阅读说明：本技术 一种在高废钢比条件下转炉脱磷的生产工艺 (Production process for converter dephosphorization under high scrap steel ratio condition ) 是由 王哲 赵占山 张忠福 李毅 孙海坤 晏武 赵梓云 张彦龙 李庆振 张李鹏 于 2021-08-16 设计创作，主要内容包括：本发明涉及一种在高废钢比条件下转炉脱磷的生产工艺,属于钢铁冶炼的技术领域。本发明采用顶底复合吹炼工艺,先将工业盐和废钢加入钢水中,然后通过调整氧气喷枪的位置以及加入头批料和二批料的时机,可有效地提高脱磷率。本发明只使用单渣法就可以提高脱磷效果,脱磷率可以从80％提高到90％；同时可降低终渣全铁的含量,相比现有技术,本发明终渣全铁的含量可以由25％左右降低至20％左右。(The invention relates to a production process for converter dephosphorization under the condition of high scrap steel ratio, belonging to the technical field of steel smelting. The invention adopts a top-bottom composite blowing process, the industrial salt and the scrap steel are added into the molten steel, and then the dephosphorization rate can be effectively improved by adjusting the position of the oxygen spray gun and the time of adding the first batch and the second batch. The dephosphorization effect can be improved by only using a single slag method, and the dephosphorization rate can be improved from 80% to 90%; meanwhile, the content of the total iron in the final slag can be reduced, and compared with the prior art, the content of the total iron in the final slag can be reduced from about 25 percent to about 20 percent.)

1. A production process for converter dephosphorization under the condition of high scrap steel ratio is characterized by adopting a top-bottom composite blowing process, and specifically comprises the following steps:

(1) filling normal-temperature industrial sodium chloride into a scrap steel hopper, and adding the industrial sodium chloride into a smelting furnace along with scrap steel;

(2) blowing and slagging, slowly pressing the gun to 180cm in the first 5min, and adding the first batch materials before the gun is pressed in place; then lifting the gun to 200-220 cm, opening slag for 1-2 min, and pressing the gun to 180-190 cm;

(3) adding two batches of materials into the molten steel according to the slag-removing condition, and adjusting the position of a gun to be 180-210 cm;

(4) keeping the gun position constant until the carbon drawing period, and pressing the gun position to 180cm after the carbon drawing period.

2. The production process according to claim 1, wherein in the step (1), the amount of industrial sodium chloride is 5-8 kg/t based on the amount of scrap steel charged.

3. The production process according to claim 1, wherein in the step (1), the temperature of molten steel in the smelting furnace is 1265-1270 ℃.

4. The process of claim 1, wherein in step (2), the first batch is composed of lime A and light burned dolomite.

5. The production process according to claim 4, wherein the amount of the lime A is 7-9 kg/t based on the amount of the scrap steel charged.

6. The production process according to claim 4, wherein the amount of the light burned dolomite is 13-15 kg/t based on the charging amount of the scrap steel.

7. The process according to claim 1, wherein in step (3), the second batch is lime B; the lime B is added at one time or in small quantities.

8. The production process according to claim 7, wherein the amount of the lime B is 15-20 kg/t based on the amount of the scrap steel.

Technical Field

The invention belongs to the technical field of steel smelting, and particularly relates to a production process for converter dephosphorization under the condition of high scrap steel ratio.

Background

The converter steelmaking uses molten iron, scrap steel and ferroalloy as main raw materials, does not need external energy, and completes the steelmaking process in the converter by means of heat generated by physical heat of molten iron and chemical reaction among molten iron components. After the steel-making scrap ratio of the converter is improved, the heat balance in the converter reaches the limit, and the heat is insufficient. Lime and light-burned dolomite are used as auxiliary materials in a normal converter for slagging, and effective converter slag in the early stage cannot be quickly formed due to low temperature of a molten pool in the early stage of the converter, so that the static dephosphorization capability of the converter is insufficient, and the final phosphorus content is higher.

Disclosure of Invention

The invention provides a production process for converter dephosphorization under the condition of high scrap ratio, aiming at solving the problem of high end point phosphorus caused by the phenomenon of non-slagging easily caused by low temperature during the early-stage slagging of converter production under the condition of high scrap ratio. The invention changes the ternary high-melting-point slag phase into the quaternary low-melting-point slag phase by changing the process operation and adding industrial salt into the molten steel, and utilizes the early low-temperature stage to rapidly form slag and dephosphorize. The conventional ternary slag system is prepared from FeO + SiO₂The earlier stage slagging can also meet the dephosphorization condition due to the high temperature of a converter molten pool under the conditions of more CaO added at the earlier stage, high melting point of slag system and low scrap ratio. However, under the condition of high scrap ratio, the temperature of the converter molten pool is low, and the slag is difficult to be melted well in the early stage, so that a slag system with a low melting point is required. Adding NaCl and Na into the slag system⁺Ions, composition FeO + SiO₂The four-element slag system of CaO and NaCl can effectively reduce the melting point of the slag system, quickly melt slag at low temperature, improve the dephosphorization efficiency and reduce the dephosphorization difficulty.

The technical scheme of the invention is as follows:

a production process for converter dephosphorization under the condition of high scrap steel ratio adopts a top-bottom composite blowing process, and specifically comprises the following steps:

(1) industrial sodium chloride is filled into a scrap steel hopper and is added into a smelting furnace along with scrap steel;

(2) blowing and slagging, slowly moving the muzzle of the oxygen spray gun to 180cm above the liquid level of the molten steel in the first 5min, and adding the first batch materials before the muzzle is moved in place; then, the muzzle is raised to 200-220 cm above the liquid level of the molten steel, and the muzzle is lowered to 180-190 cm above the liquid level of the molten steel after slag removal is carried out for 1-2 min; the molten steel in the step comprises industrial salt (NaCl), lime (CaO) and light-burned dolomite (SiO)₂) In addition, the existing FeO can change the ternary slag system with high melting point into the quaternary slag system with low melting point;

(3) adding two batches of materials into the molten steel according to the slag-forming condition, and adjusting the muzzle to be 180-210 cm above the liquid level of the molten steel;

(4) keeping a constant gun position until a carbon drawing period, and adjusting a gun mouth to draw carbon 180cm above the liquid level of molten steel after entering the carbon drawing period.

Preferably, in the step (1), the amount of the industrial sodium chloride is 5-8 kg/t based on the charging amount of the scrap steel.

Preferably, in the step (1), the temperature of molten steel in the smelting furnace is 1265-1270 ℃.

Preferably, in the step (2), the first batch is composed of lime A and light burned dolomite. According to the invention, by reducing the addition of lime in the first batch, CaO in the early-stage slag is reduced, and the melting point of the slag is further reduced.

Preferably, the dosage of the lime A is 7-9 kg/t based on the charging amount of the scrap steel.

Preferably, the dosage of the light-burned dolomite is 13-15 kg/t based on the charging amount of the scrap steel.

Preferably, in the step (3), the second batch of lime B; the lime B is added at one time or in small quantities.

Preferably, the dosage of the lime B is 15-20 kg/t based on the charging amount of the scrap steel.

The invention has the beneficial effects that:

the invention does not need additional investment for transforming equipment and complex process, and can improve the dephosphorization effect only by using a single slag method, and the dephosphorization rate can be improved from 80 percent to 90 percent; meanwhile, the content of the total iron in the final slag can be reduced, and compared with the prior art, the content of the total iron in the final slag can be reduced from about 25 percent to about 20 percent.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

No. E21504378, molten iron silicon content 0.34%, molten iron phosphorus content 0.124%, molten iron temperature 1265 ℃, molten iron charge 809kg, scrap steel 257 kg.

The top-bottom composite converting process is adopted, and the specific operation process is as follows:

(1) 1.6kg of industrial sodium chloride is loaded into a scrap steel hopper and is added into a smelting furnace along with scrap steel, and the loading amount of molten iron in the smelting furnace is 809 kg;

(2) blowing, wherein the muzzle of the oxygen spray gun is positioned 250cm above the liquid level of the molten steel, and the muzzle of the oxygen spray gun is slowly moved to 180cm above the liquid level of the molten steel for 5 min; when the blowing time is 2.5min, 2.1kg of lime and 3.9kg of light-burned dolomite are added; moving the gun mouth to 180cm above the liquid level of the molten steel, and lifting the gun to 200cm for slagging;

(3) blowing for 7.3min, slagging, adding 3.9kg of lime into the molten steel at 8min, moving the oxygen spray gun at 9min, and adjusting the gun mouth to 190cm above the liquid level of the molten steel; adding 0.5kg of lime in the 10 th min, and stably blowing to a lower sublance;

(4) keeping the constant lance position until the carbon drawing period, and adjusting the lance mouth to 180cm above the liquid level of the molten steel for decarburization after the carbon drawing period.

Bottom blowing flow control: due to the ratio of scrap to steelHigh, bottom blowing is controlled by adopting a mode of weak in the early middle period and strong in the later period. Front 0.030m³/(min. t), middle 0.030m³V (min. t), dynamic carbon pulling period 0.072m³/(min·t)。

Through detection, the end-point phosphorus content is 0.015 percent, the end-point temperature is 1600 ℃, and the total iron content of the final slag is 19.5 percent.

Example 2

The furnace number E21504374, the silicon content of molten iron 0.43%, the phosphorus content of molten iron 0.118%, the temperature of molten iron 1270 ℃, the charging amount of molten iron 795kg, and the scrap steel 270 kg.

The top-bottom composite converting process is adopted, and the specific operation process is as follows:

(1) 1.9kg of industrial sodium chloride is loaded into a scrap steel hopper and is added into a smelting furnace along with scrap steel, and the loading amount of molten iron in the smelting furnace is 795 kg;

(2) blowing, wherein the muzzle of the oxygen spray gun is positioned 250cm above the liquid level of the molten steel, and the muzzle of the oxygen spray gun is slowly moved to 180cm above the liquid level of the molten steel for 5 min; when the blowing time is 2.5min, 2.4kg of lime and 4.1kg of light-burned dolomite are added; moving the gun mouth to 180cm above the liquid level of the molten steel, and lifting the gun to 220cm for slagging;

(3) blowing for 7min for slagging, adding 4.6kg of lime into the molten steel in a small quantity and multiple times in 8min, moving the oxygen spray gun at 8.5min, and adjusting the gun mouth to be 180cm above the liquid level of the molten steel; then stably converting to a lower sublance;

(4) keeping a constant lance position until a carbon drawing period, and adjusting a lance opening to 170cm above the liquid level of molten steel for decarburization after the carbon drawing period.

Bottom blowing flow control: because the scrap steel ratio is high, the bottom blowing is controlled by adopting a mode of weak in the early and middle stages and strong in the later stage. Front 0.030m³/(min. t), middle 0.030m³V (min. t), dynamic carbon pulling period 0.072m³/(min·t)。

The detection shows that the end-point phosphorus content is 0.016 percent, the end-point temperature is 1598 ℃, and the total iron content of the final slag is 21.3 percent.

Comparative example

The furnace number E21504260, the silicon content of the molten iron is 0.29%, the phosphorus content of the molten iron is 0.113%, the temperature of the molten iron is 1265 ℃, the charging amount of the molten iron is 809kg, and the scrap steel is 251 kg.

The top-bottom composite converting process is adopted, and the specific operation process is as follows:

(1) adding scrap steel into a smelting furnace, wherein the molten iron loading in the smelting furnace is 809 kg;

(2) blowing, wherein the muzzle of the oxygen spray gun is positioned 250cm above the liquid level of the molten steel, and the muzzle of the oxygen spray gun is slowly moved to 180cm above the liquid level of the molten steel for 5 min; when the blowing time is 2.5min, 3.8kg of lime and 3.8kg of light-burned dolomite are added; moving the gun mouth to 180cm above the liquid level of the molten steel, and lifting the gun to 220cm for slagging;

(3) blowing for 9.5min for slagging, adding 2kg of lime into the molten steel in a small quantity and multiple times in 10min, moving the oxygen spray gun at 11min, and adjusting the gun mouth to 190cm above the liquid level of the molten steel; then stably converting to a lower sublance;

(4) keeping a constant lance position until a carbon drawing period, and adjusting a lance opening to 170cm above the liquid level of molten steel for decarburization after the carbon drawing period.

Bottom blowing flow control: because the scrap steel ratio is high, the bottom blowing is controlled by adopting a mode of weak in the early and middle stages and strong in the later stage. Front 0.030m³/(min. t), middle 0.030m³V (min. t), dynamic carbon pulling period 0.072m³/(min·t)。

Through detection, the end point phosphorus content is 0.027%, the end point temperature is 1595 ℃, and the total iron content of the final slag is 25.7%.

Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.