Method for producing molten iron using electric furnace equipped with imaging device

Abstract

The present invention reliably and stably supplies a cold iron source to a melting chamber. A method for producing molten iron uses an electric furnace equipped with a preheating chamber, a melting chamber, an extruder disposed in the preheating chamber, and an imaging device for observing the interior of the melting chamber. The method comprises: an extrusion step in which the cold iron source preheated in the preheating chamber is supplied to the melting chamber by the extruder; and a melting step in which the cold iron source supplied to the melting chamber is melted by arc heat to obtain molten iron. In the extrusion step, the movement amount of the extruder and / or the time interval for moving the extruder are controlled based on visual information obtained from the imaging device.

Description

Technical Field

[0001] The present invention relates to a method for producing molten iron from a chill source using an electric furnace equipped with an imaging device. In particular, the present invention relates to a method for producing molten iron in which the supply of the chill source from a preheating chamber to a melting chamber can be observed and the supply conditions of the chill source to the melting chamber can be controlled based on the visual information. Background Art

[0002] When producing molten iron using an electric furnace, the molten iron is obtained by melting a cold iron source such as scrap using arc heat. This generates a significant amount of electricity, leading to the problem of generating arc heat. Conventional methods for reducing electricity consumption in electric furnaces include preheating the cold iron source prior to melting using burners fueled by fossil fuels, preheating the cold iron source prior to melting using high-temperature exhaust gas generated during the previous melting process, and blowing coke into the melting chamber as an auxiliary heat source.

[0003] For example, Patent Document 1 discloses a technique in which, in an electric furnace with a preheating shaft directly connected to a melting chamber, a chill source is continuously or intermittently supplied to the preheating shaft to maintain a continuous presence in both the melting chamber and the preheating shaft, while the chill source in the melting chamber is melted by an electric arc. The technique in Patent Document 1 utilizes an electric furnace that does not require a dedicated device for supplying chill source to the melting chamber. The chill source, preheated by high-temperature exhaust gas, is melted into molten iron, effectively melting the chill source.

[0004] For example, Patent Document 2 discloses an electric furnace control system, which is an electric furnace operation control system comprising: an input unit that receives setting items that serve as operating conditions for electrolytic refining; and a control unit that inputs the setting items into a neural network and executes electric furnace refining based on an inferred value of the operating result.

[0005] For example, Patent Document 3 discloses a method for producing a molten metal using an arc melting device. The method is characterized in that the method comprises: a state change detection step for detecting a state change of the melting chamber when an arc discharge occurs; and a supply speed adjustment step for adjusting the supply speed of the iron source to the melting chamber based on the detection result of the state change detection step.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 10-292990

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2018-70926

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2011-69606 Summary of the Invention

[0011] However, the present inventors conducted research and confirmed that while the technique of Patent Document 1 essentially relies on preheating the chill and its own weight to slowly melt the chill while continuously supplying it to the melting chamber, the chill supply can actually stagnate along the path from the preheating shaft to the melting chamber. This is due to unintended circumstances, such as excessive preheating of the chill, which can lead to large lumps, or gaps forming in the chill tower. However, the technique of Patent Document 1 prevents direct observation of the chill within the melting chamber, making it impossible to detect these unintended circumstances during operation. Furthermore, it was discovered that this irregular chill supply increases power consumption in the electric furnace.

[0012] The technology in Patent Document 2 is an electric furnace operation control system that constructs a neural network that reflects the furnace's most recent state and can accurately estimate the final carbon concentration of the tapped molten steel. However, the data used is captured in the scrap loading device, specifically, the chill before it is loaded into the furnace. The chill temperature varies before and after loading, and the stacking pattern of the chills also changes after loading. Therefore, this technology is insufficient for ensuring a stable supply of chills. Furthermore, while this technology addresses the control of the final carbon concentration and temperature, it is also insufficient for producing molten iron with high efficiency and low power consumption.

[0013] The technology of Patent Document 3 describes adjusting the supply rate of the iron source to the melting chamber based on the results of the detection process. However, it does not focus on the behavior of the chill source in the electric furnace and is insufficient for stably supplying the chill source.

[0014] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing molten iron using an electric furnace, which can reliably and stably supply a cold iron source to a melting chamber and obtain molten iron with high efficiency and low power consumption.

[0015] The present inventors have conducted extensive research to find a solution to the aforementioned problems and have discovered that by installing a device (an extruder) in an electric furnace to supply a chill source to a melting chamber and providing an imaging device capable of observing the interior of the melting chamber, and by optimizing the operating conditions of the extruder based on the conditions within the melting chamber obtained from the imaging device, a stable and reliable chill source supply to the melting chamber can be achieved. Furthermore, the inventors have discovered that this stable chill source supply prevents operational failures and effectively reduces power consumption during manufacturing.

[0016] The present invention has been completed based on the above findings, and the gist of the present invention is as follows.

[0017] 1. A method for producing molten iron using an electric furnace having a preheating chamber and a melting chamber, wherein:

[0018] The electric furnace further comprises: an extruder disposed in the preheating chamber; and an imaging device for observing the interior of the melting chamber; the method for producing molten iron comprises:

[0019] extrusion process, in the preheating chamber, supplying the cold iron source preheated in the preheating chamber to the melting chamber by the extruder, and

[0020] a melting step in which, in the melting chamber, a cold iron source supplied to the melting chamber is melted by arc heat to obtain molten iron;

[0021] In the extrusion step, either or both of the amount of movement of the extruder and the time interval for moving the extruder are controlled based on the visual information obtained from the imaging device.

[0022] Here, in the present invention, the "movement amount of the extruder" refers to the movement distance of the extruder along the extrusion direction when the extruder moves from the preheating chamber side to the melting chamber side once. In addition, the "time interval for moving the extruder" refers to the time (T0) from the start of the movement of the extruder at a certain time. START ) to the next start of extruder movement (T1 START ) to the interval (refer to Figure 2A and Figure 2B ).

[0023] 2. The method for producing molten iron according to item 1 above, wherein, in the extrusion step, when it is confirmed based on visual information obtained from the imaging device that the cold iron source is not being supplied from the preheating chamber to the melting chamber, either or both of increasing the movement amount and decreasing the time interval are performed.

[0024] 3. The method for producing molten iron according to 1 or 2 above, wherein, in the extrusion step, when the extrusion pressure of the extruder is 40 MPa or less, either or both of increasing the movement amount and decreasing the time interval are performed.

[0025] According to the present invention, a cold iron source can be stably and reliably supplied to a melting chamber in an electric furnace. This improves the melting efficiency of the cold iron source, effectively reduces power consumption, and prevents operational failures, thus having a significant industrial effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a longitudinal sectional view of an electric furnace equipped with an imaging device used in one embodiment of the present invention.

[0027] FIG2 is a conceptual diagram illustrating the amount of movement of the extruder and the time interval for moving the extruder. Figure 2A Indicates the extrusion behavior at a certain moment, Figure 2B Indicates the extrusion behavior at the next moment after a certain moment. DETAILED DESCRIPTION

[0028] Next, embodiments of the present invention will be described in detail.

[0029] The following embodiment shows a preferred example of the present invention, and the present invention is not limited to these examples.

[0030] (Method for producing molten iron)

[0031] The method for producing molten iron of the present invention utilizes an electric furnace having a predetermined structure and comprises: an extrusion step in which a cold iron source preheated in a preheating chamber is supplied to a melting chamber by an extruder; and a melting step in which the cold iron source supplied to the melting chamber is melted using arc heat to produce molten iron. The method may optionally include other steps. Furthermore, in the extrusion step of the present invention, operating conditions of the extruder are controlled based on visual information obtained from an imaging device for observing the interior of the melting chamber.

[0032] By appropriately and timely controlling the operating conditions of the extruder based on visual information within the melting chamber, a cold iron source can be stably and reliably supplied to the melting chamber, effectively reducing power consumption in the electric furnace.

[0033] [Electric stove]

[0034] Hereinafter, an electric furnace to which the present invention can be suitably applied will be described in detail with reference to the drawings.

[0035] The electric furnace 1 includes: a melting chamber 2, which melts a cold iron source 15 using heat from an arc 18 to obtain molten iron 16; a preheating chamber 3, which is used to preheat the cold iron source 15 and supply the preheated cold iron source 15 to the melting chamber 2 using an extruder 10; and an imaging device 30, which is installed at an arbitrary position.

[0036] Chilled iron source 15 as a raw material is loaded into supply bucket 14 and transported to above a desired chilled iron source supply port 19 via traveling carriage 23. Next, chilled iron source supply port 19 is opened and chilled iron source 15 is supplied to preheating chamber 3 from above.

[0037] The cold iron source 15 supplied to the preheating chamber 3 can be preheated by any method. For example, if the cold iron source 15 is preheated by passing the highly heated exhaust gas previously generated in the melting chamber 2 through the preheating chamber 3, production efficiency can be improved. The exhaust gas is drawn through the duct 20 and passed through the preheating chamber 3, and excess exhaust gas can be exhausted through the duct 20.

[0038] The preheated cold iron source 15 is continuously supplied to the melting chamber 2 through the extruder 10. The extruder 10 continuously extrude the cold iron source 15 in the preheating chamber 3 into the melting chamber by repeatedly moving its front end toward the melting chamber side. The supply amount and supply timing of the cold iron source 15 to the melting chamber 2 by the extruder 10 can usually be adjusted by the movement amount of the extruder 10 and the time interval for moving the extruder 10. The greater the movement amount of the extruder 10 or the shorter the time interval for moving the extruder 10, the more the supply of the cold iron source 15 is promoted. In addition, from the perspective of operating efficiency, these movement amounts and time intervals are usually initially set to a certain value and then automatically operated. However, in the present invention, as described in detail later, it is important to confirm on the spot the situation of supplying the cold iron source 15 to the melting chamber 2, and based on the confirmation result, control the operating conditions of the extruder 10 in a simultaneous manner.

[0039] It should be noted that the extruder 10 generally has a barrel structure.

[0040] The melting chamber 2 is divided by a furnace wall 4 and a furnace roof 5. It is typically equipped with an electrode 6 for generating an arc 18 for heating, an oxygen injection lance 7 and a carbon material injection lance 8 for maintaining a desired high temperature, and a burner 9 for locally heating low-temperature areas. A cold iron source 15 supplied to the melting chamber 2 is melted by the arc heat, forming molten iron 16 and molten slag 17. The resulting molten iron 16 can be tapped from a tapping port 12 by opening a tapping door 21. The molten slag 17 can be discharged from a tapping port 13 by opening a tapping door 22.

[0041] As the cold iron source 15, there are usually internal waste generated in the ironworks, waste generated from the city, pig iron obtained by solidifying molten iron, etc., but it is not limited to these. As internal waste generated in the ironworks, there are, for example, the unstable part (the part at the beginning of casting, the part generated at the end of casting) of the casting sheet cast by continuous casting or agglomeration method, and the steel ingot produced by rolling steel materials such as steel strips. In addition, as waste generated from the city, there are construction steel (H-shaped steel, etc.), automobile steel, tanks and other recycled materials. In addition, pig iron obtained by solidifying molten iron is obtained by flowing out and solidifying molten iron obtained from iron ore, coke, etc. in a smelting furnace such as a blast furnace.

[0042] The imaging device 30 is not particularly limited; any device capable of capturing an image of the object being observed may be used. It typically includes a lens and a camera. A cooling gas of any flow rate is preferably passed around a lens (not shown) located at the front end of the imaging device 30. Proper cooling of the imaging device 30 allows the device to withstand the high temperatures within the electric furnace and prevents the field of view from being narrowed by the scattering of slag and molten steel. Examples of cooling gases include inert gases such as air and nitrogen. Furthermore, when the imaging device 30 is installed on the furnace wall 4, for example, it is preferable to also cool the furnace wall 4 with water or air.

[0043] From the perspective of accurately capturing the behavior of the cold iron source 15 being extruded from the preheating chamber 3 into the melting chamber 2, the imaging device 30 is preferably installed on the furnace wall 4 or furnace cover 5 that divides the melting chamber 2, and more preferably on the furnace wall 4. Furthermore, from the same perspective as above, it is preferably installed in the melting chamber 2 at an appropriate height where slag and molten steel are less likely to fly. The installation method is not particularly limited. When the imaging device 30 is installed on the furnace wall 4, it is preferable to install it through a hole (not shown) opened in the furnace wall 4. This allows the lens to be located inside the melting chamber 2 and the camera to be located outside the electric furnace 1, achieving both a clear image field of view and simple operability. The image captured by the imaging device 30 is typically connected to a monitor or recording device (both not shown) in the operator's operating room via a cable (not shown).

[0044] [Extrusion process]

[0045] In the extrusion process of the present invention, a chill source 15 preheated in the preheating chamber 3 is extruded and supplied to the melting chamber 2 by an extruder 10 installed in the preheating chamber 3. The amount of chill source 15 extruded and the timing of its supply are determined by the amount of movement of the extruder 10 and the time interval at which the extruder 10 is moved. Furthermore, in normal operation, multiple setting modes are provided for the values ​​of the movement amount and time interval depending on the type of chill source and the preheating conditions, and automatic operation is performed using the appropriate setting mode. In the present invention, as a result of visual information obtained from the imaging device 30, while confirming that the chill source 15 is being supplied to the melting chamber 2 without any problems, control can be performed such as continuing automatic operation without changing the setting mode for the movement amount and / or time interval.

[0046] However, as mentioned above, the supply of the cold iron source 15 may sometimes stagnate for some reason. Specifically, as visual information from the imaging device 30, it is sometimes confirmed that the movement of the cold iron source 15 entering the melting chamber 2 becomes slow and intermittent, or stops completely, or the interface of the molten iron 16 in the melting chamber 2 does not rise to the desired position. In this way, when it is confirmed through the imaging device 30 that the cold iron source 15 is not being supplied from the preheating chamber 3 to the melting chamber 2, the setting mode of the movement amount and / or time interval of the extruder 10 can be immediately changed to control it. When the movement amount and / or time interval are set to different values, it is only necessary to temporarily switch the automatic operation to manual setting, and after confirming the good supply of the cold iron source 15 again, it is sufficient to resume automatic operation in the normal setting mode.

[0047] Movement

[0048] One of the features of the present invention is the ability to control whether or not to change the extruder 10's travel distance based on visual information obtained from the imaging device 30. In particular, when the imaging device 30 confirms that the chill 15 is not being supplied normally, it is preferable to increase the travel distance and extruder 10 for a longer distance to facilitate smooth movement of the chill 15. For example, to intentionally move a one-ton chill 15, the extruder 10's travel distance can be increased by approximately 10%.

[0049] The changed movement amount can be used until the normal supply of the chill source 15 is resumed. The movement amount of the extruder 10 can be constantly monitored by a position sensor.

[0050] Time interval

[0051] Another feature of the present invention is the ability to control whether or not to change the time interval for moving the extruder 10 based on visual information obtained from the imaging device 30. In particular, when the imaging device 30 confirms that the chill source 15 is not being supplied normally, it is preferable to shorten the time interval and operate the extruder 10 more times within a certain period of time to promote smooth movement of the chill source 15. For example, to intentionally move a one-ton chill source 15, the time interval for moving the extruder 10 can be shortened by approximately 20%.

[0052] The changed time interval can be used until the normal supply of the chill source 15 is resumed. The time interval of the extruder 10 can also be constantly monitored by a timer and a position sensor.

[0053] pressure

[0054] The pressure applied to the extruder 10 can be measured continuously. Further research by the present inventors has also revealed a correlation between the visual information from the imaging device 30 and the extrusion pressure when the extruder 10 moves toward the melting chamber 2. Specifically, the inventors discovered that when the visual information from the imaging device 30 indicates that the chill source 15 is not being supplied normally, specifically, when the chill source 15 is completely stopped or its movement is slow until the next extrusion timing, the extrusion pressure of the extruder 10 is 40 MPa or less.

[0055] The visual information from the imaging device 30 primarily concerns the surface of the chill source 15, which is within the imaging device's field of view. Therefore, for example, it is difficult to use the imaging device 30 to confirm the condition of the chill source 15, which is located within the tower closer to the chill source 15 than the surface, and to determine whether the entire tower of chill source 15 has moved in depth. However, if the extrusion pressure applied to the extruder 10 is used as an indicator in addition to the visual information from the imaging device 30, the normal supply of the chill source 15 to the melting chamber 2 can be more accurately controlled. Specifically, if the visual information from the imaging device 30 indicates that the chill source 15 is not being supplied normally and the extrusion pressure of the extruder 10 is 40 MPa or less, it is preferable to increase the amount of movement of the extruder 10 and / or decrease the time interval between movements of the extruder 10, as described above.

[0056] [Melting process]

[0057] In the melting process of the present invention, a preheated cold iron source 15 supplied to the melting chamber 2 is melted by arc heat to produce molten iron. The specific melting method is as described above with respect to the electric furnace. In the present invention, while observing the interior of the melting chamber 2 using an imaging device 30, the operating conditions of the extruder 10 are appropriately controlled during operation to ensure that the cold iron source 15 is supplied from the preheating chamber 3 to the melting chamber 2 without stagnation. This reduces the power consumption required for the melting process.

[0058] [Other processes]

[0059] Examples of other steps include a preheating step and a tapping step.

[0060] In the preheating step, the cold iron source 15 can be preheated by any heating method before the extrusion step, thereby improving the efficiency of the subsequent melting step. Furthermore, as described above, if the high-temperature exhaust gas previously generated in the melting chamber 2 is used in the preheating step, the power consumption required for the preheating step can also be reduced.

[0061] In the tapping process, the molten iron 16 accumulated in the melting chamber 2 can be taken out of the electric furnace 1 through the tapping port 12 after the melting process.

[0062] Example

[0063] Below, based on embodiment, the present invention is specifically described.It should be noted that the following examples represent a preferred example of the present invention and do not limit the present invention in any way.In addition, the following examples can also be changed and implemented within the scope that can meet the gist of the present invention, and such a mode is also included in the technical scope of the present invention.

[0064] exist Figure 1In the electric furnace shown, which includes a melting chamber 2, a preheating chamber 3, an extruder 10, and an imaging device 30 installed in the melting chamber 2, a cold iron source is melted according to the extrusion conditions listed in Table 1 to produce molten iron. The movement amount and time interval in the extrusion conditions listed in Table 1 are manually set values, and the pressure is the value applied to the extruder 10 as a result of extrusion at these set movement amounts and time intervals. The equipment specifications of this electric furnace are shown below.

[0065] Molten iron capacity of melting chamber: 130 tons

[0066] Power: AC 50Hz

[0067] Transformer capacity: 75MVA

[0068] Number of electrodes: 3

[0069] A hole is provided in the furnace wall 4 at a position 500 mm higher than the designed molten iron interface when 130 tons of molten iron is obtained, and an imaging device 30 is provided through the hole. Along the outer surface of the imaging device 30, air prepared and supplied in the factory is circulated as cooling air at a flow rate of 200 NL / min. In addition, a heating-based dryer method is used to dry the air. The visual information (image) from the imaging device 30 is extended by a cable to the command room and the electrical control room for operating the electric furnace 1 and stored in a separate recording medium. In the command room, a new monitor is prepared in such a way that the operator operating the electric furnace 1 can directly monitor the image from the imaging device 30. In addition, data on the movement amount of the extruder 10, the time interval for moving the extruder 10, and the extrusion pressure are transmitted to the electrical control room so that these data and the image information can be confirmed at the same time.

[0070] Existing Example 1

[0071] Conventional Example 1 is an example of operating within a normal power consumption rate range in a manufacturing method that does not use an imaging device.

[0072] The extruder (barrel) was set to move 1000 mm at a time, with a time interval of 20 seconds. The pressure applied to the barrel during extrusion under these conditions was 58 MPa.

[0073] Without changing the next barrel movement amount and time interval, the barrel is extruded at a movement amount of 1000 mm after 20 seconds, and the pressure applied to the barrel is 64 MPa. In this way, the molten iron of a single feed amount is obtained without changing the extrusion conditions.

[0074] While the chill supply status could not be confirmed due to the lack of an imaging device, the operator's experience suggests that in Conventional Example 1, a constant amount of chill was supplied to the melting chamber at regular intervals, as intended. Consequently, during operation of the electric furnace, the power consumption per charge was 333 kWh / t.

[0075] Existing Example 2

[0076] Conventional Example 2 is an example in which the power consumption rate is higher than usual in a manufacturing method that does not use an imaging device.

[0077] The amount of movement set for the barrel at a certain moment was 1000 mm, and the time interval between movements was 20 seconds. In addition, the pressure applied to the barrel during extrusion under these conditions was 33 MPa, which was lower than that of the prior art example 1.

[0078] Because no imaging device was used, the reason for the lower-than-usual pressure was unclear. Without changing the next barrel movement amount and time interval, the pressure applied to the barrel was kept low at 31 MPa while extrusion continued at a 1000 mm movement for 20 seconds. This allowed the production of a single-feed quantity of molten iron without changing the extrusion conditions. The melting time required to produce a single-feed quantity of molten iron was longer than the design assumed.

[0079] While the lack of an imaging device prevented the chill supply status from being confirmed, it is believed that in Conventional Example 2, the chill was not being supplied to the melting chamber as intended for some reason, preventing efficient melting. Consequently, the power consumption per charge was 362 kWh / t, which was lower than that of Conventional Example 1.

[0080] Comparative Example

[0081] The comparative example is an example in which the extrusion conditions are not controlled based on visual information obtained from the imaging device in the production method using the imaging device.

[0082] At a certain point in time, the barrel was set to move 1000 mm per stroke, with a 20-second interval between movements. Furthermore, the pressure applied to the barrel during extrusion under these conditions was 34 MPa, lower than that of Conventional Example 1. In reality, visual information obtained from the imaging device confirmed that the chill source had stagnated without moving into the melting chamber.

[0083] Despite confirmation by the imaging device that the cold iron source was not being properly supplied to the melting chamber, the pressure applied to the barrel remained low at 34 MPa when the barrel continued to be extruded at a movement of 1000 mm after 20 seconds, without changing the barrel's movement amount and time interval at the next moment. In fact, the visual information obtained from the imaging device confirmed that the cold iron source had not moved into the melting chamber and remained stagnant. In this way, molten iron for a single feed was obtained without changing the extrusion conditions. The melting time required to obtain a single feed of molten iron was longer than the time assumed in the design. As a result, the power consumption rate per feed was 347 kWh / t, which was worse than that of Conventional Example 1. Therefore, the comprehensive evaluation was rated as × (unacceptable).

[0084] Inventive Examples 1 to 6 are examples in which, in a production method using an imaging device, extrusion conditions are controlled based on visual information obtained from the imaging device.

[0085] Invention Example 1

[0086] At a certain point in time, the barrel was set to move 1000 mm per stroke, with a 20-second interval between movements. Furthermore, the pressure applied to the barrel during extrusion under these conditions was 30 MPa, lower than that of Conventional Example 1. In reality, visual information obtained from the imaging device confirmed that the chill source had stagnated without moving into the melting chamber.

[0087] Therefore, the time interval for moving the barrel at the next moment is shortened to 5 seconds. The setting mode of maintaining the movement amount of the barrel at one time at 1000mm and shortening the time interval to 5 seconds is repeated many times until the normal supply of the cold iron source is confirmed by the imaging device. The pressure applied to the barrel at the time when the normal supply of the cold iron source is confirmed to have returned to 58MPa. Then, the time interval is temporarily returned to 20 seconds, but the stagnation of the cold iron source is confirmed in the same way (at this time, the barrel pressure is below 40MPa), so the time interval is temporarily changed to 5 seconds in the same way as above. While repeating this operation, a feeding amount of molten iron is obtained. As a result, the power consumption rate for each feeding is 327kWh / t, which is better than that of the existing example 1. Therefore, the comprehensive evaluation is rated as ○ (qualified).

[0088] Invention Example 2

[0089] At a certain point in time, the barrel was set to move 1000 mm per stroke, with a 20-second interval between movements. Furthermore, the pressure applied to the barrel during extrusion under these conditions was 34 MPa, lower than that of Conventional Example 1. In reality, visual information obtained from the imaging device confirmed that the chill source had stagnated without moving into the melting chamber.

[0090] Therefore, the movement amount of the barrel at the next moment is increased to 1200mm. The setting mode of keeping the time interval of the barrel movement at 20 seconds and increasing the movement amount to 1200mm is repeated many times until the normal supply of the cold iron source is confirmed by the imaging device. The pressure applied to the barrel at the time when the normal supply of the cold iron source is confirmed to have returned to 62MPa. Then, the movement amount is temporarily returned to 1000mm, but the stagnation of the cold iron source is confirmed in the same way (at this time, the barrel pressure is below 40MPa), so the movement amount is temporarily changed to 1200mm in the same way as above. While repeating this operation, a feeding amount of molten iron is obtained. As a result, the power consumption rate for each feeding is 329kWh / t, which is better than that of the existing example 1. Therefore, the comprehensive evaluation is rated as ○ (qualified).

[0091] Invention Example 3

[0092] At a certain point in time, the barrel was set to move 1000 mm per stroke, with a 20-second interval between movements. Furthermore, under these conditions, the pressure applied to the barrel during extrusion was 31 MPa, lower than that of Conventional Example 1. In reality, visual information obtained from the imaging device confirmed that the chill source had stagnated without moving into the melting chamber.

[0093] Therefore, the time interval for moving the barrel at the next moment is shortened to 5 seconds, and the movement amount of the barrel is increased to 1200mm. This setting mode is repeated many times until the normal supply of the cold iron source is confirmed by the imaging device. Confirm that the pressure applied to the barrel at the time of normal supply of the cold iron source is restored to 67MPa. Then, the time interval is temporarily returned to 20 seconds and the movement amount is returned to 1000mm, but the stagnation of the cold iron source is confirmed in the same way (at this time, the barrel pressure is below 40MPa), so the time interval and movement amount are temporarily changed to 5 seconds and 1200mm respectively as described above. While repeating this operation, a feeding amount of molten iron is obtained. As a result, the power consumption rate for each feeding is 326kWh / t, which is better than that of the existing example 1. Therefore, the comprehensive evaluation is rated as ○ (qualified).

[0094] Invention Example 4

[0095] At a certain point in time, the barrel was set to move 1000 mm per stroke, with a 20-second interval. Furthermore, the pressure applied to the barrel during extrusion under these conditions was 32 MPa, lower than that of Conventional Example 1. In reality, visual information obtained from the imaging device confirmed that the chill source was moving slowly toward the melting chamber.

[0096] Therefore, the movement amount of the barrel at the next moment is increased to 1200mm. The setting mode of keeping the time interval of the barrel movement at 20 seconds and increasing the movement amount to 1200mm is repeated many times until it is confirmed by the imaging device that the cold iron source has started to be supplied normally. It is confirmed that the pressure applied to the barrel at the time when the cold iron source is supplied normally has returned to 66MPa. Then, the movement amount is temporarily returned to 1000mm, but the phenomenon that the movement of the cold iron source becomes slow is also confirmed (at this time, the barrel pressure is below 40MPa), so the movement amount is temporarily changed to 1200mm in the same way as above. While repeating this operation, a feeding amount of molten iron is obtained. As a result, the power consumption rate for each feeding is 319kWh / t, which is better than that of the existing example 1. Therefore, the comprehensive evaluation is rated as ○ (qualified).

[0097] Invention Example 5

[0098] At a certain point in time, the barrel was set to move 1000 mm per stroke, with a 20-second interval. Furthermore, the pressure applied to the barrel during extrusion under these conditions was 35 MPa, lower than that of Conventional Example 1. In reality, visual information obtained from the imaging device confirmed that the chill source was moving slowly toward the melting chamber.

[0099] Therefore, the time interval for moving the barrel at the next moment is shortened to 5 seconds, and the movement amount of the barrel is increased to 1200mm. This setting mode is repeated many times until the normal supply of the cold iron source is confirmed by the imaging device. It is confirmed that the pressure applied to the barrel at the time of normal supply of the cold iron source is restored to 71MPa. Then, the time interval is temporarily returned to 20 seconds and the movement amount is returned to 1000mm, but it is also confirmed that the movement of the cold iron source becomes slow (at this time, the barrel pressure is below 40MPa), so the time interval and movement amount are temporarily changed to 5 seconds and 1200mm respectively as described above. While repeating this operation, a feeding amount of molten iron is obtained. As a result, the power consumption rate for each feeding is 315kWh / t, which is better than that of the existing example 1. Therefore, the comprehensive evaluation is rated as ○ (qualified).

[0100] Invention Example 6

[0101] At a certain point in time, the barrel was set to move 1000 mm per stroke, with a 20-second interval. Furthermore, the pressure applied to the barrel during extrusion under these conditions was 30 MPa, lower than that of Conventional Example 1. In reality, visual information obtained from the imaging device confirmed that the chill source was moving slowly toward the melting chamber.

[0102] Therefore, the time interval for moving the barrel at the next moment is shortened to 5 seconds. The setting mode of maintaining the movement amount of the barrel at one time at 1000mm and shortening the time interval to 5 seconds is repeated many times until it is confirmed by the imaging device that the cold iron source has started to be supplied normally. It is confirmed that the pressure applied to the barrel at the time when the cold iron source is supplied normally has returned to 69MPa. Then, the time interval is temporarily returned to 20 seconds, but the phenomenon that the movement of the cold iron source becomes slow is also confirmed (at this time, the barrel pressure is below 40MPa), so the time interval is temporarily changed to 5 seconds in the same way as above. While repeating this operation, a feeding amount of molten iron is obtained. As a result, the power consumption rate for each feeding is 318kWh / t, which is better than that of the existing example 1. Therefore, the comprehensive evaluation is rated as ○ (qualified).

[0103]

[0104] Table 1 demonstrates that, in an electric furnace, the extruder's extrusion conditions are appropriately controlled based on visual information from the melting chamber obtained from an imaging device. This allows for a consistent supply of chill to the melting chamber, even in unexpected situations, resulting in highly efficient molten iron production. Furthermore, this significantly reduces power consumption, a significant factor in manufacturing costs, resulting in a significant improvement.

[0105] Industrial applicability

[0106] According to the present invention, a chill source can be stably and reliably supplied to a melting chamber in an electric furnace, thereby improving the melting efficiency of the chill source.

[0107] Explanation of symbols

[0108] 1 electric stove

[0109] 2 Melting Chamber

[0110] 3 Preheating chamber

[0111] 4 Furnace wall

[0112] 5 Furnace cover

[0113] 6 electrodes

[0114] 7 Oxygen blowing into the spray gun

[0115] 8 Carbon material blown into the spray gun

[0116] 9 Burner

[0117] 10 Extruder

[0118] 12 Water outlet

[0119] 13 slag outlet

[0120] 14 Supply bucket

[0121] 15 Cold Iron Source

[0122] 16 molten iron

[0123] 17 Molten slag

[0124] 18 Arc

[0125] 19 Cold iron source supply port

[0126] 20 Pipeline

[0127] 21 Water outlet door

[0128] 22 Slag discharge door

[0129] 23 Traveling trolley

[0130] 30 video installations.

Claims

1. A method for producing molten iron, comprising: using an electric furnace having a preheating chamber and a melting chamber; The electric furnace further comprises an extruder disposed in the preheating chamber and an imaging device for observing the interior of the melting chamber; The method for producing molten iron comprises the following steps: an extrusion process in which, in the preheating chamber, a cold iron source preheated in the preheating chamber is supplied to the melting chamber by the extruder, and a melting step in which a cold iron source supplied to the melting chamber is melted by arc heat to obtain molten iron; In the extrusion process, either or both of the amount of movement of the extruder and the time interval for moving the extruder are controlled based on the visual information obtained from the imaging device. When it is confirmed based on the visual information obtained from the imaging device that the cold iron source is not being supplied from the preheating chamber to the melting chamber, either or both of the amount of movement and the time interval are increased.

2. The method for producing molten iron according to claim 1, wherein: In the extrusion step, when the extrusion pressure of the extruder is 40 MPa or less, either or both of increasing the movement amount and decreasing the time interval are performed.

Images