A smelting process and smelting system for high-carbon steel wire rod in a short-process electric furnace

Abstract

The present invention relates to a smelting process and a smelting system for high-carbon steel wire rods in a short-process electric furnace. The smelting stage in the furnace is divided into several stages, including the scrap addition period, the hot metal charging period, the molten pool formation period, the melting and heating period, and the composition adjustment period. According to the characteristics of the oxygen supply requirements in different smelting stages, the oxygen supply timing and the oxygen supply flow rate are adjusted, so as to achieve precise control of oxygen supply in the furnace, improve the molten pool stirring effect, accelerate the melting of scrap iron, improve the dephosphorization effect, and thus achieve the improvement of smelting efficiency and the stability of end point control.

Description

Technical Field

[0001] The present invention relates to a smelting process and a smelting system for high-carbon steel wire rods in a short-process electric furnace, belonging to the technical field of iron and steel metallurgy. Background Art

[0002] With the development of industry, the electric furnace steelmaking has developed rapidly because the short-process smelting process of the electric furnace uses scrap steel as the main raw material. Compared with the long-process smelting process of blast furnace-converter, the short-process reduces energy consumption by 50% and reduces CO 2 emissions by 75%.

[0003] In the short-process of the electric furnace, in order to improve the stirring effect of the molten bath during the electric furnace smelting process, improve the uniformity of the molten bath, accelerate the melting of scrap steel, and at the same time accelerate the removal of impurity elements, a certain amount of oxygen needs to be blown into the electric furnace during the smelting process. The blowing of oxygen is of great significance for improving the stirring effect of the molten bath, accelerating the melting of scrap steel, increasing the removal rate of impurity elements such as phosphorus, and improving the stability of endpoint control.

[0004] Regarding the oxygen supply system during the smelting process, the blowing timing and blowing amount are key factors. At present, the most common control method of the oxygen supply system mainly relies on long-term smelting experience. When the power consumption of the electric furnace smelting reaches a certain stage or the melting state of the scrap steel is estimated, the oxygen supply flow rate and the blowing timing are adjusted. For example, the application with the publication number CN102312044A provides an electric furnace smelting method. In this method, when the scrap steel near the oxygen lance melts or the adjacent scrap iron material becomes red-hot, the wall lance starts to supply oxygen; when the power consumption reaches a certain amount, the oxygen supply is stopped or the oxygen supply intensity is changed. However, since the electric furnace smelting is in a black box state, it is difficult to achieve precise control of the oxygen supply during the electric furnace smelting process only by experience. The application with the publication number CN113215354A provides an all-scrap steel smelting process for an electric furnace. This method adjusts and controls the oxygen supply timing and oxygen supply flow rate of the wall lance according to the power consumption during the electric furnace smelting process. In fact, due to the changes in factors such as the type and collocation method of the scrap steel charged into the furnace and the timing of hot metal charging, it is also impossible to precisely control the oxygen supply only through the power consumption, which has a greater impact on the smelting efficiency, smelting cost, and the stability of endpoint control. Summary of the Invention

[0005] The present invention provides a smelting process and a smelting system for high-carbon steel wire rods in a short-process electric furnace, which realizes precise control of oxygen supply in the furnace, improves the stirring effect of the molten bath, accelerates the melting of scrap steel, improves the dephosphorization effect, and thus realizes the improvement of smelting efficiency and the stability of endpoint control.

[0006] The technical solution adopted by the present invention to solve its technical problems is:

[0007] A smelting process for high-carbon steel wire rods in a short-process electric furnace, comprising the following steps:

[0008] Step S1, KR hot metal pretreatment;

[0009] Step S2, electric furnace smelting. Select the influencing factors affecting the oxygen supply of the electric furnace from the database, and use the least squares method to fit the oxygen supply required for the furnace to be smelted. Among them, the influencing factors include the weight of the hot metal charged into the furnace and the silicon content of the hot metal charged into the furnace. Confirm that the calculation formula for the oxygen supply required for the furnace to be smelted is: , is the weight of the hot metal charged into the furnace, is the silicon content of the hot metal charged into the furnace, is the oxygen supply required for the furnace to be smelted, with the unit of Nm 3 ;

[0010] Obtain the hot metal charging conditions on the hot metal charging side, the change of electrode height, and the oxygen consumption conditions of oxygen supply in the electric furnace. Divide the electric furnace smelting process into a scrap charging period, a hot metal charging period, a molten pool formation period, a melting and heating period, and a composition adjustment period; adjust the oxygen supply timing and oxygen supply flow according to the oxygen supply curve during the scrap charging period, hot metal charging period, molten pool formation period, melting and heating period, and composition adjustment period;

[0011] Simultaneously determine the end point composition and temperature control requirements of the steel grade to be smelted from the database, and start tapping when the determined control requirements are met;

[0012] Step S3, LF refining. After tapping, lift the ladle into the LF refining station to complete the temperature and composition adjustment, and control the molten steel temperature within the set range;

[0013] Step S4, continuous casting of bloom. Protect the casting throughout the continuous casting process. Use a low basicity and low alumina tundish covering agent, use a low melting point mold powder, and use mold electromagnetic stirring; Adopt a weak cooling mode in the secondary cooling section, and set different water volumes in the four zones of the secondary cooling section;

[0014] Step S5, blooming;

[0015] Step S6, high-speed wire rolling;

[0016] Furthermore, the end point composition of the steel grade to be smelted determined from the database includes, by mass fraction: C > 0.04%, P < 0.012%, S < 0.012%; N < 50 ppm; end point temperature > 1600 °C;

[0017] Furthermore, the chemical composition of the scrap added during the scrap charging period includes, by mass percentage: S ≤ 0.005%, Ni ≤ 0.01%, Cr ≤ 0.03%, Cu ≤ 0.01%, Al ≤ 0.01%, Ti ≤ 0.01%;

[0018] Furthermore, the charging amount of the electric furnace is controlled at 115t - 118t, and the ratio of hot metal charged into the furnace is controlled at 25% - 50%;

[0019] Furthermore, the lime consumption range in the electric furnace smelting process is 30 - 35 kg / t, and the secondary side voltage control range during the power-on process is 713V - 900V;

[0020] Furthermore, in step S2, the scrap charging period is defined as the time period from adding scrap from the ladle to starting power-on, the hot metal pouring period is defined as the time period from starting power-on to completing the pouring of hot metal, the molten bath formation period is defined as the time period from completing the pouring of hot metal to the electrode height dropping to the lowest point, the melting and heating-up period is defined as the time period from the electrode height dropping to the lowest point to when the oxygen supply reaches 90% of the oxygen supply required for the furnace to be smelted, and the composition adjustment period is defined as the time period from when the oxygen supply reaches 90% of the oxygen supply required for the furnace to be smelted to the smelting end point of the steel grade to be smelted;

[0021] During the scrap charging period, the main oxygen flow rate is set at 100 - 120 Nm 3 / h, the epoxy flow rate is 100 - 120 Nm 3 / h, and the coke oven gas flow rate is 80 - 100 Nm 3 / h;

[0022] During the hot metal pouring period, the main oxygen flow rate is set at 200 - 250 Nm 3 / h, the epoxy flow rate is 200 - 250 Nm 3 / h, and the coke oven gas flow rate is 400 - 500 Nm 3 / h;

[0023] During the molten bath formation period, the main oxygen flow rate is set at 1000 - 1200 Nm 3 / h, the epoxy flow rate is 100 - 120 Nm 3 / h, and the coke oven gas flow rate is 100 - 120 Nm 3 / h;

[0024] During the melting and heating-up period, the main oxygen flow rate is set at 1600 - 1800 Nm 3 / h, the epoxy flow rate is 100 - 120 Nm 3 / h, and the coke oven gas flow rate is 100 - 120 Nm 3 / h;

[0025] During the composition adjustment period, the main oxygen flow rate is 1400 - 1500 Nm 3 / h, the epoxy flow rate is 100 - 120 Nm 3 / h, and the coke oven gas flow rate is 100 - 120 Nm 3 / h;

[0026] Furthermore, when one-third of the molten steel is tapped from the electric furnace, a low-nitrogen carburizer is added, and metallic manganese and low-titanium low-aluminum ferrosilicon are added for preliminary deoxidation; during LF refining, the molten steel temperature is controlled at 1525°C - 1535°C;

[0027] After the temperature and composition adjustment are completed during LF refining, the bottom blowing argon gas in the ladle is turned down to the soft stirring state to remove inclusions. The argon gas flow rate is set at 60 NL / min - 110 NL / min, and the soft stirring time is set at 26 min - 31 min;

[0028] Furthermore, when casting with a bloom caster, the superheat of the molten steel in the tundish is controlled at 20°C - 30°C; the water volume in the mold is set at 2975 L / min - 3025 L / min;

[0029] The water volumes in the four zones of the secondary cooling section are sequentially set at 60 NL / min - 100 NL / min, 20 NL / min - 50 NL / min, 20 NL / min - 40 NL / min, and 10 NL / min - 30 NL / min;

[0030] Furthermore, in the blooming process, the blooming heating temperature is set at 1180°C - 1250°C, and the bloom is formed into 140 mm × 140 mm;

[0031] In the high-speed wire rolling process, the heating temperature is set at 1080°C - 1160°C, the rolling start temperature is set at 960°C - 1030°C, and the laying head temperature is set at 860°C - 920°C;

[0032] The smelting system for the high-carbon steel wire rod smelting process of the short-process electric furnace includes electrodes, industrial cameras, wire rope encoders, and several supersonic clustered oxygen lances;

[0033] The electrodes are inserted into the electric furnace, and they are drivenly connected to the electrode lifting hydraulic cylinders through electrode cross arms. The wire ropes of the wire rope encoders are installed on the electrode lifting hydraulic cylinders. When the electrodes move up and down in the electric furnace, the wire rope encoders can measure the height changes of the electrodes in real time;

[0034] The industrial cameras are installed on the side of the hot metal ladle for charging to monitor the charging working conditions in real time;

[0035] One supersonic clustered oxygen lance is installed on each side of the furnace door of the electric furnace. The position deviating from the center relative to the center of the electric furnace is defined as the eccentric zone, and one supersonic clustered oxygen lance is installed in the eccentric zone respectively.

[0036] Through the above technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The smelting process of high-carbon steel wire rod in a short-process electric furnace provided by the present invention divides the in-furnace smelting stage into several stages including scrap addition period, hot metal charging period, molten pool formation period, melting and heating period, and composition adjustment period. According to the oxygen supply demand characteristics of different smelting stages, the oxygen supply timing and oxygen supply flow rate are adjusted, thereby improving the electric furnace smelting effect.

[0038] 2. The smelting system of the high-carbon steel wire rod smelting process provided by the present invention can real-time feedback the hot metal charging situation during the electric furnace smelting process and real-time track the change of electrode height, conduct dynamic analysis of the smelting state, and achieve precise control of oxygen supply during the electric furnace smelting process. Detailed Embodiment

[0039] Now, the present invention will be further described in detail. The specific dimensions adopted in this embodiment are only for illustrating the technical solution and do not limit the protection scope of the present invention.

[0040] As described in the background technology, in actual working conditions, the electric furnace smelting is in a black box state, and there is a lack of appropriate feedback on the changes of factors such as the type and matching method of the scrap charged into the furnace and the hot metal charging timing, and it is even more impossible to conduct dynamic analysis of the smelting state during the electric furnace smelting process.

[0041] The present application provides a smelting process of high-carbon steel wire rod in a short-process electric furnace. Through corresponding monitoring means, the in-furnace smelting state is real-time feedback, the smelting state is dynamically analyzed, and the entire smelting stage is refined into: scrap addition period, hot metal charging period, molten pool formation period, melting and heating period, and composition adjustment period. Then, according to the oxygen supply demand characteristics of different smelting stages, the oxygen supply timing and oxygen supply flow rate are adjusted, thereby improving the electric furnace smelting effect.

[0042] The smelting process includes the following steps:

[0043] Step S1, KR hot metal pretreatment.

[0044] Step S2, electric furnace smelting. There are several innovation points in this step. First, it is about obtaining the required oxygen supply for the furnace to be smelted. When obtaining it, there are two innovation points. One is the selection of factors affecting the oxygen supply of the electric furnace, and the other is how to form a functional balance relationship between various factors. During the electric furnace smelting process, since hot metal needs oxygen to complete the oxidation reaction, if the weight of the hot metal increases, in order to make these oxidation reactions proceed fully, the oxygen supply needs to be increased accordingly. At the same time, because the injection of oxygen can play a role in stirring the molten pool, when the weight of the hot metal is large and a deeper molten pool is formed, sufficient oxygen is required to penetrate the molten pool to promote chemical reactions and the circulation flow of the molten pool. Therefore, the weight of the hot metal charged into the furnace must be one of the important factors affecting the oxygen supply.

[0045] Secondly, the oxidation reaction of silicon during the electric furnace smelting process is one of the important reactions. The higher the silicon content, the more oxygen is consumed. During this process, in order to fully oxidize and remove silicon, sufficient oxygen supply is required. The oxidation reaction product of silicon, silicon dioxide, enters the slag, so the silicon content will change the properties of the slag such as viscosity. Therefore, the silicon content of the hot metal charged into the furnace is the second important factor affecting the oxygen supply amount.

[0046] After selecting the influencing factors, assuming there is a series of sample data in the database, including different hot metal weights, silicon contents, and the corresponding actual oxygen supply amounts, a linear model is needed to find the best function matching of the data. At this time, the least squares method that minimizes the sum of the squares of the errors is most suitable. Therefore, the influencing factors affecting the oxygen supply amount of the electric furnace are selected from the database, and the least squares method is used to fit the oxygen supply amount required for the furnace to be smelted. Among them, the influencing factors include the hot metal weight charged into the furnace and the silicon content of the hot metal charged into the furnace. The calculation formula for confirming the oxygen supply amount required for the furnace to be smelted is: , is the hot metal weight charged into the furnace, is the silicon content of the hot metal charged into the furnace, is the oxygen supply amount required for the furnace to be smelted, with the unit of Nm 3 ;

[0047] Before the electric furnace smelting, it is necessary to set the electric furnace charging amount to be controlled at 115t - 118t, and the ratio of hot metal charged into the furnace to be controlled at 25% - 50%; after the electric furnace smelting starts, by detecting the hot metal charging condition on the hot metal charging side, the change of electrode height, and the oxygen supply and consumption condition in the electric furnace, the electric furnace smelting process is divided into the scrap addition period, the hot metal charging period, the molten pool formation period, the melting and heating period, and the composition adjustment period. At the same time, the oxygen supply timing and oxygen supply flow rate are adjusted according to the oxygen supply curve in different stages to improve the electric furnace smelting effect.

[0048] Specifically, the scrap addition period is defined as the time period from adding scrap from the ladle to starting power on. In this stage, the furnace is mainly filled with solid scrap, and almost no large-scale oxidation reaction occurs. At this time, the oxygen consumption is mainly used for a small amount of preheating oxidation in the furnace and removing impurities on the surface of the scrap. Since there is no molten pool and a large amount of oxygen is not required to participate in the reaction, it is the starting stage of oxygen consumption. Therefore, the main oxygen flow rate is set to 100 - 120 Nm 3 / h, the epoxy flow rate is 100 - 120 Nm 3 / h, and the coke oven gas flow rate is 80 - 100 Nm 3 / h. At this time, the oxygen supply can be paid attention to, and a suitable initial atmosphere in the furnace can be established to create conditions for subsequent reactions.

[0049] Preferably, the present application also provides the composition of the scrap added during the scrap addition period, and its chemical composition by mass percentage includes: S≤0.005%, Ni≤0.01%, Cr≤0.03%, Cu≤0.01%, Al≤0.01%, Ti≤0.01%.

[0050] The hot metal charging period is defined as the time period from the start of power-on to the completion of hot metal charging. When hot metal is charged, elements in the hot metal (such as carbon, silicon, manganese, etc.) will undergo oxidation reactions with oxygen. The high temperature and highly active components of the hot metal require a certain amount of oxygen to control the reaction process. For example, the decarburization reaction begins to proceed initially. Therefore, it needs to be separately divided to better control the oxygen supply and reaction. Specifically, the main oxygen flow rate is set to 200 - 250 Nm 3 / h, the epoxy flow rate is 200 - 250 Nm 3 / h, and the coke oven gas flow rate is 400 - 500 Nm 3 / h.

[0051] The molten bath formation period is defined as the time period from the completion of hot metal charging to the lowest point of the electrode height drop. The main oxygen flow rate is set to 1000 - 1200 Nm 3 / h, the epoxy flow rate is 100 - 120 Nm 3 / h, and the coke oven gas flow rate is 100 - 120 Nm 3 / h. The molten bath formation period is set separately because as the scrap continuously melts, the molten bath begins to form, the contact area between the molten steel in the molten bath and oxygen increases, the oxidation reaction becomes more intense, and the oxygen consumption significantly increases. This period is a transitional stage in the electric furnace smelting process from mainly solid reactions to mainly liquid reactions. The oxygen supply is crucial for the formation and stability of the molten bath and the continuous progress of the oxidation reaction. Therefore, it is divided according to the change characteristics of oxygen consumption to facilitate precise oxygen supply.

[0052] After the molten bath is formed, a large amount of heat is required to completely melt the remaining solid scrap. The oxygen consumption reaches a peak during this process. To ensure the melting and heating-up efficiency, this period has significant differences in both oxygen consumption and process requirements. Therefore, the melting and heating-up period is set and defined as the time period from the lowest point of the electrode height drop to when the oxygen supply reaches 90% of the required oxygen supply for the furnace charge to be smelted. Specifically, the main oxygen flow rate is set to 1600 - 1800 Nm 3 / h, the epoxy flow rate is 100 - 120 Nm 3 / h, and the coke oven gas flow rate is 100 - 120 Nm 3 / h.

[0053] Finally, when all the molten steel is melted and the temperature reaches the required level, the composition adjustment begins. Thus, it is the composition adjustment period, which is defined as the time period starting from when the oxygen supply reaches 90% of the required oxygen supply for the furnace to be smelted until the end point of the steel grade to be smelted. The key point in this period is to precisely control the composition of the molten steel. The oxygen supply is mainly used for fine-tuning reactions, which is different from the purpose of obtaining heat by supplying a large amount of oxygen in the melting and heating-up period. Therefore, it needs to be separately divided to control the oxygen flow according to the specific requirements of the composition adjustment. Specifically, the main oxygen flow is set to 1400 - 1500 Nm 3 / h, the epoxy flow is 100 - 120 Nm 3 / h, and the coke oven gas flow is 100 - 120 Nm 3 / h.

[0054] The end-point composition of the steel grade to be smelted determined from the database in terms of mass fraction includes: C > 0.04%, P < 0.012%, S < 0.012%; N < 50 ppm; the end-point temperature > 1600 °C. When the above settings are reached, tapping begins. When one-third of the steel is tapped from the electric furnace, a low-nitrogen carburizer is added, and metallic manganese and low-titanium and low-aluminum ferrosilicon are added for pre-deoxidation. After tapping is completed, the ladle is lifted into the LF refining station for LF refining in step S3 to complete the temperature and composition adjustment, and the temperature of the molten steel is controlled at 1525 °C - 1535 °C.

[0055] After the composition adjustment is completed, the bottom blowing argon of the ladle is gradually reduced to the soft stirring state to remove inclusions. The argon flow is set to 60 NL / min - 110 NL / min. In the early stage, the fluctuation of the slag surface should be observed frequently. With the slag surface fluctuating slightly, the soft stirring time is set to 26 min - 31 min.

[0056] In the entire above-mentioned electric furnace smelting process, the lime consumption range is 30 - 35 kg / t, and the control range of the secondary-side voltage during the power-on process is 713 V - 900 V.

[0057] Step S4, continuous casting of bloom. The whole continuous casting process is carried out under protective casting. A low-alkalinity and low-aluminum oxide tundish covering agent is used to control the superheat of the molten steel in the tundish at 20 °C - 30 °C; a low-melting-point mold powder is used, and mold electromagnetic stirring is used; the mold water volume is set to 2975 L / min - 3025 L / min; the secondary cooling section adopts a weak cooling mode, and the water volumes in the four zones of the secondary cooling section are sequentially set to 60 NL / min - 100 NL / min, 20 NL / min - 50 NL / min, 20 NL / min - 40 NL / min, and 10 NL / min - 30 NL / min.

[0058] Step S5, blooming. The blooming heating temperature is set to 1180 °C - 1250 °C, and the bloom is formed into 140 mm × 140 mm.

[0059] Step S6, high-speed wire rolling, with the heating temperature set at 1080°C - 1160°C, the starting rolling temperature at 960°C - 1030°C, and the wire spitting temperature at 860°C - 920°C.

[0060] In implementing the above-mentioned high-carbon steel wire rod smelting process, relevant working condition data needs to be provided in real time. Therefore, this application also provides a smelting system for the high-carbon steel wire rod smelting process of the short-process electric furnace, which mainly includes electrodes, industrial cameras, wire rope encoders, and several supersonic clustered oxygen lances; the electrodes are inserted into the electric furnace and are driven and connected to the electrode lifting hydraulic cylinders through electrode cross arms. The wire rope of the wire rope encoder is installed on the lifting hydraulic cylinder. When the electrodes move up and down in the electric furnace, the wire rope encoder can measure the height change of the electrodes in real time; the industrial camera is installed on the side of the ladle for hot metal charging to monitor the hot metal charging working condition in real time; one supersonic clustered oxygen lance is installed on each side of the furnace door of the electric furnace. The position deviating from the center relative to the center of the electric furnace is defined as the eccentric area, and one supersonic clustered oxygen lance is installed in each eccentric area.

[0061] In the smelting process, since the oxygen consumption needs to be measured in real time, a mass flow meter, an orifice flow meter, etc. can be used, without special limitation.

[0062] The following gives 3 embodiments in the specific application of the present invention to verify the feasibility of the high-carbon steel wire rod smelting process of the short-process electric furnace provided by this application.

[0063] After the hot metal charged into the furnace undergoes KR desulfurization, the weight of the hot metal charged into the furnace and the silicon content of the hot metal charged into the furnace for this heat are obtained from the database, and the required oxygen supply for this heat is calculated using the oxygen supply formula. The results provided in Embodiment 1 - Embodiment 3 are shown in Table 1.

[0064] Table 1

[0065]

[0066] Obtain the hot metal charging working condition on the hot metal charging side, the height change of the electrodes, and the oxygen supply and oxygen consumption working condition in the electric furnace. Divide the electric furnace smelting process into a scrap addition period, a hot metal charging period, a molten pool formation period, a melting and heating period, and a composition adjustment period, and adjust the oxygen supply in different periods, as shown in Table 2 (Embodiment 1), Table 3 (Embodiment 2), and Table 4 (Embodiment 3). The lime consumption during the electric furnace smelting process is controlled at 30 - 35 kg / t, and the secondary side voltage during the power-on process is controlled at 713V - 900V.

[0067] Table 2

[0068]

[0069] Table 3

[0070]

[0071] Table 4

[0072]

[0073] The tapping temperature at the end of electric furnace smelting, and the contents of phosphorus, sulfur and nitrogen at the end are shown in Table 5:

[0074] Table 5

[0075]

[0076] When one-third of the steel is tapped from the electric arc furnace, a low-nitrogen carburizer is first added to the ladle, metallic manganese is added for pre-deoxidation, and low-titanium low-aluminum ferrosilicon is added. After tapping is completed, a low-nitrogen carburizer is added to the ladle, and the flow rate of bottom-blown argon is controlled. The addition amounts of carburizer and alloy during tapping, the addition amount of carburizer after tapping is completed, and the bottom-blowing control mode are shown in Table 6:

[0077] Table 6

[0078]

[0079] Temperature measurement and sampling are carried out. According to the composition of the molten steel sample and the requirements of the steel grade, the remaining low-nitrogen carburizer, metallic manganese and low-titanium low-aluminum ferrosilicon are added for composition adjustment. After the composition adjustment is completed, the temperature of the molten steel is controlled within a suitable range. Soft stirring is used to remove inclusions, and the bottom-blowing argon of the ladle is gradually reduced to the soft stirring state, and the soft stirring time is controlled. The carburizer, alloy, molten steel temperature, soft stirring bottom-blowing flow rate and soft stirring time are shown in Table 7:

[0080] Table 7

[0081]

[0082] Immediately afterwards, the continuous casting process is entered. The continuous caster is a straight-arc rectangular billet continuous caster. The cross-sectional size of the continuous casting billet is 300 mm×390 mm, and the arc radius is 12.5 m. The starting casting tonnage of the tundish is set at 19 t, the tundish tonnage during normal casting is 35 t, and the tundish tonnage during continuous casting ladle change is 32 t. The superheat of the molten steel in the tundish is controlled at 28 °C, and the continuous casting drawing speed is controlled at 0.6 m / min. The reduction amount in each section, the pressure of the reduction roll, the thickness of the mold powder layer, the argon flow rate of the long nozzle, the electromagnetic current of the mold, the mold frequency, and the mold water volume are shown in Table 8.

[0083] Table 8

[0084]

[0085] In the secondary cooling section, a weak cooling mode is adopted. The water flow rates in the secondary cooling section from Zone 1 to Zone 4 are as follows: 80 NL / min in Zone 1, 45 NL / min in Zone 2, 30 NL / min in Zone 3, and 25 NL / min in Zone 4. In the bloom casting and rolling processes, the bloom casting heating temperature, rolling heating temperature, rolling start temperature, and wire laying temperature for a bloom of 140 mm × 140 mm are set as shown in Table 9:

[0086] Table 9

[0087]

[0088] In summary, according to the division of the electric furnace smelting stage, the oxygen supply adjustment method for each stage is set to achieve precise control of the oxygen supply in the furnace, improve the molten bath stirring effect, accelerate the melting of scrap, improve the dephosphorization effect, thereby improving the smelting efficiency and stabilizing the end point control.

[0089] Those skilled in the art of this technology can understand that unless otherwise defined, all terms (including technical terms and scientific terms) used here have the same meaning as the general understanding of those of ordinary skill in the technical field to which this application belongs. It should also be understood that terms defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless defined as here.

[0090] The meaning of "and / or" as described in this application refers to the situation where each exists alone or both exist simultaneously.

[0091] The meaning of "connection" as described in this application can be a direct connection between components or an indirect connection between components through other components.

[0092] Taking the ideal embodiments based on the present invention as inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A short-process electric furnace high carbon steel wire smelting process, characterized in that: The following steps are involved: Step S1, KR molten iron pretreatment; Step S2, electric furnace smelting, select the factors affecting the oxygen supply of the electric furnace from the database, and use the least squares method to fit the required oxygen supply for the furnace to be smelted, where the influencing factors include the weight of the molten iron entering the furnace and the silicon content of the molten iron entering the furnace. The calculation formula for confirming the required oxygen supply for the furnace to be smelted is: ， is the weight of molten iron entering the furnace, in t, is the silicon content of molten iron entering the furnace, in %, The oxygen supply required for the smelting furnace, in Nm 3 ; Obtain the molten iron addition conditions on the iron addition side, the electrode height change, and the oxygen supply and oxygen consumption conditions in the electric furnace, and divide the electric furnace smelting process into the scrap steel addition period, the iron addition period, the molten pool formation period, the melting temperature rise period, and the composition adjustment period; during the scrap steel addition period, the iron addition period, the molten pool formation period, the melting temperature rise period, and the composition adjustment period, adjust the oxygen supply timing and oxygen supply flow rate according to the oxygen supply curve; The scrap steel adding period is defined as the time period from the addition of scrap steel to the start of power on, the iron adding period is defined as the time period from the start of power on to the completion of molten iron adding, the molten pool formation period is defined as the time period from the completion of molten iron adding to the drop in the electrode height to the lowest point, the melting temperature rising period is defined as the time period from the drop in the electrode height to the lowest point to the oxygen supply reaching 90% of the oxygen supply required for the smelting furnace, and the composition adjustment period is defined as the time period from the oxygen supply reaching 90% of the oxygen supply required for the smelting furnace to the end of smelting of the steel grade to be smelted; During the scrap steel adding period, set the main oxygen flow rate to 100-120Nm 3 / h, epoxy flow rate is 100-120 Nm 3 / h, coke oven gas flow rate is 80-100Nm 3 / h; During the iron addition period, set the main oxygen flow rate to 200-250Nm 3 / h, epoxy flow rate is 200-250 Nm 3 / h, coke oven gas flow rate is 400-500Nm 3 / h; During the molten pool formation period, set the main oxygen flow rate to 1000-1200Nm 3 / h, epoxy flow rate is 100-120 Nm 3 / h, coke oven gas flow rate is 100-120Nm 3 / h; During the melting and heating period, set the main oxygen flow rate to 1600-1800Nm 3 / h, epoxy flow rate is 100-120 Nm 3 / h, coke oven gas flow rate is 100-120Nm 3 / h; During the composition adjustment period, the main oxygen flow rate is 1400-1500Nm 3 / h, epoxy flow rate is 100-120 Nm 3 / h, coke oven gas flow rate is 100-120Nm 3 / h; The end point composition and temperature control requirements of the steel to be smelted are determined from the database at the same time, and steel tapping begins when the determined control requirements are met; Step S3, LF refining, after the steel is tapped, the ladle is hoisted into the LF refining station to complete the temperature and composition adjustment, and the temperature of the molten steel is controlled within the set range; Step S4, casting of large square billets by continuous casting machine, protection casting during the whole continuous casting process, using low basicity and low alumina tundish covering agent, using low melting point crystallizer protection slag, and using crystallizer electromagnetic stirring; the second cooling section adopts weak cooling mode, and different water volumes are set in the four zones of the second cooling section; Step S5, blanking; Step S6, high-speed wire rolling.

2. The high carbon steel wire smelting process of the short process electric furnace according to claim 1, characterized in that: The endpoint composition of the steel to be smelted determined from the database includes, by mass fraction: C>0.04%, P<0.012%, S<0.012%; N<50ppm; endpoint temperature>1600℃.

3. The high carbon steel wire smelting process of the short process electric furnace according to claim 1, characterized in that: The charging amount of the electric furnace is controlled at 115t-118t, and the molten iron ratio is controlled at 25%-50%.

4. The high carbon steel wire smelting process of the short process electric furnace according to claim 1, characterized in that: The lime consumption range of the electric furnace smelting process is 30-35kg / t, and the secondary side voltage control range during the power-on process is 713V-900V.

5. The high carbon steel wire smelting process of the short process electric furnace according to claim 1, characterized in that: The chemical composition of the scrap steel added during the scrap steel adding period includes, by mass percentage: S≤0.005%, Ni≤0.01%, Cr≤0.03%, Cu≤0.01%, Al≤0.01%, and Ti≤0.01%.

6. The high carbon steel wire smelting process of the short process electric furnace according to claim 1, characterized in that: When one third of the steel is discharged from the electric furnace, a low nitrogen carburizer is added, and metallic manganese and low titanium and low aluminum ferrosilicon are added for pre-deoxidation; during LF refining, the temperature of the molten steel is controlled at 1525℃-1535℃; After the temperature and composition are adjusted after LF refining, the argon gas at the bottom of the ladle is adjusted to a soft stirring state to remove inclusions. The argon gas flow rate is set to 60 NL / min -110NL / min, and the soft stirring time is set to 26min -31min.

7. The high carbon steel wire smelting process of the short process electric furnace according to claim 1, characterized in that: When using a large square billet continuous casting machine for casting, control the superheat of the molten steel in the tundish to 20℃-30℃; set the water volume of the crystallizer to 2975 L / min-3025L / min; The water volume in the four zones of the secondary cooling section is set to 60 NL / min -100 NL / min, 20 NL / min -50 NL / min, 20NL / min -40 NL / min, and 10 NL / min-30 NL / min respectively.

8. The high carbon steel wire smelting process of the short process electric furnace according to claim 1, characterized in that: In the blanking process, the blanking heating temperature is set to 1180°C-1250°C, and the blank is formed into 140mm×140mm; In the high-speed wire rolling process, the heating temperature is set to 1080℃-1160℃, the rolling start temperature is set to 960℃-1030℃, and the wire laying temperature is set to 860℃-920℃.

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