Low-slag and high-efficiency smelting method and system based on submerged supersonic gas-solid injection

Abstract

The present application relates to the field of metallurgy. Provided is a low-slag and high-efficiency smelting method and system based on submerged supersonic gas-solid injection. The method comprises a raw material charging period, a melting period, an oxidation and heating period and a steel tapping stage. The low-slag and high-efficiency smelting system based on submerged supersonic gas-solid injection comprises: an electric arc furnace, a powder injection tank, a submerged supersonic gas-solid oxygen lance and a control device; the electric arc furnace is used for smelting a target steel grade; the powder injection tank is used for transporting a slag-forming material to the submerged supersonic gas-solid oxygen lance; the submerged supersonic gas-solid oxygen lance is used for transporting the slag-forming material, methane, oxygen and a protective gas into a steel slag layer of the electric arc furnace; the control device is used for controlling the submerged supersonic gas-solid oxygen lance. The low-slag and high-efficiency smelting method and system provided by the present application improves the dephosphorization efficiency by about 2.5-5%, reduces the slag amount by 5-20 kg / t, reduces the consumption of the slag-forming material by 5-10%, and increases the metal yield by more than 0.5%.

Description

A low-slag, high-efficiency smelting method and system based on submerged supersonic gas-solid injection Technical Field

[0001] This application relates to the field of metallurgy, and in particular to a low-slag, high-efficiency smelting method and system based on submerged supersonic gas-solid injection. Background Technology

[0002] Dephosphorization is one of the important tasks in steelmaking. The key to efficient dephosphorization with less slag lies in controlling the early temperature of the molten pool, the slag-forming rate, and the utilization efficiency of lime, while also providing favorable kinetic conditions. With the increase in oxygen supply intensity and the emergence of bottom-blowing stirring technology, the smelting pace of steelmaking is constantly accelerating. How to quickly complete slag formation, reduce slag volume, and efficiently dephosphorize has become one of the key issues in steelmaking.

[0003] Currently, steelmaking slag-forming materials mainly rely on CaO-based slag-forming agents. These are typically added in block form from the top of the furnace feed hopper. The oxides need to gradually penetrate the lime blocks from the outside in to complete the slag formation process, and then react with CaO at high temperatures to generate some low-melting-point compounds. To improve the melting rate of the slag-forming materials, a certain amount of slag-forming agent is usually added, and methods such as enhanced stirring (bottom blowing or top blowing) are used to accelerate the melting of lime. However, this still falls short of meeting the requirements for rapid slag formation and dephosphorization.

[0004] This application proposes a low-slag, high-efficiency smelting method and system based on submerged supersonic gas-solid injection, in order to achieve rapid slag formation, reduce slag volume, and improve dephosphorization efficiency, thereby meeting the requirements for low-slag, high-efficiency dephosphorization in the steelmaking process. Summary of the Invention

[0005] The purpose of this application is to provide a low-slag, high-efficiency smelting method and system based on submerged supersonic gas-solid injection to solve the above-mentioned problems.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] A low-slag, high-efficiency smelting method based on submerged supersonic gas-solid injection includes:

[0008] Raw material addition period: During the stage of adding scrap steel and molten iron, the submersible supersonic gas-solid oxygen lance is in protective gas mode with a protective gas flow rate of 10-200 m3 / h;

[0009] Melting Period: After raw material addition is complete, the submersible supersonic gas-solid oxygen lance switches to oxygen supply mode, extending into the steel slag layer with an oxygen flow rate of 600-3000 m³ / h. Once the oxygen flow rate reaches the predetermined value, the submersible supersonic gas-solid oxygen lance switches to gas-solid injection mode. The outlet of the submersible supersonic gas-solid oxygen lance includes, from the inside out, a gas-solid channel, a first epoxy channel, a combustion channel, and a second epoxy channel. The flow rate of the slag-forming material in the gas-solid channel is 30-200 kg / min (the melting period is divided into early and late melting stages; the flow rate of the slag-forming material in the early melting stage is 30-50 kg / min, and in the late melting stage it is 50-200 kg / min), and the oxygen flow rate is 600-3000 m³ / h. The oxygen flow rate in the first epoxy channel is 10-200 m³ / h, and the methane flow rate in the combustion channel is 20-400 m³ / h. m3 / h, the oxygen flow rate of the second epoxy channel is 10-200 m3 / h;

[0010] Oxidation heating period: In the early stage of oxidation heating, maintain the flow rate of slag-forming material at 50-200 kg / min; in the later stage of oxidation heating, control the flow rate of slag-forming material to not exceed 50 kg / min; after completing slag formation and dephosphorization, the submerged supersonic gas-solid oxygen gun is changed to gas supply mode, with an oxygen flow rate of 1500-2500 m3 / h.

[0011] Steel tapping stage: When the molten steel reaches the expected temperature, the submersible supersonic gas-solid oxygen lance stops supplying oxygen and starts the protective gas mode, the steel smelting ends, and the steel is tapped.

[0012] Preferably, the oxygen pressure of the immersion supersonic gas-solid oxygen gun is 0.5-1.6 MPa.

[0013] Preferably, the slag-forming material includes one or more of quicklime powder, limestone powder, fluorite powder, and magnesium sphere powder.

[0014] Preferably, the particle size of the slag-forming material is 100-400 mesh.

[0015] By partially or completely replacing the block slag-forming materials used in traditional steelmaking with powdered slag-forming materials, the specific surface area of ​​the powdered particles in submerged supersonic gas-solid injection is much larger than that of block slag-forming materials. This increases the reaction contact area between the oxidation products of various elements and the slag-forming materials, and eliminates the dense, high-melting-point 2CaO•SiO2 shell formed on the surface of block slag-forming materials such as lime or limestone when they melt. This accelerates the slag formation and reaction rate of the injected powdered slag-forming materials at the steel-slag interface.

[0016] Preferably, the slag-forming material in block form is added during the melting period and the oxidation heating period.

[0017] Preferably, the carrier gas flow rate of the slag-forming material is 100-3000 m³ / h. 3 / h.

[0018] Preferably, the protective gas includes nitrogen and / or carbon dioxide.

[0019] This application also provides a low-slag, high-efficiency smelting system based on submerged supersonic gas-solid injection, for performing the aforementioned low-slag, high-efficiency smelting method based on submerged supersonic gas-solid injection.

[0020] The slag-free and high-efficiency smelting system based on submerged supersonic gas-solid injection includes: an electric arc furnace, a powder injection tank, a submerged supersonic gas-solid oxygen lance, and a control device.

[0021] The electric arc furnace is used to smelt the target steel grade, the powder injection tank is used to supply slag-forming materials to the submerged supersonic gas-to-oxygen lance, the submerged supersonic gas-to-oxygen lance is used to supply the slag-forming materials, methane, oxygen and protective gas to the steel slag layer of the electric arc furnace, and the control device is used to control the submerged supersonic gas-to-oxygen lance.

[0022] Preferably, the powder supply tube of the immersion supersonic gas-solid oxygen lance is made of wear-resistant stainless steel and has an inner diameter of 10-150 mm.

[0023] The powder supply pipe outlet is located at the tail of the oxygen lance, and all powder supply pipes are made of wear-resistant materials. To improve the service life of the Raoult tube of the supersonic gas-solid injection oxygen lance, wear-resistant materials such as tungsten copper alloy, corundum, chromium, or stainless steel are used in the vulnerable parts of the oxygen lance nozzle.

[0024] Preferably, the nozzle Mach number of the immersion supersonic gas-solid oxygen gun is 1.5-2.2.

[0025] Compared with the prior art, the beneficial effects of this application include:

[0026] This application provides a low-slag, high-efficiency smelting method and system based on submerged supersonic gas-solid injection, which addresses the problems of slow slag formation, large slag volume, and low dephosphorization rate due to weak stirring intensity during the dephosphorization period in traditional electric arc furnace (EAF) steelmaking processes. By using a supersonic gas-solid oxygen lance device in the EAF, lime powder, a slag-forming material, is submerged and injected to the steel-slag interface, increasing the impact force of the jet on the molten pool. This ensures sufficient contact between the jet and the molten pool, enhances stirring, and improves the thermodynamic and kinetic conditions of the dephosphorization reaction, achieving low-slag, high-efficiency dephosphorization during the smelting process. This is beneficial for improving the dephosphorization rate in EAF steelmaking and reducing slag-forming material consumption and iron loss. The submerged supersonic gas-solid injection-based EAF low-slag, high-efficiency dephosphorization method controls the injection volume of slag-forming material in stages. The EAF smelting process is divided according to the dephosphorization requirements and smelting characteristics at different stages, and the injection volume of slag-forming material is allocated as needed to achieve low-slag, high-efficiency dephosphorization in the EAF.

[0027] The solution provided in this application is applicable to the dephosphorization process of 50-150 t electric arc furnace. Compared with the traditional electric arc furnace steelmaking process, the dephosphorization efficiency is increased by about 2.5-5%, the slag volume is reduced by 5-20 kg / t, the consumption of slag-forming materials is reduced by about 5%-10%, and the metal recovery rate is increased by more than 0.5%. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0029] Figure 1 is a schematic diagram of a low-slag, high-efficiency smelting system based on submerged supersonic gas-solid injection provided in an embodiment of this application.

[0030] Figure 2 is a schematic diagram of the nozzle structure of an immersion supersonic gas-solid oxygen gun.

[0031] Figure label:

[0032] 1-Electric arc furnace; 2-Powder injection tank; 3-Immersion supersonic gas-solid oxygen lance; 4-Control device;

[0033] 31-Gas-solid channel; 32-First epoxy channel; 33-Flammable channel; 34-Second epoxy channel. Detailed Implementation

[0034] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0035] Example 1

[0036] As shown in Figure 1, this embodiment provides a low-slag, high-efficiency smelting system based on submerged supersonic gas-solid injection, including: an electric arc furnace 1, a powder injection tank 2, a submerged supersonic gas-solid oxygen lance 3, and a control device 4.

[0037] Electric arc furnace 1 is used to smelt the target steel grade, powder injection tank 2 is used to deliver slag-forming materials to submerged supersonic gas-to-oxygen lance 3, submerged supersonic gas-to-oxygen lance 3 is used to deliver slag-forming materials, methane, oxygen and protective gas to the steel slag layer of electric arc furnace 1, and control device 4 is used to control submerged supersonic gas-to-oxygen lance 3.

[0038] As shown in Figure 2, the outlet (nozzle) of the submersible supersonic gas-solid oxygen gun 3 includes, from the inside out, a gas-solid channel 31, a first epoxy channel 32, an epoxidation channel 33, and a second epoxy channel 34.

[0039] Lime powder and other slag-forming materials are transported to the electric arc furnace smelting site by tank trucks and intermediate tanks. The lime powder and other slag-forming materials are input into the gas-solid channel 31 from the tail of the oxygen lance through the powder injection tank device. The gas-solid mixed jet is injected at supersonic speed through the submerged supersonic gas-solid oxygen lance, so that the gas-solid mixed jet directly impacts the steel-slag interface for rapid, low-slag, and efficient dephosphorization.

[0040] Example 2

[0041] This embodiment provides a low-slag, high-efficiency smelting method based on submerged supersonic gas-solid injection. It uses the smelting system provided in Embodiment 1, employing a 75-ton electric arc furnace. A wear-resistant pipe connects the outlet of the injection equipment to the oxygen pipeline at the tail end of the oxygen lance, using oxygen as the gas medium for transporting the powder. The powder supply pipeline is made of Ф50×5 mm wear-resistant stainless steel. The powder is directly input into the tail end of the supersonic gas-solid injection oxygen lance through a powder injection tank, with a nozzle Mach number of 2.1. Oxygen is directly used as the carrier gas for transporting the powder material, with an oxygen flow rate of 600-2000 m³ / h. 3 / h, pressure 0.6-1.5 MPa. The slag-forming material is limestone powder with a particle size of less than 2 mm.

[0042] The method includes the following steps:

[0043] Raw material addition period: During the electric arc furnace smelting process, in the stage of adding scrap steel and molten iron, the submerged supersonic gas oxygen lance is in protective gas mode with a flow rate of 30 m³ / h. 3 / h, to prevent splashing during the feeding process from clogging the supersonic gas-solid jet nozzle.

[0044] Melting Period: After the raw materials are added, the electrodes are powered on, and the melting period begins. The submersible supersonic gas-to-oxygen lance is in oxygen supply mode, extending into the slag with an oxygen flow rate of 2000 m³ / s. 3 When the oxygen flow rate of the submersible supersonic gas-solid oxygen lance reaches the set flow rate, the powder injection system is controlled to discharge the powder, thus initiating the submersible supersonic oxygen lance gas-solid injection mode. The lime powder flow rate is 30-50 kg / min, and the gas flow rate is 600-2000 m³ / min. 3 / h, the flow rate of the first epoxy channel is 10-100 m³ / h. 3 / h, the flow rate of the cyclic combustion channel is 20-200 m³ / h. 3 / h, the flow rate of the second epoxy channel is 10-100 m³ / h. 3 / h. Simultaneously, depending on the on-site smelting conditions, some blocky slag-forming materials can be added to the silo. In the early stages of melting, use a low flow rate (powder flow rate 30 kg / min, oxygen flow rate 1000 m³ / min). 3 / h, first epoxy channel flow rate 50 m³ / h 3 / h, ionization flow rate 100 m³ 3 / h, second epoxy channel flow rate 50 m³ / h 3 Lime powder is injected at a rate of 40 kg / min for rapid melting and slag formation, reducing slag volume and shortening slag formation time. The later stage of melting is the main period for dephosphorization, during which a high flow rate (powder flow rate 40 kg / min, oxygen flow rate 2000 m³ / min) is used. 3 / h, First epoxy channel 100 m 3 / h, ionization flow rate 200 m³ 3 / h, second epoxy channel flow rate 100 m³ / h 3 (h) Supersonic gas-solid injection is used for deep dephosphorization, with the addition of some block slag-forming materials. The powder has a larger specific surface area than block lime, maximizing the acceleration of the metallurgical chemical reaction, reducing slag volume, and improving the dephosphorization rate. Furthermore, by adopting the submerged supersonic gas-solid oxygen lance gas-solid injection mode, the jet length is increased, the jet impact force is enhanced, and the stirring effect on the molten pool is strengthened.

[0045] Oxidation heating period: In the early stage of oxidation heating, when the dephosphorization temperature is reached, continue to maintain a high flow rate (powder flow rate 50 kg / min, oxygen flow rate 2000 m³ / min). 3 / h, first epoxy channel flow rate 100 m³ / h 3 / h, 200 m³ / h flow rate in the ignition channel 3 / h, second epoxy channel flow rate 100 m³ / h 3 During the deep dephosphorization process, the slag is injected at a rate of 1000 m³ / h, with the addition of lime blocks, magnesium balls, slag-forming agents, fluorite, and other slag-forming materials. In the later stages of oxidation and heating, the dephosphorization reaction decreases or ceases, and the slag primarily serves as arc-submerged insulation. At this stage, the powder injection flow rate of the submerged supersonic gas-solid oxygen lance can be appropriately reduced, controlled at 30 kg / min. Simultaneously, some blocky slag-forming materials are added according to the smelting conditions. After the slag-forming and dephosphorization stage is completed, the gas-solid injection mode of the submerged supersonic gas-solid oxygen lance is shut off, the powder injection tank stops feeding powder, and the submerged supersonic gas-solid oxygen lance is switched to gas supply mode with an oxygen flow rate of 2000 m³ / min. 3 / h, first epoxy channel flow rate 100 m³ / h 3 / h, 200 m³ / h flow rate in the ignition channel 3 / h, second epoxy channel flow rate 100 m³ / h 3 / h.

[0046] Steel tapping stage: When the molten steel reaches the expected temperature, the submerged supersonic gas-solid oxygen lance stops supplying oxygen, the oxygen is removed from the slag, the protective gas mode is started, the steel smelting is completed, and the steel is tapped.

[0047] Experimental results show that the immersion supersonic gas-solid injection limestone powder dephosphorization process for steelmaking in a 75 t electric arc furnace increases the dephosphorization rate by 2.5%, reduces slag volume by 10 kg / t, reduces lime powder consumption by 3%, and increases metal recovery by 1% compared to the traditional electric arc furnace dephosphorization process with top slag-forming materials.

[0048] Example 3

[0049] This embodiment provides a low-slag, high-efficiency smelting method based on submerged supersonic gas-solid injection. It uses the smelting system provided in Embodiment 1, employing a 115-ton electric arc furnace. The powder supply pipeline uses Ф50×5 mm wear-resistant stainless steel pipe. The powder is directly input into the tail end of the submerged supersonic gas-solid oxygen lance via a powder injection tank, with a nozzle Mach number of 2.1. Oxygen is used directly as the carrier gas for transporting the powder material, with an oxygen flow rate of 2500 m³ / h. 3 / h, pressure 0.6-1.5 MPa. The slag-forming material is limestone powder with a particle size of less than 2 mm.

[0050] The method includes the following steps:

[0051] Raw material addition period: During the electric arc furnace smelting process, in the stage of adding scrap steel and molten iron, the submerged supersonic gas oxygen lance is in protective gas mode with a flow rate of 30 m³ / h. 3 / h, to prevent splashing during the feeding process from clogging the supersonic gas-solid jet nozzle.

[0052] Melting Period: After the raw materials are added, the electrodes are powered on, and the melting period begins. The submerged supersonic gas-to-oxygen lance is in oxygen supply mode, extending into the slag with an oxygen flow rate of 2500 m³ / s. 3 When the oxygen flow rate of the submersible supersonic gas-solid oxygen lance reaches the set flow rate, the powder injection system is controlled to discharge the powder, thus initiating the submersible supersonic oxygen lance gas-solid injection mode. The lime powder flow rate is 35-50 kg / min, and the gas flow rate is 600-2500 m³ / min. 3 / h, the flow rate of the first epoxy channel is 10-125 m³ / h. 3 / h, the flow rate of the cyclic combustion channel is 20-250 m³ / h. 3 / h, the flow rate of the second epoxy channel is 10-125 m³ / h. 3 / h. Simultaneously, depending on the on-site smelting conditions, some blocky slag-forming materials can be added to the silo. In the early stages of melting, use a low flow rate (powder flow rate 40 kg / min, oxygen flow rate 1000 m³ / min). 3 / h, first epoxy channel flow rate 50 m³ / h 3 / h, 100 m³ / h flow rate in the ignition channel3 / h, second epoxy channel flow rate 50 m³ / h 3 Lime powder is injected at a rate of 50 kg / min for rapid melting and slag formation, reducing slag volume and shortening slag formation time. The later stage of melting is the main period for dephosphorization, during which a high flow rate (powder flow rate 50 kg / min, oxygen flow rate 2500 m³ / min) is used. 3 / h, first epoxy channel flow rate 125 m³ / h 3 / h, 250 m³ / h, cyclic combustion channel flow rate 3 / h, second epoxy channel flow rate 125 m³ / h 3 (h) Supersonic gas-solid injection is used for deep dephosphorization, with the addition of some block slag-forming materials. The powder has a larger specific surface area than block lime, maximizing the acceleration of the metallurgical chemical reaction, reducing slag volume, and improving the dephosphorization rate. Furthermore, by adopting the submerged supersonic gas-solid oxygen lance gas-solid injection mode, the jet length is increased, the jet impact force is enhanced, and the stirring effect on the molten pool is strengthened.

[0053] Oxidation heating period: In the early stage of oxidation heating, when the dephosphorization temperature is reached, continue to maintain a high flow rate (powder flow rate 60 kg / min, oxygen flow rate 2500 m³ / min). 3 / h, first epoxy channel flow rate 125 m³ / h 3 / h, 250 m³ / h, cyclic combustion channel flow rate 3 / h, second epoxy channel flow rate 125 m³ / h 3 During the deep dephosphorization process, the slag is injected at a rate of 1000 kg / min, and some lime blocks, magnesium balls, slag-forming agents, fluorite, and other slag-forming materials are added. In the later stages of oxidation and heating, the dephosphorization reaction is less frequent or ceases, and the slag mainly serves as an arc-submerged insulation material. At this stage, the powder injection flow rate of the submerged supersonic gas-solid oxygen lance can be appropriately reduced, controlled at 40 kg / min. Simultaneously, some blocky slag-forming materials are added according to the smelting conditions. After the slag-forming and dephosphorization stage is completed, the gas-solid injection mode of the submerged supersonic gas-solid oxygen lance is turned off, the powder injection tank stops feeding powder, and the submerged supersonic gas-solid oxygen lance is in gas supply mode with an oxygen flow rate of 2500 m³ / min. 3 / h, first epoxy channel flow rate 125 m³ / h 3 / h, 250 m³ / h, cyclic combustion channel flow rate 3 / h, second epoxy channel flow rate 125 m³ / h 3 / h.

[0054] Steel tapping stage: When the molten steel reaches the expected temperature, the submerged supersonic gas-solid oxygen lance stops supplying oxygen, the oxygen is removed from the slag, the protective gas mode is started, the steel smelting is completed, and the steel is tapped.

[0055] Experimental results show that the supersonic gas-solid injection limestone powder dephosphorization process for 115 t electric arc furnace steelmaking improves the dephosphorization rate by 3%, reduces slag volume by 15 kg / t, reduces limestone powder consumption by 5%, and increases metal recovery by 1% compared with the traditional electric arc furnace top-addition slag-forming material dephosphorization process.

[0056] Comparative Example 1

[0057] Traditional electric arc furnace (EAF) steelmaking processes typically employ dephosphorization using lumpy lime. This lumpy lime is usually added in two batches. Taking a vertical shaft EAF in a steel plant in Northeast China as an example, the first batch of slag-forming material (3 tons) is added through a hopper after the third batch of scrap steel is added to the molten pool. The second batch of slag-forming material (0.7 tons) is added through the hopper after the last batch of scrap steel is added to the molten pool. This traditional EAF dephosphorization method requires the lime lumps to melt in the molten pool before participating in the dephosphorization reaction, resulting in low dephosphorization efficiency. Therefore, a steel plant in southern China adopted a lime powder injection method to improve dephosphorization efficiency, changing the way slag-forming materials are added. Taking a 90-ton conventional EAF in a southern steel plant as an example, this EAF steelmaking plant uses a straight-tube spray gun for lime powder injection to improve dephosphorization efficiency. The lime powder injection dephosphorization process is as follows: the total lime powder injection rate is 45 kg / min, and the injection time is 35 min. Part of the slag-forming material is added in block form, with a block lime weight of 1.3 t. Compared to dephosphorization using only block slag-forming materials, this method improves dephosphorization efficiency by 1.2%. Although using a straight-tube spray gun can improve dephosphorization efficiency, it was found that by changing the structure of the spray gun, its dephosphorization efficiency can be further improved. For example, the supersonic gas-solid spray gun designed in this case can improve the dephosphorization efficiency by 2.5-5%.

[0058] This submersible supersonic gas-solid injection method and system for low-slag and high-efficiency smelting changes the original injection method of slag-forming materials and the structure of the nozzle, and provides a supersonic lime powder injection scheme and a supersonic gas-solid injection lance structure. By changing the injection parameters of the supersonic gas-solid injection lance during the smelting process, different injection modes are adjusted according to the smelting characteristics of different stages to adapt to the dephosphorization requirements of each stage, thereby achieving low-slag and high-efficiency smelting in the electric arc furnace.

[0059] Comparative Example 2

[0060] This case study compares the powdered material with Example 2, differing only in the injection parameters. The electric arc furnace used is a 75-ton unit, while the nozzle structure remains the same as in Example 2. Oxygen is used directly as the carrier gas for transporting the powdered material, with an oxygen flow rate of 600-2000 m³ / h. 3 / h, pressure 0.6-1.5 MPa. The slag-forming material is limestone powder with a particle size of less than 2 mm.

[0061] The method includes the following steps:

[0062] Raw material addition period: During the electric arc furnace smelting process, in the stage of adding scrap steel and molten iron, the submerged supersonic gas oxygen lance is in protective gas mode with a flow rate of 30 m³ / h. 3 / h, to prevent splashing during the feeding process from clogging the supersonic gas-solid jet nozzle.

[0063] Melting Period: After the raw materials are added, the electrodes are powered on, and the melting period begins. The submersible supersonic gas-to-oxygen lance is in oxygen supply mode, extending into the slag with an oxygen flow rate of 2000 m³ / s. 3 When the oxygen flow rate of the submersible supersonic gas-solid oxygen lance reaches the set flow rate, the powder injection system is controlled to discharge the powder, thus initiating the submersible supersonic oxygen lance gas-solid injection mode. The lime powder flow rate is 10-25 kg / min, and the gas flow rate is 600-2000 m³ / min. 3 / h, the flow rate of the first epoxy channel is 10-100 m³ / h. 3 / h, the flow rate of the cyclic combustion channel is 20-200 m³ / h. 3 / h, the flow rate of the second epoxy channel is 10-100 m³ / h. 3 / h. Simultaneously, depending on the on-site smelting conditions, some blocky slag-forming materials can be added to the silo. In the early stages of melting, use a low flow rate (powder flow rate 10-15 kg / min, oxygen flow rate 1000 m³ / min). 3 / h, first epoxy channel flow rate 50 m³ / h 3 / h, ionization flow rate 100 m³ 3 / h, second epoxy channel flow rate 50 m³ / h 3 Lime powder is injected at a rate of 20 kg / min for rapid melting and slag formation, reducing slag volume and shortening slag formation time. The later stage of melting is the main period for dephosphorization, during which a high flow rate (powder flow rate 20 kg / min, oxygen flow rate 2000 m³ / min) is used. 3 / h, First epoxy channel 100 m 3 / h, ionization flow rate 200 m³ 3 / h, second epoxy channel flow rate 100 m³ / h 3 / h).

[0064] Oxidation heating period: In the early stage of oxidation heating, when the dephosphorization temperature is reached, continue to maintain a high flow rate (powder flow rate 25 kg / min, oxygen flow rate 2000 m³ / min). 3 / h, first epoxy channel flow rate 100 m³ / h 3 / h, 200 m³ / h flow rate in the ignition channel 3 / h, second epoxy channel flow rate 100 m³ / h 3During the deep dephosphorization process, the slag is injected at a rate of 10-15 kg / min, with the addition of lime blocks, magnesium balls, slag-forming agents, fluorite, and other slag-forming materials. In the later stages of oxidation and heating, the dephosphorization reaction decreases or ceases, and the slag primarily serves as arc-submerged insulation. At this stage, the powder injection flow rate of the submerged supersonic gas-solid oxygen lance can be appropriately reduced, controlled at 10-15 kg / min. Simultaneously, some blocky slag-forming materials are added according to the smelting conditions. After the slag-forming and dephosphorization stage is completed, the gas-solid injection mode of the submerged supersonic gas-solid oxygen lance is shut off, the powder injection tank stops feeding powder, and the submerged supersonic gas-solid oxygen lance is switched to gas supply mode with an oxygen flow rate of 2000 m³ / min. 3 / h, first epoxy channel flow rate 100 m³ / h 3 / h, 200 m³ / h flow rate in the ignition channel 3 / h, second epoxy channel flow rate 100 m³ / h 3 / h.

[0065] Steel tapping stage: When the molten steel reaches the expected temperature, the submerged supersonic gas-solid oxygen lance stops supplying oxygen, the oxygen is removed from the slag, the protective gas mode is started, the steel smelting is completed, and the steel is tapped.

[0066] Experimental results show that the submerged supersonic gas-solid injection limestone powder dephosphorization process in 75-ton electric arc furnace steelmaking did not improve the dephosphorization rate compared to the traditional electric arc furnace dephosphorization process with top slag-forming materials. In some heats, the dephosphorization effect was even worse, with no significant change in slag volume, a slight decrease in lime powder consumption, and essentially no change in metal yield. When using the same injection method, different injection schemes need to be developed based on the characteristics of electric arc furnace smelting to better leverage the advantages of the supersonic gas-solid injection oxygen lance. However, importantly, the amount of injected lime powder needs to reach a certain flow rate. Within a suitable range, a higher relative flow rate results in a more significant impact of the gas-solid jet on the molten pool, improving the molten pool dynamics and exhibiting a better dephosphorization effect.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A low-slag, high-efficiency smelting method based on submerged supersonic gas-solid injection, characterized in that, include: Raw material addition period: During the stage of adding scrap steel and molten iron, the submersible supersonic gas-solid oxygen lance is in protective gas mode, with a protective gas flow rate of 10-200 m³ / h. 3 / h; Melting period: After the raw materials are added, the submersible supersonic gas-solid oxygen lance is switched to oxygen supply mode. The submersible supersonic gas-solid oxygen lance is inserted into the steel slag layer, and the oxygen flow rate is 600-3000 m³ / h. 3 / h; After the oxygen flow rate reaches the predetermined value, the submersible supersonic gas-solid oxygen lance changes to gas-solid injection mode; the outlet of the submersible supersonic gas-solid oxygen lance includes, from the inside out, a gas-solid channel, a first epoxy channel, an epoxy combustion channel, and a second epoxy channel. The flow rate of the slag-forming material in the gas-solid channel is 30-200 kg / min, and the oxygen flow rate is 600-3000 m³ / min. 3 / h; the oxygen flow rate of the first epoxy channel is 10-200 m³ / h. 3 The methane flow rate in the cyclone combustion channel is 20-400 m³ / h. 3 / h, the oxygen flow rate of the second epoxy channel is 10-200 m³ / h. 3 / h; Oxidation heating period: In the early stage of oxidation heating, maintain the flow rate of slag-forming material at 50-200 kg / min; in the later stage of oxidation heating, control the flow rate of slag-forming material to not exceed 50 kg / min; after completing slag formation and dephosphorization, switch the submerged supersonic gas-solid oxygen lance to gas supply mode, with an oxygen flow rate of 1500-2500 m³ / min. 3 / h; Steel tapping stage: When the molten steel reaches the expected temperature, the submersible supersonic gas-solid oxygen lance stops supplying oxygen and starts the protective gas mode, the steel smelting ends, and the steel is tapped.

2. The low-slag, high-efficiency smelting method based on submerged supersonic gas-solid injection according to claim 1, characterized in that, The oxygen pressure of the immersion supersonic gas-solid oxygen lance is 0.5-1.6 MPa.

3. The low-slag, high-efficiency smelting method based on submerged supersonic gas-solid injection according to claim 1, characterized in that, The slag-forming material includes one or more of quicklime powder, limestone powder, fluorite powder, and magnesium spherical powder.

4. The low-slag, high-efficiency smelting method based on submerged supersonic gas-solid injection according to claim 3, characterized in that, The particle size of the slag-forming material is 100-400 mesh.

5. The low-slag, high-efficiency smelting method based on submerged supersonic gas-solid injection according to claim 1, characterized in that, The slag-forming material in block form is also added during the melting period and the oxidation heating period.

6. The low-slag, high-efficiency smelting method based on submerged supersonic gas-solid injection according to claim 1, characterized in that, The carrier gas flow rate of the slag-forming material is 100-3000 m³ / h. 3 / h.

7. The low-slag, high-efficiency smelting method based on submersible supersonic gas-solid injection according to any one of claims 1-6, characterized in that, The protective gas includes nitrogen and / or carbon dioxide.

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