CN114774616A

CN114774616A - Method for reducing oxygen consumption by controlling lance position of oxygen lance of top-blown converter

Info

Publication number: CN114774616A
Application number: CN202210447620.4A
Authority: CN
Inventors: 于生鹏; 苏庆林; 刘晓东; 路大鹏; 王秋坤
Original assignee: Shandong Laigang Yongfeng Steel and Iron Co Ltd
Current assignee: Shandong Laigang Yongfeng Steel and Iron Co Ltd
Priority date: 2022-04-26
Filing date: 2022-04-26
Publication date: 2022-07-22

Abstract

The invention discloses a method for controlling the lance position of an oxygen lance of a top-blown converter to reduce oxygen consumption, which comprises the following steps: after blowing and ignition, the distance between the oxygen lance position and the liquid level is 1200mm, high oxygen pressure and large flow rate heating operation is carried out, meanwhile, slag is added, after Si in a molten pool is fully oxidized, the oxygen lance position is increased to 1500mm when carbon-oxygen reaction is started, and the oxygen pressure is reduced to 0.8-0.83 MPa for slagging; according to the reduction of the CO concentration, the lance position is reduced to 1100-1200 mm away from the liquid level, the residual slag and part of cold charge are added, and the oxygen pressure is increased to 0.83-0.85 MPa; the lance position of the oxygen lance is adjusted in time according to the changes of flame and CO, and the fluidity of slag in the whole converting process is ensured; after blowing for 9min, increasing the distance between the lance position of the oxygen lance and the liquid level by more than 1500mm, and waiting for the flame to shrink and become soft and the ascending force to gradually descend; gradually reducing the gun position, and ensuring that the flame strength does not rise in the process of reducing the gun position; when the carbon drawing gun position is reduced, the oxygen pressure is increased to 1.1-1.2 Mpa within 3-5S, and the effective gun pressing time lasts for 15S.

Description

Method for reducing oxygen consumption by controlling lance position of oxygen lance of top-blown converter

Technical Field

The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a method for controlling the lance position of an oxygen lance of a top-blown converter to reduce oxygen consumption.

Background

In the smelting process of the converter, the main tasks of oxidation-reduction reaction of various elements, slagging dephosphorization, desulfurization, molten pool temperature rise and the like are completed through the action of oxygen streams and a metal molten pool. The oxygen supply can control the reaction rate of various elements, the formation of slag, the oxidation of slag and the like. However, how to efficiently utilize the oxygen stream to smelt a furnace of qualified molten steel with the least oxygen energy consumption is an important control project in converter smelting at present.

The oxygen utilization rate of the prior converter oxygen supply is low in the middle and later smelting periods, and the reaction in a molten pool cannot reach the optimal state, so that part of the oxygen is discharged out of the converter by a dust removal system without reacting with a metal molten pool. The heat value of the recovered gas of the converter gas is reduced, and the end temperature and the components of the converter do not reach the standard.

Poor slag fluidity and insufficient bath stirring lead to low oxygen utilization.

Disclosure of Invention

The invention aims to provide a method for controlling the lance position of an oxygen lance of a top-blown converter to reduce oxygen consumption.

The technical scheme adopted by the invention for solving the technical problems is as follows: a method for controlling the lance position of an oxygen lance of a top-blown converter to reduce oxygen consumption comprises the following steps:

1) after blowing and ignition, the distance between the lance position of the oxygen lance and the liquid level is 1200mm, high-oxygen-pressure large-flow temperature rise operation is carried out, meanwhile, slag materials are added, after Si in a molten pool is fully oxidized, the lance position of the oxygen lance is increased to 1500mm when carbon-oxygen reaction is started, and oxygen pressure is reduced to 0.8-0.83 MPa for slagging;

2) according to the reduction of the CO concentration, the lance position is reduced to 1100-1200 mm away from the liquid level, the residual slag and part of cold charge are added, and the oxygen pressure is increased to 0.83-0.85 MPa;

3) the lance position of the oxygen lance is adjusted in time according to the changes of flame and CO, and the fluidity of slag in the whole converting process is ensured;

4) after blowing for 9min, increasing the distance between the lance position of the oxygen lance and the liquid level by more than 1500mm, and waiting for the flame to shrink and become soft and the ascending force to gradually descend; gradually reducing the gun position, and ensuring that the flame strength does not rise in the process of reducing the gun position;

5) when the carbon drawing gun position is reduced, the oxygen pressure is increased to 1.1-1.2 Mpa within 3-5S, and the effective gun pressing time lasts for 15S.

The invention has the following beneficial effects:

1) the oxygen consumption of the converter smelting is reduced, and the converter smelting cost is reduced;

2) the fluidity of the slag is improved during the smelting of the converter, and the splashing rate of the converter is reduced by 10 percent;

3) the recovery time of the converter gas is prolonged by 10-20 s, and the calorific value of the converter gas is improved;

4) provides guarantee for converter negative energy steelmaking.

Detailed Description

The present invention will now be described in further detail.

A method for controlling the lance position of an oxygen lance of a top-blown converter to reduce oxygen consumption is characterized by comprising the following steps:

1) the cold charge addition in the process is pre-judged according to the conditions of molten iron and steel scraps and the last furnace end point condition before blowing;

2) after blowing and ignition are carried out, reducing the distance between a lance position and the liquid level by about 1200mm, carrying out high-oxygen-pressure large-flow temperature rise operation, meanwhile, adding slag materials, after Si in a molten pool is fully oxidized, increasing the lance position to about 1500mm at the beginning of carbon-oxygen reaction, and reducing the oxygen pressure to 0.8-0.83 MPa for slagging operation;

3) reducing the lance position to about 1100-1200 mm away from the liquid level in time according to the reduction of the CO concentration, adding the residual slag and part of cold materials, and increasing the oxygen pressure to 0.83-0.85 MPa;

4) adjusting the lance position of the oxygen lance in time according to the changes of flame and CO, and ensuring the fluidity of slag in the whole converting process;

5) after 9min of blowing. The distance between the integral oxygen lance position and the liquid level is increased by more than 1500mm, and the flame is waited to shrink and become soft and the ascending force is gradually reduced; gradually reducing the gun position, and ensuring that the flame strength cannot rise in the process of reducing the gun position;

6) when the carbon drawing gun position is reduced, the oxygen pressure is increased to 1.1-1.2 Mpa within 3-5S, and the effective gun pressing time is kept for 15S.

Through actual production data on site and data fed back by a flue gas analysis system, the oxygen utilization rate in the earlier stage of the converter is higher, but the phenomenon of oxygen waste occurs in the middle and later stages, abnormal conditions occur according to the conditions, and technical attack and shutdown need to be carried out from the fluidity of the slag and the stirring of a molten pool.

The converter is heated and melted at the early stage, and the converter cannot completely carry out carbon-oxygen reaction due to the influence of molten iron and silicon at the early stage of smelting, but a large amount of heat released by the oxidation of silicon element at the early stage creates thermodynamic conditions for the melting of the converter. As the oxidation of silicon element in the molten pool is completed, the carbon-oxygen reaction is carried out, the temperature in the molten pool is also increased, the solvent of the converter also begins to melt, the melting of the solvent is influenced by the heat absorption of the converter scrap, and a part of iron oxide is needed to assist in slagging.

Iron oxide in slag in the middle and later periods maintains balance, the iron oxide in the slag mainly reacts with carbon element in a molten pool during converter decarburization, a large amount of oxygen is supplied to an oxygen lance to contact with the molten pool, so that certain iron oxide can be formed to enter the slag, on one hand, the oxygen is supplied to the converter to form a large amount of iron oxide, on the other hand, the carbon in the molten pool reacts with the iron oxide in the slag to consume the iron oxide in the slag, a balance reaction taking the iron oxide as the center is formed, the iron oxide can keep the fluidity of the slag, the carbon-oxygen reaction in the molten pool can be expanded only if the slag has good fluidity, and the oxygen utilization rate of the converter can be improved.

And controlling the metal loss at the later stage, wherein in the later stage, in order to ensure the uniformity of the components and the temperature at the end point in converter smelting, soft blowing generally occurs at the later stage, the aim is to ensure better fluidity of the slag, iron oxide in the slag is more accumulated under the condition of only the situation, the phenomenon of converter splashing can occur under the condition of improving the oxygen supply strength, the metal loss is caused, and the oxygen supply strength of the converter is ensured to be not less than 3.5m 3/(t.min) as much as possible in the soft blowing.

The present invention is not limited to the above embodiments, and any structural changes made under the teaching of the present invention shall fall within the scope of the present invention, which is similar or similar to the technical solutions of the present invention.

The techniques, shapes, and configurations not described in detail in the present invention are all known techniques.

Claims

1. A method for controlling the lance position of an oxygen lance of a top-blown converter to reduce oxygen consumption is characterized by comprising the following steps:

3) adjusting the lance position of the oxygen lance in time according to the changes of flame and CO, and ensuring the fluidity of slag in the whole converting process;