阅读说明：本技术 一种aod炉用高镍铁水冶炼镍铬不锈钢的方法 (Method for smelting nickel-chromium stainless steel by using high-nickel molten iron for AOD furnace ) 是由 游香米 吴燕萍 赵运锋 史彩霞 于 2021-08-27 设计创作，主要内容包括：本发明属于不锈钢冶炼技术领域,提出一种AOD炉用高镍铁水冶炼镍铬不锈钢的方法,包括：将高镍铁水兑入AOD炉内；下顶枪顶吹氧气进行脱硅吹炼,并在吹炼过程中加入石灰造渣,待脱硅结束后提枪；向炉内加入高碳铬铁,并用侧枪侧吹惰气进行搅拌,待还原结束后倒前渣；再次下顶枪顶吹氧气进行脱碳吹炼,并辅以侧枪侧吹惰气进行搅拌,且在钢水碳含量低于脱碳速度的临界碳含量后顶枪停吹；向炉内加入还原剂和调渣剂,并使用侧枪侧吹惰气进行强搅拌,以促进脱氧和还原脱硫至目标钢水成分。本发明方法充分利用高镍铁水中的Si、Cr等发热元素和有益合金元素,节约能源,并降低合金消耗量,同时提高了铬收得率,保证了AOD冶炼的稳定性。(The invention belongs to the technical field of stainless steel smelting, and provides a method for smelting nickel-chromium stainless steel by using high-nickel molten iron for an AOD furnace, which comprises the following steps: adding high-nickel molten iron into an AOD furnace; blowing oxygen from the top of a lower top gun for desiliconization blowing, adding lime for slagging in the blowing process, and lifting the gun after desiliconization is finished; adding high-carbon ferrochrome into the furnace, laterally blowing inert gas by using a side gun for stirring, and pouring the front slag after the reduction is finished; blowing oxygen at the top of the top lance again for decarburization blowing, stirring by assisting side lance side blowing inert gas, and stopping blowing after the carbon content of the molten steel is lower than the critical carbon content of the decarburization speed; reducing agents and slag modifiers are added into the furnace, and strong stirring is carried out by side lance side blowing of inert gas, so as to promote deoxidation and reduction desulfurization to target molten steel components. The method of the invention fully utilizes heating elements such as Si, Cr and the like and beneficial alloy elements in the high-nickel molten iron, saves energy, reduces alloy consumption, improves chromium yield and ensures the stability of AOD smelting.)

1. A method for smelting nickel-chromium stainless steel by using high-nickel molten iron for an AOD furnace is characterized by comprising the following steps:

adding nickel-iron water: adding high-nickel molten iron into an AOD furnace;

desiliconization blowing: blowing oxygen from the top of a lower top gun for desiliconization blowing, adding lime for slagging in the blowing process, and lifting the gun after desiliconization is finished;

reducing and deslagging: adding high-carbon ferrochrome into the furnace, laterally blowing inert gas by using a side gun for stirring, and pouring the front slag after the reduction is finished;

decarburization and blowing: blowing oxygen at the top of the top lance again for decarburization blowing, stirring by assisting side lance side blowing inert gas, and stopping blowing after the carbon content of the molten steel is lower than the critical carbon content of the decarburization speed;

reduction and desulfurization: reducing agents and slag modifiers are added into the furnace, and strong stirring is carried out by side lance side blowing of inert gas, so as to promote deoxidation and reduction desulfurization to target molten steel components.

2. The method for smelting nickel-chromium stainless steel by using high-nickel molten iron for the AOD furnace according to claim 1, wherein the adding amount of the high-nickel molten iron in the added nickel molten iron is controlled to be 670-710 kg/t molten steel, and the components of the high-nickel molten iron are as follows by mass percent: 2.0-3.5% of C, 1.0-2.0% of Si, 0.10-0.20% of Mn, less than or equal to 0.045% of P, less than or equal to 0.12% of S, 10-12% of Ni, less than or equal to 2% of Cr, and the balance of Fe.

3. The method for smelting Ni-Cr stainless steel with molten ferronickel for AOD furnace as claimed in claim 1, wherein the oxygen supply strength of the top lance is controlled to 1.0-1.5 Nm in the desiliconization blowing³/min.t。

4. The method for smelting nickel-chromium stainless steel by using high-nickel molten iron for the AOD furnace according to claim 1, wherein in desiliconization blowing, the activity degree of lime is controlled to be not less than 320, the CaO content in the lime is controlled to be not less than 90%, and the slagging alkalinity is controlled to be 1.0-1.5.

5. The method for smelting nickel-chromium stainless steel with high-nickel molten iron for AOD furnace according to claim 1, wherein in the desiliconization blowing, the end of desiliconization means that the silicon content in the molten bath is 0.6% or less.

6. The method for smelting nickel-chromium stainless steel by using high-nickel molten iron for the AOD furnace according to claim 1, wherein in the reduction deslagging, the addition amount of the high-carbon ferrochrome is controlled to be 10-30% of the total addition amount of the ferrochrome required by producing the target chromium-nickel stainless steel, and the Cr content in the high-carbon ferrochrome is not lower than 50%.

7. The method for smelting Ni-Cr stainless steel with molten ferronickel for AOD furnace according to claim 1, wherein the stirring intensity of the inert gas is controlled to not less than 0.3Nm in the reduction and deslagging³T, and the stirring time is not less than 6 min.

8. The method for smelting Ni-Cr stainless steel with GaoNi molten iron for AOD furnace according to claim 1, wherein during the reduction deslagging, the reduction end means Cr in slag₂O₃The content is not higher than 0.2%.

9. The method for smelting nickel-chromium stainless steel by using ferronickel high-iron water for the AOD furnace according to claim 1, characterized in that decarburization is divided into a high-carbon zone and a low-carbon zone in decarburization blowing: when the high carbon zone is decarbonized, the top lance and the side lance are blown in a composite way; in the decarburization in the low carbon zone, only the side lance was used for the blowing.

Technical Field

The invention belongs to the technical field of stainless steel smelting, and particularly relates to a method for smelting nickel-chromium stainless steel by using high-nickel molten iron for an AOD furnace.

Background

The production process flow of the chromium-nickel stainless steel taking the molten nickel iron as the raw material fully utilizes the physical heat of the molten nickel iron, avoids energy loss, has the shortest process flow and has cost advantage. But the Si content in the nickel-iron water brings great challenges to the smelting of the AOD. In order to shorten the smelting period of the subsequent AOD and control the stability of the smelting operation, the common operation method is to configure a pretreatment desiliconization facility, firstly desiliconize and then enter the AOD for smelting. For example, patent CN103614609A discloses a molten iron desiliconization method for stainless steel smelting, which is to add a desiliconization converter in front of an AOD furnace, and then to perform desiliconization treatment on the molten iron for AOD smelting, but this method, although ensuring the stability of AOD smelting, adds one more treatment process, increasing the temperature loss of iron conversion, and after desiliconization treatment of molten nickel iron, the chromium in the molten nickel iron will be oxidized and enter slag to be lost, which will reduce the yield of chromium in the whole process. For example, patent CN110819880A discloses a pretreatment process of chromium-containing low-nickel molten iron for producing 200 series stainless steel and an application thereof, which aims at the situation that 200 series stainless steel is produced by using low-nickel molten iron, and adopts a solution that a desiliconization converter is still additionally arranged in front of a stainless steel smelting furnace.

Disclosure of Invention

In view of the above, the present invention aims to provide a method for smelting nickel-chromium stainless steel by using high-nickel molten iron for an AOD furnace, and aims to solve the problems of insufficient utilization of heating elements in the nickel molten iron, low chromium yield and the like in the existing process.

The invention is realized by the following technical scheme:

the invention provides a method for smelting nickel-chromium stainless steel by using high-nickel molten iron for an AOD furnace, which comprises the following steps:

adding nickel-iron water: adding high-nickel molten iron into an AOD furnace;

desiliconization blowing: blowing oxygen from the top of a lower top gun for desiliconization blowing, adding lime for slagging in the blowing process, and lifting the gun after desiliconization is finished;

reducing and deslagging: adding high-carbon ferrochrome into the furnace, laterally blowing inert gas by using a side gun for stirring, and pouring the front slag after the reduction is finished;

decarburization and blowing: blowing oxygen at the top of the top lance again for decarburization blowing, stirring by assisting side lance side blowing inert gas, and stopping blowing after the carbon content of the molten steel is lower than the critical carbon content of the decarburization speed;

reduction and desulfurization: reducing agents and slag modifiers are added into the furnace, and strong stirring is carried out by side lance side blowing of inert gas, so as to promote deoxidation and reduction desulfurization to target molten steel components.

Preferably, in the nickel-iron mixing water, the adding amount of the high-nickel molten iron is controlled to be 670-710 kg/t molten steel, and the high-nickel molten iron comprises the following components in percentage by mass: 2.0-3.5% of C, 1.0-2.0% of Si, 0.10-0.20% of Mn, less than or equal to 0.045% of P, less than or equal to 0.12% of S, 10-12% of Ni, less than or equal to 2% of Cr, and the balance of Fe.

Preferably, in the desiliconization blowing, the oxygen supply intensity of the top lance is controlled to be 1.0 to 1.5Nm³/min.t。

Preferably, in desiliconization blowing, the activity degree of lime is controlled to be not less than 320, the content of CaO in the lime is controlled to be not less than 90%, and the slagging alkalinity is controlled to be 1.0-1.5.

Preferably, in the desiliconization blowing, the end of desiliconization means that the silicon content in the molten bath is 0.6% or less.

Preferably, in the reduction deslagging, the adding amount of the high-carbon ferrochrome is controlled to be 10-30% of the total adding amount of the ferrochrome required by producing the target chromium-nickel stainless steel, and the Cr content in the high-carbon ferrochrome is not lower than 50%.

Preferably, in the reduction deslagging, the stirring intensity of the inert gas is controlled to be not less than 0.3Nm³T, and the stirring time is not less than 6 min.

Preferably, in the reduction deslagging, the reduction end means Cr in the slag₂O₃The content is not higher than 0.2%.

Preferably, the decarburization in the decarburization blowing is divided into a high carbon zone decarburization and a low carbon zone decarburization: when the high carbon zone is decarbonized, the top lance and the side lance are blown in a composite way; in the decarburization in the low carbon zone, only the side lance was used for the blowing.

The invention has the advantages that: the invention provides a method for smelting nickel-chromium stainless steel by using high-nickel molten iron for an AOD furnace, which is characterized in that the high-nickel molten iron is used as a raw material and is added into the AOD furnace to be desiliconized and blown firstly, lime is added in the blowing process to form slag, a gun is lifted after desiliconization is finished, then reduction and deslagging are carried out, high-carbon ferrochrome is added into the furnace through a high-position bin, meanwhile, inert gas is blown laterally to be stirred, and slag before full reduction is poured; then decarburization blowing and reduction desulfurization are carried out to the target molten steel components. The production process can fully utilize heating elements such as Si, Cr and the like and beneficial alloy elements in the high-nickel molten iron, saves energy, reduces the alloy consumption, improves the yield of chromium, and effectively ensures the stability of AOD smelting.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a method for smelting nickel-chromium stainless steel by using high-nickel molten iron for an AOD furnace.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

As shown in fig. 1, the method for smelting nickel-chromium stainless steel by using the AOD furnace mentioned in this embodiment comprises the following steps:

1) adding nickel-iron water: adding high-nickel molten iron into an AOD furnace, and controlling the adding amount of the high-nickel molten iron to be about 670-710 kg/t molten steel, wherein the high-nickel molten iron comprises, by mass, 2.0-3.5% of C, 1.0-2.0% of Si, 0.10-0.20% of Mn, less than or equal to 0.045% of P, less than or equal to 0.12% of S, 10-12% of Ni, less than or equal to 2% of Cr, and the balance of iron;

2) desiliconization blowing: blowing oxygen from the top of a lower top gun for desiliconization blowing, adding lime for slagging in the blowing process, and lifting the gun after desiliconization is finished; the oxygen supply intensity of the top blowing oxygen of the top lance is controlled to be 1.0-1.5 Nm³T is/min; controlling the lime activity degree to be not less than 320, and controlling the CaO content in the lime to be not less than 90%; controlling the slag-making alkalinity to be 1.0-1.5; and the end of desiliconization means that the silicon content in the molten pool is 0.6% or less.

3) Reducing and deslagging: adding high-carbon ferrochrome into the furnace through a high-level stock bin, simultaneously blowing inert gas on the side for stirring, and pouring the front slag after the reduction is fully finished; during the period, the Cr content in the high-carbon ferrochrome is controlled to be not less than 50 percent, and the addition of the high-carbon ferrochrome is 10-30 percent of the total addition of the ferrochrome required by producing the target chromium-nickel stainless steel; and the inert gas used is N₂、CO₂Ar gas, etc., and the stirring intensity of the inert gas is not less than 0.3Nm³T, and the stirring time is not less than 6 min. Moreover, the term "sufficient reduction" means that Cr is contained in the slag₂O₃The content is not higher than 0.2%.

4) Decarburization and blowing: after deslagging is finished, top blowing oxygen by a lower top lance to perform decarburization blowing, wherein the decarburization blowing is divided into high-carbon decarburization and low-carbon decarburization, the top lance and a side lance are subjected to combined blowing during the decarburization of the high-carbon decarburization, and the top lance stops blowing after the carbon content of molten steel is lower than the critical carbon content of the decarburization speed; when the low-carbon zone is decarbonized, only a side gun is used for blowing;

5) reduction and desulfurization: after decarburization blowing is finished, a reducing agent and a slag modifier are added, and strong stirring is carried out by using a side gun so as to promote deoxidation and reduction desulfurization to the target molten steel components. The reducing agent is ferrosilicon, ferrosilicon-aluminum and aluminum; the slag modifier is lime, carbide slag or fluorite, etc. and the lime and fluorite are added according to the viscosity degree of the slag to maintain the good flowability of the slag, and the usage amount is 0.2-3% of the total slag mass. The phase can adsorb deoxidation and desulfurization products in the molten steel, improve the quality of the molten steel and shorten the smelting time.

One specific operation is briefly described as follows: adding a certain amount of high-nickel molten iron into an AOD furnace, and carrying out desiliconization treatment to obtain a desiliconized oxygen lance with oxygen supply intensity of 1.2Nm³Adding lime for slagging in the desiliconization process, wherein the slagging alkalinity is 1.0-1.5, and lifting the gun when the silicon content in the molten pool is lower than 0.6%; then, carrying out reduction and deslagging to add high-carbon ferrochrome with the proportion of 20 percent of the total addition of the ferrochrome required by producing the target chromium-nickel stainless steel into the molten pool through a high-temperature bin, simultaneously blowing inert gas on the side for stirring to reduce oxidized chromium in the slag, and dumping the slag after reduction; then, the AOD conventional operation is carried out, namely decarburization blowing and reduction desulfurization are carried out until the target molten steel component is reached.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and it is apparent that those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.