Low-slag efficient smelting method and system based on immersed supersonic gas-solid injection

Abstract

The invention provides a low-slag efficient smelting method and system based on immersed supersonic gas-solid injection, and relates to the field of metallurgy. The method comprises a raw material adding stage, a melting stage, an oxidation heating stage and a tapping stage. The low-slag efficient smelting system based on immersed supersonic speed gas-solid injection comprises an electric arc furnace, a powder injection tank, an immersed supersonic speed gas-solid oxygen lance and a control device, the electric arc furnace is used for smelting a target steel grade, the powder spraying tank is used for conveying a slagging material to the immersed supersonic gas-solid oxygen lance, and the immersed supersonic gas-solid oxygen lance is used for conveying the slagging material, methane, oxygen and shielding gas into a steel slag layer of the electric arc furnace; and the control system is used for controlling the immersed supersonic gas-solid oxygen lance. According to the low-slag efficient smelting method and system, the dephosphorization efficiency is improved 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 improved by 0.5% or above.

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: A low-slag and high-efficiency smelting method based on submerged supersonic gas-solid injection, comprising: 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-forming material in the gas-solid channel is 30-200kg / min (the melting period is divided into the early melting period and the late melting period, the flow rate of the slag-forming material in the early melting period is 30-50 kg / min, and the flow rate of the slag-forming material in the late melting period is 50-200 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.

[0007] Preferably, the oxygen pressure of the submerged supersonic gas-solid oxygen gun is 0.5-1.6 MPa.

[0008] Preferably, the slag-making material includes one or more of quicklime powder, limestone powder, fluorite powder and magnesium ball powder.

[0009] Preferably, the particle size of the slag-forming material is 100-400 mesh.

[0010] The block slag-making materials used in traditional steelmaking are partially or completely replaced with powder slag-making materials. The specific surface area of ​​the powder particles in the submerged supersonic gas-solid injection is much larger than that of the block slag-making materials, which increases the reaction contact area between the oxidation products of each element and the slag-making materials, and eliminates the dense high-melting-point 2CaO•SiO formed on the surface of block slag-making materials such as lime or limestone when they are melted. 2 The shell accelerates the slag formation and reaction rate of the sprayed powdered slag-forming material at the steel slag interface.

[0011] Preferably, the slag-forming material in a block form is also added during the melting period and the oxidation temperature rising period.

[0012] Preferably, the carrier gas flow rate of the slag-making material is 100-3000 m 3 / h.

[0013] Preferably, the protective gas comprises nitrogen and / or carbon dioxide.

[0014] The present application also provides a low-slag high-efficiency smelting system based on submerged supersonic gas-solid injection, which is used to perform the low-slag high-efficiency smelting method based on submerged supersonic gas-solid injection; The low-slag high-efficiency smelting system based on submerged supersonic gas-solid injection comprises: an electric arc furnace, a powder spraying tank, a submerged supersonic gas-solid oxygen gun and a control device; The electric arc furnace is used to smelt the target steel grade, the powder spray tank is used to transport slag-forming materials to the submerged supersonic gas-solid oxygen gun, the submerged supersonic gas-solid oxygen gun is used to transport the slag-forming materials, methane, oxygen and protective gas into the steel slag layer of the electric arc furnace, and the control device is used to control the submerged supersonic gas-solid oxygen gun.

[0015] Preferably, the powder supply pipe of the submerged supersonic gas-solid oxygen gun is made of a wear-resistant stainless steel pipe with an inner diameter of 10-150 mm.

[0016] The powder supply pipe outlet is located at the tail of the oxygen lance, and the powder supply pipes are made of wear-resistant materials. In order to increase 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 at the vulnerable parts of the oxygen lance nozzle.

[0017] Preferably, the nozzle Mach number of the submerged supersonic gas-solid oxygen gun is 1.5-2.2.

[0018] Compared with the prior art, the beneficial effects of this application include: The present application provides a method and system for efficient smelting with less slag based on submerged supersonic gas-solid injection, which is used to solve the problems of slow slag formation speed, large slag volume and low stirring intensity during the dephosphorization period, resulting in low dephosphorization rate, etc. in the traditional electric arc furnace steelmaking process. The electric arc furnace supersonic gas-solid oxygen gun device is used to submerge the slag-making material lime powder to the steel slag interface and increase the impact force of the jet on the molten pool, so that it is fully in contact with the molten pool, enhance the stirring of the molten pool, improve the thermodynamic and kinetic conditions of the dephosphorization reaction, and achieve efficient dephosphorization with less slag during the smelting process, which is beneficial to improve the dephosphorization rate of electric arc furnace steelmaking and reduce the consumption of slag-making materials and iron loss during the steelmaking process. The method for efficient dephosphorization with less slag in an electric furnace based on submerged supersonic gas-solid injection controls the injection amount of slag-making materials in stages, divides the electric arc furnace smelting process according to the dephosphorization requirements and smelting characteristics of different periods, and allocates the injection amount of slag-making materials as needed to achieve efficient dephosphorization with less slag in the electric arc furnace.

[0019] The solution provided in this application is applicable to the dephosphorization process of a 50-150 t electric arc furnace. Compared with the traditional electric arc furnace steelmaking process, the dephosphorization efficiency of the present invention is increased by about 2.5-5%, the slag volume is reduced by 5-20 kg / t, the slag material consumption is reduced by about 5%-10%, and the metal recovery rate is increased by more than 0.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0021] Figure 1 A schematic diagram of a low-slag high-efficiency smelting system based on submerged supersonic gas-solid injection provided in an embodiment of the present application; Figure 2 This is a schematic diagram of the structure of the nozzle of the submerged supersonic gas-solid oxygen gun.

[0022] Reference numerals: 1- electric arc furnace; 2- powder spraying tank; 3- submerged supersonic gas solid oxygen gun; 4- control device; 31-gas-solid channel; 32-first epoxy channel; 33-ring combustion channel; 34-second epoxy channel. DETAILED DESCRIPTION

[0023] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0024] Example 1 like Figure 1 As shown, this embodiment provides a low-slag high-efficiency smelting system based on submerged supersonic gas-solid injection, comprising: an electric arc furnace 1, a powder spraying tank 2, a submerged supersonic gas-solid oxygen gun 3 and a control device 4; The electric arc furnace 1 is used to smelt the target steel grade, the powder spraying tank 2 is used to transport slag-forming materials to the submerged supersonic gas-solid oxygen gun 3, the submerged supersonic gas-solid oxygen gun 3 is used to transport slag-forming materials, methane, oxygen and protective gas into the slag layer of the electric arc furnace 1, and the control device 4 is used to control the submerged supersonic gas-solid oxygen gun 3.

[0025] like Figure 2 As shown, the outlet (nozzle) of the submerged supersonic gas-solid oxygen gun 3 includes, from inside to outside, a gas-solid channel 31 , a first epoxy channel 32 , a ring combustion channel 33 and a second epoxy channel 34 .

[0026] Lime powder and other slag-forming materials are transported to the electric arc furnace smelting site by means of tank trucks and intermediate tanks. Lime powder and other slag-forming materials are input into the gas-solid channel 31 from the tail end of the oxygen gun through a powder spraying tank device, and are supersonic submerged sprayed by an submerged supersonic gas-solid oxygen gun, so that the gas-solid mixed jet directly impacts the steel slag interface, thereby achieving rapid and efficient dephosphorization with less slag.

[0027] Example 2 This embodiment provides a method for high-efficiency smelting with less slag 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. The outlet of the injection equipment is connected to the oxygen pipeline at the tail end of the oxygen lance by a wear-resistant pipe. Oxygen is used as the gas medium for conveying powder. The powder supply pipeline adopts a wear-resistant stainless steel pipe of Ф50×5 mm. The powder is directly input into the tail end of the supersonic gas-solid injection oxygen lance through a powder spraying tank. The nozzle Mach number is 2.1. Oxygen is directly used as the carrier gas for conveying powder materials. The oxygen flow rate is 600-2000 m 3 / h, pressure 0.6-1.5 Mpa. The slag-making material is limestone powder with a particle size of less than 2mm.

[0028] The method comprises the following steps: Raw material adding period: During the arc furnace smelting process, scrap steel and molten iron are added. 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 during the feeding process from clogging the supersonic gas-solid injection gun tip.

[0029] Melting period: After the raw materials are added, the electrodes start to supply power, the melting period begins, the submerged supersonic gas-solid oxygen gun is in oxygen supply mode, the submerged supersonic gas-solid oxygen gun is inserted into the slag, and the oxygen flow rate is 2000 m 3 / h, when the oxygen flow rate of the submerged supersonic gas-solid oxygen gun reaches the set flow rate, the submerged supersonic oxygen gun gas-solid injection mode is started by controlling the powder spraying tank spraying system to discharge the material, the lime powder flow rate is 30-50 kg / min, and 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 conditions, some block slag-making materials can be added through the silo. In the early stage of melting, a small flow rate (powder flow rate 30 kg / min, oxygen flow rate 1000 m 3 / h, flow rate of the first epoxy channel is 50 m 3 / h, annular combustion flow rate 100 m 3 / h, the second epoxy channel flow rate is 50 m3 / h) to spray lime powder for rapid melting and slag making, reduce the slag volume and shorten the slag forming time. The late melting period is the main time period for dephosphorization. In this stage, a large flow rate (powder flow rate of 40 kg / min, oxygen flow rate of 2000 m 3 / h, first epoxy channel 100 m 3 / h, annular combustion flow rate 200 m 3 / h, the flow rate of the second epoxy channel is 100 m 3 / h) supersonic gas-solid injection for deep dephosphorization, while adding some block slag-making materials. The powder has a larger specific surface area than the block lime, which accelerates the metallurgical chemical reaction to the maximum extent, reduces the slag volume and improves the dephosphorization rate. In addition, after adopting the submerged supersonic gas-solid oxygen gun gas-solid injection mode, the jet length is increased, the jet impact force is enhanced, and the stirring effect on the molten pool is enhanced.

[0030] Oxidation heating period: In the early stage of oxidation heating, when the dephosphorization temperature is reached, continue to maintain a large flow rate (powder flow rate 50kg / min, oxygen flow rate 2000 m 3 / h, flow rate of the first epoxy channel is 100 m 3 / h, annular combustion channel flow rate 200 m 3 / h, the flow rate of the second epoxy channel is 100 m 3 / h) and add some lime blocks, magnesium balls, slagging agents, fluorite and other slag-forming materials to continue deep dephosphorization. After entering the late stage of oxidation and heating, the dephosphorization reaction is less or no longer taking place, and the slag mainly plays the role of submerged arc insulation. At this stage, the powder agent spraying flow rate of the submerged supersonic gas-solid oxygen gun can be appropriately reduced, and the flow rate can be controlled at 30 kg / min. At the same time, some block slag-forming materials are added according to the smelting conditions. After the slag-making and dephosphorization stage is completed, turn off the gas-solid spraying mode of the submerged supersonic gas-solid oxygen gun, stop the powder spraying tank, and put the submerged supersonic gas-solid oxygen spray gun into the gas supply mode with an oxygen flow rate of 2000 m 3 / h, flow rate of the first epoxy channel is 100 m 3 / h, annular combustion channel flow rate 200 m 3 / h, the second epoxy channel flow rate is 100m 3 / h.

[0031] Steel-tapping stage: When the molten steel reaches the expected temperature, the submerged supersonic gas-solidified oxygen gun stops supplying oxygen, the oxygen is removed from the slag, the protective gas mode begins, the smelting of the molten steel is completed, and steel is tapped.

[0032] The experimental results show that the 75 t electric arc furnace steelmaking process using submerged supersonic gas-solid injection of limestone powder with less slag and high efficiency dephosphorization can increase the dephosphorization rate by 2.5%, reduce the slag volume by 10 kg / t, reduce the lime powder consumption by 3%, and increase the metal recovery rate by 1% compared with the traditional dephosphorization process with slag-making materials added to the top of the electric arc furnace.

[0033] Example 3 This embodiment provides a method for high-efficiency smelting with less slag based on submerged supersonic gas-solid injection. The smelting system provided in Example 1 is used. The electric arc furnace is a 115 t electric arc furnace. The powder supply pipeline adopts a wear-resistant stainless steel pipe of Ф50×5 mm. The powder is directly input into the tail end of the submerged supersonic gas-solid oxygen gun through the powder spraying tank. The nozzle Mach number is 2.1. Oxygen is directly used as the carrier gas for conveying the powder material. The oxygen flow rate is 2500 m 3 / h, pressure 0.6-1.5 Mpa. The slag-making material is limestone powder with a particle size of less than 2mm.

[0034] The method comprises the following steps: Raw material adding period: During the arc furnace smelting process, scrap steel and molten iron are added. 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 during the feeding process from clogging the supersonic gas-solid injection gun tip.

[0035] Melting period: After the raw materials are added, the electrodes start to supply power, the melting period begins, the submerged supersonic gas-solid oxygen gun is in oxygen supply mode, the submerged supersonic gas-solid oxygen gun is inserted into the slag, and the oxygen flow rate is 2500 m 3 / h, when the oxygen flow rate of the submerged supersonic gas-solid oxygen gun reaches the set flow rate, the submerged supersonic oxygen gun gas-solid injection mode is started by controlling the powder spraying tank spraying system to discharge the material, the lime powder flow rate is 35-50 kg / min, and 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, the flow rate of the second epoxy channel is 10-125 m 3 / h. At the same time, according to the on-site smelting conditions, some block slag-making materials can be added through the silo. In the early stage of melting, a small flow rate (powder flow rate 40 kg / min, oxygen flow rate 1000 m 3 / h, flow rate of the first epoxy channel is 50 m 3 / h, annular combustion channel flow rate 100 m 3 / h, the second epoxy channel flow rate is 50 m 3 / h) to spray lime powder for rapid melting and slag making, reduce the slag volume and shorten the slag forming time. The late melting period is the main time period for dephosphorization. In this stage, a large flow rate (powder flow rate of 50 kg / min, oxygen flow rate of 2500 m 3 / h, flow rate of the first epoxy channel is 125 m 3 / h, annular combustion channel flow rate 250 m 3 / h, the flow rate of the second epoxy channel is 125 m 3 / h) supersonic gas-solid injection for deep dephosphorization, while adding some block slag-making materials. The powder has a larger specific surface area than the block lime, which accelerates the metallurgical chemical reaction to the maximum extent, reduces the slag volume and improves the dephosphorization rate. In addition, after adopting the submerged supersonic gas-solid oxygen gun gas-solid injection mode, the jet length is increased, the jet impact force is enhanced, and the stirring effect on the molten pool is enhanced.

[0036] Oxidation heating period: In the early stage of oxidation heating, when the dephosphorization temperature is reached, continue to maintain a large flow rate (powder flow rate 60kg / min, oxygen flow rate 2500 m 3 / h, flow rate of the first epoxy channel is 125 m 3 / h, annular combustion channel flow rate 250 m 3 / h, the flow rate of the second epoxy channel is 125 m 3 / h) and add some lime blocks, magnesium balls, slagging agents, fluorite and other slag-forming materials to continue deep dephosphorization. After entering the late stage of oxidation and heating, the dephosphorization reaction is less or no longer taking place, and the slag mainly plays the role of submerged arc insulation. At this stage, the powder spraying flow rate of the submerged supersonic gas-solid oxygen gun can be appropriately reduced, and the flow rate can be controlled at 40 kg / min. At the same time, some block slag-forming materials are added according to the smelting conditions. After the slag-making and dephosphorization stage is completed, turn off the gas-solid spraying mode of the submerged supersonic gas-solid oxygen gun, stop the powder spraying tank, and put the submerged supersonic gas-solid oxygen spray gun into the gas supply mode with an oxygen flow rate of 2500 m 3 / h, flow rate of the first epoxy channel is 125 m 3 / h, annular combustion channel flow rate 250 m 3 / h, the second epoxy channel flow rate is 125m 3 / h.

[0037] Steel-tapping stage: When the molten steel reaches the expected temperature, the submerged supersonic gas-solidified oxygen gun stops supplying oxygen, the oxygen is removed from the slag, the protective gas mode begins, the smelting of the molten steel is completed, and steel is tapped.

[0038] The experimental results show that the high-efficiency dephosphorization process of limestone powder with less slag in 115 t electric arc furnace steelmaking using supersonic gas-solid injection increases the dephosphorization rate by 3% compared with the traditional dephosphorization process of adding slag-making materials on the top of the electric arc furnace, reduces the slag volume by 15 kg / t, reduces the lime powder consumption by 5%, and increases the metal recovery rate by 1%.

[0039] Comparative Example 1 In the traditional electric arc furnace steelmaking process, dephosphorization is generally carried out by adding block lime. Block lime is usually added in two batches. Taking the shaft electric arc furnace of a steel plant in Northeast China as an example, the first batch of slag-making materials is added through the silo after the third batch of scrap steel is added to the molten pool, and the amount of lime blocks added is 3 t. The second batch of slag-making materials is added through the silo after the last batch of scrap steel is added to the molten pool, and the amount of lime blocks added is 0.7 t. This method is a traditional electric arc furnace steelmaking dephosphorization method. The lime blocks need to be melted in the molten pool before participating in the dephosphorization reaction, and the dephosphorization efficiency is low. Therefore, in order to improve the dephosphorization efficiency, a southern steel plant adopts the method of lime powder injection, and changes the method of adding slag-making materials to improve the dephosphorization efficiency. Taking the 90 t ordinary electric arc furnace of a southern steel plant as an example, the electric arc furnace steelmaking plant uses a straight tube spray gun for lime powder injection to improve the dephosphorization efficiency. The dephosphorization process of lime powder spraying is as follows: the whole process lime powder spraying rate is 45 kg / min, the spraying time is 35 min, and some slag-making materials are put into the form of blocks, and the weight of block lime is 1.3 t. Compared with the dephosphorization using all block slag-making materials, this method improves the dephosphorization by 1.2%. Although the use of a straight tube spray gun can improve the dephosphorization efficiency, it is found that the dephosphorization efficiency can be further improved by changing the structure of the spray gun, such as the supersonic gas-solid spray gun designed in this case, which can improve the dephosphorization efficiency by 2.5-5%.

[0040] The present invention relates to an immersion-type supersonic gas-solid injection low-slag and efficient smelting method and system, which changes the original injection method of slag-forming materials and the structure of the nozzle, provides a supersonic lime powder injection scheme, and a supersonic gas-solid injection gun structure. By changing the injection parameters of the supersonic gas-solid injection gun 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 efficient smelting of the electric arc furnace.

[0041] Comparative Example 2 This case is a comparison with Example 2. The difference from Example 2 is the different injection parameters. The arc furnace is a 75t arc furnace, and the gun head structure used is the same as that of Example 2. Oxygen is directly used as the carrier gas for conveying powder materials, and the oxygen flow rate is 600-2000 m 3 / h, pressure 0.6-1.5 Mpa. The slag-making material is limestone powder with a particle size of less than 2 mm.

[0042] The method comprises the following steps: Raw material adding period: During the arc furnace smelting process, scrap steel and molten iron are added. 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 during the feeding process from clogging the supersonic gas-solid injection gun tip.

[0043] Melting period: After the raw materials are added, the electrodes start to supply power, the melting period begins, the submerged supersonic gas-solid oxygen gun is in oxygen supply mode, the submerged supersonic gas-solid oxygen gun is inserted into the slag, and the oxygen flow rate is 2000 m 3 / h, when the oxygen flow rate of the submerged supersonic gas-solid oxygen gun reaches the set flow rate, the submerged supersonic oxygen gun gas-solid injection mode is started by controlling the powder spraying tank spraying system to discharge the material, the lime powder flow rate is 10-25 kg / min, and 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 conditions, some block slag-making materials can be added through the silo. In the early stage of melting, a small flow rate (powder flow rate 10-15 kg / min, oxygen flow rate 1000 m 3 / h, flow rate of the first epoxy channel is 50 m 3 / h, annular combustion flow rate 100 m 3 / h, the second epoxy channel flow rate is 50 m 3 / h) to spray lime powder for rapid melting and slag making, reduce the slag volume and shorten the slag forming time. The late melting period is the main time period for dephosphorization. In this stage, a large flow rate (powder flow rate of 20 kg / min, oxygen flow rate of 2000 m 3 / h, first epoxy channel 100 m 3 / h, annular combustion flow rate 200 m 3 / h, the flow rate of the second epoxy channel is 100 m 3 / h).

[0044] Oxidation heating period: In the early stage of oxidation heating, when the dephosphorization temperature is reached, continue to maintain a large flow rate (powder flow rate 25kg / min, oxygen flow rate 2000 m 3 / h, flow rate of the first epoxy channel is 100 m 3 / h, annular combustion channel flow rate 200 m 3 / h, the flow rate of the second epoxy channel is 100 m 3 / h) and add some lime blocks, magnesium balls, slagging agents, fluorite and other slag-forming materials to continue deep dephosphorization. After entering the late stage of oxidation and heating, the dephosphorization reaction is less or no longer taking place, and the slag mainly plays the role of submerged arc insulation. At this stage, the powder spraying flow rate of the submerged supersonic gas-solid oxygen gun can be appropriately reduced, and the flow rate can be controlled at 10-15 kg / min. At the same time, some block slag-forming materials are added according to the smelting conditions. After the slag-making and dephosphorization stage is completed, turn off the gas-solid spraying mode of the submerged supersonic gas-solid oxygen gun, stop the powder spraying tank, and put the submerged supersonic gas-solid oxygen spray gun into the gas supply mode with an oxygen flow rate of 2000 m3 / h, flow rate of the first epoxy channel is 100 m 3 / h, annular combustion channel flow rate 200 m 3 / h, the second epoxy channel flow rate is 100m 3 / h.

[0045] Steel-tapping stage: When the molten steel reaches the expected temperature, the submerged supersonic gas-solidified oxygen gun stops supplying oxygen, the oxygen is removed from the slag, the protective gas mode begins, the smelting of the molten steel is completed, and steel is tapped.

[0046] The experimental results show that the dephosphorization rate of 75 t electric arc furnace steelmaking using submerged supersonic gas-solid injection limestone powder less slag high-efficiency dephosphorization process is not improved compared with the traditional electric arc furnace top slag material dephosphorization process, and even the dephosphorization effect of some furnaces has deteriorated, the slag amount has no obvious change, the lime powder consumption has slightly decreased, and the metal recovery rate has remained basically unchanged. When using the same injection method, different injection schemes need to be formulated according to the characteristics of electric arc furnace smelting in order to better play the advantages of supersonic gas-solid injection oxygen gun; however, it is more important that the amount of lime powder injected needs to reach a certain flow rate. Within the appropriate range, the larger the relative flow rate, the more obvious the impact effect of the gas-solid jet on the molten pool, the better the kinetic conditions of the molten pool, and the better the dephosphorization effect.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to 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 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 less 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, 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.

8. A low-slag and high-efficiency smelting system based on submerged supersonic gas-solid injection, characterized in that: Used to implement the low-slag and high-efficiency smelting method based on submerged supersonic gas-solid injection as described in any one of claims 1 to 7; The low-slag high-efficiency smelting system based on submerged supersonic gas-solid injection comprises: an electric arc furnace, a powder spraying tank, a submerged supersonic gas-solid oxygen gun and a control device; The electric arc furnace is used to smelt the target steel grade, the powder spray tank is used to transport slag-forming materials to the submerged supersonic gas-solid oxygen gun, the submerged supersonic gas-solid oxygen gun is used to transport the slag-forming materials, methane, oxygen and protective gas into the steel slag layer of the electric arc furnace, and the control device is used to control the submerged supersonic gas-solid oxygen gun.

9. The low-slag high-efficiency smelting system based on submerged supersonic gas-solid injection according to claim 8 is characterized in that: The powder supply pipe of the submerged supersonic gas-solid oxygen gun is made of a wear-resistant stainless steel pipe with an inner diameter of 10-150 mm.

10. The low-slag high-efficiency smelting system based on submerged supersonic gas-solid injection according to claim 8 or 9, characterized in that: The Mach number of the nozzle of the submerged supersonic gas-solid oxygen gun is 1.5-2.2.

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