls: m _{Magnesium ball} =0.0108 × 92.5+0.0694=1.068 ton

The slag basicity at 6 minutes of converter blowing was 2.0.

S5, when BT is more than 6min and less than or equal to 10min during blowing, adding sinter to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to be 19000Nm ³ The gun position is 0.9m, and the intensity of nitrogen supplied by bottom blowing is 0.06Nm ³ /t·min；

S6, when converting is carried out for 10min and BT is less than BT, adding sintered ore to control the temperature of molten steel and controlling the oxygen supply flow of an oxygen lance to 21000Nm ³ The gun position is 1.4m, and the intensity of nitrogen supplied by bottom blowing is 0.04Nm ³ /t·min；

The final point P of the converter is 0.026%, the control requirement that P is less than or equal to 0.035% is met, C is 0.08%, the steel tapping amount is 92t, the temperature is 1660 ℃, the early-stage dephosphorization rate is 54%, and the total dephosphorization rate is 77%. The consumption of slagging materials is 11.55kg/t of lime, 71.44kg/t of limestone, 11.55kg/t of magnesium balls and 28.82kg/t of sintered ore.

The method realizes the reduction of lime under the condition of high iron consumption, can reduce the lime consumption to 50.84kg/t from 55kg/t of the comprehensive lime of the original process, and saves the lime consumption.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. A steelmaking method for reducing comprehensive lime consumption by rapidly slagging in a converter with high iron loss is characterized by comprising the following steps:

s3, adding the molten iron and the scrap steel in the step S2 into a converter, wherein the weight ratio of the scrap steel to the molten iron is less than or equal to 5%, and the temperature of the molten iron is more than or equal to 1240 ℃;

2. The steelmaking method as claimed in claim 1, wherein in S1, when the tapping temperature of the previous furnace is more than 1670 ℃ or the molten steel is over-oxidized, 1/2 of the slag in the furnace is left.

3. The steelmaking process as claimed in claim 1,

when Mn of the molten iron in S2 is less than 0.6% and Si is less than 0.20%, in S2:

adding amount of limestone: m is a group of _Limestone ＝0.0108M _{Molten iron} +0.0694，

When Mn of the molten iron in the S2 is less than 0.6 percent and Si is more than or equal to 0.2 percent and less than 0.5 percent, in the S2:

adding amount of limestone: m _Limestone ＝(0.0161～0.0267)M _{Molten iron} +(0.1165～0.1969)，

Adding amount of sinter: m _{Sintered ore} ＝(0.01085～0.01355)M _{Molten iron} +(0.06625～0.08255)；

When Mn in the molten iron in the S2 is less than 0.6 percent and Si in the range of 0.5 percent to 0.8 percent, in the S2:

Adding amount of sinter: m is a group of _{Sintered ore} ＝0.01625M _{Molten iron} +0.1010；

When the molten iron Mn in the S2 is less than 0.6 percent, si is more than 0.8 percent and less than or equal to 1.2 percent, in the S2:

Wherein, M is _Limestone Is the added weight of limestone, M _{Sintered ore} For the weight of the added sinter, said M _{Molten iron} Is the weight of the molten iron added into the converter.

4. The steelmaking process as claimed in claim 1,

when Mn is more than or equal to 0.6% and less than 1.2% and Si is less than 0.20% in the S2, in the S2:

Adding amount of sinter: m is a group of _{Sintered ore} ＝0.00815M _{Molten iron} +0.0487；

When 0.6% to 1.2% of Mn and 0.2% to 0.5% of Si in the molten iron in the S2 are more than or equal to each other, in the S2:

When 0.6% to less than 1.2% of Mn and 0.5% to less than 0.8% of Si in the molten iron in the S2, in the S2:

adding amount of limestone: m _Limestone ＝(0.0457～0.0571)M _{Molten iron} +(0.548～0.8898)+(0.5～1.0)，

Addition amount of sinter: m _{Sintered ore} ＝0.01625M _{Molten iron} +0.1010；

When 0.6% to less than 1.2% of Mn and 0.8% to less than 1.2% of Si in the molten iron in the S2, in the S2:

Adding amount of sinter: m is a group of _{Sintered ore} ＝0.01375M _{Molten iron} +0.06095；

5. A method as claimed in any one of claims 1 to 4, in which in S2 the limestone is present in an amount of 52 to 55% CaO by mass.

6. The steelmaking process as claimed in claim 1,

when the Si of the molten iron in the S2 is less than 0.20%, in the S4:

adding amount of lime: m _Lime ＝0.0108M _{Molten iron} +0.0694，

When Si is more than or equal to 0.2% and less than 0.5% in the molten iron in the S2, in the S4:

adding amount of lime: m _Lime ＝0.0163M _{Molten iron} +0.0974，

When Si is more than or equal to 0.5% and less than or equal to 0.8% in the molten iron in the S2, in the S4:

lime addition: m _Lime ＝0.0108M _{Molten iron} +0.0694，

When 0.8% < Si in the molten iron in S2 is less than or equal to 1.2%, in S4:

lime addition: m _{Lime (lime)} ＝0.0108M _{Molten iron} +0.0694，

Said M _Lime For the weight of lime added, said M _{Magnesium ball} Weight of the added magnesium balls, said M _{Molten iron} Is the weight of the molten iron added into the converter.

7. A steelmaking process as claimed in any one of claims 1 to 4, in which the sinter ore comprises, in mass%: TFe not less than 54%, feO<10％，9％＜CaO＜13％，5.5％＜SiO ₂ < 8%, basicity R = CaO/SiO ₂ ≥1.6，S<0.04％。

8. The steel-making method according to claim 1, wherein in S4, the basicity of the slag at 6 minutes of converter blowing is 1.8 to 2.3.

9. The steel-making method according to claim 1, wherein when Mn of said molten iron in S2 is less than 0.6%, the lance height is controlled to be 1.8 to 2.4m in S4, 0.9 to 1.2m in S5, and 1.2 to 1.6m in S6.

10. The steel making method according to claim 3, wherein when the molten iron in S2 has Mn of 0.6% to 1.2%, the oxygen lance in S4, S5 and S6 is operated at a constant lance position of 1.2 to 1.8 m.