Device and method for reducing center defect of large steel ingot

Abstract

The invention provides a device and method for reducing center defects of a large steel ingot, and relates to the technical field of molten steel casting, the device comprises a vacuum chamber used for placing a steel ingot mold, a vacuum chamber cover is arranged above the vacuum chamber, a powder spraying disc is installed in the center of the vacuum chamber cover, the vacuum chamber cover is of a hollow structure, and a powder supply and gas supply pipeline is arranged in the hollow structure; a steel ladle is placed above the vacuum chamber cover, the lower portion of a water opening of the steel ladle is inserted into a core hole of the powder spraying disc, and the core hole of the powder spraying disc is formed over an inlet of the steel ingot mold. According to the method, the superheat degree of the molten steel flow can be reduced in the pouring process of the large steel ingot instead of reducing the superheat degree of the molten steel in the molten steel tank, so that the defects of center segregation, center looseness and the like of the steel ingot are reduced, the quality of the steel ingot is improved, and nozzle freezing caused by too low temperature of the molten steel in the later period of pouring is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of molten steel casting, and more particularly to a device and method for reducing the central defects of large ingots. Background Art

[0002] Taking the ingot mold as the carrier for the cooling and solidification of molten steel, although this ingot casting method has been used for more than a hundred years, it is still widely used at present. The ingot casting method has quality problems such as low cooling rate, coarse solidification structure of the ingot, and severe segregation. One of the main reasons for the low cooling rate of the ingot is that during the cooling process of the ingot, since the ingot starts to solidify and cool from the liquid state and the temperature difference reaches more than 1200 °C, its shrinkage is much higher than that of the ingot mold. Therefore, during the cooling process of the ingot after pouring, an air gap appears between the ingot mold and the ingot. Since the air gap surrounded by the ingot mold and the ingot body is relatively closed, the air in the air gap cannot convect with the outside atmosphere, resulting in the gas in the air gap becoming a limiting link for the ingot to transfer heat outward.

[0003] Chinese Patent Authorization Publication No.: CN201220216783.3, "A Water-Cooled Ingot Mold", adopts the technical solution that cooling pipes are arranged around the inside of the ingot mold body, and a cooling pipe water inlet and a cooling pipe water outlet are arranged on the outside of the ingot mold body. This water-cooled ingot mold can accelerate the cooling rate of the ingot, shorten the cooling cycle of the ingot, and improve production efficiency. Cooling pipes are arranged around the inside of the ingot mold body, and a cooling pipe water inlet and a cooling pipe water outlet are arranged on the outside of the ingot mold body.

[0004] Chinese Patent Authorization Publication No.: CN201210256037.1, "A Water and Air-Cooled Ingot Mold for Realizing the Progressive Solidification of an Ingot and Its Application", adopts the technical solution that the ingot mold is provided with independent cooling grooves for water passing and ventilation from bottom to top. Each layer of cooling groove is provided with a partition on the back of the ingot mold, and outer sleeves are fixed on both sides of the partition, connecting the respective water and air pipeline reversing valves. This invention can accelerate the cooling rate of the ingot by using a forced cooling process, and at the same time, by controlling the cooling intensity of the ingot to gradually increase from top to bottom and the cooling time to gradually increase from top to bottom, it ensures that the ingot solidifies sequentially from bottom to top, thereby reducing the looseness of the ingot and improving the density. The structure of the ingot mold is as follows: the cross-section of the ingot mold is rectangular, circular or polygonal, the material of the ingot mold includes metals with good heat conduction such as cast iron or copper, and the ingot mold is provided with 2 to 1000 independent cooling grooves for water passing and ventilation from bottom to top. Each layer of cooling groove is provided with a partition on the back of the ingot mold, and outer sleeves are fixed on both sides of the partition, connecting the respective water and air pipeline reversing valves.

[0005] In the above two inventions, pipes are cast into the ingot mold during casting. When in use, water or gas is passed through the pipes to accelerate the cooling of the ingot mold, achieving the effect of accelerating the temperature drop of the ingot mold. However, this technology has major defects: First, it cannot solve the problem of heat transfer restricted by the air gap, and the cooling effect is poor; second, the manufacturing cost is very high; third, the thermal stress on the ingot mold surges, and its service life is greatly reduced. Therefore, the practicality of this technology is poor.

[0006] Chinese Patent Authorization Publication No.: CN201320224416.2, "An Ingot Casting Device for Sequential Solidification of Steel Ingot from Bottom to Top". The technical solution adopted is: heat sinks are installed on the ingot mold, and the heat sinks are arranged in an array and integrated with the ingot mold. The surface of the ingot mold is cooled through the heat sinks to achieve the purpose of sequential solidification of the steel ingot. This invention obtains the effect of accelerating the temperature drop of the ingot mold by installing heat sinks on the ingot mold. However, this technology has major defects: First, it cannot solve the problem of heat transfer restricted by the air gap, and the cooling effect is poor; second, the manufacturing cost of installing heat sinks is very high; third, after the heat sinks are installed on the ingot mold, it is extremely easy to be damaged under the usage conditions where the ingot mold is extremely prone to being knocked. Therefore, the practicality of this technology is poor.

[0007] In order to accelerate the superheat of the molten steel in the ingot mold and increase the speed of heat transfer from the steel ingot to the outside, technicians have developed some technologies. For example, water-cooled ingot molds, air-cooled ingot molds, etc. The method is to cast pipes into the ingot mold during casting. When in use, water or gas is passed through the pipes to accelerate the cooling of the ingot mold. However, these methods still cannot solve the problem of heat transfer restricted by the air gap, the cooling effect is poor, and their manufacturing cost is very high. The thermal stress on the ingot mold surges, and its service life is greatly reduced. Therefore, they have not been widely used.

[0008] Currently, there is no feasible technology to solve the problem of slow heat dissipation of the ingot mold. Summary of the Invention

[0009] Based on the above-mentioned existing methods for accelerating the superheat of the molten steel in the ingot mold and increasing the speed of heat transfer from the steel ingot to the outside, which cannot solve the technical problem of slow heat dissipation of the ingot mold, a device and method for reducing the central defects of large steel ingots are provided. The present invention can reduce the superheat of the molten steel, increase the cooling speed of the steel ingot, and is beneficial to reducing defects such as central segregation and central porosity of the steel ingot, improving the quality of the steel ingot.

[0010] The technical means adopted by the present invention are as follows:

[0011] A device for reducing the central defect of a large ingot, comprising a vacuum chamber for placing an ingot mold, a vacuum chamber cover is arranged above the vacuum chamber, a powder spraying disc is installed at the center of the vacuum chamber cover, the vacuum chamber cover is of a hollow structure and a powder supply and gas supply pipeline is arranged in the hollow structure; a ladle is placed above the vacuum chamber cover, the lower part of the nozzle of the ladle is inserted into the central hole of the powder spraying disc, and the central hole of the powder spraying disc is arranged directly above the inlet of the ingot mold.

[0012] Further, a positioning sealing rubber ring is arranged on the upper surface of the vacuum chamber cover, the bottom of the ladle is a ladle support ring, and the ladle support ring is seated on the positioning sealing rubber ring.

[0013] Further, the powder supply and gas supply pipeline communicates with a high-pressure argon gas storage tank.

[0014] Further, argon gas circulation cooling systems are respectively arranged on both side walls of the vacuum chamber, and a vacuum system is arranged on the side wall of one of the vacuum chambers.

[0015] The present invention also provides a working method of a device for reducing the central defect of a large ingot, comprising the following steps:

[0016] S1. Place the baked ingot mold in the vacuum chamber, move the vacuum chamber cover to close the vacuum chamber, and complete the evacuation of the vacuum chamber through the vacuum system.

[0017] S2. Place the ladle on the vacuum chamber cover, the ladle support ring is seated on the positioning sealing rubber ring, and the lower part of the nozzle 3 is inserted into the central hole of the powder spraying disc.

[0018] S3. Turn on the argon gas circulation cooling system, open the nozzle to form a molten steel flow into the vacuum chamber, and at the same time open the powder supply and gas supply pipeline of the powder spraying disc, and high-pressure argon gas and steel powder are ejected from the annular gap of the powder spraying disc.

[0019] S4. The molten steel flow is injected into the ingot mold to form a molten pool, and continuous pouring is carried out until the ingot mold is filled with molten steel; after the ingot mold is allowed to stand, it is lifted out to complete the treatment.

[0020] Further, in S3, the molten steel flow rate ranges from 5 to 40 t / min; the argon gas flow rate ranges from 2 to 300 Nm 3 / min, and the flow rate range of the steel powder is: 10 to 400 Kg / min.

[0021] Further, during the pouring process, monitor the temperature of the pouring molten steel flow, and determine the size of the powder spraying amount by calculation according to its superheat degree and the control target superheat degree.

[0022] Further, the composition of the sprayed steel powder is the same as the molten steel composition in the ladle, and the particle size range of the steel powder is: 0.01 to 0.5 mm.

[0023] Furthermore, during the entire working process, argon gas is sucked away by the argon cooling circulation system, dust is removed, the temperature is lowered, and the pressure is increased before entering the high-pressure argon gas storage tank for recycling by the powder spraying disc.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The present invention can reduce the superheat degree of the molten steel flow during the pouring process of large steel ingots, rather than reducing the superheat degree of the molten steel in the ladle. Thus, it can not only reduce defects such as central segregation and central porosity of the steel ingot, improve the quality of the steel ingot, but also prevent the nozzle from freezing due to the too low molten steel temperature in the later stage of pouring.

[0026] The additional equipment of the present invention is simple to manufacture and has low cost; the process is simple, easy to implement, reliable, safe, and has low investment and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 It is a schematic diagram of the device of the present invention.

[0029] In the figure: 1, ladle; 2, molten steel; 3, nozzle; 4, ladle support ring; 5, positioning seal ring; 6, vacuum chamber cover; 7, powder and gas supply pipeline; 8, powder spraying disc; 9, steel ingot mold; 10, vacuum chamber; 11, vacuum system; 12, argon circulation cooling system; 13, steel powder. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The following will refer to the drawings and combine the embodiments to detail the present invention.

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0032] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] Unless otherwise specifically stated, the relative arrangements of the components and steps, numerical expressions, and values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorized specification. In all the examples shown and discussed here, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0034] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom", etc. are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Without contrary instructions, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present invention: the orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0035] For ease of description, spatial relative terms, such as "above", "over", "on the upper surface", "upper", etc., may be used herein to describe the spatial positional relationship of one device or feature to other devices or features as shown in the figures. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above" or "over" other devices or structures will then be positioned "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations will be made for the spatial relative descriptions used herein.

[0036] As Figure 1 shown, the present invention provides a device for reducing the central defect of a large ingot, which includes: a vacuum chamber 10 for placing an ingot mold 9, a vacuum chamber cover 6, a powder injection disk 8, and a powder and gas supply pipeline 7. A vacuum chamber cover 6 is provided above the vacuum chamber 10. A powder injection disk 8 and a powder and gas supply pipeline 7 are arranged inside the vacuum chamber cover 6. A positioning sealing rubber ring 5 is provided on the upper surface of the vacuum chamber cover 6. The bottom of the ladle 1 with both ladle positioning and sealing functions is a ladle support ring 4.

[0037] The central part of the vacuum chamber cover 6 is a through hole, and a powder injection disk 8 is installed. The nozzle of the powder injection disk 8 is an annular slit, and the disk body is a hollow structure, which is connected to the powder and gas supply pipeline 7 and communicates with a high-pressure argon gas storage tank. The argon gas pressure range is: 1 to 15 MPa.

[0038] Argon gas circulation cooling systems 12 are respectively arranged on both side walls of the vacuum chamber 10, and a vacuum system 11 is arranged on the side wall of one side of the vacuum chamber 10.

[0039] The composition of the blown steel powder is the same as that of the molten steel in the ladle 1, and the particle size range is: 0.01 to 0.5 mm.

[0040] The operation of the present invention includes the following steps:

[0041] Place the baked ingot mold 9 at the bottom of the vacuum chamber 10, and then move the vacuum chamber cover 6 to close the vacuum chamber 10;

[0042] Place the ladle 1 on the vacuum chamber cover 6, and the ladle support ring 4 is seated on the positioning sealing rubber ring 5. At this time, the lower part of the nozzle 3 is inserted into the central hole of the injection disk 8;

[0043] Complete the evacuation of the vacuum chamber 10 through the vacuum system 11;

[0044] Start the argon circulation cooling system 12, open the nozzle 3 to form a molten steel flow into the vacuum chamber 10 (molten steel flow rate range: 5 - 40 t / min). At the same time, open the powder injection disk powder supply and gas supply pipeline 7, and high-pressure argon and steel powder 13 are ejected from the annular gap of the powder injection disk 8. Argon flow rate range: 2 - 300 Nm3 / min, steel powder 13 flow rate range: 10 - 400 Kg / min;

[0045] During the pouring process, monitor the temperature of the pouring molten steel flow, and determine the amount of powder injection by calculation according to its superheat degree and the control target superheat degree (it can be calculated based on the specific heat of the steel powder and the temperature rise value, as well as the specific heat of the molten steel and the temperature drop value, which belongs to common sense calculations);

[0046] The powder agent and argon impact and enter the molten steel flow and are fully mixed. The powder agent quickly heats up and melts into molten steel droplets, becoming part of the molten steel in the flow, and at the same time will reduce the temperature, i.e., the superheat degree, of the molten steel in the flow;

[0047] The molten steel flow is injected into the ingot mold 9 to form a molten pool. Argon is sucked away by the argon cooling circulation system 12, dust removed, temperature reduced, pressurized and then enters the high-pressure argon gas storage tank for recycling to the powder injection disk 8. Due to the lower superheat degree of the molten steel, the central defects such as central porosity and central segregation after solidification of the ingot are lower than those of the ingots cast by ordinary methods;

[0048] When the molten steel level rises to the riser, in order to improve the riser feeding effect, reduce the powder injection amount or even stop powder injection.

[0049] Continue pouring until the molten steel fills the ingot mold 9. After leaving the ingot mold 9 standing for a period of time, it is lifted out and the treatment is completed.

[0050] Example 1

[0051] Cast a 60-ton hexagonal ingot, material: 45# steel.

[0052] Purchase 45# steel powder, particle size range: 0.01 mm - 0.5 mm, vacuum packaged.

[0053] Place the baked 60-ton hexagonal ingot mold 9 at the bottom of the vacuum chamber 10, then move the vacuum chamber cover 6 to close the vacuum chamber 10;

[0054] Place the ladle 1 on the vacuum chamber cover 6, and the ladle support ring 4 sits on the positioning seal rubber ring 5. At this time, the lower part of the nozzle 3 is inserted into the central hole of the powder injection disk 8;

[0055] Complete the evacuation of the vacuum chamber 10 through the vacuum system 11;

[0056] Start the argon gas circulation cooling system 12, open the nozzle 3 to form a molten steel flow into the vacuum chamber 10 (molten steel flow rate range: 3 t / min). At the same time, open the powder injection disc powder supply and gas supply pipeline 7, and high-pressure argon gas and steel powder 13 are ejected from the annular gap of the powder injection disc 8. Argon gas flow rate range: 0 - 100 Nm 3 / min, the flow rate of steel powder 13 is: 0 - 300 Kg / min;

[0057] During the casting process, the superheat range of the cast molten steel flow is monitored as: 70 - 150 °C. The target value for controlling the superheat of the pouring molten steel in this casting is 15 ± 3 °C. According to the superheat range of 70 - 150 °C, the corresponding range of the powder injection amount is calculated and determined as: 93 - 230 kg / min;

[0058] The powder agent and argon gas impact and enter the molten steel flow. The powder agent quickly heats up and melts into molten steel droplets, which become the composition of the pouring molten steel flow, and at the same time will reduce the temperature of the pouring molten steel flow, that is, the superheat;

[0059] The molten steel flow is injected into the ingot mold 9 and forms a molten pool. The argon gas is sucked away by the argon gas cooling circulation system 12, dust removed, temperature reduced, pressurized and then enters the high-pressure argon gas storage tank, and is supplied to the powder injection disc 8 for recycling. When the molten steel level rises to the riser, in order to improve the riser feeding effect, the powder injection amount is reduced or even the powder injection is stopped;

[0060] Continue casting until the molten steel fills the ingot mold 9. After the ingot mold 9 is left standing for a period of time, it is lifted out.

[0061] After inspection, the central porosity and central segregation of the ingot are both 0.5 level, while the central porosity and central segregation of the ingot cast by the ordinary method are 1.5 level and 2.5 level respectively. It can be seen that using the method and device of the present invention significantly reduces the central defects of the 60-ton 45# hexagonal steel ingot.

[0062] Example 2

[0063] Cast a 70-ton octagonal steel ingot, material: 20# steel.

[0064] Purchase 20# steel powder, particle size range: 0.01 mm - 0.4 mm, vacuum packaged.

[0065] Place the baked 70-ton octagonal steel ingot mold 9 at the bottom of the vacuum chamber 10, then move the vacuum chamber cover 6 to close the vacuum chamber 10;

[0066] Place the ladle 1 on the vacuum chamber cover 6, and the ladle support ring 4 is seated on the positioning seal rubber ring 5. At this time, the lower part of the nozzle 3 is inserted into the central hole of the powder injection disc 8;

[0067] Complete the evacuation of the vacuum chamber 10 through the vacuum system 11;

[0068] Start the argon circulation cooling system 12, open the tundish nozzle 3 to form a molten steel flow into the vacuum chamber 10 (molten steel flow rate range: 2.5 t / min). At the same time, open the powder injection disk powder supply and gas supply pipeline 7, and high-pressure argon gas and steel powder 13 are ejected from the annular gap of the powder injection disk 8. Argon gas flow rate range: 0 - 85 Nm 3 / min, the flow rate of the steel powder 13 is: 0 - 300 Kg / min;

[0069] During the casting process, the superheat range of the molten steel flow of the cast is monitored to be: 70 - 150 °C. The target value of controlling the superheat of the molten steel of the casting stream this time is 15 ± 3 °C. According to the superheat range of 70 - 150 °C, the corresponding range of the powder injection amount is calculated to be: 77.5 - 192 kg / min;

[0070] The powder agent and argon gas impact and enter the molten steel flow. The powder agent quickly heats up and melts into molten steel droplets, which become the composition of the molten steel of the casting stream, and at the same time will reduce the temperature of the molten steel of the casting stream, that is, the superheat;

[0071] The molten steel flow is injected into the ingot mold 9 and forms a molten pool. The argon gas is sucked away by the argon cooling circulation system 12, dust removed, temperature reduced, pressurized and then enters the high-pressure argon gas storage tank, and is supplied to the powder injection disk 8 for recycling. When the molten steel surface rises to the riser, in order to improve the riser feeding effect, the powder injection amount is reduced or even the powder injection is stopped;

[0072] Continue casting until the molten steel fills the ingot mold 9. After the ingot mold 9 is left standing for a period of time, it is lifted out.

[0073] After inspection, the central porosity and central segregation of the ingot are both grade 0.5, while the central porosity and central segregation of the ingot cast by the ordinary method are grade 2.0 and grade 2.5 respectively. It can be seen that using the method and device of the present invention significantly reduces the central defects of the 70-ton 20# steel octagonal ingot.

[0074] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for reducing the central defect of a large steel ingot, characterized in that: The invention comprises a vacuum chamber (10) for placing a steel ingot mold (9), wherein a vacuum chamber cover (6) is arranged above the vacuum chamber (10), a powder spraying disk (8) is installed at the center of the vacuum chamber cover (6), the vacuum chamber cover (6) is a hollow structure and a powder supply and air supply pipeline (7) is arranged in the hollow structure; a steel ladle (1) is placed above the vacuum chamber cover (6), the lower part of the water inlet (3) of the steel ladle (1) is inserted into the central hole of the powder spraying disk (8), and the central hole of the powder spraying disk (8) is arranged directly above the entrance of the steel ingot mold (9).

2. The device for reducing the central defect of a large steel ingot according to claim 1, characterized in that: The upper surface of the vacuum chamber cover (6) is provided with a positioning sealing rubber ring (5), the bottom of the ladle (1) is a ladle support ring (4), and the ladle support ring (4) is seated on the positioning sealing rubber ring (5).

3. The device for reducing the center defect of a large steel ingot according to claim 1, characterized in that: The powder supply and gas supply pipeline (7) is communicated with a high-pressure argon gas storage tank.

4. The device for reducing the center defect of a large steel ingot according to claim 1, characterized in that: Argon gas circulation cooling systems (12) are respectively arranged on both side walls of the vacuum chamber (10), and a vacuum system (11) is arranged on one side wall of the vacuum chamber (10).

5. A working method of a device for reducing central defects of large steel ingots, which is implemented based on the device for reducing central defects of large steel ingots as claimed in any one of claims 1 to 4, characterized in that: The steps include: S1, placing the baked steel ingot mold (9) in a vacuum chamber (10), moving the vacuum chamber cover (6), closing the vacuum chamber (10), and evacuating the vacuum chamber (10) through a vacuum system (11); S2. Place the ladle (1) on the vacuum chamber cover (6), the ladle support ring (4) is seated on the positioning sealing rubber ring (5), and the lower part of the water inlet (3) is inserted into the center hole of the powder spraying plate (8); S3, start the argon circulation cooling system, open the water inlet (3) to form the molten steel (2) to flow into the vacuum chamber (10), and at the same time open the powder supply and gas supply pipeline (7), and the high-pressure argon gas and steel powder (13) are sprayed out from the annular gap of the powder spraying disk (8); S4, the molten steel (2) is poured into the steel ingot mold (9) to form a molten pool, and the pouring is continued until the molten steel (2) fills the steel ingot mold (9); after the steel ingot mold (9) is left to stand, it is lifted out to complete the processing.

6. The working method of the device for reducing the central defect of large steel ingot according to claim 5, characterized in that: In the S3, the flow rate of the molten steel (2) is in the range of 5 to 40 t / min; the flow rate of the argon gas is in the range of 2 to 300 Nm3 / min; and the flow rate of the steel powder (13) is in the range of 10 to 400 Kg / min.

7. The working method of the device for reducing the central defect of large steel ingot according to claim 6, characterized in that: During the pouring process, the temperature of the pouring molten steel flow is monitored, and the amount of powder injection is determined by calculation based on the level of superheat and the control target superheat.

8. The working method of the device for reducing the central defect of large steel ingot according to claim 5, characterized in that: The composition of the sprayed steel powder (13) is the same as that of the molten steel (2) in the ladle (1), and the particle size range of the steel powder (13) is 0.01-0.5 mm.

9. The working method of the device for reducing the central defect of large steel ingot according to claim 5, characterized in that: During the whole working process, the argon gas is sucked away by the argon gas cooling circulation system (12), dusted, cooled, and pressurized before entering the high-pressure argon gas storage tank and being supplied to the powder spraying disk (8) for recycling.

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