Electric furnace steelmaking method adopting high-density carbon balls to match carbon

Abstract

The invention discloses an electric furnace steelmaking method adopting high-density carbon balls to match carbon. The method comprises the following steps: calculating the mass of high-density carbon balls according to the recarburization content required by a smelted steel grade through a specific carbon blending theoretical calculation model, paving the carbon balls at the bottom of a material basket, then adding direct reduced iron, and enabling the carbon balls to enter a furnace before the direct reduced iron by utilizing the design of a special discharge port of the material basket so as to improve the carbon blending efficiency. The volume density of the high-density carbon spheres is 2.0-3.5 g / cm < 3 >, the particle size is 30-50 mm, the adding amount is flexibly adjusted according to actual conditions, and the consumption of each ton of steel is 20-30 kg. The method overcomes the defects in the prior art, carbon can be accurately prepared, the electric furnace smelting power consumption is reduced, the steelmaking cost is reduced, and the nitrogen content of molten steel is effectively controlled. Compared with a conventional raw material mode, the power consumption of each test furnace is reduced by 463 KWh, the power consumption of each ton of steel is reduced by 35 KWh / t, and the method is simple and convenient to operate, free of equipment transformation, suitable for an electric arc furnace steelmaking process and good in application prospect.

Description

Technical Field

[0001] The present invention relates to electric arc furnace steelmaking, and particularly to an electric arc furnace steelmaking method using high-density carbon balls for carbon addition. Background Art

[0002] Reducing the application ratio of hot metal (or pig iron) raw materials in the steelmaking process can significantly reduce carbon emissions throughout the manufacturing process. However, when using all scrap steel for smelting in the raw material structure of electric arc furnace steelmaking, the quality of scrap steel fluctuates greatly. It is mainly manifested in that the impurity content in scrap steel is relatively high, and scrap steel often contains high impurities (such as copper, zinc, sulfur, phosphorus, etc.). These impurities are difficult to completely remove and will affect the quality of molten steel. The composition of scrap steel raw materials is uneven. The sources of scrap steel are diverse and the composition is not unified, which brings complexity to the batching and smelting processes and increases the uncertainty of production. In addition, the supply of high-quality scrap steel resources is insufficient, and the supply of high-grade and low-impurity high-quality scrap steel is insufficient.

[0003] When the electric arc furnace uses all scrap steel smelting and direct reduced iron smelting, there is a problem that it is difficult to achieve the best carbon addition during the smelting process:

[0004] If there is no carbon in the raw materials of the electric arc furnace, the chemical energy cannot be effectively released by blowing oxygen during the electric arc furnace smelting process. Then the power consumption of the electric arc furnace smelting is very high, reaching more than 700 KWh / t, and even up to 1000 KWh / t. This undoubtedly greatly increases the electric arc furnace smelting time, and the electric arc furnace smelting cannot meet the requirements of the subsequent high-efficiency continuous casting rhythm. Under the current technical conditions, a certain amount of carbon must be added during all scrap steel smelting or all scrap steel + direct reduced iron smelting to ensure normal smelting. However, if the added amount exceeds the required amount, it will cause waste of energy and increase CO 2 emissions. Therefore, it is necessary to establish a carbon addition and carbon increment model in the electric arc furnace. At the same time, using pig iron or hot metal for carbon addition in the electric arc furnace has a high steelmaking cost, and it is not easy to control the reaction speed of carbon addition with electrode powder in the furnace. Therefore, in the field of electric arc furnace steelmaking, there is an urgent need to find a carbon-containing substance that can replace pig iron or hot metal for carbon addition and is suitable for large-scale electric arc furnace smelting, and some changes also need to be made in the raw material structure, and develop a corresponding electric arc furnace smelting process. The establishment of the carbon addition and carbon increment model is also beneficial to the development of new carbon addition raw materials and the determination of the process. Summary of the Invention

[0005] To achieve the above object, the present invention provides an electric arc furnace steelmaking method using high-density carbon balls for carbon addition, including the following steps:

[0006] (1) According to the carbon increment content required for each furnace of steel grade to be smelted, calculate the required mass of high-density carbon balls through the following carbon addition theoretical calculation model:

[0007]

[0008] In the formula:

[0009] C T is the carbon content increase, %;

[0010] m c is the mass of high-density carbon balls, with the unit of Kg;

[0011] VM is the volatile content in high-density carbon balls, %;

[0012] ASH is the ash content in high-density carbon balls, %;

[0013] M is the moisture content in high-density carbon balls, %;

[0014] C raw，i is the carbon content in the i-th furnace charge material, %;

[0015] L c is the loss of carbon balls during the entire smelting process, %;

[0016] W raw，i is the total weight of the i-th furnace charge material, with the unit of Kg;

[0017] C f is the fixed carbon content in carbon balls, %;

[0018] (2) First, lay high-density carbon balls at the bottom of the charging basket, then add direct reduced iron on the high-density carbon balls, lift the charging basket above the electric furnace by the overhead crane, and at the same time open the discharge port of the charging basket to add high-density carbon balls and direct reduced iron into the electric furnace. Among them, the discharge port is set at the side plate of the charging basket, and the side plate is turned upward, so that when the discharge port is opened, the high-density carbon balls at the lower part of the charging basket enter the electric furnace prior to the direct reduced iron above them.

[0019] Furthermore, the bulk density of the high-density carbon balls is 2.0 - 3.5 g / cm 3 .

[0020] Furthermore, the high-density carbon balls are processed into flat balls or spherical balls with a particle size of

[0021] Furthermore, during the smelting process, the power supply parameters are controlled in stages: at the starting stage, the voltage of gear 1 is used to strike an arc, and after the arc is stable, it is switched to the voltage of gear 2 for power supply;

[0022] After the molten pool is formed, oxygen is blown in batches to assist melting. In the early stage, the amount of oxygen blown is controlled to accelerate the melting of the raw materials and the temperature rise of the molten steel. In the later stage, oxygen is blown to accelerate decarburization and impurity oxidation, and the total amount of oxygen blown is controlled within 50 m 3 ; The slag-making agent is added in batches according to the molten pool state. The lime consumption per ton of steel is 30 - 50 kg, and high-density carbon balls are added in real time according to the effect of the foamy slag to prevent the molten steel from being over-oxidized.

[0023] Further, when adding the second basket of materials after the first basket of raw materials is melted completely, stop blowing oxygen and strike an arc with the voltage at gear 1. After the arc is stable, resume the voltage at gear 2 and the oxygen-blowing operation.

[0024] Further, during the smelting process, monitor the carbon content in the molten bath. When it is lower than the target value of 0.2%, add 200 - 300 kg of high-density carbon balls to adjust the composition of the molten steel.

[0025] Further, when the charging amount is 12 - 13 tons, charge in two baskets. The addition amount of high-density carbon balls in the first basket of charge is 200 - 400 kg, accounting for 60 - 80% of the total carbon addition.

[0026] Further, it is used to produce medium and high carbon steel castings with a carbon content control accuracy of ≤ ±0.05%, and the nitrogen content of the castings is ≤ 80 ppm.

[0027] The electric furnace steelmaking method using high-density carbon balls for carbon addition provided by the present invention shows remarkable technical effects in many aspects:

[0028] Optimize the carbon addition process: With the help of an accurate carbon addition theoretical calculation model, according to the required carbon increment of the steel grade to be smelted, the usage amount of high-density carbon balls can be accurately calculated. This accurate carbon addition method not only avoids the problem of high power consumption caused by ineffective oxygen blowing and release of chemical energy due to insufficient carbon addition during electric furnace smelting, but also prevents energy waste and increased CO 2 emissions caused by excessive carbon addition, ensuring the stable and efficient progress of the smelting process. For example, when smelting cast steel ZG25Mn2-Ⅱ and AISI8630 in a 10-ton electric furnace of Yuanping Zhongying Wanwei, the carbon can be added reasonably according to this model to ensure the smooth smelting.

[0029] Improve the carbon addition efficiency: Lay the high-density carbon balls at the bottom of the material basket. With the special design of the discharge port, they enter the electric furnace prior to the direct reduced iron. This feeding method effectively improves the carbon addition efficiency and reduces the electric furnace smelting time. Taking the actual production data as an example, compared with the conventional feeding method, after adopting this method, the electric furnace smelting time is significantly shortened, improving the production efficiency.

[0030] Improve the quality of the molten steel: Use high-density carbon balls and direct reduced iron to replace some raw materials, improving the raw material structure. Compared with scrap steel, direct reduced iron has better performance in terms of composition stability, impurity content, and porosity, and has a higher carbon content, being an excellent raw material for steelmaking. This raw material substitution strategy helps to improve the quality of the molten steel and reduce the adverse effects of impurities on the quality of the molten steel.

[0031] Reducing smelting power consumption: By using high-density carbon balls and direct reduced iron for smelting and combining with an optimized smelting process, the power consumption of electric furnace smelting is significantly reduced. Compared with the conventional raw material mode of the factory, the average power consumption data of the test furnace batches of the present invention is 2842 KWh / furnace. The power consumption per furnace is effectively reduced by 463 KWh / furnace, and the power consumption per ton of steel is effectively reduced by 35 KWh / t, greatly reducing the production cost.

[0032] Simplifying operation and wide applicability: The present invention does not require purchasing or modifying any equipment. The operation method is simple and easy to implement, and is applicable to the batch smelting tasks of actual electric furnaces in various factories. It has good application and promotion prospects and can bring significant economic and environmental benefits to the electric arc furnace steelmaking industry.

[0033] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the drawings to fully understand the purpose, features and effects of the present invention. Brief Description of the Drawings

[0034] Figure 1 is a schematic diagram of the electric furnace charging process in a preferred embodiment of the present invention;

[0035] Figure 2 is a comparison chart of the power consumption of electric furnace smelting. Detailed Embodiments

[0036] The following introduces multiple preferred embodiments of the present invention with reference to the accompanying 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.

[0037] In the drawings, components with the same structure are denoted by the same numerical labels, and components with similar structures or functions everywhere are denoted by similar numerical labels. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. To make the drawings clearer, the thickness of some parts in the drawings is appropriately exaggerated.

[0038] The present invention provides an electric arc furnace steelmaking method using high-density carbon balls and direct reduced iron to replace electrode powder and scrap steel, overcomes the defects of the prior art, has obvious progress in controlling the nitrogen content and successfully incorporating the carbon content, reduces the power consumption of electric furnace smelting, reduces the steelmaking cost, and is applicable to the electric arc furnace steelmaking process.

[0039] The electric furnace is smelted with all scrap steel and direct reduced iron as raw materials. High-density carbon balls are used to replace all or part of the electrode powder. The production is carried out by laying high-density carbon balls at the bottom of the raw material basket and adding them into the furnace or adding high-density carbon balls from the furnace door during the smelting process. According to the size of the electric furnace and the different steel grades to be smelted, the production is carried out by laying high-density carbon balls at the bottom of the raw material basket and adding them into the furnace or adding high-density carbon balls from the furnace door during the smelting process. The specific steps or control methods are as follows:

[0040] a. Control variables in the raw material structure for all-scrap-steel smelting and the mode of all-scrap-steel + direct reduced iron, conduct batch tests, and use two carbon addition modes: adding with the raw materials into the furnace and adding during the smelting process for comparison. Finally, calculate the carbon addition efficiency of the carbon balls into the molten steel, as well as their effects on the smelting time, power consumption, and molten steel composition.

[0041] b. When the on-site test adopts the smelting method of laying high-density carbon balls at the bottom of the raw material basket and adding them into the furnace, two furnace tests should be completed for each carbon addition ratio. The test requires measuring the carbon content at the melting point, calculating the theoretical carbon increase according to the theoretical carbon addition model, and evaluating the carbon addition efficiency through material balance calculation.

[0042] c. When the on-site test is carried out by adding high-density carbon balls from the furnace door during the smelting process, two furnace tests should be completed for each carbon addition ratio. Each time, it can be manually added, observe the metallurgical reaction after carbon addition, and measure the foamy slag.

[0043] d. According to the required carbon increase content of the steel grade to be smelted in each furnace, calculate the required amount of high-density carbon balls through the following carbon addition theoretical calculation model:

[0044] The carbon addition theoretical calculation model is as follows:

[0045]

[0046] In the formula:

[0047] C T is the carbon increase content;

[0048] m c is the mass of the high-density carbon balls, with the unit of Kg;

[0049] VM is the volatile content in the high-density carbon balls;

[0050] ASH is the ash content in the high-density carbon balls;

[0051] M is the moisture content in the high-density carbon balls;

[0052] C raw，i is the carbon content in the i-th type of raw material added to the furnace;

[0053] L cis the loss amount of carbon balls during the entire smelting process;

[0054] W raw，i is the total weight of the i-th raw material charged into the furnace, with the unit of Kg;

[0055] C f is the fixed carbon content in the carbon balls;

[0056] e. When power is supplied for smelting, the arc is initiated at the first gear voltage, with the first-generation reactor at 9000. After the arc is stable about forty minutes later, switch to the second gear voltage level for power supply.

[0057] f. After the molten pool is formed, open the lance of the furnace door. In the early stage, blow oxygen to assist melting to make the raw materials melt better, rapidly raise the temperature of the molten steel, and strengthen the smelting process. In the later stage, accelerate the oxidation rate of impurities in the molten steel and the decarburization process. It is used to clean the furnace door before temperature measurement and sampling, and the oxygen blowing amount is controlled within 50m 3 within.

[0058] g. Compared with all scrap steel, the raw material direct reduced iron has poor electrical conductivity, and phenomena such as raw material wall hanging or non-collapse of materials may occur during the smelting process. Extend the time for adding the second batch of materials according to the actual situation on site.

[0059] h. According to the situation of making foamy slag, carbon can be supplemented in a timely manner to ensure the effect of foamy slag. In the later stage, add high-density carbon balls according to the sampled composition to prevent the molten steel from being over-oxidized.

[0060] i. After the temperature and composition of the molten steel are appropriate, check whether there is any hanging material in the furnace. Only when there is no abnormality can the molten steel be tapped.

[0061] Furthermore, the high-density carbon balls are processed into flat balls or spherical balls with a particle size of 30 - 50 mm.

[0062] Furthermore, the addition amount of high-density carbon balls in the furnace should be flexibly adjusted according to the actual required carbon addition amount and oxygen blowing amount. In the later stage of smelting, appropriate supplementary addition can be made according to the temperature measurement and sampling situation. The consumption of high-density carbon balls per ton of steel is 20 - 30 kg.

[0063] Example 1: The 10-ton electric furnace of Yuanping Zhongying Wanwei uses the method of the present invention to smelt cast steel ZG25Mn2-Ⅱ with the raw material structure of all scrap steel and direct reduced iron.

[0064] Two baskets of materials are charged, with a total charging amount of 12.95 t. The weight of the direct reduced iron + scrap steel in the first basket is 7 t. 300 Kg of high-density carbon balls are added at the bottom of the first basket of materials. The arc is started at voltage level 1, with the first-generation resistance being 9000. After the arc is stable in about 40 minutes, the voltage level is changed to 2 for power supply. The second-generation resistance is used, with the resistance being 9000. After 140 minutes of power supply, the furnace door oxygen lance is opened for oxygen blowing to assist melting. After the first batch of materials in the furnace is completely melted, the second basket of materials is added. The arc is still started at voltage level 1, and after the arc is stable, the voltage level is changed to 2 for power supply. After power supply, the furnace door oxygen lance continues to blow oxygen to assist melting. Then, 450 Kg of the first batch of lime is added. The total oxygen blowing amount at the furnace door is controlled within 50 m 3 and within, the lime is added in 2 batches, with a total lime consumption of 400 Kg and a total oxygen blowing amount of 18.2 m 3 . 400 Kg of high-density carbon balls are used, 3600 KWh of power is supplied, and the carbon addition amount is 1.8%. The carbon content after melting is 0.94%, and the tapping amount is 11.86 t. The total smelting time is 4 h 10 min.

[0065] Example 2: The 10-ton electric furnace of Yuanping Zhongying Wanwei uses the method of the present invention to smelt steel AISI 8630 with a raw material structure of all scrap steel and direct reduced iron.

[0066] Two baskets of materials are charged, with a total charging amount of 12.2 t. The weight of the direct reduced iron + scrap steel in the first basket is 6 t, including 3 t of scrap steel and 2.68 t of direct reduced iron, and 320 Kg of return material from the previous furnace; The arc is started at voltage level 1, with the first-generation resistance being 9000. After the arc is stable in about 40 minutes, the voltage level is changed to 2 for power supply. The second-generation resistance is used, with the resistance being 9000. After slag flowing, the furnace door oxygen lance is used to start oxygen blowing. After 85 minutes of power supply, after the first batch of materials in the furnace is completely melted, 175 Kg of high-density carbon balls are prepared to be added from the furnace door for carbon addition operation during the smelting process. After recording the relevant data of this carbon addition, the second basket of materials is added. The arc is still started at voltage level 1, and after the arc is stable, the voltage level is changed to 2 for power supply. After power supply, the furnace door oxygen lance continues to blow oxygen to assist melting. Then, 400 Kg of the first batch of lime is added. The total oxygen blowing amount at the furnace door is controlled within 50 m 3 and within, the lime is added in 3 batches, with a total lime consumption of 600 Kg and a total oxygen blowing amount of 16.1 m 3 . 175 Kg of high-density carbon balls are used, 2840 KWh of power is supplied, and the carbon addition amount is 0.98%. The carbon content after melting is 0.52%, and the tapping amount is 11.4 t. The total smelting time is 3 h 25 min.

[0067] In the direct reduced iron yard, the high-density carbon balls cannot be attracted by the magnetic disk, so they are spread out and laid at the bottom of the material basket. The total iron content in the supplied direct reduced iron is 93%, and the metallic iron content is 88%; The average weight of each bag of the supplied high-density carbon balls is 25 Kg (which can be changed according to the actual situation), the C content is about 50%, and the particle size is about 30 - 50 mm. When the charging amount is 12.95 t, through the theoretical calculation of the carbon addition amount, it can be known that:

[0068] The carbon content of one bag of high-density carbon balls is 0.096% (the carbon content is 9.6 units), and the carbon content of one bag of electrode powder is 0.16% (the carbon content is 16 units). Comparing the densities of high-density carbon balls and electrode powder, due to the poor quality and low density of the electrode powder, during the process of charging the furnace, the electrode powder cannot effectively pass through the slag layer in the furnace and enter the molten steel to complete carbon addition, resulting in a low recovery rate. Therefore, high-density carbon balls are used for the carbon addition step. At the same time, because the carbon content of the electrode powder is relatively high, high-density carbon balls are used to replace the electrode powder in actual smelting.

[0069] Comparing the raw materials of scrap steel and direct reduced iron, in terms of composition stability, impurity content, and porosity, direct reduced iron shows more excellent aspects. In addition, the carbon content in direct reduced iron is also higher than that in scrap steel. It can be concluded that direct reduced iron is a high-quality raw material for steelmaking. Currently, the electric furnace is considered to be a better metallurgical furnace for using hydrogen-reduced direct reduced iron solid materials. If green and low-carbon electric energy is used, the entire smelting process can achieve a low emission level. Therefore, direct reduced iron is used to replace part of the scrap steel in actual smelting.

[0070] According to the calculation of the carbon addition amount and the poor electrical conductivity of direct reduced iron, when the charging amount is 12 - 13t, the following scheme is adopted: add 300 Kg of high-density carbon balls to each furnace. Spread high-density carbon balls at the bottom of the first basket of materials. Adding at the bottom of the material basket can make the raw material direct reduced iron press the high-density carbon balls into the furnace when entering the furnace, thereby improving the carbon addition efficiency.

[0071] As Figure 1 shown, first, spread high-density carbon balls 5 at the bottom inside the material basket 3, and then add direct reduced iron 6 on the high-density carbon balls 5. Lift the material basket 3 above the electric furnace 1 by the traveling crane 2. At the same time, open the discharge port 4 of the material basket 4 to add the high-density carbon balls 5 and direct reduced iron 6 into the electric furnace 1. Among them, the discharge port 4 is arranged at the side plate of the material basket 4. When discharging, the side plate is turned upward, so that when the discharge port 4 is opened, the high-density carbon balls 5 at the lower part of the material basket 4 enter the electric furnace 1 before the direct reduced iron 6 above it, thereby improving the carbon addition efficiency and reducing the smelting time of the electric furnace.

[0072] As Figure 2 shown, in terms of smelting power consumption, combined with the raw material ratio mode adopted in the present invention and compared with the conventional raw material mode in the factory, it can be concluded that the power consumption shows an obvious downward trend. As Figure 2As shown: Through theoretical calculation, relevant data can be obtained: The average power consumption for smelting in a conventional furnace charge = 3305 KWh / furnace, while the average power consumption data for the test furnace charge of the present invention = 2842 KWh / furnace. The power consumption per furnace is effectively reduced by 463 KWh / furnace, and the power consumption per ton of steel is effectively reduced by 35 KWh / t. The above examples show that when using the electric arc furnace steelmaking method with high-density carbon balls and direct reduced iron replacing electrode powder and scrap steel, it is completely possible to effectively release chemical energy by means of the carbon-oxygen reaction, improve the carbon addition efficiency, and promote the temperature rise of the molten steel. At the same time, it can make the raw materials better melt and slag, significantly reduce both the smelting duration and the smelting power consumption, greatly reduce the smelting cost, optimize the electric arc furnace smelting parameters, and improve the smelting efficiency. The present invention does not require the purchase or modification of any equipment, and the operation method is simple and easy to implement. It is especially suitable for the batch smelting tasks of actual electric arc furnaces in factories and has good application prospects.

[0073] 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 labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on 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. An electric furnace steelmaking method using high-density carbon balls to match carbon, characterized in that: The steps include: (1) According to the carbon content required for each furnace of steel, the required mass of high-density carbon balls is calculated through the following carbon matching theoretical calculation model: Where: C T is the carbon content, %; m c is the mass of high-density carbon balls, in kg; VM is the volatile matter content in high-density carbon spheres, %; ASH is the ash content in high-density carbon balls, %; M is the moisture content in high-density carbon spheres, %; C raw，i is the carbon content of the i-th raw material entering the furnace, %; L c is the amount of carbon ball burned during the entire smelting process, %; W raw，i is the total weight of the i-th raw material entering the furnace, in kg; C f is the fixed carbon content in the carbon sphere, %; (2) First, high-density carbon balls are placed at the bottom of the basket, and then direct reduced iron is added to the high-density carbon balls. The basket is hoisted above the electric furnace by a crane, and at the same time, the discharge port of the basket is opened to add the high-density carbon balls and direct reduced iron into the electric furnace. The discharge port is set at the side plate of the basket, and the side plate is flipped upward so that when the discharge port is opened, the high-density carbon balls located at the bottom of the basket enter the electric furnace before the direct reduced iron above it.

2. The electric furnace steelmaking method using high-density carbon balls and carbon as claimed in claim 1, wherein: The volume density of high-density carbon spheres is 2.0-3.5g / cm 3 .

3. The electric furnace steelmaking method using high-density carbon balls and carbon according to claim 1, wherein: The high-density carbon balls are processed into oblate balls or spherical balls with a particle size of 30-50 mm.

4. The electric furnace steelmaking method using high-density carbon balls and carbon according to claim 1, wherein: During the smelting process, the power supply parameters are controlled in stages: in the initial stage, the arc is started at level 1 voltage, and the power is switched to level 2 voltage after the arc is stable; after the molten pool is formed, oxygen is blown in batches to assist melting. In the early stage, the oxygen blowing amount is controlled to accelerate the melting of raw materials and the heating of the molten steel. In the later stage, oxygen blowing is used to accelerate decarburization and impurity oxidation, and the total oxygen blowing amount is controlled within 50m3; slag-forming agents are added in batches according to the state of the molten pool, and the lime consumption per ton of steel is 30-50kg. High-density carbon balls are added in real time according to the foam slag effect to prevent overoxidation of the molten steel.

5. The electric furnace steelmaking method using high-density carbon balls and carbon according to claim 4, wherein: When the second basket of materials is added after the first basket of materials is completely melted, oxygen blowing is suspended and the arc is started using the first voltage. After the arc is stable, the second voltage and oxygen blowing operations are resumed.

6. The electric furnace steelmaking method using high-density carbon balls and carbon according to claim 4, wherein: During the smelting process, the carbon content of the molten pool is monitored. If it is lower than the target value of 0.2%, 200-300 kg of high-density carbon balls are added to adjust the composition of the molten steel.

7. The electric furnace steelmaking method using high-density carbon balls and carbon according to claim 4, wherein: When the loading amount is 12-13 tons, it is loaded in two baskets, in which the amount of high-density carbon balls added in the first basket is 200-400kg, accounting for 60-80% of the total carbon content.

8. The electric furnace steelmaking method using high-density carbon balls and carbon according to claim 4, wherein: Used to produce medium and high carbon steel castings with carbon content control accuracy ≤±0.05% and nitrogen content ≤80ppm.

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