Denitrification method of electric arc furnace smelting direct reduction iron in molten steel in molten pool

Abstract

The invention discloses a method for denitrifying direct reduced iron in molten steel in a molten pool during smelting of an electric arc furnace. According to the method, DRI is preheated through a raw material preheating device, CO is introduced for pretreatment, then the DRI and waste steel are laid in an electric arc furnace in a layered mode, and the proportion of the DRI and the waste steel is adjusted according to smelted steel types. Carbon powder is added into a molten pool in the smelting period, nitrogen is promoted to enter slag, meanwhile, a regulation and control unit controls the oxygen flow and carbon-oxygen reaction heat production, the molten pool is stirred, the denitrification dynamic condition is improved, and finally secondary feeding prevents secondary nitrogen absorption. The DRI preheating temperature is controlled to be 600-850 DEG C, the heating speed is 30-50 DEG C / min, the CO partial pressure is 0.25-0.35 atm, and the preheating and pretreatment time is 10-20 minutes. By means of the method, the end point nitrogen content of the molten steel in the molten pool can reach 28-35 ppm.

Description

Technical Field

[0001] The present invention relates to the technical field of pre-denitrification technology in the steelmaking process of the iron and steel metallurgy process, and particularly relates to a method for denitrifying molten steel in a molten bath of direct reduced iron smelted in an electric arc furnace. Background Art

[0002] At present, the main methods of steel production are blast furnaces and electric arc furnaces (referred to as electric furnaces). The carbon emissions of blast furnaces dominate the steel production process (commonly known as the long process) with iron ore as the main raw material. However, both blast furnaces and electric furnaces rely on fossil fuels to provide heat and electricity. The existing technical path is to transition from the current short process (steel production process with scrap iron as the main raw material) to short process green steel. The latter realizes the production of green steel by using renewable electricity based on existing or newly added electric furnace production capacity. In the medium term, the application of low-carbon direct reduced iron (DRI) and electric furnaces may be the decarbonization technical path for long process green steel. By 2050, the entire industry needs to minimize the use of blast furnaces. Then, the short process of electric furnace smelting with DRI as the main raw material will gradually dominate the future steel market. The production method of DRI is to place iron ore and synthesis gas (usually carbon monoxide generated by burning natural gas or coal) in a shaft furnace for treatment. This gas removes the oxygen in the iron ore and produces sponge iron. Different from the blast furnace in the blast furnace-converter process, the shaft furnace itself does not burn coal.

[0003] The task of iron and steel metallurgy is to smelt iron ore into qualified finished steel, including the processes of reduction melting and oxidation refining. The reduction melting process is the ironmaking process, which mainly removes gangue and impurities from iron ore and reduces and deoxidizes it into hot metal or DRI. The oxidation refining process is the steelmaking process, which changes hot metal or DRI into molten steel through oxidation refining (removing C, Si, Mn, P). Under normal smelting conditions, nitrogen in the atmosphere will be adsorbed during the contact with molten steel. When the nitrogen content exceeds 100 ppm, pores will be generated in cast iron and steel. In IN100 superalloy, when the nitrogen content exceeds 15 ppm, a large number of microshrinkage pores will be formed. When nitrogen forms brittle nitrides with Ti, V, etc., it seriously affects the high-temperature strength and high-temperature plasticity of steel. In addition, when the nitrogen content in steel is too high, the phenomenon of age hardening will occur, that is, nitrogen in steel precipitates in the form of FeN nitrides. The precipitation rate of nitrides is very slow. For steel grades with high nitrogen content, after long-term placement, the strength and hardness of the steel increase with time, while the plasticity and toughness decrease. And in the temperature range of 250-450 °C, its surface turns blue, the strength of the steel increases, the impact toughness decreases, and blue brittleness is likely to occur.

[0004] The most common current denitrification methods are the aluminum denitrification method and the vacuum denitrification method. The aluminum denitrification method mainly involves adding aluminum powder or aluminum alloy, causing aluminum to react with nitrogen to form aluminum nitride. The aluminum nitride slag floats out of the molten steel to achieve the denitrification effect. This method is convenient to control, and the denitrification effect can reach 90%, but the cost is relatively high as aluminum powder is expensive. The vacuum denitrification method involves denitrifying molten steel under vacuum conditions. The denitrification effect is relatively good, reaching 95%, but it has high requirements for equipment and high investment costs. Currently, these methods mainly target denitrification means in the long process of blast furnace-converter steelmaking, and there is no in-depth study on the short-process denitrification method for electric furnace smelting of DRI in the future development trend, which does not conform to the industry policies and trends of carbon emission reduction and carbon neutrality in the steel industry. Summary of the Invention

[0005] In view of the above-mentioned defects of the prior art, the present invention provides a denitrification method for molten steel in a molten bath during the electric arc furnace smelting of direct reduced iron, including the steps:

[0006] (1) Provide a denitrification system for molten steel in a molten bath during the electric arc furnace smelting of direct reduced iron; including an electric arc furnace main body, electrode rods, a raw material preheating device, a layered batching device, a feeder, a raw material assembly unit, including a CO gas source, an oxygen gas source, an oxygen flow control unit, a temperature measurement and sampling detection device; at the same time, a control unit is connected to the raw material assembly unit to enable real-time control of the addition of raw materials; an oxygen lance is connected to the oxygen flow control unit to perform real-time control of the oxygen flow; the control unit is connected to the temperature measurement and sampling device to provide real-time feedback on the composition and temperature of the molten slag and molten steel during the smelting process; the system also includes an oxygen branch pipeline gas supply channel and a porous plug.

[0007] (2) During the batching process of electric furnace smelting, first preheat the direct reduced iron through the raw material preheating device. At the same time, introduce CO into the raw material preheating device through the CO gas source to perform pretreatment on the direct reduced iron. During the pretreatment process, CO enters the pores of the direct reduced iron, further increasing its porosity through physical scouring and the FeO reduction reaction. At the same time, maintain the metallization rate of the direct reduced iron during the preheating process.

[0008] (3) Then, in a layered batching manner, lay the direct reduced iron and scrap steel in layers at the bottom of the electric arc furnace, and adjust the ratio of direct reduced iron to scrap steel according to the steel grade to be smelted.

[0009] (4) During the melting period of electric arc furnace smelting, add carbon powder to the molten bath, and the reaction occurs:

[0010]

[0011] So that the nitrogen in the molten bath enters the slag in the form of free state and combined state;

[0012] (5) The control unit controls the oxygen flow control unit; the oxygen blowing amount is controlled through the electromagnetic flow regulating valve and the mass flow sensor; after the oxygen is introduced into the molten bath, the carbon-oxygen reaction generates CO and CO while providing heat. 2 The bubbles stir the molten bath, thereby improving the kinetic conditions of the above denitrification reaction;

[0013] (6) Secondary feeding, adding direct reduced iron preheated by the raw material preheating device and pretreated with CO, further forming a slag layer to isolate air and prevent secondary nitrogen absorption.

[0014] Furthermore, the preheating temperature of the direct reduced iron in the raw material preheating device is controlled at 600 - 850 °C, and the heating rate is 30 - 50 °C / min; to avoid the closure of pores caused by DRI sintering.

[0015] Furthermore, during pretreatment, the partial pressure of CO in the raw material preheating device is controlled at 0.25 - 0.35 atm.

[0016] Furthermore, the preheating and pretreatment time is controlled at 10 - 20 minutes.

[0017] Furthermore, the initial temperature of the direct reduced iron after preheating reaches above 650 °C, and the metallization rate is above 92%.

[0018] Furthermore, the end-point nitrogen in the molten steel in the molten bath is 28 - 35 ppm.

[0019] The method for denitrifying direct reduced iron in the molten steel of an electric arc furnace in the present invention has significant technical effects in terms of denitrification efficiency, cost control, resource utilization, environmental protection and energy conservation, and product quality improvement, strongly promoting the development of the steel industry towards the direction of green, efficient and sustainable. The specific technical effects are as follows:

[0020] High-efficiency denitrification: Utilizing the low-nitrogen raw material characteristics of direct reduced iron (DRI), the sponge-like porous structure to increase the reaction area, and the layered charging to reduce the probability of nitrogen absorption, and cooperating with adding carbon powder and controlling oxygen during the melting period, the end-point nitrogen content of the molten steel in the molten bath reaches 28 - 35 ppm, and the denitrification effect is good. During the electric arc furnace smelting process, by controlling the parameters of each link, the nitrogen content in the molten steel is effectively reduced, meeting the strict requirements of high-quality steel for nitrogen content.

[0021] Cost reduction: Compared with the aluminum denitrification method that requires the use of expensive aluminum powder and the vacuum denitrification method that relies on high-cost equipment, this method reduces the usage amount of denitrification alloys by optimizing the use of raw materials and technological steps, thereby reducing the production cost.

[0022] Improve resource utilization efficiency: The metallization rate of DRI > 92%, reducing the probability of nitrogen desorption from the decomposition of iron oxides. Meanwhile, preheating and CO pretreatment can increase the metallization rate by 1% - 3%, improving resource utilization efficiency. At the same time, the pretreatment removes impurities in the pores of DRI, reduces impurities in the furnace, and improves the utilization value of raw materials.

[0023] Energy conservation and emission reduction: Preheated DRI reduces the melting stage time of the electric furnace by 20% - 30% and the power consumption by 15% - 25%. The heat generated by the carbon-oxygen reaction saves electric energy, realizing the green and low-carbon transformation of the steelmaking denitrification process, which is in line with the carbon emission reduction and carbon neutrality policy trends in the steel industry.

[0024] Optimize process control: The control unit is connected to each device, enabling real-time regulation of raw material addition and oxygen flow rate. According to the feedback from the temperature measurement and sampling detection device, process parameters are adjusted to ensure precise control of the denitrification process, improving production stability and product quality consistency.

[0025] Prevent secondary nitrogen absorption: Secondary feeding with preheated and CO-pretreated DRI forms a slag layer to isolate air, effectively preventing secondary nitrogen absorption by the molten steel, ensuring the sustainability of the denitrification effect, and stabilizing the quality of the molten steel.

[0026] The present invention pre-treats direct reduced iron (DRI), which has significant effects in maintaining the metallization rate, reducing impurities, enhancing the denitrification reaction efficiency, reducing energy consumption, and reducing free nitrogen, comprehensively improving the quality and efficiency of steel smelting. It is of great significance for the denitrification process of molten steel in the electric arc furnace smelting DRI. The specific effects are as follows:

[0027] Maintain the metallization rate: During the preheating process, CO is introduced into the raw material preheating device through a CO gas source to provide reduction protection for the direct reduced iron, preventing its secondary oxidation and maintaining the metallization rate above 92%, providing guarantee for subsequent efficient smelting.

[0028] Remove impurities: CO can enter the pores of DRI, washing away adsorbed dust and volatile substances (such as S and P compounds), reducing impurities in the furnace, decreasing the content of harmful elements in the molten steel, enhancing the purity of the molten steel, and thus improving the quality of steel.

[0029] Enhance the denitrification reaction efficiency: On the one hand, CO reacts with the residual FeO in DRI for further reduction, increasing the metallization rate by 1% - 3%. Further increasing the porosity of DRI, the porosity increases from 70% to 75%, the average pore diameter increases from 10μm to 15μm, and the effective reaction interface area increases by 20% - 40%, making it easier for CO and the subsequently blown-in oxygen to penetrate into the pores. The denitrification product (N 2On the other hand, the preheating process is controlled at 600 - 850 °C to activate the surface active sites of the pores, making it easier for them to adsorb the denitrification medium in subsequent smelting and creating more favorable conditions for the denitrification reaction.

[0030] Reduce energy consumption: After preheating, the initial temperature of DRI reaches above 650 °C, the time of the electric furnace melting stage is reduced by 20% - 30%, and the power consumption is reduced by 15% - 25%, effectively reducing the production cost and improving the production efficiency.

[0031] Reduce free nitrogen: After pre - activation of DRI, the adsorbed free nitrogen (≤5 ppm) on the surface is reduced by 30% - 50%, directly reducing the initial nitrogen content in the molten steel, reducing the subsequent denitrification burden, and being beneficial to further reducing the final nitrogen content of the molten steel and improving the quality of the molten steel. Brief Description of the Drawings

[0032] Figure 1 is the process flow chart of the present invention.

[0033] The description of the reference numerals in the drawings is as follows:

[0034] 1 - Raw material pre - heating device; 2 - Raw material assembly unit; 3 - Layered batching device; 4 - Feeder; 5 - Electrode rod; 6 - Oxygen gas source; 7 - Electromagnetic flow regulating valve; 8 - Mass flow sensor; 9 - Check valve; 10 - Oxygen flow control unit; 11 - Oxygen lance; 12 - Arc furnace main body; 13 - Temperature - measuring and sampling detection device; 14 - Regulation unit; 15 - CO gas source. Detailed Embodiments

[0035] The following introduces multiple preferred embodiments of the present invention with reference to the drawings of the specification to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0036] Direct reduced iron (DRI) can achieve more efficient denitrification as an electric furnace raw material. Its advantages stem from the characteristics of low - nitrogen raw materials, physical structure promoting reaction kinetics, slag composition optimization, and process controllability. During the solid - state reduction process of DRI (such as in a shaft furnace or gas - based direct reduction), its production temperature (≈800 °C) is much lower than that of liquid steel (≥1600 °C), and its nitrogen solubility is extremely low. The nitrogen content of the raw material is usually <50 ppm (the nitrogen content of scrap is usually 60 - 150 ppm). At the same time, the metallization rate of DRI >92% (high reduction degree of iron oxides), reducing the probability of nitrogen absorption due to the decomposition of iron oxides during smelting. The rust layer (Fe 2 O 3)It will absorb nitrogen during melting, while DRI isolates this problem due to its high reduction degree. Direct reduced iron has a spongy porous structure. The specific surface area of DRI reaches 0.5 - 1.2 m² / kg, which is 3 - 5 times that of scrap steel, and the porosity > 70%. The high-speed decarburization reaction in the molten bath generates micro-region gas stirring in the pores, accelerating the diffusion of nitrogen to the slag-steel interface. Due to its own high density and layered charging (scrap steel at the bottom + DRI on the top), the molten bath forms quickly, and the proportion of the slag layer covering the liquid surface ≥ 70% (50% - 60% for scrap steel smelting), reducing the nitrogen absorption probability of air by more than 40%.

[0037] The denitrification system of direct reduced iron in the molten steel in the electric arc furnace smelting according to the present invention is as Figure 1 shown, including a raw material preheating device 1, a CO gas source 15, a layered batching device 3, an oxygen gas source 6, an oxygen flow control unit 10, an oxygen lance 11, an electric arc furnace main body 12, a temperature measurement and sampling device 13, and a regulation unit 14.

[0038] The raw material preheating device 1 is composed of a sealed container and heating elements. The container is responsible for storing direct reduced iron, and the heating elements provide heat for raw material preheating. During the batching process of electric furnace smelting, first, the direct reduced iron is preheated by the raw material preheating device 1. At the same time, CO is introduced into the raw material preheating device 1 through the CO gas source 15 to carry out reduction protection on the direct reduced iron during the preheating process, preventing secondary oxidation of DRI during preheating and maintaining the metallization rate above 92%. CO can also pre-activate the pores of direct reduced iron. CO enters the pores of DRI, flushing and removing adsorbed dust and volatile substances (such as S and P compounds), reducing impurities in the furnace. CO reacts with the residual FeO in DRI and continues to reduce, increasing the metallization rate by 1% - 3%. At the same time, the porosity of DRI is further increased, from 70% to 75%. The temperature rising range during the preheating process: controlled at 600 - 850 °C, avoiding pore closure caused by DRI sintering, and at the same time activating the surface active sites of the pores to make it easier to adsorb the denitrification medium in the subsequent smelting. During pretreatment, the partial pressure of CO in the raw material preheating device is controlled at 0.25 - 0.35 atm, and the treatment time is controlled at 10 - 20 minutes, then the pore cleaning and mild reduction of direct reduced iron can be completed. The heating elements adopt gas radiant tubes or electric heating systems to ensure the stability of the CO atmosphere. The initial temperature of DRI after preheating reaches above 650 °C, reducing the electric furnace melting stage time by 20% - 30% and reducing the power consumption by 15% - 25%. The availability of the pores of DRI after pretreatment is enhanced: the average pore diameter increases from 10 μm to 15 μm, and CO and the subsequently blown-in oxygen are more likely to penetrate into the pores; the effective reaction interface area is increased by 20% - 40%, and the denitrification products (N 2 or nitrides) are more likely to escape. The free nitrogen adsorbed on the surface of DRI after pre-activation (≤5 ppm) is reduced by 30% - 50%.

[0039] The layered batching device 3 consists of a magnet, a belt, and a batching container. The direct reduced iron is adsorbed onto the belt by the magnet. After measuring the weight, it is conveyed to the batching container by the belt according to the instructions of the control unit. After the raw materials are preheated, the direct reduced iron and scrap steel are layer-by-layer spread to the bottom of the electric arc furnace by using the layered batching device 3, and the ratio of direct reduced iron to scrap steel is adjusted according to the steel grade to be smelted. For high-quality steel grades, the steel-retaining operation is adopted. Scrap steel is used for melting in the early stage of melting. After the molten pool is formed, secondary feeding is carried out, and the direct reduced iron is put into the molten pool.

[0040] The oxygen flow control unit 10 includes an electromagnetic flow regulating valve 8, a mass flow sensor 9, and a check valve 10 connected in sequence; among them, the electromagnetic flow regulating valve 8 is installed at the inlet of the oxygen flow control unit 10; the check valve 10 is installed at the outlet of the oxygen flow control unit 10 and is then connected to the oxygen lance 11 through an oxygen delivery pipeline; the oxygen flow control unit 10 is set to stir the molten steel with oxygen and enhance the heat supply effect of the carbon-oxygen reaction. When the pressure in the pipeline exceeds the set threshold, the control valve will open or close to adjust the gas flow, so as to maintain the pressure within the normal range to ensure the continuity and stability of gas transportation. The electromagnetic flow regulating valve can control the gas flow in the pipeline by adjusting the opening and closing of the valve according to the system requirements. This helps to ensure that the gas flow volume in the pipeline meets the actual needs and improves the operation efficiency and stability of the pipeline system. The mass flow sensor can accurately measure the mass flow of the gas in the pipeline, that is, the mass of the gas passing through the cross-sectional area of the pipeline per unit time. This measurement method is more accurate than the volume flow because it is not affected by the gas density. It provides real-time flow data to help the operators monitor the operation status of the pipeline system. By monitoring the flow changes, abnormal situations in the pipeline system, such as leaks, blockages, or other faults, can be detected in a timely manner, and corresponding measures can be taken for adjustment or repair. The check valve can effectively prevent the gas from flowing backward in the pipeline, ensure that the gas flows in the designed direction, and maintain the normal operation of the pipeline system.

[0041] In a preferred example, when smelting scrap steel plus DRI in the electric arc furnace, it takes 4 hours and 15 minutes from power-on to tapping, the power consumption is 3020 KW·h, the oxygen consumption is 290 kg, the charging amount is 14.96 tons, and the tapping amount is 13.96 tons. The charging situation during the smelting process is shown in Table 1 below:

[0042] Table 1 Raw material charging situation during the smelting process

[0043]

[0044] During the melting period of the electric arc furnace smelting, the temperature measuring and sampling detection device 13 is used to detect the content of each component in the molten steel and molten slag, and the real-time feedback is given to the control unit 14. The detected component data is shown in Table 2 below:

[0045] Table 2 Raw material charging conditions during the smelting process

[0046]

[0047] Based on the detection data, the nitrogen capacity of the slag is calculated. Nitrogen in the steel diffuses to the steel-slag interface, reacts with the slag to form compounds and enters the slag phase for removal. The reaction process is as follows:

[0048]

[0049] The reaction constant K is obtained from the formula 1 :

[0050]

[0051] Definition formula of slag nitrogen capacity:

[0052]

[0053] In the formula: P O2 is the oxygen partial pressure at the slag-metal interface; P N2 is the nitrogen partial pressure at the slag-metal interface; O 2- and N 3- are free oxygen ions and free nitrogen ions; (%N 3- ) is the mass percentage of nitrogen ions in the slag; a O2- is the activity of oxygen ions in the slag; f N2- is the activity coefficient of nitrogen ions in the slag.

[0054] Observe the state of the molten pool and adjust the amount of carbon powder added during the secondary feeding. The control unit 14 controls the oxygen blowing amount according to the detection results. Adding carbon powder into the molten pool during the smelting period can effectively increase the nitrogen capacity of the slag and help denitrify the molten steel. The reaction equation is as follows:

[0055]

[0056] In the multi-component slag system, nitrogen may exist in the slag in the forms of free state and combined state simultaneously.

[0057] After adding carbon powder into the molten pool, the control unit 14 immediately controls the oxygen flow control unit 10; the oxygen blowing amount is controlled through the electromagnetic flow regulating valve 8 and the mass flow sensor 9; after the oxygen lance 11 passes oxygen into the molten pool, it reacts with the carbon powder:

[0058]

[0059] A large amount of heat can be generated through the carbon-oxygen reaction, achieving the effect of saving electric energy; at the same time, the CO and CO 2 bubbles generated by the carbon-oxygen reaction can stir the molten pool, and through kinetic action, the nitrogen in the molten steel is removed.

[0060] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field according to the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A method for denitrification of molten steel in a molten pool of direct reduced iron in an electric arc furnace, characterized in that: Includes steps: (1) A denitrification system for smelting direct reduced iron in molten steel in an electric arc furnace is provided; the system comprises an electric arc furnace body, an electrode rod, a raw material preheating device, a layered batcher, a feeder, a raw material assembly unit, a CO gas source, an oxygen gas source, an oxygen flow control unit, and a temperature measurement sampling detection device; at the same time, the control unit is connected to the raw material assembly unit to achieve real-time control of raw material addition; the oxygen gun is connected to the oxygen flow control unit to perform real-time control of the oxygen flow; The control unit is connected to the temperature measurement and sampling device to provide real-time feedback on the composition and temperature of slag and molten steel during the smelting process; the system also includes an oxygen branch pipeline gas supply channel and a gas-permeable brick; (2) In the process of smelting and batching in an electric furnace, the direct reduced iron is first preheated by a raw material preheating device, and at the same time, CO is introduced into the raw material preheating device through a CO gas source to pretreat the direct reduced iron. During the pretreatment process, CO enters the pores of the direct reduced iron, further increasing its porosity through physical scouring and the reduction reaction of CO and FeO, while maintaining the metallization rate of the direct reduced iron during the preheating process; (3) Then, the direct reduced iron and scrap steel are layered at the bottom of the electric arc furnace by using a layered batching method, and the ratio of direct reduced iron to scrap steel is adjusted according to the type of steel being smelted; (4) During the smelting period of the electric arc furnace, carbon powder is added to the molten pool to cause a reaction: The nitrogen in the molten pool enters the slag in the form of free and combined state; (5) The control unit controls the oxygen flow control unit; the oxygen blowing amount is controlled by the electromagnetic flow control valve and the mass flow sensor; after the oxygen is introduced into the molten pool, the CO and CO2 bubbles generated by the carbon-oxygen reaction while providing heat stir the molten pool, thereby improving the kinetic conditions of the above-mentioned denitrification reaction; (6) Secondary charging: adding direct reduced iron that has passed through the raw material preheating device and CO pretreatment to further form a slag layer to isolate the air and prevent secondary nitrogen absorption.

2. The method for denitrification of direct reduced iron in molten steel in a molten pool during electric arc furnace smelting as claimed in claim 1, wherein: The preheating temperature of direct reduced iron in the raw material preheating device is controlled at 600-850°C, and the heating rate is 30-50°C / min; to avoid pore closure caused by DRI sintering.

3. The method for denitrification of direct reduced iron in molten steel in a molten pool during electric arc furnace smelting as claimed in claim 2, wherein: During pretreatment, the partial pressure of CO in the raw material preheating device is controlled at 0.25-0.35 atm.

4. The method for denitrification of direct reduced iron in molten steel in a molten pool during electric arc furnace smelting as claimed in claim 3, wherein: The preheating and pretreatment time is controlled within 10 to 20 minutes.

5. The method for denitrification of direct reduced iron in molten steel in a molten pool during electric arc furnace smelting as claimed in claim 4, wherein: After preheating, the initial temperature of the direct reduced iron reaches above 650°C, and the metallization rate is above 92%.

6. The method for denitrification of direct reduced iron in molten steel in a molten pool during electric arc furnace smelting as claimed in claim 1, wherein: The final nitrogen content of the molten steel in the molten pool is 28-35ppm.

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