Steelmaking method for smelting high-grade plate through electric furnace DRI

Abstract

The invention discloses a steelmaking method for smelting a high-grade plate through electric furnace DRI, and the steelmaking method comprises the following steps: S1, during electric furnace smelting, leaving slag after tapping of a previous furnace; s2, waste steel and carbon powder are added into an electric furnace, after the waste steel is melted down to form a molten pool, direct reduction iron and lime are added, power-on smelting is carried out, it is ensured that the carbon content in molten steel reaches 0.5%-1.5%, then iron ore powder is added, and meanwhile top blowing oxygen smelting is carried out; and S3, before tapping of the electric furnace, limestone powder is laid at the bottom of a steel ladle, and then tapping is conducted. According to the method, the electric furnace DRI is used as a raw material, and the problem of nitrogen increase in the electric furnace smelting process is solved from two aspects of nitrogen absorption reduction and nitrogen removal increase.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy, and more specifically, to a method for steelmaking high-grade steel plates by electric arc furnace DRI smelting. Background Technology

[0002] Currently, countries worldwide are paying close attention to carbon emission reduction. As a responsible major power, China is focusing on carbon peaking and the development of carbon-neutral steelmaking technologies. From a current technological perspective, high-grade steel plates are produced using conventional converters. To reduce carbon emissions, electric arc furnaces can be used to smelt steel using scrap steel circulating in the market or direct reduced iron (DRI) from vertical shaft furnaces. The latter, hydrogen-based DRI, is currently the largest source of carbon-reducing raw materials.

[0003] However, the biggest problem in electric arc furnace (EAF) smelting is nitrogen accumulation. Conventional converter steelmaking can control the nitrogen content at 20-40 ppm, while EAF steelmaking requires 50-70 ppm, exceeding converter levels by 30 ppm. This high nitrogen content in EAF smelting leads to nitrogen presence in high-grade steel plates, resulting in reduced plasticity and strength. Chinese patent CN211035983U proposes a gas protection device that uses protective gas to isolate the steel from air, addressing the limitation of EAF systems in producing low-nitrogen steel. Furthermore, the cooling effect of the inert gas effectively improves electrode consumption in the EAF. Chinese patent publication CN108715912A discloses a method for smelting low-nitrogen steel in an electric arc furnace (EAF). In the initial smelting process, the iron content is 35-55%, the tapped steel is slightly over-oxidized with an oxygen content of 100-500 ppm, and the tapping temperature is 1620-1680℃. 3-4 kg / t of lime is added to the ladle during tapping. The resulting steel reportedly has an N content of ≤0.0040%. This technology primarily utilizes highly surface-active oxygen to prevent nitrogen from dissolving into the molten steel. Japanese patent JP6485058B2 discloses a method for smelting low-nitrogen steel, focusing on controlling the rate of nitrogen absorption during tapping. This technology provides a method for smelting low-nitrogen steel that suppresses nitrogen absorption from the surrounding air during tapping. Before tapping, an opening is placed around the ladle to introduce sealed gas, thus isolating the air and reducing nitrogen absorption. The technology for controlling nitrogen absorption proposed in Chinese patent CN112981038B involves using a smelting charge containing scrap steel and molten iron for primary smelting in an EAF (Electric Arc Furnace) to obtain primary molten steel. The oxygen content of the primary molten steel is 0.02-0.04%, and the carbon content is 0.5-1.0%. A first portion of lime is added to the smelting charge at the 8th-12th minute of the start of the electric arc melting process, and a second portion of lime is added at the 20th-30th minute to form a slag layer within the EAF. During the electric arc melting process, oxygen is injected from the oxygen lance on the furnace wall side of the EAF as a carrier gas for smokeless carbon powder, allowing the smokeless carbon powder to be blown into the slag layer to form foamed slag. The main technical principle of this technology is to use foamed slag and rapid slag formation to protect the surface of the molten steel and prevent nitrogen absorption.

[0004] In summary, these technologies mainly prevent nitrogen absorption by molten steel by isolating air or using protective slag. However, these technologies have drawbacks such as high cost, low efficiency, and complex processes. Furthermore, they do not systematically analyze and control the metallurgical physical thermodynamics of nitrogen dissolution and detection, thus failing to achieve the effect of nitrogen control from the perspective of low-cost metallurgy. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a steelmaking method for high-grade steel plates using electric arc furnace DRI smelting, which solves the problem of nitrogen increase during electric arc furnace smelting by reducing nitrogen absorption and increasing nitrogen removal.

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

[0007] This invention provides a steelmaking method for high-grade steel plates using electric arc furnace DRI smelting, comprising the following steps:

[0008] S1 refers to the slag left after the previous batch of steel is tapped during electric furnace smelting.

[0009] S2, add scrap steel and carbon powder to the electric furnace. After the scrap steel melts and forms a molten pool, add direct reduced iron and lime, and smelt with electricity to ensure that the carbon content of the molten steel reaches 0.5-1.5%. Then add iron ore powder and smelt with oxygen blown from the top.

[0010] S3: Before tapping steel from the electric furnace, limestone powder is laid at the bottom of the ladle before tapping.

[0011] Preferably, in step S1, 1 / 3 to 1 / 2 of the slag is left after the previous furnace tapping.

[0012] Preferably, in step S2:

[0013] The amount of scrap steel added is 40-60% of the electric furnace capacity;

[0014] The carbon powder is one or more of electrode powder, coke, and coal powder;

[0015] The particle size of the lime is controlled between 1 and 5 mm, and the amount of lime added is determined according to the target basicity of the molten pool, which is 1.0 to 2.5.

[0016] The amount of direct reduced iron added is 40-60% of the electric furnace capacity;

[0017] The amount of iron ore powder added is 10-15 wt% of the total slag.

[0018] Preferably, in step S2, at the end of electric furnace smelting, the temperature of the molten steel is 1580-1640℃; the carbon content of the molten steel is ≤0.4wt%, and the nitrogen content is ≤35ppm.

[0019] Preferably, in step S3, the mass of limestone powder laid at the bottom of the ladle is 100-250 kg / furnace.

[0020] Preferably, in step S3, the nitrogen content in the molten steel after tapping is ≤35ppm.

[0021] The steelmaking method for high-grade steel plates using electric arc furnace DRI smelting provided by this invention has the following beneficial effects:

[0022] 1. This invention increases the carbon content in molten steel to 0.5-1.5%, and then supplements it with top-blown oxygen and high-priced ore powder to create a high-iron oxidizing electric furnace slag. This can form an oxygen-rich surface atom at the slag / gold interface, which avoids low-nitrogen dissolution in the air.

[0023] 2. This invention utilizes the oxidation reaction between high-iron slag and carbon in the molten pool to remove dissolved nitrogen from the steel. Furthermore, during tapping, quicklime is added to create a CO2 protective atmosphere, controlling nitrogen levels in the electric arc furnace ladle to below 35 ppm.

[0024] 3. This invention can be widely used in the electric furnace smelting process of steel plates, reducing nitrogen content and improving the purity of molten steel;

[0025] 4. This invention uses electric arc furnace DRI as raw material to smelt high-grade plate steel, solving the problem of efficient and low-cost nitrogen control. Attached Figure Description

[0026] Figure 1 This is a graph showing the trend of nitrogen content in molten steel during the electric furnace smelting process in Embodiment 1 of the present invention;

[0027] Figure 2 This is a graph showing the changing trend of nitrogen content in molten steel during the electric furnace smelting process in Embodiment 2 of the present invention;

[0028] Figure 3 This is a graph showing the trend of nitrogen content in molten steel during the electric furnace smelting process in Embodiment 3 of the present invention;

[0029] Figure 4 This is a graph showing the trend of nitrogen content in molten steel during the electric furnace smelting process in Embodiment 4 of the present invention;

[0030] Figure 5 This is a graph showing the trend of nitrogen content in molten steel during the electric furnace smelting process in Embodiment 5 of the present invention. Detailed Implementation

[0031] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] To reduce the problem of high nitrogen levels during electric arc furnace smelting, this invention addresses both nitrogen absorption and nitrogen removal. Specifically, the carbon content in the molten steel is increased to 0.5-1.5%, followed by the addition of top-blown oxygen and high-grade iron ore powder to create a high-iron, oxidizing top slag. This top slag forms an oxygen-rich surface at the slag / metal interface, preventing nitrogen dissolution from the air. Simultaneously, the reaction between the high-oxygen slag and carbon in the steel rapidly removes dissolved nitrogen from the molten steel. Furthermore, the addition of quicklime during tapping creates a CO2 protective atmosphere, further controlling nitrogen levels in the electric arc furnace ladle to below 35 ppm.

[0033] This invention provides a method for steelmaking of high-grade steel plates using electric arc furnace DRI smelting, which involves nitrogen control in three steps, specifically including the following steps:

[0034] S1 refers to the slag left after the previous batch of steel is tapped during electric furnace smelting.

[0035] First, the electric arc furnace employs rapid slag formation technology. At the start of electric arc furnace smelting, 1 / 3 to 1 / 2 of the slag from the previous heat is retained, and a large amount of slag is used to quickly cover the molten pool.

[0036] S2, add scrap steel and carbon powder to the electric furnace. After the scrap steel melts and forms a molten pool, add direct reduced iron and lime, and smelt with electricity to ensure that the carbon content of the molten steel reaches 0.5-1.5%. Then add iron ore powder and smelt with oxygen blown from the top.

[0037] Secondly, after the electric furnace forms a molten pool, direct reduced iron (DRI) is added. Specifically, scrap steel and carbon powder are first added to the electric furnace, with the amount of scrap steel being 40-60% of the furnace capacity. The carbon powder is one or more of electrode powder, coke powder, or coal powder. If coke powder or coal powder is used, it is necessary to ensure that it contains as few impurities as sulfur. After the scrap steel melts and forms a molten pool, direct reduced iron (DRI) and lime are added. The amount of DRI added is 40-60% of the electric furnace capacity. The amount of lime added is determined based on the target basicity of the molten pool, where the target basicity (%CaO) / (%SiO2) is 1.0-2.5. The SiO2 content can generally be obtained through testing or calculated based on the DRI addition amount. The lime particles should be small, controlled at 1-5 mm, to facilitate the formation of a high-basicity molten pool. After adding DRI and lime, the electrodes are energized for smelting. Once the molten pool is clear, the initial composition of the molten steel is measured to ensure the carbon content is between 0.5-1.5%. At this point, the basicity of the molten pool (%CaO) / (%SiO2) is 1.0-2.5. The total amount of scrap steel and DRI equals the electric furnace capacity. Then, iron ore powder (oxides of high-valence iron) is added, at a rate of 10-15 wt% of the total slag. Simultaneously, the top lance of the electric furnace begins to blow oxygen for electric furnace smelting. During this process, through the rapid oxidation reaction between carbon in the molten steel and high-valence iron oxides in the iron ore powder, as shown in equation (1), a large number of CO bubbles are formed, creating a vacuum chamber due to high-temperature expansion, which carries nitrogen out of the molten pool. The reaction is as follows:

[0038] The reaction C + O = CO (1)

[0039] The CO bubbles formed create a protective gas above the molten pool, preventing the ionization and dissolution of nitrogen in the air and thus avoiding nitrogen from entering the molten pool. It is important to further emphasize that both the oxygen lance and the iron ore powder are strong deoxidizers. The oxygen lance supply is achieved through the following reaction:

[0040] O2 = 2[O] reaction (2)

[0041] This reaction requires the cracking of oxygen, first forming FeO, which then supplies [O].

[0042] In the above process, lime is added, and since lime dissolution requires FeO, but FeO is consumed by C, the slag formation rate is slow. This invention uses direct feeding of iron ore powder, i.e., FeO powder, which can accelerate the supply of FeO and quickly form lime into slag.

[0043] At the end of electric arc furnace smelting, the temperature of molten steel is 1580–1640℃; the carbon content of the molten steel is ≤0.4wt%, and the nitrogen content is ≤35ppm.

[0044] S3: Before tapping steel from the electric furnace, limestone powder is laid at the bottom of the ladle before tapping.

[0045] Finally, a certain amount of limestone powder (whose main component is CaCO3) is laid at the bottom of the ladle. After the electric furnace finishes smelting high-grade plate steel, limestone powder is laid at the bottom of the ladle to form a CO2 protective atmosphere according to the following reaction formula (3) to prevent nitrogen accumulation during tapping. The mass of limestone powder laid at the bottom of the ladle is 100-250 kg / heat.

[0046] The reaction CaCO3 = CaO + CO2 (3)

[0047] The nitrogen content in the molten steel after tapping from the electric furnace is ≤35ppm.

[0048] The following section provides a further description of the steelmaking method for high-grade steel plates using electric furnace DRI smelting, with specific examples.

[0049] Example 1

[0050] On a certain day, in a 100-ton electric arc furnace, it is necessary to smelt steel plates using relevant raw materials. The operational steps are illustrated in the following embodiment: The electric arc furnace DRI steelmaking method for smelting high-grade steel plates in this embodiment is as follows:

[0051] (1) In a 100-ton electric furnace, after the previous furnace is tapped, the remaining slag is not completely dumped, leaving about half, approximately 10 tons of electric furnace slag.

[0052] (2) First, add 60 tons of scrap steel and 2000 kg of electrode powder to the electric furnace. Once the scrap steel has melted and formed a molten pool, the nitrogen content of the pool is 64 ppm. Then, add 40 tons of direct reduced iron and 6000 kg of lime powder with a particle size of 3 mm (the target basicity of the molten pool is 1.8). The electrodes are then energized for smelting. After the molten pool has melted, the initial composition of the molten steel is measured; the carbon content is 1.00%, and the basicity of the molten pool is 1.8. Simultaneously with the introduction of oxygen into the top lance of the electric furnace, add 900 kg of iron ore powder (12% of the actual total slag amount) to the molten pool. The iron ore powder is an oxide of high-valence iron. Through the oxidation of high-valence iron, it reacts with the carbon in the molten steel, forming a large number of bubbles that carry away the nitrogen from the molten steel. At the end of the electric furnace smelting process, the temperature of the molten steel is 1610℃, and the carbon content is measured to be 0.03%, and the nitrogen content is 33 ppm.

[0053] (3) Before tapping, 100 kg of limestone powder is laid at the bottom of the ladle before tapping. After tapping, the nitrogen content is 33 ppm.

[0054] In this embodiment, the trend of nitrogen content change in molten steel during electric furnace smelting is as follows: Figure 1As shown, the nitrogen content in the molten steel is highest during the scrap steel melting process. During the electric furnace smelting process after the addition of direct reduced iron, the nitrogen content in the molten steel gradually decreases and stabilizes in the range of 26-33 ppm with the increase of smelting time, until the nitrogen content in the molten steel stabilizes at 33 ppm before tapping. In addition, since limestone powder is laid at the bottom of the ladle, a CO2 protective atmosphere is formed, so no nitrogen increase phenomenon is observed in the molten steel after tapping. The denitrification rate in this embodiment reaches 48.44%.

[0055] Example 2

[0056] On a certain day, in a 100-ton electric arc furnace, it is necessary to smelt steel plates using relevant raw materials. The operational steps are illustrated in the following embodiment: The electric arc furnace DRI steelmaking method for smelting high-grade steel plates in this embodiment is as follows:

[0057] (1) In a 100-ton electric furnace, after the previous furnace is tapped, the remaining slag is not completely dumped, leaving 40%, about 8 tons of electric furnace slag.

[0058] (2) First, add 50 tons of scrap steel and 1800 kg of electrode powder to the electric furnace. Once the scrap steel melts and forms a molten pool, the nitrogen content of the pool is 76 ppm. Then, add 50 tons of direct reduced iron and 2800 kg of lime powder with a particle size of 3 mm (the target basicity of the molten pool is 1.2). The electrodes are then energized for smelting. After the molten pool melts, the initial composition of the molten steel is measured; the carbon content is 0.9%, and the basicity of the molten pool is 1.2. Simultaneously with the introduction of oxygen into the top lance of the electric furnace, add 1800 kg of iron ore powder (15% of the actual total slag amount) to the molten pool. The iron ore powder is an oxide of high-valence iron. Through the oxidation of high-valence iron, it reacts with the carbon in the molten steel, forming a large number of bubbles that carry away the nitrogen from the molten steel. At the end of the electric furnace smelting process, the temperature of the molten steel is 1580℃, and the carbon content is measured to be 0.04%, and the nitrogen content is 28 ppm.

[0059] (3) Before tapping, 150 kg of limestone powder is laid at the bottom of the ladle before tapping. After tapping, the nitrogen content is 26 ppm.

[0060] In this embodiment, the trend of nitrogen content change in molten steel during electric furnace smelting is as follows: Figure 2 As shown, the nitrogen content in the molten steel is highest during the scrap steel melting process. During the electric furnace smelting process after the addition of direct reduced iron, the nitrogen content in the molten steel gradually decreases and stabilizes in the range of 28-33 ppm with the increase of smelting time, until the nitrogen content in the molten steel stabilizes at 28 ppm before tapping. In addition, since limestone powder is laid at the bottom of the ladle, a CO2 protective atmosphere is formed, and the nitrogen content of the molten steel after tapping is slightly reduced to 26 ppm. The denitrification rate in this embodiment reaches 65.79%.

[0061] Example 3

[0062] On a certain day, in a 100-ton electric arc furnace, it is necessary to smelt steel plates using relevant raw materials. The operational steps are illustrated in the following embodiment: The electric arc furnace DRI steelmaking method for smelting high-grade steel plates in this embodiment is as follows:

[0063] (1) In a 100-ton electric furnace, after the previous furnace is tapped, the remaining slag is not completely dumped, leaving 30%, or about 6 tons of electric furnace slag.

[0064] (2) First, 40 tons of scrap steel and 1400 kg of electrode powder are added to the electric furnace. Once the scrap steel melts and forms a molten pool, the nitrogen content of the pool is 88 ppm. Then, 60 tons of direct reduced iron and 6000 kg of lime powder with a particle size of 3 mm are added (the target basicity of the molten pool is 1.5). The electrodes are then energized for smelting. After the molten pool melts, the initial composition of the molten steel is measured; the carbon content is 0.7%, and the basicity of the molten pool is 1.5. Simultaneously with the introduction of oxygen into the top lance of the electric furnace, 1100 kg of iron ore powder (added at 10% of the actual total slag amount) is added to the molten pool. The iron ore powder is an oxide of high-valence iron. Through the oxidation of high-valence iron, it reacts with the carbon in the molten steel, forming a large number of bubbles that carry away the nitrogen element from the molten steel. At the end of the electric furnace smelting process, the temperature of the molten steel is 1640℃, and the carbon content of the molten steel is measured to be 0.035%, and the nitrogen content is 34 ppm.

[0065] (3) Before tapping, 150 kg of limestone powder is laid at the bottom of the ladle before tapping. After tapping, the nitrogen content is 32 ppm.

[0066] In this embodiment, the trend of nitrogen content change in molten steel during electric furnace smelting is as follows: Figure 3 As shown, the nitrogen content in the molten steel is highest during the scrap steel melting process. During the electric furnace smelting process after the addition of direct reduced iron, the nitrogen content in the molten steel gradually decreases and stabilizes in the range of 34-46 ppm with the increase of smelting time. Until the nitrogen content in the molten steel stabilizes at 34 ppm before tapping, and because lime powder is laid at the bottom of the ladle, a CO2 protective atmosphere is formed, the nitrogen content of the molten steel after tapping is slightly reduced to 32 ppm. The denitrification rate in this embodiment reaches 63.64%.

[0067] Example 4

[0068] On a certain day, in a 100-ton electric arc furnace, it is necessary to smelt steel plates using relevant raw materials. The operational steps are illustrated in the following embodiment: The electric arc furnace DRI steelmaking method for smelting high-grade steel plates in this embodiment is as follows:

[0069] (1) In a 100-ton electric furnace, after the previous furnace is tapped, the remaining slag in the furnace is not completely dumped, leaving about 45% of the slag, approximately 9 tons of electric furnace slag.

[0070] (2) First, 45 tons of scrap steel and 1500 kg of electrode powder were added to the electric furnace. The scrap steel was melted to form a molten pool, at which point the nitrogen content of the pool was 72 ppm. Then, 55 tons of direct reduced iron and 4500 kg of lime powder with a particle size of 3 mm were added (the target basicity of the molten pool was 1.3). The electrodes were energized for smelting. After the molten pool was melted, the initial composition of the molten steel was measured; the carbon content was 0.75%, and the basicity of the molten pool was 1.3. Simultaneously with the introduction of oxygen into the top lance of the electric furnace, 1250 kg of iron ore powder (added at 13% of the actual total slag volume) was added to the molten pool. The iron ore powder is an oxide of high-valence iron. Through the oxidation of high-valence iron, it reacts with the carbon in the molten steel, forming a large number of bubbles that carry away the nitrogen element from the molten steel. At the end of the electric furnace smelting process, the temperature of the molten steel was 1610℃, and the carbon content of the molten steel was measured to be 0.03%, and the nitrogen content was 31 ppm.

[0071] (3) Before tapping, 150 kg of limestone powder is laid at the bottom of the ladle before tapping. After tapping, the nitrogen content is 30 ppm.

[0072] In this embodiment, the trend of nitrogen content change in molten steel during electric furnace smelting is as follows: Figure 4 As shown, the nitrogen content in the molten steel is highest during the scrap steel melting process. During the electric furnace smelting process after the addition of direct reduced iron, the nitrogen content in the molten steel gradually decreases and stabilizes in the range of 31-40 ppm with the increase of smelting time, until the nitrogen content in the molten steel stabilizes at 31 ppm before tapping. In addition, since lime powder is laid at the bottom of the ladle, a CO2 protective atmosphere is formed, so the nitrogen content of the molten steel after tapping is slightly reduced to 30 ppm. The denitrification rate in this embodiment reaches 58.33%.

[0073] Example 5

[0074] On a certain day, in a 100-ton electric arc furnace, it is necessary to smelt steel plates using relevant raw materials. The operational steps are illustrated in the following embodiment: The electric arc furnace DRI steelmaking method for smelting high-grade steel plates in this embodiment is as follows:

[0075] (1) In a 100-ton electric furnace, after the previous furnace is tapped, the remaining slag is not completely dumped, leaving 35%, or about 7 tons of electric furnace slag.

[0076] (2) First, 55 tons of scrap steel and 1700 kg of electrode powder were added to the electric furnace. The scrap steel was melted to form a molten pool, at which point the nitrogen content of the pool was 68 ppm. Then, 45 tons of direct reduced iron and 7100 kg of lime powder with a particle size of 3 mm were added (the target basicity of the molten pool was 2.0). The electrodes were energized for smelting. After the molten pool was melted, the initial composition of the molten steel was measured; the carbon content was 0.85%, and the basicity of the molten pool was 2.0. Simultaneously with the introduction of oxygen into the top lance of the electric furnace, 1150 kg of iron ore powder (added at 11% of the actual total slag volume) was added to the molten pool. The iron ore powder is an oxide of high-valence iron. Through the oxidation of high-valence iron, it reacts with the carbon in the molten steel, forming a large number of bubbles that carry away the nitrogen element from the molten steel. At the end of the electric furnace smelting process, the temperature of the molten steel was 1610℃, and the carbon content of the molten steel was measured to be 0.035%, and the nitrogen content was 32 ppm.

[0077] (3) Before tapping, 250 kg of limestone powder is laid at the bottom of the ladle before tapping. After tapping, the nitrogen content is 29 ppm.

[0078] In this embodiment, the trend of nitrogen content change in molten steel during electric furnace smelting is as follows: Figure 5 As shown, the nitrogen content in the molten steel is highest during the scrap steel melting process. During the electric furnace smelting process after the addition of direct reduced iron, the nitrogen content in the molten steel gradually decreases and stabilizes in the range of 32-43 ppm with the increase of smelting time. Until the nitrogen content in the molten steel stabilizes at 32 ppm before tapping, and because lime powder is laid at the bottom of the ladle, a CO2 protective atmosphere is formed, the nitrogen content of the molten steel after tapping is slightly reduced to 29 ppm. The denitrification rate in this embodiment reaches 57.35%.

[0079] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A steelmaking process for the production of high-grade plates from an electric furnace DRI smelt, characterized in that, The method comprises the following steps: S1, during electric furnace smelting, leaving slag after tapping of a previous furnace; S2, adding scrap steel and carbon powder into the electric furnace, adding direct reduced iron and lime after formation of a molten pool by melting of the scrap steel, electric smelting to ensure that the carbon content in the molten steel reaches 0.5-1.5%, and then adding iron ore powder while top blowing oxygen; S3, laying limestone powder at the bottom of a ladle before tapping of the electric furnace, and then tapping.

2. The steelmaking method of electric furnace DRI melting high-grade plate according to claim 1, characterized by, In the step S1, the slag left after tapping of the previous furnace is 1 / 3-1 / 2.

3. The steelmaking method of electric furnace DRI melting high-grade plate according to claim 1, characterized by, In the step S2: The adding amount of the scrap steel is 40-60% of the electric furnace capacity; The carbon powder is one or more of electrode powder, coke and coal powder; The particle size of the lime is controlled to be 1-5 mm, the adding amount of the lime is determined according to the target basicity of the molten pool, and the target basicity of the molten pool is 1.0-2.5; The adding amount of the direct reduced iron is 40-60% of the electric furnace capacity; The adding amount of the iron ore powder is 10-15 wt% of the total slag amount.

4. The steelmaking method of electric furnace DRI melting high-grade plate according to claim 1, characterized by, In the step S2, at the end of electric furnace smelting, the temperature of the molten steel is 1580-1640℃, the carbon content in the molten steel is ≤0.4 wt%, and the nitrogen content is ≤35 ppm.

5. The steelmaking method of electric furnace DRI melting high-grade plate according to claim 1, characterized by, In the step S3, the mass of the limestone powder laid at the bottom of the ladle is 100-250 kg per furnace cycle.

6. The steelmaking method of electric furnace DRI melting high-grade plate according to claim 1, characterized by, In the step S3, the nitrogen content in the molten steel after tapping is ≤35 ppm.

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