Electric arc furnace steelmaking plant and method

Abstract

This application relates to the field of steelmaking equipment technology, and more particularly to an electric arc furnace steelmaking apparatus and method, including a furnace body, hollow graphite electrodes, a bottom anode, a charging assembly, a power control unit, a top blowing assembly, and a bottom blowing assembly. By pre-reserving molten iron and slag within the furnace, the charging assembly adds slag-forming material to the molten iron to form a slag layer. The top blowing assembly supplies hydrogen-containing gas and argon gas to the hollow graphite electrodes, forming a hydrogen-containing plasma arc for submerged arc smelting, thus isolating air and actively denitrifying. The power control unit increases the voltage and lengthens the arc before each addition of metal charge to prevent slag from solidifying and forming a shell under large slag volumes, ensuring that the slag always covers the molten iron. Simultaneously, the bottom blowing assembly supplies gas to the bottom of the molten iron to enhance stirring, and switches to hydrogen gas during the refining stage, working in conjunction with the top-blown hydrogen plasma for denitrification. Therefore, this apparatus, through slag isolation, active denitrification by hydrogen plasma, dynamic charging control, and the coordinated operation of bottom-blown hydrogen, can suppress nitrogen accumulation in the molten iron and improve denitrification efficiency.

Description

Technical Field

[0001] This application relates to the field of steelmaking equipment technology, and in particular to an electric arc furnace steelmaking apparatus and steelmaking method. Background Technology

[0002] Electric arc furnace steelmaking uses scrap steel or direct reduced iron as raw materials, offering advantages such as a short process and low carbon emissions, leading to its increasingly widespread application in the steel industry. However, during the electric arc furnace smelting process, the high-temperature electric arc ionizes nitrogen in the air, resulting in increased nitrogen content in the molten iron. Nitrogen is mostly a harmful element in steel, forming nitrides that precipitate, impairing the steel's impact resistance and plasticity, and causing defects such as corner cracks in slabs, severely affecting steel quality. Therefore, effectively controlling the nitrogen content in steel is crucial for producing high-quality steel.

[0003] In the prior art, patent CN116837173A discloses a method for controlling nitrogen content in the direct reduction iron smelting process with low slag in an electric arc furnace. This method involves injecting calcium carbide to deoxidize the molten iron, and the deoxidation product, carbon monoxide, creates a reducing atmosphere, effectively preventing nitrogen accumulation in the molten iron. Simultaneously, the calcium oxide produced in the reaction forms foamy slag, controlling nitrogen absorption in the molten iron. However, this method has significant drawbacks: calcium carbide storage conditions are extremely stringent, and leaks can seriously endanger production safety; when using oxygen lances to inject powder, the carrier gas used is nitrogen, which may cause nitrogen to dissolve, leading to nitrogen accumulation in the molten iron; furthermore, the formation of foamy slag in the direct reduction iron smelting process easily causes the surface slag to solidify into a shell, requiring extended smelting time to melt the frozen shell, thus affecting smelting efficiency.

[0004] Therefore, how to suppress nitrogen increase in molten iron and improve denitrification efficiency is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] This application provides an electric arc furnace steelmaking apparatus and steelmaking method to suppress nitrogen accumulation in molten iron and improve denitrification efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An electric arc furnace steelmaking apparatus includes a furnace body, hollow graphite electrodes, a bottom anode, a charging assembly, a power control unit, a top blowing assembly, and a bottom blowing assembly, wherein:

[0008] The interior of the furnace body forms a chamber;

[0009] The hollow graphite electrode is suspended above the furnace body. The first end of the hollow graphite electrode is connected to the top-blowing assembly, and the second end of the hollow graphite electrode extends into the interior of the chamber to inject gas into the chamber and generate an electric arc.

[0010] The bottom anode is located at the bottom of the furnace body and is used to form an electric arc circuit in conjunction with the hollow graphite electrode;

[0011] The top-blowing assembly is connected to the first end of the hollow graphite electrode and is used to supply hydrogen-containing gas and argon gas to the hollow graphite electrode to form a hydrogen-containing plasma arc inside the chamber.

[0012] The bottom blowing assembly is connected to the bottom of the furnace body and is used to supply gas to the molten iron in the chamber;

[0013] The charging assembly is connected to the furnace body. The charging assembly is used to add slag-forming material to the molten iron in the chamber to regulate the composition of the slag. The charging assembly is also used to add metal furnace charge to the molten iron in the chamber and control the amount and rate of metal furnace charge added at one time.

[0014] The power control unit is electrically connected to the hollow graphite electrode and is used to regulate the power supply voltage and current.

[0015] Optionally, in the above-mentioned electric arc furnace steelmaking apparatus, the top-blowing assembly includes a top-blowing argon gas supply unit for supplying argon gas, a top-blowing hydrogen-containing gas supply unit for supplying hydrogen-containing gas, and a top-blowing mixing chamber that is connected to the top-blowing argon gas supply unit, the top-blowing hydrogen-containing gas supply unit, and the first end of the hollow graphite electrode, respectively. The top-blowing mixing chamber is used to mix argon gas and hydrogen-containing gas and then deliver them to the hollow graphite electrode.

[0016] The bottom blowing assembly includes a bottom blowing argon gas supply unit for supplying argon gas, a bottom blowing hydrogen gas supply unit for supplying hydrogen gas, and a vent plug disposed at the bottom of the furnace body and selectively connected to the bottom blowing argon gas supply unit and the bottom blowing hydrogen gas supply unit. The vent plug is used to blow gas into the bottom of the molten iron.

[0017] Optionally, in the above-mentioned electric arc furnace steelmaking apparatus, the charging assembly includes:

[0018] The silo is used to store metal furnace charge;

[0019] A slag-forming material storage unit, wherein the slag-forming material storage unit is used to store slag-forming materials;

[0020] The material pipe has a first end connected to the silo and the slag-forming material storage unit, and a second end connected to the furnace body.

[0021] A slide gate valve is installed in the material pipe to control the rate and amount of metal furnace charge or slag material added.

[0022] Optionally, the above-mentioned electric arc furnace steelmaking apparatus also includes an infrared thermal imager, which is disposed above the furnace body and is used to monitor the temperature of the molten slag surface.

[0023] The electric arc furnace steelmaking apparatus provided by this invention, by pre-reserving molten iron and slag within the furnace, uses a charging assembly to add slag-forming material to the molten iron to form a slag layer. Combined with a top-blowing assembly supplying hydrogen-containing gas and argon gas to hollow graphite electrodes, a hydrogen-containing plasma arc is formed for submerged arc smelting, effectively isolating air and actively denitrifying. A power control component increases the voltage and lengthens the arc before each addition of metal charge, preventing slag from solidifying and forming a shell under large slag volumes, ensuring that slag always covers the molten iron. Simultaneously, a bottom-blowing assembly supplies gas to the bottom of the molten iron to enhance stirring, switching to hydrogen gas during the refining stage, working in synergy with the top-blown hydrogen plasma for denitrification. Therefore, this apparatus, through slag isolation, active denitrification with hydrogen plasma, dynamic charging control, and the coordinated operation of bottom-blown hydrogen, can suppress nitrogen accumulation in the molten iron and improve denitrification efficiency.

[0024] This application also provides a steelmaking method using an electric arc furnace steelmaking apparatus as described in any of the above embodiments, comprising the following steps:

[0025] Step S1: Molten iron and slag are reserved inside the electric arc furnace. The volume of the molten iron accounts for 30% to 50% of the furnace volume of the electric arc furnace, and the volume of the slag accounts for 10% to 40% of the furnace volume of the electric arc furnace. Argon gas is supplied to the hollow graphite electrode through the top blowing component to ignite an argon plasma arc and perform submerged arc heating to raise the temperature of the molten pool to above 1540°C.

[0026] Step S2: A mixture of hydrogen and argon is supplied to the hollow graphite electrode through the top-blowing assembly to form a hydrogen-containing plasma arc, while argon is supplied to the bottom of the molten iron through the bottom-blowing assembly for stirring.

[0027] Step S3: The power control unit increases the supply voltage to lengthen the arc, and the metal furnace charge is added in batches through the feeding assembly, with each addition amounting to 20%~40% of the preset total metal furnace charge.

[0028] Step S4: When the surface temperature of the molten slag rises to above 1540°C, repeat step S3 until the metal charge is completely added into the electric arc furnace and the metal charge is completely melted.

[0029] Step S5: Add slag-forming material to the molten iron through the feeding assembly to adjust the slag composition, and switch the gas supplied by the bottom blowing assembly to hydrogen;

[0030] Step S6: When the composition and temperature of the molten iron reach the target, the steel is tapped, and molten iron and slag are reserved inside the electric arc furnace. The volume of the molten iron accounts for 30% to 50% of the furnace volume of the electric arc furnace, and the volume of the slag accounts for 10% to 40% of the furnace volume of the electric arc furnace, for use in the next furnace smelting.

[0031] Optionally, in the above steelmaking method, in step S5, the added slag-forming material includes limestone and / or dolomite, and the basicity of the molten slag is adjusted to 1.0~1.1.

[0032] Optionally, in the above steelmaking method, in step S3, before each addition of metal charge, the power supply voltage is increased by 5% to 20% based on the current power supply voltage value, while keeping the current intensity constant. After each addition of metal charge, the surface temperature of the molten slag is monitored by an infrared thermal imager. When the surface temperature of the molten slag reaches above 1540°C, the next addition is carried out.

[0033] Optionally, in the above steelmaking method, in step S1, the blowing pressure of the top-blown argon gas supply unit of the top-blown assembly is 0.2~1 MPa;

[0034] In step S2, the blowing pressure of the top-blown argon gas supply unit is 0.2~0.8MPa, the blowing pressure of the top-blown hydrogen-containing gas supply unit of the top-blown assembly is 0.2~0.8MPa, the blowing pressure of the bottom-blown argon gas supply unit of the bottom-blown assembly is 0.3~1MPa, and the argon gas flow rate provided by the bottom-blown argon gas supply unit is 10~50 NL / (min·t).

[0035] Optionally, in the above steelmaking method, in steps S1 and S2, the argon flow rate provided by the top-blown argon supply unit is 10~50 NL / (min·t), and the hydrogen flow rate provided by the top-blown hydrogen gas supply unit is 2~20 NL / (min·t).

[0036] Optionally, in the above steelmaking method, in step S5, after the gas supplied by the bottom blowing assembly is switched to hydrogen, the hydrogen flow rate provided by the bottom blowing hydrogen supply unit of the bottom blowing assembly is 5~30 NL / (min·t), and the blowing pressure of the bottom blowing hydrogen supply unit is 0.5~0.8MPa.

[0037] The specific structure of the electric arc furnace steelmaking device is as described in the above embodiments. Since this steelmaking method adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here. Attached Figure Description

[0038] The accompanying drawings, incorporated in and forming part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort. One or more embodiments are illustrated by way of example through the corresponding images in the accompanying drawings. These exemplary descriptions do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings represent similar elements. Unless otherwise stated, the figures in the drawings do not constitute a limitation on scale.

[0039] Figure 1 This is a schematic diagram of the structure of an electric arc furnace steelmaking apparatus provided in an embodiment of this application.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1-Hollow graphite electrode; 2-Infrared thermal imager; 3-Slag; 4-Molten iron; 5-Ventilator plug; 6-Bottom anode; 7-Top-blown hydrogen gas storage tank; 8-Top-blown hydrogen gas pressure regulating valve; 9-Top-blown hydrogen gas flow regulating valve; 10-Top-blown hydrogen gas circuit switch; 11-Top-blown argon gas storage tank; 12-Top-blown argon gas pressure regulating valve; 13-Top-blown argon gas flow regulating valve; 14-Top-blown argon gas circuit 15-Switch; 16-Top-blown mixing manifold; 17-Bottom-blown hydrogen storage tank; 18-Bottom-blown hydrogen gas path pressure regulating valve; 19-Bottom-blown hydrogen gas path switch; 20-Bottom-blown argon gas storage tank; 21-Bottom-blown argon gas path pressure regulating valve; 22-Bottom-blown argon gas flow regulating valve; 23-Bottom-blown argon gas path switch; 24-Blouse; 25-Metal furnace charge; 26-Slide valve; 27-Power control component. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0044] For ease of description, spatial relative terms may be used in the text to describe the relative position or movement of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "front," "back," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure undergoes a positional flip, orientation change, or change of motion, these directional indications will change accordingly. For instance, an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0045] See Figure 1This application provides an electric arc furnace steelmaking apparatus, including a furnace body, a hollow graphite electrode 1, a bottom anode 6, a charging assembly, a power control component 27, a top blowing assembly, and a bottom blowing assembly. The furnace body forms an internal chamber. The hollow graphite electrode 1 is suspended above the furnace body, with its first end connected to the top blowing assembly and its second end extending into the chamber to inject gas into the chamber and generate an electric arc. The bottom anode 6 is located at the bottom of the furnace body and cooperates with the hollow graphite electrode 1 to form an electric arc circuit. The top blowing assembly is connected to the first end of the hollow graphite electrode 1. The furnace body is equipped with a bottom blowing assembly connected to the bottom of the furnace body for supplying gas to the molten iron 4 in the chamber. The bottom blowing assembly is connected to the furnace body for supplying gas to the molten iron 4 in the chamber. The charging assembly is connected to the furnace body and is used to add slag-forming material to the molten iron 4 in the chamber to control the composition of slag 3. The charging assembly is used to add metal charge 25 to the molten iron 4 in the chamber and controls the single addition amount and addition rate of metal charge 25 through the gate valve 26. The power control unit 27 is electrically connected to the hollow graphite electrode 1 and is used to adjust the power supply voltage and current.

[0046] Specifically, the hollow graphite electrode 1 adopts a hollow structure, and gas can be injected into the molten pool along the central channel of the electrode to form plasma under the action of high-temperature electric arc.

[0047] The electric arc furnace steelmaking apparatus provided by this invention, by pre-reserving slag 3 and molten iron 4 in the furnace, using a charging component to add slag-forming material to control the slag composition, and combining a top-blowing component to supply hydrogen-containing gas and argon gas to the hollow graphite electrode 1, forms a hydrogen-containing plasma electric arc and performs submerged arc smelting, effectively isolating air and actively denitrifying (wherein, coupled hydrogen-containing plasma denitrification, the chemical reaction equation is: 3H + [N] = NH3↑, hydrogen plasma directly reacts with nitrogen in molten iron 4 to generate NH3, realizing active chemical denitrification, and the ammonia gas generated in the reaction escapes from molten iron 4 in gaseous form at high temperature) and bottom-blowing hydrogen bubble denitrification (chemical reaction equation is: 2[N] = N2↑ generates nitrogen molecules that enter hydrogen bubbles and float to the surface, escaping from the molten iron 4, thus achieving physical denitrification. Power control unit 27 increases the voltage and lengthens the arc before each addition of metal charge 25, preventing the slag 3 from solidifying and forming a shell under heavy slag loads, ensuring the slag 3 always covers the molten iron 4. Simultaneously, the bottom-blowing assembly supplies gas to the bottom of the molten iron 4 to enhance stirring, switching to hydrogen during the refining stage (the chemical reaction equation for the reduction of FeO in the slag 3 by the blown hydrogen is: FeO + H2 → Fe + H2O; the bottom-blown hydrogen reacts with the ferrous oxide in the slag 3 to generate iron and gaseous water, not only reducing the oxidizing properties of the slag 3 and improving the denitrification kinetics, but also increasing the metal yield), working in synergy with top-blown hydrogen plasma for denitrification. Therefore, this device, through slag 3 isolation, active hydrogen plasma denitrification, dynamic feeding control, and the synergistic operation of bottom-blown hydrogen, can suppress nitrogen accumulation in the molten iron 4 and improve denitrification efficiency.

[0048] To optimize the above technical solution, the top-blowing assembly includes a top-blowing argon supply unit for supplying argon gas, a top-blowing hydrogen gas supply unit for supplying hydrogen gas, and a top-blowing mixing chamber 15 that is connected to the top-blowing argon gas supply unit, the top-blowing hydrogen gas supply unit, and the first end of the hollow graphite electrode 1, respectively. The top-blowing mixing chamber 15 is used to mix argon gas and hydrogen gas and then deliver them to the hollow graphite electrode 1. The bottom-blowing assembly includes a bottom-blowing argon gas supply unit for supplying argon gas, a bottom-blowing hydrogen gas supply unit for supplying hydrogen gas, and a vent plug 5 located at the bottom of the furnace body and selectively connected to the bottom-blowing argon gas supply unit and the bottom-blowing hydrogen gas supply unit. The vent plug 5 is used to blow gas into the bottom of the molten iron 4.

[0049] Specifically, the top-blown argon supply unit comprises a top-blown argon storage tank 11, a top-blown argon gas pressure regulating valve 12, a top-blown argon gas flow regulating valve 13, and a top-blown argon gas circuit switch 14. The top-blown argon storage tank 11 is used to store high-pressure argon gas, the top-blown argon gas pressure regulating valve 12 is used to control the output pressure (0.2~1MPa during the arc initiation stage, 0.2~0.8MPa during the hydrogen plasma stage), the top-blown argon gas flow regulating valve 13 is used to control the argon gas flow rate (10~50 NL / (min·t)), and the top-blown argon gas circuit switch 14 is used to control the on / off state of the output argon gas.

[0050] Specifically, the top-blown hydrogen gas supply unit comprises a top-blown hydrogen gas storage tank 7, a top-blown hydrogen gas pressure regulating valve 8, a top-blown hydrogen gas flow regulating valve 9, and a top-blown hydrogen gas circuit switch 10. The top-blown hydrogen gas storage tank 7 stores hydrogen gas (hydrogen, methane, or liquefied petroleum gas), the top-blown hydrogen gas pressure regulating valve 8 controls the output pressure (0.2~0.8 MPa), the top-blown hydrogen gas flow regulating valve controls the hydrogen gas flow rate (2~20 NL / (min·t steel)), and the top-blown hydrogen gas circuit switch 10 controls the on / off state of the output hydrogen gas. The top-blown mixing manifold 15 is connected to the top-blown argon gas supply unit, the top-blown hydrogen gas supply unit, and the first end of the hollow graphite electrode 1, respectively. It is used to uniformly mix argon and hydrogen gas in a specific ratio and then deliver the mixture to the hollow graphite electrode 1, ensuring a stable gas composition entering the arc region and forming a stable hydrogen-containing plasma arc.

[0051] Specifically, the bottom-blown argon supply unit comprises a bottom-blown argon storage tank 20, a bottom-blown argon gas pressure regulating valve 21, a bottom-blown argon gas flow regulating valve 22, and a bottom-blown argon gas circuit switch 23. The bottom-blown argon storage tank 20 is used to store high-pressure argon gas. The bottom-blown argon gas pressure regulating valve 21 is used to control the output pressure, with a pressure control range of 0.3~1MPa. The bottom-blown argon gas flow regulating valve 22 is used to control the argon gas flow rate, with a control range of 10~50 NL / (min·t). The bottom-blown argon gas circuit switch 23 is used to control the on / off state of the output argon gas.

[0052] Specifically, the bottom-blown hydrogen supply unit comprises a bottom-blown hydrogen storage tank 16, a bottom-blown hydrogen gas path pressure regulating valve 17, a bottom-blown hydrogen gas flow regulating valve 18, and a bottom-blown hydrogen gas path switch 19. The bottom-blown hydrogen gas storage tank is used to store hydrogen-containing gas. The bottom-blown hydrogen gas path pressure regulating valve 17 is used to control the output pressure, with a pressure control range of 0.5~0.8MPa. The bottom-blown hydrogen gas flow regulating valve 18 is used to control the flow rate of hydrogen-containing gas, with a flow control range of 5~30 NL / (min·t). The bottom-blown hydrogen gas path switch 19 is used to control the on / off of the output hydrogen.

[0053] The vent plug 5 is located at the bottom of the furnace body and can be selectively connected to the bottom-blown argon supply unit and the bottom-blown hydrogen supply unit through pipelines. The gas type can be quickly changed by switching the gas circuit switch.

[0054] This application preferably has two vent plugs 5, both of which are connected to the bottom of the furnace body. The two vent plugs 5 are respectively connected to the bottom-blown argon gas supply unit and the bottom-blown hydrogen gas supply unit.

[0055] Specifically, the vent plug 5 is made of a dispersion-type refractory material, which can disperse the gas into a large number of tiny bubbles and evenly enter the bottom of the molten iron 4.

[0056] It should be noted that the above "NL / (min·t)" means: the volume of gas (liters) introduced per minute per ton of steel (or per ton of furnace charge) under standard conditions (0℃, 1 atmosphere).

[0057] The top-blown argon supply unit and the top-blown hydrogen-containing gas supply unit of the top-blown assembly achieve a smooth transition between pure argon gas in the arc initiation stage and mixed gas in the hydrogen plasma stage through independent pressure regulating valves, flow regulating valves, and gas path switches; the top-blown mixing chamber 15 ensures uniform mixing of argon gas and hydrogen-containing gas, stabilizing arc characteristics. The bottom-blown assembly, through a dual-gas path design and a breather plug 5, achieves seamless switching from argon gas stirring during the melting period to hydrogen gas stirring during the refining period, avoiding pressure fluctuations during gas switching. During bottom-blown hydrogen, fine hydrogen bubbles provide a large number of nucleation interfaces for dissolved nitrogen (2[N] = N2↑), while hydrogen reacts with FeO in slag 3 (FeO + H2 → Fe + H2O), which can reduce the oxidizing properties of slag 3 and improve denitrification kinetics. Therefore, this structure enables the top-blown hydrogen plasma chemical denitrification and the bottom-blown hydrogen bubble physical denitrification to work synergistically, improving denitrification efficiency.

[0058] To optimize the above technical solution, the feeding assembly includes: a hopper 24 for storing metal furnace charge 25; a slag-forming material storage unit for storing slag-forming material; a material pipe, the first end of which is connected to the hopper 24 and the slag-forming material storage unit, and the second end of which is connected to the furnace body; and a slide valve 26, which is installed on the material pipe to control the feeding rate and amount of metal furnace charge 25 or slag-forming material.

[0059] Specifically, the silo 24 and the slag-forming material storage unit can be designed separately or as a single unit. When the silo 24 and the slag-forming material storage unit are designed separately, they can be connected to the furnace body separately for feeding, or one can be connected to the furnace body while the other is fed manually or by other means. Each of the silo 24 and the slag-forming material storage unit has a material pipe and a gate valve 26. When the silo 24 and the slag-forming material storage unit are designed as a single unit, they are combined into a cylindrical structure that is connected to the furnace body. There is an isolation plate between the silo 24 and the slag-forming material storage unit to isolate the metal furnace charge 25 and the slag-forming material. The material pipe is Y-shaped, with its first end connected to both the silo 24 and the slag-forming material storage unit, and its second end connected to the interior of the furnace body. Both forks at the first end of the Y-shaped material pipe have gate valves 26 to control the feeding of materials from the silo 24 and the slag-forming material storage unit respectively.

[0060] Specifically, the metal charge 25 includes, but is not limited to, direct reduced iron and scrap steel, and the slag-forming material includes, but is not limited to, limestone, dolomite, and fluorite.

[0061] Specifically, the feeding assembly also includes a feeding control component. The slide valve 26 is electrically connected to the feeding control component and is driven by the feeding control component, which can realize precise opening and closing control and opening degree adjustment to meet the requirements of batch feeding and feeding rate control.

[0062] During operation, the slide gate valve 26 controls the single-time addition amount and rate, and in conjunction with the voltage adjustment of the power control component 27, a dynamic control process of "increasing voltage before adding material - adding material - measuring temperature - adding material again" is achieved. Batch addition can prevent the molten slag 3 from solidifying and forming a shell under large slag volumes, ensuring that the molten slag 3 always covers the molten iron 4; the slag-forming material is added during the refining stage to adjust the basicity of the molten slag 3 to 1.0~1.1, ensuring that the molten slag 3 has good fluidity and denitrification ability.

[0063] It should be noted that the above refining stage corresponds to step S5 in the steelmaking process.

[0064] To optimize the above technical solution, the electric arc furnace steelmaking device also includes an infrared thermal imager 2, which is located above the furnace body and is used to monitor the temperature of the surface of the molten slag 3.

[0065] Specifically, the infrared thermal imager 2 acquires real-time images of the temperature distribution on the surface of the molten slag 3 through non-contact temperature measurement and transmits the data to the control system of the electric arc furnace steelmaking unit (the aforementioned charging control component and power control component 27 are electrically connected to the control system). The infrared thermal imager 2 is installed in the observation hole or dedicated detection port on the furnace top, covering the entire molten pool area, and can accurately identify local cold zones or temperature unevenness. Real-time monitoring of the molten slag 3 surface temperature provides a basis for dynamic charging control. During the charging and melting stage (step S3 below), after each addition of metal charge 25, the infrared thermal imager 2 monitors the surface temperature of the molten slag 3. Only when the temperature reaches above 1540℃ will the next charging be performed. This control logic avoids premature charging due to insufficient molten slag 3 temperature, leading to condensation and ensuring that the molten slag 3 remains in a flowing state. Simultaneously, the infrared thermal imager 2 can identify local cold zones, prompting adjustments to the gas or power of the bottom blowing components to optimize the temperature uniformity of the molten pool. The infrared thermal imager 2, together with the power control unit 27 and the feeding assembly, realizes a closed-loop control of "temperature feedback-voltage regulation-feeding control", thereby improving the smoothness of smelting and the stability of denitrification.

[0066] This application also provides a steelmaking method using an electric arc furnace steelmaking apparatus as described above, comprising the following steps:

[0067] Step S1: Molten iron 4 and slag 3 are reserved inside the electric arc furnace. The volume of molten iron 4 accounts for 30% to 50% of the furnace volume of the electric arc furnace, and the volume of slag 3 accounts for 10% to 40% of the furnace volume of the electric arc furnace. Argon gas is supplied to the hollow graphite electrode 1 through the top blowing component to ignite an argon plasma electric arc and perform submerged arc heating to raise the temperature of the molten pool to above 1540℃.

[0068] Step S2: A mixture of hydrogen and argon is supplied to the hollow graphite electrode 1 through the top blowing assembly to form a hydrogen-containing plasma arc, while argon is supplied to the bottom of the molten iron 4 through the bottom blowing assembly for stirring.

[0069] Step S3: The power control unit 27 increases the supply voltage to lengthen the electric arc, and the metal furnace charge 25 is added in batches through the feeding component, with each addition amount being 20% ​​to 40% of the preset total amount of metal furnace charge 25;

[0070] Step S4: When the surface temperature of the molten slag 3 rises to above 1540°C, repeat step S3 until the metal charge 25 is completely added into the electric arc furnace and the metal charge 25 is completely melted.

[0071] Step S5: Add slag-forming material to molten iron 4 through the feeding component, adjust the composition of molten slag 3, and switch the gas supplied by the bottom blowing component to hydrogen;

[0072] Step S6: When the composition and temperature of the molten iron 4 reach the target, the steel is tapped, and molten iron 4 and slag 3 are reserved inside the electric arc furnace. The volume of molten iron 4 accounts for 30% to 50% of the furnace volume of the electric arc furnace, and the volume of slag 3 accounts for 10% to 40% of the furnace volume of the electric arc furnace, for use in the next furnace smelting.

[0073] Specifically, the reserved slag 3 can immediately cover the electric arc, preventing the electric arc from directly ionizing the air; argon can be used as a protective gas to further isolate nitrogen.

[0074] Specifically, the power control component 27 increases the voltage and lengthens the electric arc, allowing more heat to be transferred to the molten slag 3, preventing the surface molten slag 3 from condensing into a shell under a large amount of slag. The charging component adds metal furnace charge 25 in batches (20%~40% each time), which can ensure that the molten slag 3 always covers the molten iron 4 and prevent nitrogen absorption.

[0075] Specifically, after the surface temperature of molten slag 3 rises back to above 1540°C, step S3 is repeated until all the metal charge 25 is melted. This closed-loop control ensures that each batch of charging is carried out under conditions where molten slag 3 has good fluidity, preventing the risk of crusting and nitrogen increase due to insufficient temperature.

[0076] Specifically, 30%~50% of molten iron and 10%~40% of slag 3 are reserved during tapping for the next continuous smelting, achieving seamless connection of processes and avoiding the exposure of molten iron 4 to nitrogen absorption during each arc ignition, thereby improving overall production efficiency and denitrification stability.

[0077] To optimize the above technical solution, in step S5, the added slag-forming material includes limestone and / or dolomite, and the basicity of the molten slag 3 is adjusted to 1.0~1.1. Specifically, this basicity range belongs to low-basicity slag, and the molten slag 3 has a low melting point, good fluidity, and is easy to cover the surface of the molten iron 4 to form a uniform protective layer.

[0078] To optimize the above technical solution, in step S3, before each addition of metal charge 25, the power supply voltage is increased by 5% to 20% based on the current power supply voltage, while maintaining a constant current intensity. After each addition of metal charge 25, the surface temperature of the molten slag 3 is monitored using an infrared thermal imager 2. The next addition is performed only after the surface temperature of the molten slag 3 reaches above 1540°C. Specifically, increasing the voltage while maintaining a constant current significantly lengthens the arc, allowing more arc heat to be transferred to the surface of the molten slag 3, increasing the temperature of the molten slag 3, and preventing localized cooling and crusting caused by adding cold charge. Based on actual use and data calculations, a voltage increase range of 5% to 20% ensures sufficient heat input while preventing excessive arc length from damaging the furnace wall.

[0079] To optimize the above technical solution, in step S1, the blowing pressure of the top-blown argon gas supply unit of the top-blown assembly is 0.2~1 MPa; in step S2, the blowing pressure of the top-blown argon gas supply unit is 0.2~0.8 MPa, the blowing pressure of the top-blown hydrogen-containing gas supply unit of the top-blown assembly is 0.2~0.8 MPa, the blowing pressure of the bottom-blown argon gas supply unit of the bottom-blown assembly is 0.3~1 MPa, and the argon gas flow rate provided by the bottom-blown argon gas supply unit is 10~50 NL / (min·t).

[0080] Specifically, in step S1, a higher pressure range helps to break down the air and form a stable electric arc, while a large flow of argon rapidly displaces the air in the furnace, reducing the nitrogen partial pressure. In step S2, the blowing pressure is appropriately reduced to match the mixed gas ratio, ensuring uniform gas mixing and a stable electric arc; the pressure of the hydrogen-containing gas is comparable to that of the argon gas, which can prevent pressure fluctuations from affecting the arc characteristics. In step S2, the bottom blowing pressure needs to overcome the static pressure of the molten iron 4; 0.3~1MPa can ensure that bubbles can smoothly penetrate the molten iron 4; a flow rate of 10~50 NL / (min·t) provides sufficient stirring intensity, promoting uniform composition and temperature, while avoiding excessive stirring that would expose the molten iron 4.

[0081] To optimize the above technical solution, in steps S1 and S2, the argon gas flow rate provided by the top-blown argon gas supply unit is 10~50 NL / (min·t), and the hydrogen gas flow rate provided by the top-blown hydrogen gas supply unit is 2~20 NL / (min·t). Specifically, argon gas serves as both a carrier gas and a protective gas, and its flow rate must ensure arc stability and electrode cooling. A lower limit of 10 NL / (min·t) can maintain a basic arc, while an upper limit of 50 NL / (min·t) can enhance protection under high current. Hydrogen gas is the source of hydrogen atoms; too low a flow rate will result in insufficient denitrification, while too high a flow rate may lead to excessive hydrogen content or increased costs. Based on actual use and data calculations, a flow rate range of 2~20 NL / (min·t) can ensure denitrification efficiency (nitrogen content reduced to 12 ppm) while controlling hydrogen addition in molten iron 4 within a safe range (≤2 ppm), thus enhancing the heating and denitrification effects on molten iron 4.

[0082] To optimize the above technical solution, in step S5, after the gas supplied by the bottom-blowing assembly is switched to hydrogen, the hydrogen flow rate provided by the bottom-blowing hydrogen supply unit of the bottom-blowing assembly is 5~30 NL / (min·t), and the blowing pressure of the bottom-blowing hydrogen supply unit is 0.5~0.8 MPa. Specifically, based on actual use and data calculation, a hydrogen flow rate range of 5~30 NL / (min·t) can form a large number of fine hydrogen bubbles, providing sufficient nucleation interfaces for dissolved nitrogen (2[N] = N2↑). The lower limit of 5 NL / (min·t) can ensure basic denitrification effect, while the upper limit of 30 NL / (min·t) can maximize the denitrification rate, while avoiding excessive stirring that leads to emulsification of slag 3. In step S5, the depth of molten iron 4 increases, requiring higher pressure to overcome static pressure to ensure bubble penetration. A pressure of 0.5~0.8MPa can maintain a stable bubble flow without causing splashing or blockage of the vent plug 5 due to excessive pressure, so that the hydrogen bubbles not only physically carry nitrogen out, but also maximize the denitrification efficiency.

[0083] It should be noted that the electric arc furnace steelmaking apparatus and method provided by this invention can be used in the field of steelmaking equipment technology or other fields. Other fields refer to any field other than the field of steelmaking equipment technology. The above are merely examples and do not limit the application areas of the electric arc furnace steelmaking apparatus and method provided by this invention.

[0084] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0085] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0086] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A steelmaking method for an electric arc furnace steelmaking plant, characterized in that, The electric arc furnace steelmaking apparatus includes a furnace body, hollow graphite electrodes, a bottom anode, a charging assembly, a power control unit, a top blowing assembly, and a bottom blowing assembly, wherein: The interior of the furnace body forms a chamber; The hollow graphite electrode is suspended above the furnace body. The first end of the hollow graphite electrode is connected to the top-blowing assembly, and the second end of the hollow graphite electrode extends into the interior of the chamber to inject gas into the chamber and generate an electric arc. The bottom anode is located at the bottom of the furnace body and is used to form an electric arc circuit in conjunction with the hollow graphite electrode; The top-blowing assembly is connected to the first end of the hollow graphite electrode and is used to supply hydrogen-containing gas and argon gas to the hollow graphite electrode to form a hydrogen-containing plasma arc inside the chamber. The bottom blowing assembly is connected to the bottom of the furnace body and is used to supply gas to the molten iron in the chamber; The charging assembly is connected to the furnace body. The charging assembly is used to add slag-forming material to the molten iron in the chamber to regulate the slag composition. The charging assembly is also used to add metal furnace charge to the molten iron in the chamber and control the amount and rate of metal furnace charge added at one time. The power control unit is electrically connected to the hollow graphite electrode and is used to adjust the power supply voltage and current; The top-blowing assembly includes a top-blowing argon gas supply unit for supplying argon gas, a top-blowing hydrogen gas supply unit for supplying hydrogen gas, and a top-blowing mixing bag that is connected to the top-blowing argon gas supply unit, the top-blowing hydrogen gas supply unit, and the first end of the hollow graphite electrode, respectively. The top-blowing mixing bag is used to mix argon gas and hydrogen gas and then deliver them to the hollow graphite electrode. The bottom blowing assembly includes a bottom blowing argon gas supply unit for supplying argon gas, a bottom blowing hydrogen gas supply unit for supplying hydrogen gas, and a vent plug disposed at the bottom of the furnace body and selectively connected to the bottom blowing argon gas supply unit and the bottom blowing hydrogen gas supply unit. The vent plug is used to blow gas into the bottom of the molten iron. It also includes an infrared thermal imager, which is positioned above the furnace body and is used to monitor the temperature of the molten slag surface; The steelmaking method includes the following steps: Step S1: Molten iron and slag are reserved inside the electric arc furnace. The volume of the molten iron accounts for 30% to 50% of the furnace volume of the electric arc furnace, and the volume of the slag accounts for 10% to 40% of the furnace volume of the electric arc furnace. Argon gas is supplied to the hollow graphite electrode through the top blowing component to ignite an argon plasma arc and perform submerged arc heating to raise the temperature of the molten pool to above 1540°C. Step S2: A mixture of hydrogen and argon gas is supplied to the hollow graphite electrode through the top-blowing assembly to form a hydrogen-containing plasma arc. Simultaneously, argon gas is supplied to the bottom of the molten iron through the bottom-blowing assembly for stirring. The argon gas flow rate provided by the top-blowing argon gas supply unit of the top-blowing assembly is 10~50 NL / (min·t), and the blowing pressure is 0.2~0.8MPa. The hydrogen gas flow rate provided by the top-blowing hydrogen gas supply unit of the top-blowing assembly is 2~20 NL / (min·t), and the blowing pressure is 0.2~0.8MPa. The argon gas flow rate provided by the bottom-blowing argon gas supply unit of the bottom-blowing assembly is 10~50 NL / (min·t), and the blowing pressure is 0.3~1MPa. Step S3: Before each addition of metal charge, based on the current supply voltage value, increase the supply voltage by 5% to 20% while keeping the current intensity constant. The power control unit increases the supply voltage to lengthen the arc. The metal charge is added in batches through the feeding assembly. Each addition is 20% to 40% of the preset total metal charge. After each addition of metal charge, the surface temperature of the molten slag is monitored by an infrared thermal imager. Step S4: When the surface temperature of the molten slag rises to above 1540°C, repeat step S3 until the metal charge is completely added into the electric arc furnace and the metal charge is completely melted. Step S5: Add slag-forming material to the molten iron through the feeding assembly. The added slag-forming material includes limestone and / or dolomite. Adjust the slag basicity to 1.0~1.1 and adjust the slag composition. Switch the gas supplied by the bottom blowing assembly to hydrogen. The hydrogen flow rate provided by the bottom blowing hydrogen supply unit of the bottom blowing assembly is 5~30 NL / (min·t), and the blowing pressure is 0.5~0.8MPa. Step S6: When the composition and temperature of the molten iron reach the target, the steel is tapped, and molten iron and slag are reserved inside the electric arc furnace. The volume of the molten iron accounts for 30% to 50% of the furnace volume of the electric arc furnace, and the volume of the slag accounts for 10% to 40% of the furnace volume of the electric arc furnace, for use in the next furnace smelting.

2. The steelmaking method for an electric arc furnace steelmaking plant according to claim 1, characterized in that, The charging assembly of the electric arc furnace steelmaking apparatus includes: The silo is used to store metal furnace charge; A slag-forming material storage unit, wherein the slag-forming material storage unit is used to store slag-forming materials; The material pipe has a first end connected to the silo and the slag-forming material storage unit, and a second end connected to the furnace body. A slide gate valve is installed in the material pipe to control the rate and amount of metal furnace charge or slag material added.

3. The steelmaking method for an electric arc furnace steelmaking plant according to claim 1, characterized in that, In step S3, when the surface temperature of the molten slag reaches above 1540°C, the next feeding is carried out.

4. The steelmaking method for an electric arc furnace steelmaking plant according to claim 1, characterized in that, In step S1, the blowing pressure of the top-blowing argon gas supply unit of the top-blowing assembly is 0.2~1 MPa.

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