Method and system for slag-reduced and high-efficiency smelting based on submerged supersonic gas-solid injection

Abstract

The present application provides a slag-reducing and high-efficiency smelting method and system based on submerged supersonic gas-solid injection, which relates to the metallurgical field. The method includes: a raw material addition period, a melting period, an oxidation and heating period, and a tapping stage. The slag-reducing 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; the electric arc furnace is used for smelting a target steel grade, the powder injection tank is used for conveying slag-making materials to the submerged supersonic gas-solid oxygen lance, the submerged supersonic gas-solid oxygen lance is used for conveying the slag-making materials, methane, oxygen, and protective gas into the steel slag layer of the electric arc furnace, and the control system is used for controlling the submerged supersonic gas-solid oxygen lance. The slag-reducing and high-efficiency smelting method and system provided by the present application have the following advantages: the dephosphorization efficiency is increased by about 2.5-5%, the slag amount is reduced by 5-20 kg / t, the consumption of slag-making materials is reduced by 5-10%, and the metal yield is increased by more than 0.5%.

Description

Technical Field

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

[0002] Dephosphorization is one of the important tasks in steelmaking. The key to high-efficiency dephosphorization with less slag is to control the early temperature of the molten pool, the slag-making speed and the utilization efficiency of lime, and to provide good dynamic conditions. With the increase of oxygen supply intensity and the emergence of bottom blowing and stirring technology, the smelting rhythm of steelmaking is accelerating. How to quickly complete slag-making, reduce the amount of slag and dephosphorize efficiently has become one of the key issues in steelmaking.

[0003] At present, the slag-making materials for steelmaking mainly rely on CaO-based slag-making agents, which are mainly added in the form of blocks from the charging bin on the top of the furnace body. The oxide needs to gradually penetrate the lime blocks from the outside to the inside to complete the slag-making process, and react with CaO at high temperatures to generate some low-melting-point compounds. In order to increase the melting rate of slag-making materials, a certain amount of slag-making agent and enhanced stirring methods (bottom blowing or top blowing) are usually used to accelerate the melting of lime, but it is still difficult to meet the requirements of rapid slag-forming and dephosphorization.

[0004] The present application proposes a low-slag and efficient smelting method and system based on submerged supersonic gas-solid injection, so as to achieve the purpose of rapid slag reduction, reduce the slag amount and improve the dephosphorization efficiency, and meet the requirements of low-slag and efficient dephosphorization in the steelmaking process. Summary of the invention

[0005] The purpose of the present application is to provide a low-slag and efficient 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 solutions:

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

[0008] Raw material adding period: During the adding stage of scrap steel and molten iron, the submerged supersonic gas solid oxygen gun is in the protective gas mode, and the protective gas flow rate is 10-200 m 3 / h;

[0009] Melting period: After the raw materials are added, the submerged supersonic gas-solid oxygen gun is changed to the oxygen supply mode. The submerged supersonic gas-solid oxygen gun is extended into the slag layer, and the oxygen flow rate is 600-3000 m 3 / h; After the oxygen flow rate reaches a predetermined value, the submerged supersonic gas-solid oxygen lance changes to the gas-solid injection mode; the outlet of the submerged supersonic gas-solid oxygen lance includes a gas-solid channel, a first epoxy channel, a ring combustion channel, and a second epoxy channel from the inside to the outside. The flow rate of the slag-making material in the gas-solid channel is 30 - 200 kg / min (the melting period is divided into the early melting stage and the late melting stage. The flow rate of the slag-making material in the early melting stage is 30 - 50 kg / min, and the flow rate of the slag-making material in the late melting stage is 50 - 200 kg / min), and the oxygen flow rate is 600 - 3000 m 3 / h; The oxygen flow rate in the first epoxy channel is 10 - 200 m 3 / h, the methane flow rate in the ring combustion channel is 20 - 400 m 3 / h, the oxygen flow rate in the second epoxy channel is 10 - 200 m 3 / h;

[0010] Oxidation and heating period: In the early stage of oxidation and heating, keep the flow rate of the slag-making material at 50 - 200 kg / min; in the late stage of oxidation and heating, control the flow rate of the slag-making material not to exceed 50 kg / min; after completing slag-making and dephosphorization, the submerged supersonic gas-solid oxygen lance changes to the gas supply mode, and the oxygen flow rate is 1500 - 2500 m 3 / h;

[0011] Tapping stage: When the molten steel rises to the expected temperature, the submerged supersonic gas-solid oxygen lance stops supplying oxygen and starts the protective gas mode, and the molten steel smelting ends and tapping is carried out.

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

[0013] Preferably, the slag-making material includes one or more of quicklime powder, limestone powder, fluorite powder, and magnesia ball powder.

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

[0015] Partially or completely replace the massive slag-making material used in traditional steelmaking slag-making with powdered slag-making material. The specific surface area of the powdered particles in the submerged supersonic gas-solid injection is much larger than that of the massive slag-making material, increasing the reaction contact area between the oxidation products of each element and the slag-making material, and eliminating the dense high-melting-point 2CaO•SiO2 shell formed on the surface when massive slag-making materials such as lime or limestone melt, making the slagging and reaction speed of the injected powdered slag-making material at the steel-slag interface faster.

[0016] Preferably, massive slag-making material is also added during the melting period and the oxidation and heating period.

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

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

[0019] This application also provides a slag-reducing and high-efficiency smelting system based on submerged supersonic gas-solid injection, which is used to perform the slag-reducing and high-efficiency smelting method based on submerged supersonic gas-solid injection;

[0020] The slag-reducing 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 convey slag-making materials to the submerged supersonic gas-solid oxygen lance. The submerged supersonic gas-solid oxygen lance is used to convey the slag-making materials, methane, oxygen, and protective gas into the steel slag layer of the electric arc furnace. The control device is used to control the submerged supersonic gas-solid oxygen lance.

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

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

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

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

[0026] The slag-reducing and high-efficiency smelting method and system based on submerged supersonic gas-solid injection provided by this application are used to solve problems such as slow slag formation speed, large slag volume, and low stirring intensity during the dephosphorization period resulting in low dephosphorization rate in the traditional electric arc furnace steelmaking process. Through the submerged injection of the slag-making material lime powder to the steel slag interface by the electric arc furnace supersonic gas-solid oxygen lance device and increasing the impact force of the jet on the molten pool, it makes full contact with the molten pool, enhances the stirring of the molten pool, improves the thermodynamic and kinetic conditions of the dephosphorization reaction, realizes slag-reducing and high-efficiency dephosphorization during the smelting process, is beneficial to improving the dephosphorization rate of electric arc furnace steelmaking, and reducing the consumption of slag-making materials and iron loss during the steelmaking process. The electric arc furnace slag-reducing and high-efficiency dephosphorization method based on submerged supersonic gas-solid injection divides the electric arc furnace smelting process according to the dephosphorization requirements and smelting characteristics in different periods, and distributes the injection amount of the slag-making material as needed, realizing slag-reducing and high-efficiency dephosphorization of the electric arc furnace.

[0027] The solution provided by this application is applicable to the dephosphorization process of 50 - 150 t electric arc furnaces. Compared with the traditional electric arc furnace steelmaking process, when using the present invention, the dephosphorization efficiency is increased by about 2.5 - 5%, the slag amount is reduced by 5 - 20 kg / t, the consumption of slag-making materials is reduced by about 5% - 10%, and the metal yield is increased by more than 0.5%. Brief Description of the Drawings

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as limiting the scope of this application.

[0029] Figure 1 It is a schematic diagram of a slag-reducing and high-efficiency smelting system based on submerged supersonic gas-solid injection provided for the embodiments of this application;

[0030] Figure 2 It is a schematic diagram of the structure of the nozzle of the submerged supersonic gas-solid oxygen lance.

[0031] Reference Signs:

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

[0033] 31 - Gas-solid channel; 32 - First epoxy channel; 33 - Ring combustion channel; 34 - Second epoxy channel. Detailed Embodiments

[0034] The following will describe in detail the implementation solutions of this application in combination with specific embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate this application and should not be regarded as limiting the scope of this application. For those not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0035] Embodiment 1

[0036] As Figure 1 shown, this embodiment provides a slag-reducing and 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] The electric arc furnace 1 is used for smelting the target steel grade, the powder injection tank 2 is used to transport slag-making materials to the submerged supersonic gas-solid oxygen lance 3, the submerged supersonic gas-solid oxygen lance 3 is used to transport slag-making materials, methane, oxygen, and protective gas into the steel slag layer of the electric arc furnace 1, and the control device 4 is used to control the submerged supersonic gas-solid oxygen lance 3.

[0038] As Figure 2As shown in the figure, the outlet (spray head) of the submerged supersonic gas-solid oxygen lance 3 includes a gas-solid channel 31, a first epoxy channel 32, an annular combustion channel 33, and a second epoxy channel 34 from the inside to the outside.

[0039] The slag-making materials such as lime powder are transported to the electric arc furnace smelting site by means of a tank truck and an intermediate ladle. The slag-making materials such as lime powder are input into the gas-solid channel 31 from the tail of the oxygen lance through a powder injection tank device, and are subjected to supersonic submerged injection through the submerged supersonic gas-solid oxygen lance, so that the gas-solid mixed jet directly impacts the steel slag interface for rapid and less slag high-efficiency dephosphorization.

[0040] Example 2

[0041] This embodiment provides a less slag and high-efficiency smelting method based on submerged supersonic gas-solid injection. The smelting system provided in Example 1 is used. The electric arc furnace is a 75 t electric arc furnace. A wear-resistant pipe is used to connect the outlet of the injection equipment to the oxygen pipeline at the tail end of the oxygen lance. Oxygen is used as the gas medium for transporting the powder. The powder supply pipeline uses a wear-resistant stainless steel pipe with a diameter of Ф50×5 mm. The powder is directly input into the tail end of the supersonic gas-solid injection oxygen lance through a powder injection tank, and the Mach number of the spray head is 2.1. Oxygen is directly used as the carrier gas for transporting the powder material, and the oxygen flow rate is 600 - 2000 m 3 / h, and the pressure is 0.6 - 1.5 Mpa. The slag-making material is limestone powder with a particle size less than 2 mm.

[0042] This 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 hot metal, the submerged supersonic gas-solid oxygen lance is in the protective gas mode, and the flow rate is 30 m 3 / h to prevent splashing and blocking of the supersonic gas-solid injection gun head during the feeding process.

[0044] Melting period: After the raw materials are added, the electrode starts to supply power, and the melting period begins. The submerged supersonic gas-solid oxygen lance is in the oxygen supply mode. The submerged supersonic gas-solid oxygen lance extends into the slag. The oxygen flow rate is 2000 m 3 / h. When the oxygen flow rate of the submerged supersonic gas-solid oxygen lance reaches the set flow rate, the powder injection tank injection system is controlled to feed materials, and the submerged supersonic oxygen lance gas-solid injection mode is started. The lime powder flow rate is 30 - 50 kg / min, the gas flow rate is 600 - 2000 m 3 / h, the flow rate of the first epoxy channel is 10 - 100 m 3 / h, the flow rate of the annular combustion channel is 20 - 200 m 3 / h, and the flow rate of the second epoxy channel is 10 - 100 m 3 / h. At the same time, some massive slag-making materials can be added through the bunker according to the on-site smelting situation. In the early stage of melting, a small flow rate is used first (powder flow rate 30 kg / min, oxygen flow rate 1000 m3 / h, the flow rate of the first epoxy channel is 50 m 3 / h, the flow rate of the annular combustion is 100 m 3 / h, the flow rate of the second epoxy channel is 50 m 3 / h) to spray lime powder for rapid melting and slag formation, reducing the slag volume and shortening the slag formation time. The late melting stage is the main period for dephosphorization. In this stage, a large flow rate is adopted (powder flow rate 40 kg / min, oxygen flow rate 2000 m 3 / h, the first epoxy channel is 100 m 3 / h, the flow rate of the annular combustion is 200 m 3 / h, the flow rate of the second epoxy channel is 100 m 3 / h) for supersonic gas-solid injection for deep dephosphorization. At the same time, some massive slag-making materials are added. The powder has a larger specific surface area than massive lime, which maximally accelerates the metallurgical chemical reaction, reduces the slag volume and can improve the dephosphorization rate. In addition, after 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 and heating period: In the early stage of oxidation and heating, when the dephosphorization temperature is reached, continue to maintain a large flow rate (powder flow rate 50 kg / min, oxygen flow rate 2000 m 3 / h, the flow rate of the first epoxy channel is 100 m 3 / h, the flow rate of the annular combustion channel is 200 m 3 / h, the flow rate of the second epoxy channel is 100 m 3 / h) to spray, and at the same time add some slag-making materials such as lime lumps, magnesium balls, slag melting agents, fluorite, etc. to continue deep dephosphorization. After entering the late stage of oxidation and heating, at this time, the dephosphorization reaction is less or no longer occurs, and the furnace slag mainly plays the role of arc burying and heat preservation. In this stage, the powder injection flow rate of the submerged supersonic gas-solid oxygen lance can be appropriately reduced, and the flow rate can be controlled at 30 kg / min. At the same time, some massive slag-making materials are added according to the smelting situation. After the slag-making and dephosphorization stage is completed, the submerged supersonic gas-solid oxygen lance gas-solid injection mode is closed, the powder spraying tank stops powder feeding, and the submerged supersonic gas-solid injection oxygen lance is in the gas supply mode, with an oxygen flow rate of 2000 m 3 / h, the flow rate of the first epoxy channel is 100 m 3 / h, the flow rate of the annular combustion channel is 200 m 3 / h, the flow rate of the second epoxy channel is 100m 3 / h.

[0046] 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 furnace slag, and the protective gas mode is started, and the molten steel smelting is completed and tapped.

[0047] The experimental results show that: for the 75 t electric arc furnace steelmaking, the submerged supersonic gas-solid injection of limestone powder for slag-reducing and high-efficiency dephosphorization process can increase the dephosphorization rate by 2.5% compared with the traditional top addition of slag-making materials in the electric arc furnace for dephosphorization process, reduce the slag amount by 10 kg / t, reduce the consumption of lime powder by 3%, and increase the metal yield by 1%.

[0048] Example 3

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

[0050] This method includes the following steps:

[0051] Raw material addition stage: During the smelting process of the electric arc furnace, in the stage of adding scrap steel and hot metal, the submerged supersonic gas-solid oxygen lance is in the protective gas mode, and the flow rate is 30 m 3 / h to prevent splashing and blocking of the supersonic gas-solid injection lance head during the feeding process.

[0052] Melting stage: After the raw materials are added, the electrode starts to supply power, and the melting stage begins. The submerged supersonic gas-solid oxygen lance is in the oxygen supply mode. The submerged supersonic gas-solid oxygen lance extends into the slag, and the oxygen flow rate is 2500 m 3 / h. After the oxygen flow rate of the submerged supersonic gas-solid oxygen lance reaches the set flow rate, the powder injection tank injection system is controlled to feed materials, and the submerged supersonic oxygen lance gas-solid injection mode starts. The lime powder flow rate is 35 - 50 kg / min, the gas flow rate is 600 - 2500 m 3 / h, the flow rate of the first epoxy channel is 10 - 125 m 3 / h, the flow rate of the annular combustion channel is 20 - 250 m 3 / h, and the flow rate of the second epoxy channel is 10 - 125 m 3 / h. At the same time, according to the on-site smelting situation, some bulk slag-making materials can be added through the bunker. In the early stage of melting, a small flow rate is used first (powder flow rate 40 kg / min, oxygen flow rate 1000 m 3 / h, the flow rate of the first epoxy channel is 50 m 3 / h, the flow rate of the annular combustion channel is 100 m 3 / h, the flow rate of the second epoxy channel is 50 m 3 / h) Inject lime powder for rapid melting and slag formation, reducing the slag volume and shortening the slag formation time. The latter stage of melting is the main period for dephosphorization. During this stage, a large flow rate is adopted (powder flow rate: 50 kg / min, oxygen flow rate: 2500 m 3 / h, the flow rate of the first epoxy channel: 125 m 3 / h, the flow rate of the annular combustion channel: 250 m 3 / h, the flow rate of the second epoxy channel: 125 m 3 / h) Supersonic gas-solid injection is carried out for deep dephosphorization. At the same time, some massive slag-making materials are added. The powder has a larger specific surface area than massive lime, which maximally accelerates the metallurgical chemical reaction, reduces the slag volume and can improve the dephosphorization rate. In addition, after adopting the submerged supersonic gas-solid oxygen lance gas-solid injection mode, the jet length increases, the jet impact force enhances, and the stirring effect on the molten pool is strengthened.

[0053] Oxidation and heating period: In the early stage of oxidation and heating, when the dephosphorization temperature is reached, continue to maintain a large flow rate (powder flow rate: 60 kg / min, oxygen flow rate: 2500 m 3 / h, the flow rate of the first epoxy channel: 125 m 3 / h, the flow rate of the annular combustion channel: 250 m 3 / h, the flow rate of the second epoxy channel: 125 m 3 / h) Injection, and at the same time, some slag-making materials such as lime lumps, magnesium balls, slag melting agents, and fluorite are added to continue deep dephosphorization. After entering the later stage of oxidation and heating, at this time, the dephosphorization reaction is less or no longer carried out, and the furnace slag mainly plays the role of submerged arc heat preservation. The powder injection flow rate of the submerged supersonic gas-solid oxygen lance can be appropriately reduced during this stage, and the flow rate is controlled at 40 kg / min. At the same time, some massive slag-making materials are added according to the smelting situation. After the slag-making and dephosphorization stage is completed, the gas-solid injection mode of the submerged supersonic gas-solid oxygen lance is closed, the powder injection tank stops powder feeding, and the submerged supersonic gas-solid injection oxygen lance is in the gas supply mode, with an oxygen flow rate of 2500 m 3 / h, the flow rate of the first epoxy channel: 125 m 3 / h, the flow rate of the annular combustion channel: 250 m 3 / h, the flow rate of the second epoxy channel: 125 m 3 / h.

[0054] Tapping stage: When the molten steel reaches the expected temperature, the submerged supersonic gas-solid oxygen lance stops oxygen supply, the oxygen is removed from the furnace slag, and the protective gas mode is started. The smelting of the molten steel is completed and tapping begins.

[0055] The experimental results show that: For 115 t electric arc furnace steelmaking, the dephosphorization rate of the supersonic gas-solid injection of limestone powder for less slag and high-efficiency dephosphorization process is 3% higher than that of the traditional electric arc furnace top addition of slag-making materials for dephosphorization process, the slag volume is reduced by 15 kg / t, the lime powder consumption is reduced by 5%, and the metal yield is increased by 1%.

[0056] Comparative Example 1

[0057] In the traditional electric arc furnace steelmaking process, phosphorus removal is generally carried out by adding lump lime. The lump lime is usually added in two batches. Taking the shaft-type electric arc furnace of a steel plant in Northeast China as an example, in the first batch of slag-making materials, after the third batch of scrap steel is added to the molten bath, the lime lumps are added through a bunker, with an addition amount of 3 t. In the second batch of slag-making materials, after the last batch of scrap steel is added to the molten bath, the lime is added through a bunker, with an addition amount of 0.7 t. This method is a traditional phosphorus removal method for electric arc furnace steelmaking. The lime lumps need to be melted in the molten bath before participating in the phosphorus removal reaction, and the phosphorus removal efficiency is relatively low. Therefore, in order to improve the phosphorus removal efficiency, a steel plant in the south adopts the method of injecting lime powder and changes the addition method of the slag-making material to improve the phosphorus removal efficiency. Taking a 90 t ordinary electric arc furnace of a steel plant in the south as an example, this electric arc furnace steel plant uses a straight pipe type spray gun to inject lime powder to improve the phosphorus removal efficiency. The process of phosphorus removal by injecting lime powder is as follows: the whole-process lime powder injection rate is 45 kg / min, and the injection time is 35 min. Among them, part of the slag-making material is added in a lump form, and the weight of the lump lime is 1.3 t. Compared with the method of using all lump slag-making materials for phosphorus removal, the phosphorus removal rate of this method is increased by 1.2%. Although the use of a straight pipe type spray gun can improve the phosphorus removal efficiency, it is found that the phosphorus removal efficiency can be further improved by changing the structure of the spray gun. For example, in the supersonic gas-solid spray gun designed in this case, the phosphorus removal efficiency can be increased by 2.5 - 5%.

[0058] The submerged supersonic gas-solid injection method and system for less slag and high-efficiency smelting change the original injection method of the slag-making material and the structure of the nozzle, provide a scheme for supersonic lime powder injection, and the structure of the supersonic gas-solid injection spray gun. By changing the injection parameters of the supersonic gas-solid spray gun during the smelting process, different injection modes are regulated according to the smelting characteristics of different stages to meet the phosphorus removal requirements of each stage, so as to achieve less slag and high-efficiency smelting of the electric arc furnace.

[0059] Comparative Example 2

[0060] This case is a comparison with Example 2. The difference from Example 2 is the different injection parameters. The electric arc furnace is a 75t electric arc furnace, and the structure of the gun head used is the same as that of Example 2. Oxygen is directly used as the carrier gas for transporting the powder material, with an oxygen flow rate of 600 - 2000 m 3 / h and a pressure of 0.6 - 1.5 Mpa. The slag-making material is limestone powder with a particle size less than 2 mm.

[0061] This 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 hot metal, the submerged supersonic gas-solid oxygen gun is in the protective gas mode, with a flow rate of 30 m 3 / h to prevent splashing and clogging of the supersonic gas-solid injection lance head during the feeding process.

[0063] Melting period: After the raw materials are added, the electrodes start to supply power and the melting period begins. The submerged supersonic gas-solid oxygen lance is in the oxygen supply mode and extends into the slag. The oxygen flow rate is 2000 m 3 / h. When the oxygen flow rate of the submerged supersonic gas-solid oxygen lance reaches the set flow rate, the powder injection tank injection system is controlled to feed materials, and the submerged supersonic oxygen lance gas-solid injection mode starts. The lime powder flow rate is 10 - 25 kg / min, the gas flow rate is 600 - 2000 m 3 / h, the flow rate of the first epoxy channel is 10 - 100 m 3 / h, the flow rate of the annular combustion channel is 20 - 200 m 3 / h, the flow rate of the second epoxy channel is 10 - 100 m 3 / h. At the same time, according to the on-site smelting situation, some bulk slag-making materials can be added through the bunker. In the early stage of melting, lime powder is injected at a small flow rate (powder flow rate 10 - 15 kg / min, oxygen flow rate 1000 m 3 / h, the flow rate of the first epoxy channel is 50 m 3 / h, the annular combustion flow rate is 100 m 3 / h, the flow rate of the second epoxy channel is 50 m 3 / h) for rapid melting and slag formation, reducing the slag amount and shortening the slag formation time. The late stage of melting is the main period for dephosphorization. In this stage, a large flow rate is adopted (powder flow rate 20 kg / min, oxygen flow rate 2000 m 3 / h, the first epoxy channel is 100 m 3 / h, the annular combustion flow rate is 200 m 3 / h, the flow rate of the second epoxy channel is 100 m 3 / h).

[0064] Oxidation and heating period: In the early stage of oxidation and heating, when the dephosphorization temperature is reached, the large flow rate is continued (powder flow rate 25 kg / min, oxygen flow rate 2000 m 3 / h, the flow rate of the first epoxy channel is 100 m 3 / h, the flow rate of the annular combustion channel is 200 m 3 / h, the flow rate of the second epoxy channel is 100 m 3 / h) Blowing, while adding some lime lumps, magnesium balls, slag-making agents, fluorite and other slag-making materials, and continue deep dephosphorization. After entering the later stage of oxidation and heating up, at this time, the dephosphorization reaction is less or no longer proceeds, and the slag mainly plays the role of submerged arc heat preservation. The powder injection flow rate of the submerged supersonic gas-solid oxygen lance can be appropriately reduced at this stage, and the flow rate can be controlled at 10 - 15 kg / min. At the same time, add some massive slag-making materials according to the smelting situation. After the slag-making and dephosphorization stage is completed, turn off the gas-solid injection mode of the submerged supersonic gas-solid oxygen lance, stop the powder feeding of the powder injection tank, and the submerged supersonic gas-solid injection oxygen lance is in the oxygen supply mode, with an oxygen flow rate of 2000 m 3 / h, the flow rate of the first epoxy channel is 100 m 3 / h, the flow rate of the annular combustion channel is 200 m 3 / h, the flow rate of the second epoxy channel is 100m 3 / h.

[0065] 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, and the protective gas mode starts. The smelting of the molten steel ends and tapping begins.

[0066] The experimental results show that: For the 75 t electric arc furnace steelmaking, using the submerged supersonic gas-solid injection of limestone powder for less slag and high-efficiency dephosphorization process, the dephosphorization rate does not increase compared with the traditional electric arc furnace top addition of slag-making materials for dephosphorization process. Even in some heats, the dephosphorization effect becomes worse, the slag amount has no obvious change, the consumption of lime powder decreases slightly, and the metal yield remains basically unchanged. When using the same injection method, different injection schemes need to be formulated according to the smelting characteristics of the electric arc furnace to better play the advantages of the supersonic gas-solid injection oxygen lance; However, more importantly, the amount of lime powder injected needs to reach a certain flow rate. When the relative flow rate is within a suitable range and the larger the relative flow rate, the more obvious the impact effect of the gas-solid jet on the molten pool, the kinetic conditions of the molten pool are improved, and the dephosphorization effect shown is better.

[0067] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: They can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A low-slag and high-efficiency smelting method based on submerged supersonic gas-solid injection, characterized in that: include: Raw material adding period: During the adding stage of scrap steel and molten iron, the submerged supersonic gas solid oxygen gun is in the protective gas mode, and the protective gas flow rate is 10-200 m 3 / h; Melting period: After the raw materials are added, the submerged supersonic gas-solid oxygen gun is changed to the oxygen supply mode. The submerged supersonic gas-solid oxygen gun is extended into the slag layer, and the oxygen flow rate is 600-3000 m 3 / h; after the oxygen flow rate reaches a predetermined value, the submerged supersonic gas-solid oxygen gun is changed to a gas-solid blowing mode; the outlet of the submerged supersonic gas-solid oxygen gun includes a gas-solid channel, a first epoxy channel, a ring combustion channel and a second epoxy channel from inside to outside, the flow rate of the slag-making material in the gas-solid channel is 30-200 kg / min, and the oxygen flow rate is 600-3000 m 3 / h; the oxygen flow rate of the first epoxy channel is 10-200 m 3 / h, the methane flow rate of the annular combustion channel is 20-400 m 3 / h, the oxygen flow rate of the second epoxy channel is 10-200 m 3 / h; Oxidation heating period: In the early stage of oxidation heating, the flow rate of slag-making materials is maintained at 50-200 kg / min; in the later stage of oxidation heating, the flow rate of slag-making materials is controlled to be no more than 50 kg / min; after slag-making and dephosphorization, the submerged supersonic gas-solid oxygen gun is changed to the gas supply mode, and the oxygen flow rate is 1500-2500 m 3 / h; Steel tapping stage: When the molten steel reaches the expected temperature, the submerged supersonic gas-solidified oxygen gun stops supplying oxygen and starts the protective gas mode. The molten steel smelting is completed and steel tapping begins.

2. The method for high-efficiency smelting with little slag based on submerged supersonic gas-solid injection according to claim 1 is characterized in that: The oxygen pressure of the submerged supersonic gas-solid oxygen gun is 0.5-1.6 MPa.

3. The method for high-efficiency smelting with less slag based on submerged supersonic gas-solid injection according to claim 1 is characterized in that: The slag-making material includes one or more of quicklime powder, limestone powder, fluorite powder, and magnesium ball powder.

4. The method for high-efficiency smelting with less slag based on submerged supersonic gas-solid injection according to claim 3 is characterized in that: The particle size of the slag-making material is 100-400 meshes.

5. The method for high-efficiency smelting with less slag based on submerged supersonic gas-solid injection according to claim 1 is characterized in that: The slag-forming material in a lump form is also added during the melting period and the oxidation temperature rising period.

6. The method for high-efficiency smelting with less slag based on submerged supersonic gas-solid injection according to claim 1 is characterized in that: The carrier gas flow rate of the slag-making material is 100-3000 m 3 / h.

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

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