阅读说明：本技术 一种低碳低硅含铝镇静钢精炼快速成渣的方法 (Method for refining low-carbon low-silicon aluminum-containing killed steel to form slag quickly ) 是由 梁三清 陈帅 穆鸿敏 刘小刚 冀友军 于 2021-09-26 设计创作，主要内容包括：本发明公开了一种低碳低硅含铝镇静钢精炼快速成渣的方法,属于合金钢技术领域；步骤为在转炉出钢过程中同时加入自身总量28-35%的精炼合成渣和自身总量28-35%的石灰渣料；精炼过程中加入剩余的精炼合成渣和石灰渣料；精炼合成渣和石灰渣料的总量比为1:5-7；精炼合成渣的成分为重量百分比：20～50%的金属铝、35～60%的Al-(2)O-(3)、10～20%的CaO,所述金属铝的粒度<5mm；本发明方法的精炼过程15分钟内实现白渣操作,造成的白渣不仅为精炼后期有充足的时间脱硫、去除夹杂物,同时可以降本增效。(The invention discloses a method for refining low-carbon low-silicon aluminum-containing killed steel to form slag quickly, belonging to the technical field of alloy steel; adding refined synthetic slag accounting for 28-35% of the total amount of the refined synthetic slag and lime slag in the tapping process of the converter; adding the rest of the refining synthetic slag and lime slag materials in the refining process; the total weight ratio of the refined synthetic slag to the lime slag is 1: 5-7; the refining synthetic slag comprises the following components in percentage by weight: 20-50% of metal aluminum and 35-60% of Al 2 O 3 10-20% of CaO, and the granularity of the metallic aluminum<5 mm; refining of the process of the inventionThe white slag operation is realized within 15 minutes, and the white slag has sufficient time for desulfurization and impurity removal in the later stage of refining, and can reduce cost and improve efficiency.)

1. A method for refining and rapidly slagging low-carbon low-silicon aluminum-containing killed steel is characterized in that refined synthetic slag accounting for 28-35% of the total amount of the refined synthetic slag and lime slag accounting for 28-35% of the total amount of the refined synthetic slag are added in the tapping process of a converter; adding the rest of the refining synthetic slag and lime slag materials in the refining process; the total weight ratio of the refined synthetic slag to the lime slag is 1: 5-7; the refining synthetic slag comprises the following components in percentage by weight: 20-50% of metal aluminum and 35-60% of Al₂O₃10-20% of CaO, and the granularity of the metallic aluminum<5mm。

2. The method for refining and rapidly slagging low-carbon low-silicon aluminum-containing killed steel according to claim 1, characterized in that the refining synthetic slag with total amount 1/3 and the lime slag with total amount 1/3 are added simultaneously during the tapping process of the converter.

3. The method for refining and rapidly slagging low-carbon low-silicon aluminum-containing killed steel according to claim 1, wherein said aluminum-containing killed steel is of steel type ML08 Al.

4. The method for rapid slagging in refining of low-carbon low-silicon aluminum-containing killed steel as claimed in claim 1, wherein said rapid slagging is a white slagging operation within 15 minutes of the refining process.

5. The method for refining the low-carbon low-silicon aluminum-containing killed steel for rapid slagging of the steel as claimed in claim 1, wherein the temperature for refining the molten steel is more than 1580 ℃.

6. The method for refining the low-carbon low-silicon aluminum-containing killed steel for the rapid slagging of the steel as claimed in claim 1, wherein the total amount ratio of the refined synthetic slag to the lime slag is 1: 6.

Technical Field

The invention belongs to the technical field of alloy steel, and relates to a production process of low-carbon low-silicon aluminum-containing killed steel; in particular to a method for refining low-carbon low-silicon aluminum-containing killed steel to form slag quickly.

Background

With the increasing requirements of users on the quality of steel, the external refining is rapidly developed as a means for improving the quality of steel. In the process of external refining, the purposes of desulfurization, deoxidation and even denitrification can be achieved by reasonably slagging; can absorb the impurities in the steel; the shape of the inclusion can be controlled; foam slag can be formed to submerge the electric arc, so that the heat efficiency is improved, and the corrosion of refractory materials is reduced. Therefore, slagging is of particular concern in the external refining process.

The key point of LF furnace refining is quick white slag production. The refining station plays a role in starting and stopping, not only needs to refine the components, temperature and purity of molten steel, but also ensures the continuity of the continuous casting station, so that the refining process needs to complete all tasks within a certain time in the actual production process. Therefore, the white slag is prepared in a short time in the refining process, and good conditions are created for the subsequent sufficient time of desulfurization, component fine adjustment and inclusion removal. In order to shorten the time for making white slag, better conditions are provided by adding part of slag materials into the converter tapping process in advance, because the temperature of molten steel is higher in the converter tapping process, bottom blowing of a ladle and impact action of steel flow have better thermodynamic and kinetic conditions, and better conditions can be provided for refining early slagging and early deoxidation. However, the proper amount of the added materials is needed in the tapping process, lime is added, the materials are easy to agglomerate, the slagging effect is influenced, the fed aluminum wire cannot enter molten steel, the recovery rate of aluminum is greatly reduced, and the synthetic slag is added, so that the slag dilution effect is easy to cause, and the removal effect of large-scale inclusions is influenced; and if too little material is added in the tapping process, the slag can not be melted in time, so that the refining and slagging time is delayed.

Disclosure of Invention

The invention overcomes the defects of the prior art, provides a method for refining low-carbon low-silicon aluminum-containing killed steel to form slag quickly, and is applied to the process control of quickly generating white slag in the LF refining production process of steel grades.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a method for refining low-carbon low-silicon aluminum-containing killed steel to form slag quickly comprises the steps of adding refined synthetic slag accounting for 28-35% of the total amount of the refined synthetic slag and lime slag accounting for 28-35% of the total amount of the refined synthetic slag in the tapping process of a converter; adding the rest of the refining synthetic slag and lime slag materials in the refining process; the total weight ratio of the refined synthetic slag to the lime slag is 1: 5-7; the refining synthetic slag comprises the following components in percentage by weight: 20-50% of metal aluminum and 35-60% of Al₂O₃10-20% of CaO, and the granularity of the metallic aluminum<5mm。

Preferably, the refined synthetic slag with the total amount of 1/3 and the lime slag with the total amount of 1/3 are added simultaneously during the tapping process of the converter.

Preferably, the steel grade of the aluminum-containing killed steel is ML08 Al.

Preferably, the rapid slagging is a white slag operation within 15 minutes of the refining process.

Preferably, the temperature of the molten steel during refining is more than 1580 ℃.

Preferably, the total amount ratio of the refined synthetic slag to the lime slag is 1: 6.

The indexes of the composition of the refining slag finally formed by the method are as follows: CaO: 45-55% of SiO_2：<7%，Al₂O_3：25~35%，MgO：5~10%，FeO：<0.7%，MnO：<0.3%，R：＞8。

The refining final slag comprises the following components: FeO + MnO is less than 1, and [ O ] in the steel is less than or equal to 20 ppm.

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

the composition of the synthetic refining slag directly influences the refining slagBy adjusting CaO and SiO in the refining slag₂ The alkalinity of the refining slag can be accurately controlled. The high-alkalinity refining slag is beneficial to reducing the content of balanced oxygen in molten steel, improving the distribution ratio of sulfur between slag and steel and being beneficial to deoxidation and desulfurization, but the alkalinity is too high, the viscosity of the refining slag is too large, and the liquidity becomes poor, so that the refining effect can be reduced. Al in refining slag₂O₃The content of CaO-SiO can be effectively adjusted₂ --Al₂O₃The melting point of the ternary slag system ensures that the refining slag is in a low melting point region; adding CaCO into refining slag₃、MgCO₃、BaCO₃And the components can be used as a foaming agent, improve the foaming performance of the slag and provide a sufficient internal gas generation source for the refining process.

The invention is characterized in that when producing low-carbon low-silicon aluminum-containing killed steel, special refining synthetic slag is added, and a specific adding method is matched to achieve the purpose of quickly forming white slag. The white slag operation is realized within 15 minutes in the refining process of the method, and the white slag generated has sufficient time for desulfurization and impurity removal in the later stage of refining, and can reduce cost and improve efficiency.

Drawings

FIG. 1 is a flow chart of the production process for refining the low-carbon low-silicon aluminum-containing killed steel to rapidly form slag.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solutions of the present invention are described in detail below with reference to the embodiments and the drawings, but the scope of protection is not limited thereto.

Example 1

A method for refining low-carbon low-silicon aluminum-containing killed steel to form slag quickly comprises the following steps: the refining mode is set to be 100t of molten steel/furnace, and the total amount of slag charge is strictly regulated to be 1-1.3 t/furnace in the refining production process. Wherein the dosage of lime slag is controlled at about 900kg, and the total addition amount of the refining synthetic slag is controlled at about 150 kg.

The selected low-carbon low-silicon aluminum-containing killed steel is ML08 Al; the molten steel at the end point of the converter comprises the following components in percentage by weight: 0.06%, Mn: 0.10%, P: 0.020%, S: 0.025%, end point temperature 1620 ℃.

Adding 302kg of lime slag material and 50kg of refined synthetic slag in the converter tapping process, and performing the rest according to the original process, wherein the original process is as follows: 400kg of medium carbon ferromanganese alloy, 60kg of aluminum blocks and lime are added in sequence in the tapping process, and 300m of aluminum wire is fed after tapping.

The station entering temperature of refining is 1588 ℃, lime slag charge of 610kg and synthetic slag of refining of 100kg are added in the refining process, and the rest is carried out according to the original process, wherein the original process is to add 30k of aluminum particles for deoxidation. Wherein the refining synthetic slag comprises the following components in percentage by weight: metal aluminum: 41% of Al₂O₃: 48%, CaO: 10.5% by weight of aluminum metal<5mm。

The final slagging time is 14min, and the formed refining slag comprises the following components: CaO: 51% of SiO₂：6%，Al₂O₃: 31%, MgO: 10%, FeO: 0.5%, MnO: 0.1%, R: 8. all O in steel: 18 ppm. The indexes all reach the standard within the required time.

Example 2

The refining mode is the same as that of the example 1, the steel grade is ML08Al, and the compositions of the molten steel at the end point of the converter comprise the following components in percentage by weight: 0.04% of C, Mn: 0.06%, P: 0.016%, S: 0.023% and an end temperature of 1645 ℃. 303kg of lime slag charge and 50kg of refined synthetic slag are added in the tapping process, and the rest is carried out according to the original process. The station entering temperature of the refining is 1605 ℃, 650kg of lime and 100kg of refined synthetic slag are added in the refining process, and the rest is carried out according to the original process. The original process is the same as that of the embodiment 1; wherein the refining synthetic slag comprises the following components in percentage by weight: metal aluminum: 50% of Al₂O₃: 35%, CaO: 15% of metallic aluminum particle size<5mm。

The slagging time is 13min, and the refining slag comprises the following components in percentage by weight: CaO: 55% of SiO₂：6%，Al₂O₃: 29%, MgO: 8%, FeO: 0.7%, MnO: 0.06%, R: 9. all O in steel: 20 ppm. The indexes all reach the standard within the required time。

Comparative example 1

Refining mode the same as example 1, steel grade ML08 Al: the molten steel at the end point of the converter comprises the following components in percentage by weight: 0.06% of C, Mn: 0.11%, P: 0.023%, S: 0.025%, end point temperature 1611 ℃. 202kg of lime and 0kg of refined synthetic slag are added in the tapping process and are carried out according to the original process. The station entering temperature of refining is 1580 ℃, 750kg of lime and 150kg of refined synthetic slag are added in the refining process, and the rest is carried out according to the original process. The original process was the same as in example 1.

The slagging time is 18min, and the refining slag comprises the following components: CaO: 49% of SiO₂：7%，Al₂O₃: 35%, MgO: 7%, FeO: 0.8%, MnO: 0.22%, R: 7. all O in steel: 24 ppm. The process does not have a method for adding refined synthetic slag after the furnace is executed, and finally, indexes are not finished within the required time, and the oxidative indexes (FeO + MnO and [ O ]) do not reach the standard.

Comparative example 2

Refining mode the same as example 1, steel grade ML08 Al: the molten steel at the end point of the converter comprises the following components in percentage by weight: 0.05% of C, Mn: 0.07%, P: 0.014%, S: 0.020% and an end temperature of 1631 ℃. 320kg of lime and 75kg of refined synthetic slag are added in the tapping process, and the rest is carried out according to the original process. The station entering temperature of the refining is 1598 ℃, 610kg of lime and 75kg of refined synthetic slag are added in the refining process, and the rest is carried out according to the original process. The original process was the same as in example 1.

The slagging time is 20min, and the refining slag comprises the following components: CaO: 50% of SiO₂：7%，Al₂O₃: 32%, MgO: 9%, FeO: 0.7%, MnO: 0.19%, R: 7, total O in steel: 19 ppm. The amount of the refining synthetic slag added after the furnace reaches 50 percent of the total addition amount, so that when the steel ladle enters the refining furnace, the surface slag is over-dilute, and finally, the index is not finished in required time, thereby influencing the whole production rhythm. And the alkalinity of the slag sample does not reach the standard.

While the invention has been described in further detail with reference to specific preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.