阅读说明：本技术 一种基于高铁水比电炉炼钢降低渣中全铁的方法 (Method for reducing total iron in slag based on high molten iron ratio electric furnace steelmaking ) 是由 李晶 谢吉祥 闫威 刁承民 李波 张宝富 于 2020-11-26 设计创作，主要内容包括：本发明公开了一种高铁水比电炉炼钢降低渣中全铁的方法,涉及钢铁工艺流程冶炼控制领域。该方法包括：上一炉冶炼结束炉内留钢量大于出钢量的15％,冶炼开始前先加入废钢,并兑入铁水,兑铁水过程速度基本恒定；连续兑入铁水2.5min后开始吹氧,吹氧由炉壁氧枪完成,熔池碳含量稳定在0.6-0.8％范围；分批加入石灰和白云石,兑铁水量为总钢铁料的75～85％；连续兑完铁水2-5min,将碳含量控制在出钢要求的碳含量,停止吹氧；取样、测温,开始出钢。本发明通过优化冶炼过程供氧操作,控制炉壁氧枪的供氧流量,保持金属熔池中碳含量在0.6-0.8％范围内冶炼,出钢前2～5min内将熔池碳含量降低到出钢要求范围,实现高铁水比电炉冶炼出钢时渣中全铁含量小于15％。(The invention discloses a method for reducing total iron in slag in electric furnace steelmaking with high molten iron ratio, and relates to the field of smelting control of steel process flows. The method comprises the following steps: after the last smelting is finished, the steel amount remained in the furnace is more than 15% of the steel tapping amount, scrap steel is added before the smelting is started, molten iron is added, and the speed of the molten iron adding process is basically constant; blowing oxygen from an oxygen lance on the furnace wall after continuously adding molten iron for 2.5min, wherein the carbon content of the molten pool is stabilized within the range of 0.6-0.8%; adding lime and dolomite in batches, wherein the amount of the added iron water is 75-85% of the total iron and steel materials; continuously adding molten iron for 2-5min, controlling the carbon content to the carbon content required by tapping, and stopping oxygen blowing; sampling, measuring temperature and tapping. According to the invention, by optimizing the oxygen supply operation in the smelting process, the oxygen supply flow of the furnace wall oxygen lance is controlled, the carbon content in the metal molten pool is kept in the range of 0.6-0.8% for smelting, the carbon content in the molten pool is reduced to the required range of tapping within 2-5min before tapping, and the full iron content in the slag is less than 15% when the high molten iron ratio is smelted and tapped by an electric furnace.)

1. A method for reducing total iron in slag in electric furnace steelmaking with high molten iron ratio is characterized in that the electric furnace is provided with four furnace wall oxygen lances, and the method comprises the following steps:

step 1: after the last smelting is finished, the steel amount remained in the furnace is more than 15% of the steel tapping amount, scrap steel is added before the smelting is started, molten iron is added, and the speed of the molten iron adding process is basically constant;

step 2: blowing oxygen from an oxygen lance on the furnace wall after continuously adding molten iron for 2.5min, wherein the carbon content of the molten pool is stabilized within the range of 0.6-0.8%;

and step 3: adding lime and dolomite in batches, wherein the amount of the added iron water is 75-85% of the total iron and steel materials;

and 4, step 4: continuously adding molten iron for 2-5min, controlling the carbon content to the carbon content required by tapping, and stopping oxygen blowing;

and 5: sampling, measuring temperature and tapping.

2. The method of claim 1, wherein in the step 1, the molten steel component is left as the last steel smelting end point component.

3. The method according to claim 1, wherein in the step 1, the charging temperature of the molten iron is higher than 1300 ℃, the composition of the charged molten iron is 4.2% < C < 4.5%, and 0.065% < P < 0.085%.

4. The method as claimed in claim 1, wherein in step 2, after the furnace wall lance starts to supply oxygen, the total oxygen supply flow rate of the lance is kept constant, and the oxygen blowing flow rate of two lances near the furnace door opening is kept at 35Nm from the start of oxygen supply to the end of oxygen supply³·h^-1·t^-1The oxygen supply flow of the two oxygen lances far away from the furnace door is 30Nm respectively without change³·h^-1·t^-1And 20Nm³·h^-1·t^-1。

5. The method as claimed in claim 4, wherein the oxygen lance oxygen supply flow rate can be finely adjusted according to the slag overflow condition at the furnace door, and the oxygen lance oxygen supply flow rate of each furnace wall can be adjusted within a variation range of +/-3 Nm³·h^-1·t^-1And the total oxygen supply flow of the oxygen lances on the two furnace walls is always kept unchanged during adjustment.

6. The method as claimed in claim 5, wherein the oxygen supply flow rate is adjusted by adjusting the lance opening.

7. The method as claimed in claim 1, wherein in step 3, lime is added in portions, lime is added in three portions in each furnace, the lime is added in 9-13kg/t after the first portion is added for iron mixing, the lime is added in 7-11kg/t after the second portion is added for 8 minutes, and the lime is added in 4-8kg/t after the third portion is added for 16 minutes.

8. The method of claim 7, wherein the second batch and the third batch are added in a manner that the lime feeding speed is reduced by adjusting the vibration sieve of the lime silo, and the lime feeding amount is matched with the amount of the continuously added molten iron.

9. The method of claim 1, wherein the dolomite is added simultaneously with the lime, and the total addition of lime and dolomite is less than or equal to 35 kg/t.

10. The method of claim 1, wherein in step 5, the slag control: the alkalinity of the final slag is 2.5, and the total iron content of the final slag is 13.68 percent; end point control target: tapping carbon content: [C] 0.10 percent, tapping phosphorus content: [ P ] < 0.025%.

Technical Field

The invention relates to the field of smelting control of steel process flows, in particular to a method for reducing total iron in slag based on high molten iron ratio electric furnace steelmaking.

Background

At present, the price of scrap steel is higher, the smelting cost of a full scrap steel electric arc furnace is high, and high molten iron ratio electric arc furnace steelmaking becomes an important smelting mode in long-flow steel and iron united enterprises. The high molten iron brings a large amount of physical heat and chemical heat for the electric furnace steelmaking process compared with the iron-containing raw material, under the condition of the smelting process of the high molten iron ratio, namely under the condition of 75-85% molten iron and 15-25% scrap steel of the structure of the iron-containing raw material fed into the furnace, power supply can be omitted for smelting, power supply and temperature rise can be cancelled, the power consumption and the electrode consumption can be reduced, the temperature rise of the molten steel in the electric furnace mainly depends on the chemical heat released by oxidation reaction of carbon, silicon, manganese and other elements in the molten iron fed into the furnace, and the modern electric furnace steelmaking oxygen supply mode mainly comprises furnace door oxygen supply, furnace wall oxygen supply, EB. In the smelting mode of the electric furnace with the high molten iron ratio, the proportion of chemical energy in the energy input of the electric furnace is greatly improved, oxygen blowing control becomes a key technology of the steelmaking process of the electric furnace with the high molten iron ratio, and the total iron content in the steelmaking end-point slag of the electric arc furnace is more than 20 percent, which is caused by excessive oxygen blowing. Therefore, optimizing an oxygen supply system, and inventing a high-efficiency oxygen utilization technology for reducing total iron in slag based on high molten iron ratio electric furnace steelmaking is very important, and is very beneficial to accelerating the smelting production rhythm of the high molten iron ratio electric furnace and reducing the cost of steel per ton.

In the process of smelting high molten iron ratio electric furnaces, because molten iron is slowly added into the furnaces from a ladle through a hot metal charging chute, a smelting technology of whole-process oxygen supply is needed, relatively high oxygen blowing amount is kept, and in order to prevent over oxidation of a molten pool and guarantee proper smelting end point tapping carbon content, an efficient and reasonable oxygen blowing control technology is needed. The accurate control of the oxygen supply of the high-iron molten iron to the electric furnace is deeply influenced by various factors such as the change of the components of the molten iron entering the furnace, the change of the amount of the molten iron entering the furnace and the like, if the oxygen supply system is unreasonable, the smelting time can be prolonged, the service life of a furnace lining can be reduced, and particularly, the influence on the total iron content in slag is great, and the metal consumption can be increased.

Disclosure of Invention

In order to solve the problems, the invention provides a method for reducing total iron in slag in high-molten iron ratio electric furnace steelmaking. By optimizing the oxygen supply operation in the smelting process, controlling the oxygen supply flow of the furnace wall oxygen lance, keeping the carbon content in the metal molten pool within the range of 0.6-0.8 percent for smelting, reducing the carbon content in the molten pool within 2-5min before tapping to the required range of tapping, and realizing that the total iron content in slag during smelting and tapping of the electric furnace with high molten iron ratio is less than 15 percent.

According to the technical scheme of the invention, the method for reducing the total iron in the slag in the electric furnace steelmaking with high molten iron ratio is provided, and the electric furnace is provided with four furnace wall oxygen lances, and is characterized by comprising the following steps:

step 1: after the last smelting is finished, the steel amount remained in the furnace is more than 15% of the steel tapping amount, scrap steel is added before the smelting is started, molten iron is added, and the speed of the molten iron adding process is basically constant;

step 2: blowing oxygen from an oxygen lance on the furnace wall after continuously adding molten iron for 2.5min, wherein the carbon content of the molten pool is stabilized within the range of 0.6-0.8%;

and step 3: adding lime and dolomite in batches, wherein the iron adding water amount is 75-85% of the total iron and steel materials

And 4, step 4: continuously adding molten iron for 2-5min, controlling the carbon content to the carbon content required by tapping, and stopping oxygen blowing;

and 5: sampling, measuring temperature and tapping.

Further, in the step 1, the components of the molten steel are remained as the components of the last furnace steel smelting end point.

Further, in the step 1, the charging temperature of the molten iron is higher than 1300 ℃, the content of the charged molten iron is more than 4.2 percent and less than 4.5 percent, and the content of the charged molten iron is more than 0.065 percent and less than 0.085 percent.

Further, in step 2, after the oxygen lance on the furnace wall starts to supply oxygen, the total oxygen supply flow of the oxygen lance is kept unchanged, the two oxygen lances close to the furnace door are kept from the start of oxygen supply to the end of oxygen supply, and the oxygen blowing flow is always kept at the same value35Nm³·h^-1·t^-1The oxygen supply flow of the two oxygen lances far away from the furnace door is 30Nm respectively without change³·h^-1·t^-1And 20Nm³·h^-1·t^-1。

Furthermore, the oxygen supply flow of the oxygen lance can be finely adjusted according to the slag overflow condition of the furnace door, and the adjustment variation range of the oxygen supply flow of the oxygen lance on each furnace wall is +/-3 Nm³·h^-1·t^-1And the total oxygen supply flow of the oxygen lances on the two furnace walls is always kept unchanged during adjustment.

Furthermore, the oxygen supply flow is adjusted by adjusting the opening of the oxygen lance.

Further, in the step 3, lime is added in batches at different time intervals, lime is added into each furnace in three batches, 9-13kg/t of lime is added after the first batch starts to be mixed with iron, 7-11kg/t of lime is added after the second batch starts to be mixed with iron for 8 minutes, and 4-8kg/t of lime is added after the third batch starts to be mixed with iron for 16 minutes.

Furthermore, the lime adding speed is reduced by adjusting a lime bin vibrating screen in the second batch and the third batch, and the lime adding amount is matched with the amount of continuously added molten iron.

Furthermore, the lime and the dolomite are added simultaneously, and the total adding amount of the lime and the dolomite is less than or equal to 35 kg/t.

Further, in step 5, slag control: the alkalinity of the final slag is 2.5, and the total iron content of the final slag is 13.68 percent; end point control target: tapping carbon content: [C] 0.10 percent, tapping phosphorus content: [ P ] < 0.025%.

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

(1) the method is simple and convenient to operate and easy to master, under the condition that only the furnace wall oxygen lance supplies oxygen, lime is added in batches at different times according to the condition of molten iron entering the furnace, the molten pool is operated at constant carbon in the smelting process, the total oxygen supply amount in unit time is stable, and the total iron content in slag during steel making and steel tapping of the high-iron-content ratio electric arc furnace is lower than 15% under the condition of meeting dephosphorization.

(2) The invention realizes that the oxygen consumption of the high molten iron per ton steel in the electric arc furnace is reduced to 55Nm compared with the oxygen consumption of the electric arc furnace steel-making under the condition of oxygen supply of the oxygen lance on the furnace wall³Below/t, a method is provided for reasonable oxygen supply and reasonable slagging of electric furnace steelmaking with high molten iron ratio, which is beneficial to reducing the total iron content in slag and improving the metal yield.

(3) The invention can realize the smelting end point carbon content [ C ] of the high molten iron ratio electric furnace and the smelting of the electric furnace, and the phosphorus content [ P ] is less than 0.025 percent; and the addition amount of slag charge is low, so that the cost of per ton steel can be effectively reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a flow chart illustrating a method for reducing total iron in slag based on electric steelmaking with a high molten iron ratio according to the present invention.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

The terms "first," "second," and the like in the description and in the claims of the present disclosure are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the disclosure described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.

Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

A plurality, including two or more.

And/or, it should be understood that, for the term "and/or" as used in this disclosure, it is merely one type of association that describes an associated object, meaning that three types of relationships may exist. For example, a and/or B, may represent: a exists alone, A and B exist simultaneously, and B exists alone.

The invention discloses a method for reducing total iron in slag based on electric furnace steelmaking with a high molten iron ratio, which comprises the following steps of:

step 101: and (5) ending the previous smelting, wherein the steel remaining amount in the furnace is more than 15% of the steel tapping amount → the step 102: adding scrap steel before smelting begins → step 103: molten iron charging is started, the speed of the molten iron charging process is basically constant → step 104: and (3) beginning to blow oxygen 2.5min after adding molten iron, wherein the oxygen blowing is completed by an oxygen lance on the furnace wall, the carbon content of the molten pool is stabilized within the range of 0.6-0.8% → step 105: adding lime and dolomite in batches, wherein the hot metal adding amount is 75-85% of the total iron and steel materials → step 106: after the molten iron is added for 2-5min, controlling the carbon content to be the carbon content required by tapping, stopping oxygen blowing → step 107: sampling, measuring temperature and tapping. Wherein, the raw materials containing iron in the furnace comprise 75-85% of molten iron and 15-25% of scrap steel, the molten iron is slowly added into the furnace from a ladle through an iron charging chute, and the speed of the process of charging the molten iron is basically constant. Oxygen is supplied by a furnace wall oxygen lance, oxygen supply is started after iron is added, the furnace wall oxygen lance is always in an oxygen blowing state, and oxygen supply is stopped until tapping.

The steel retaining operation is carried out during the EBT steel tapping of a common electric furnace, the carbon content of the steel retaining liquid steel is low, the carbon in an oxygen supply molten pool is quickly oxidized after the beginning of iron adding, the peroxidation phenomenon exists, and the total iron content in slag is high. According to the invention, under the smelting mode of continuously adding molten iron, the iron adding time accounts for more than 90% of the smelting time of each furnace, the problem of high total iron content in slag caused by metal molten pool peroxidation in the smelting process can be effectively avoided through an efficient and reasonable oxygen supply technology, and the total iron content in the slag can be effectively controlled to be lower than 15% under the condition of ensuring that the proper tapping temperature and the smelting end point carbon content meet the requirements. The operation improves the utilization rate of oxygen and reduces the total iron content in slag by reasonably adjusting the oxygen supply time and the oxygen supply flow of the furnace wall oxygen lance. Meanwhile, the carbon content of the molten pool is stably controlled to be 0.6-0.8% in the converting process, the invention can effectively reduce the total iron content and oxygen consumption in the slag during the steelmaking of the electric furnace with high molten iron ratio, realize the reduction of iron loss during the converting and improve the economic benefit of the electric furnace steelmaking.

Example 1

73t (78.5%) of molten iron entering the furnace, 20t (21.5%) of scrap steel, 4.3% of carbon content of the molten iron, 0.075% of P content of the molten iron, 1381 ℃ of molten iron temperature, more than 15% of steel left in the furnace, 28.36kg/t of lime, 3.70kg/t of dolomite, 81.1t of steel left, 22.6min of oxygen blowing smelting time, 32.06kg/t of slag charge, 53.477Nm oxygen consumption³The end point C was 0.12% and P was 0.02%.

The method mainly comprises the following steps:

(1) after the EBT in the previous furnace finishes tapping, steel is left in the furnace more than 15% of the tapping amount, and the steel liquid component is the smelting end point component of the steel in the previous furnace;

(2) the charging temperature of molten iron is more than 1300 ℃, and the charging molten iron comprises the following components: 4.3%, P: 0.075%;

(3) oxygen blowing only depends on the furnace wall oxygen lance, after the furnace wall oxygen lance starts oxygen supply, the total oxygen supply flow of the oxygen lance keeps unchanged, the two oxygen lances close to the furnace door are kept from oxygen supply to oxygen supply, and the oxygen blowing flow is always kept at 2850Nm³·h^-1(35Nm³·h^-1·t^-1) The oxygen supply flow of the two oxygen lances far away from the furnace door is 2450Nm respectively without change³·h^-1(30Nm³·h^-1·t^-1) And 1650Nm³·h^-1(20Nm³·h^-1·t^-1) The oxygen supply flow of the two furnace wall oxygen lances can be finely adjusted according to the slag overflow condition of the furnace door, and the oxygen supply flow of each furnace wall oxygen lance can be adjusted within the variation range of +/-300 Nm³·h^-1(3Nm³·h^-1·t^-1) When in adjustment, the sum of the oxygen supply flow of the two furnace wall oxygen lances needs to be ensured to be always kept unchanged;

(4) lime is added in batches at different time intervals, lime is added into each furnace in three batches, the lime is added into the furnace at 12.18kg/t after the first batch is added with iron, the lime is added into the furnace at 10.18kg/t after the second batch is added with iron for 8 minutes, the lime is added into the furnace at 8kg/t after the third batch is added with iron for 16 minutes, the temperature change of a molten pool is comprehensively considered, in order to meet the tapping temperature requirement, the lime adding speed can be reduced by adjusting a vibrating screen of a lime bin in the last two batches, the lime adding amount is matched with the amount of continuously added molten iron, and the total adding amount of the lime and the dolomite is less than or equal to 35 kg/t; (ii) a

(5) Controlling the slag: the alkalinity of the final slag is 2.5, and the total iron content of the final slag is 13.68 percent;

(6) end point control target: tapping carbon content: [C] 0.10 percent, tapping phosphorus content: [ P ] < 0.025%;

through the control, when the smelting end point meets the requirements of temperature and components, the constant carbon oxygen blowing operation and the time-sharing and batch adding operation of the slag former are adopted in the process of continuously adding molten iron, the amount of slag charge per ton of steel is controlled to be 32.06kg/t, and the total iron content in slag is 13.68%.

Example 2

74.3t (80.5%) of molten iron, 18t (19.5%) of scrap steel is added, the carbon content of the molten iron is 4.4%, the P content of the molten iron is 0.073%, the temperature of the molten iron is 1368 ℃, the steel remaining in the furnace is more than 15% of the steel tapping amount, 29.05kg/t of lime, 3.63kg/t of dolomite, 82.6t of the steel tapping amount, the oxygen blowing smelting time is 23.2min, 32.68kg/t of slag charge is counted, and the oxygen consumption is 53.95Nm³And/t, the end point C is 0.12 percent, the P is 0.023 percent, the end point slag alkalinity is 2.5, and the total iron content in the slag is 14.24 percent.

Example 3

71.8t (76.5%) of molten iron, 22t (23.5%) of scrap steel and 4.3% of carbon content in molten ironPercent, the P content of the molten iron is 0.068 percent, the temperature of the molten iron is 1387 ℃, the steel remaining in the furnace is more than 15 percent of the steel tapping amount, 28.71kg/t of lime, 3.75kg/t of dolomite, 80.1t of the steel tapping amount, 22.4min of oxygen blowing smelting time, 32.46kg/t of slag charge in total and 53.93Nm oxygen consumption³And/t, the end point C is 0.11 percent, the P is 0.022 percent, the end point slag alkalinity is 2.4, and the total iron content in the slag is 14.19 percent.

As described above, the present invention can be preferably realized.

The process flow of the invention is simple and convenient to operate, and can effectively realize the purpose that the total iron content in the electric furnace steel-making slag with high molten iron ratio is less than 15 percent.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.