Method and device for blocking and removing pouring stuffing sand

Abstract

The method comprises the following steps: descending a long nozzle before casting, enabling the end part of the long nozzle to be positioned below the lower surface of a middle ladle cover, and reserving a space for blocking and removing the stuffing sand between the end part of the long nozzle and the slag surface of casting powder; the casting disc is moved to the position under the long nozzle to be in a rotating state; a steel ladle sliding plate is opened, the stuffing sand and a small amount of molten steel fall on the disc face of the casting disc, and stuffing sand particles and smashed molten steel droplets are scattered on a sintering layer of the casting powder; and after the drainage sand is completely discharged, the casting disc is moved out of the molten steel flow flowing out of the long nozzle. The device comprises a conical casting disc, a driving device and a bearing structural member, the surface of the casting disc is made of refractory materials, and a disc shaft connected with the driving device is arranged at the bottom of the casting disc. According to the invention, harmful gases in the ladle filler sand, gaps of the ladle filler sand and a long nozzle and a small part of molten steel in contact with the ladle filler sand in a steel ladle can be discharged out of tundish molten steel, so that the purity of the molten steel is obviously improved.

Description

Technical Field

[0001] The invention relates to a pouring drainage sand blocking method and device, which is suitable for ladle pouring in processes such as continuous steel casting, steel ingot casting and casting casting. Background Art

[0002] During the continuous steel casting process, multiple ladles are used for casting. When the slide plate at the bottom of the ladle mechanism opens, the static pressure of the molten steel causes the drainage sand and the portion of the molten steel in the ladle that comes into contact with the drainage sand to fall into the tundish. The drainage sand contains particles of refractory materials such as zirconia, which are only a few microns in size and can contaminate the molten steel. At the same time, air, containing oxygen and nitrogen, is trapped in the gaps between the drainage sand and in the long nozzle before casting begins. This air can enter the molten steel in the tundish and contaminate it. Furthermore, the small portion of molten steel in the ladle that comes into contact with the drainage sand (approximately 15 kg) is contaminated by the drainage sand, which in turn contaminates the molten steel in the tundish.

[0003] Therefore, removing the drainage sand and the small amount of molten steel in the ladle that comes into contact with it from the tundish can significantly improve the purity of the molten steel. Numerous attempts have been made to achieve this goal, but none have been effective due to the stringent restrictions on pouring operations between each ladle during continuous casting. These restrictions include: ① If the drainage sand is removed externally, the drainage sand must be removed from the ladle outlet before installing the shroud. The procedure is as follows: first, open the slide to release the drainage sand and then close it; then, connect the shroud, and finally, open the slide to pour the molten steel from the ladle. However, the interval between closing the slide after releasing the drainage sand and opening it must be very short (required to be within 7 seconds); otherwise, the molten steel in the ladle outlet will solidify, interrupting the pouring process. However, it is difficult to achieve a 7-second interval between closing and opening the slide plate with external drainage sand removal. Secondly, after installation, the end of the shroud is below the tundish cover, only 300-400mm away from the slag surface of the molten steel inside the tundish, leaving limited space for drainage sand removal. Therefore, a method and device for removing drainage sand suitable for use in special environments is urgently needed. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and device for removing drainage sand during casting, which can exclude the drainage sand, harmful gases in the drainage sand gaps and the long nozzle, and a small part of the molten steel in contact with the drainage sand in the ladle from the molten steel in the tundish, thereby significantly improving the purity of the molten steel.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] One of the technical solutions of the present invention is to provide a method for removing cast drainage sand, comprising the following contents:

[0007] 1) Before the ladle starts pouring, lower the shroud so that the end of the shroud is below the lower surface of the tundish cover, and leave space between the end of the shroud and the surface of the protective slag for removing the drainage sand;

[0008] 2) Move the ejection disc connected to the driving device to the position directly below the long shroud, and start the driving device to rotate the ejection disc;

[0009] 3) Open the ladle slide, and the drainage sand and a small amount of molten steel fall onto the ejection disk in succession. They are thrown around by the rotating ejection disk. In a relatively closed space, the drainage sand particles and the broken small droplets of molten steel are scattered on the sintering layer of the protective slag surface.

[0010] 4) After the drainage sand is drained, remove the ejection disc from the molten steel flow out of the long nozzle, clean the surface of the ejection disc, and prepare to execute the pouring of the next ladle.

[0011] Furthermore, the end of the long nozzle is located 10 to 300 mm below the lower surface of the tundish cover, and the distance between the end of the long nozzle and the protective slag surface is greater than 100 mm; the distance from the upper surface of the ejection disk to the end of the long nozzle is 50 to 150 mm, and the number of revolutions of the ejection disk is 10 to 150 r / s.

[0012] Furthermore, before changing the ladle, inert gas is blown into the middle ladle to form a protective atmosphere; the descending shroud is achieved by lowering the height of the ladle through the continuous casting ladle turret.

[0013] The second technical solution of the present invention is to provide a device for realizing the method of removing pouring drainage sand, including a projection disk, a driving device and a bearing structure for fixing the driving device. The projection disk body is conical, the surface is made of refractory material, and the bottom is provided with a disk shaft connected to the driving device.

[0014] Furthermore, the conical body of the projection disc has a support frame inside, and the disc shaft is fixedly connected to the support frame; or, the conical body of the projection disc is solid, and the disc shaft and the conical body are an integral structure.

[0015] Furthermore, the cone bottom diameter of the projection disk is 100-300 mm, the top angle is 60°-170°, and the carbon content of the surface refractory material is greater than 5%.

[0016] Furthermore, the conical surface of the projection disk has 3 to 15 scattering grooves from the top to the bottom of the cone.

[0017] Furthermore, the bearing structure is installed on the cantilever of the long nozzle manipulator, and its lifting and rotation are controlled by a rotary lifting mechanism.

[0018] Furthermore, the bearing structure is "L"-shaped, the column of the "L"-shaped component is installed on the cantilever of the long water nozzle manipulator, the driving device is installed on the cross arm of the "L"-shaped component, and the cross arm and the column close to the cross arm are provided with a refractory guard plate.

[0019] Furthermore, a protective shell is provided around the driving device, an opening is left at the position of the output shaft of the driving device, and thermal insulation felt is added around the protective shell; pressure-resistant hoses for electricity and gas are laid in the bearing structure, the pressure-resistant hoses are connected to the protective shell, high-temperature resistant cables are passed through the pressure-resistant hoses, and argon gas is passed as cooling gas, and the gas is discharged from the opening of the protective shell.

[0020] Furthermore, the rotary lifting mechanism includes a motor, a transmission mechanism, and a sensor. The start and stop of the motor are controlled by the detection signal of the sensor. The started motor drives the transmission mechanism and drives the bearing structure to move along a predetermined trajectory.

[0021] Furthermore, the driving device is a high-temperature resistant electric motor or pneumatic motor.

[0022] Compared with the prior art, the beneficial effects are as follows:

[0023] ① The drainage sand and a small amount of molten steel are ejected and broken by the ejection disk, and at the same time, fine particles are scattered on the sintering layer of the protective slag surface, thereby blocking the drainage sand, the harmful gases in the drainage sand gaps and the long nozzle, and a small part of the molten steel in contact with the drainage sand in the ladle, and excluding them from the tundish steel liquid, which significantly improves the purity of the molten steel; ② The processing time is short and does not occupy the normal pouring time; ③ There are no other adverse factors that affect the smooth production, and the operation is simple and safe; ④ It can be applied on an industrial scale, which will produce great economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the working state of the drainage sand removal device of the present invention;

[0025] Figure 2 This is a structural schematic diagram of the drainage sand removal device of the present invention;

[0026] Figure 3 for Figure 2 Schematic diagram of the structure of the projectile disc;

[0027] Figure 4 for Figure 2 A top view of the projectile disc.

[0028] In the figure, there are ladle 1, tundish 2, tundish cover 3, protective slag surface 4, molten steel 5, slide mechanism 6, long nozzle 7, tundish platform 8, manipulator cantilever 9, projectile 10, bearing structure 11, projectile disk 12, groove 13, disk shaft 14, output shaft 15, protective shell 16, insulation felt 17, drive device 18, cross arm 19, column 20, pressure-resistant hose 21, refractory protective plate 22, rotary lifting mechanism 23, and opening 24. DETAILED DESCRIPTION

[0029] The present invention will be described in further detail below with reference to the accompanying drawings.

[0030] See also Figures 1 to 4 A method for removing drainage sand by pouring, comprising the following contents:

[0031] 1) Before the ladle 1 starts casting, the shroud 7 is lowered by the continuous casting ladle turret so that the end of the shroud is located 10 to 300 mm below the lower surface of the tundish cover 3, and the distance between the end of the shroud and the mold slag surface 4 is greater than 100 mm, leaving space between the end of the shroud and the mold slag surface 4 for blocking and removing drainage sand;

[0032] 2) Move the ejection disc 12 connected to the driving device 18 to the position directly below the shroud 7, with the distance between the upper surface of the ejection disc 12 and the end of the shroud 7 being 50 to 150 mm; start the driving device 18 to rotate the ejection disc 12, with the rotation speed of the ejection disc 12 being 10 to 150 r / s.

[0033] 3) The ladle slide is opened, and drainage sand and a small amount of molten steel fall onto the projection disk surface in succession. The rotating projection disk 12 throws the projectiles 10 to the surroundings. In the relatively closed space, the drainage sand particles and the broken molten steel droplets and other projectiles 10 are scattered on the sintered layer of the protective slag surface 4;

[0034] 4) After the drainage sand is completely drained, the ejection disc 12 is removed from the molten steel flow flowing out of the long nozzle, the surface of the ejection disc 12 is cleaned, and preparation is made for the pouring of the next ladle 1.

[0035] In addition, in order to avoid oxidation of the molten steel, an inert gas (such as argon) can be blown into the tundish 2 before changing the ladle to form a protective atmosphere.

[0036] like Figures 1 to 4As shown, a pouring drainage sand removal device includes an ejection disc 12, a driving device 18 and a bearing structure 11 for fixing the driving device. The ejection disc 12 has a conical body, the surface of which is made of refractory material, and a disc shaft 14 connected to the driving device 18 is provided at the bottom. The bearing structure 11 is installed on the cantilever 9 of the long nozzle manipulator, and its lifting and rotation are controlled by a rotary lifting mechanism 23. The bearing structure 11 is "L"-shaped, and the column 20 of the "L"-shaped component is installed on the cantilever 9 of the long nozzle manipulator, and the driving device 18 is installed on the cross arm 19 of the "L"-shaped component. A refractory guard plate 22 is provided on the cross arm 19 and the column 20 close to the cross arm 19. The conical body of the ejection disk 12 contains a support frame (made of steel or a high-temperature alloy), with the disk shaft 14 fixedly connected to the support frame. Alternatively, the conical body of the ejection disk 12 (excluding the surface refractory material, which is made of steel or a high-temperature alloy) is solid, with the disk shaft 14 integrally formed with the conical body. The disk shaft 14 is located at the center of the bottom of the ejection disk. The cone base diameter of the ejection disk 12 is 100-300 mm, with a vertex angle of 60°-170°. The carbon content of the surface refractory material is greater than 5%, making it non-wetting with molten steel. The ejection disk 12 has 3-15 scattered grooves 13 (with straight or involute edges) extending from the top to the bottom of the cone. These grooves 13 facilitate the fragmentation and ejection of material that falls onto the cone surface. The drive unit 18 is surrounded by a protective housing 16, with an opening 24 located at the location of the output shaft 15 of the drive unit 18. Insulation felt 17 is placed around the protective housing 16. Pressure-resistant hoses 21 for electricity and gas are laid within the load-bearing structure 11 (if the load-bearing structure 11 is a steel pipe, the pressure-resistant hoses 21 can be omitted). The pressure-resistant hoses 21 are connected to the protective housing 16 and are threaded with high-temperature-resistant cables. Argon gas is passed through the hoses 21 as a cooling gas. The gas enters through the outer end of the pressure-resistant hose 21, flows through the hose 21 and the protective housing 16, and is discharged through the opening 24. The rotary lifting mechanism 23 includes a motor, a transmission mechanism, and a sensor. A gravity sensor measures the impact force on the projectile disc 12. The sensor's detection signal controls the motor's start and stop. The activated motor drives the transmission mechanism, which in turn causes the load-bearing structure 11 to rotate and lift along a predetermined trajectory. The drive unit 18 is a high-temperature-resistant motor or pneumatic motor.

[0037] Example 1:

[0038] Continuous casting of automobile plate steel, a total of 6 tanks, ladle capacity of 260 tons. Figures 1 to 4 As shown, the pouring drainage sand blocking method includes the following:

[0039] 1. Before changing the ladle 1, blow argon into the tundish 2 to form a protective atmosphere.

[0040] 2. Before the ladle 1 starts pouring, operate the long nozzle manipulator on the middle ladle platform 8, install the long nozzle 7 on the lower nozzle of the ladle 1, adjust the continuous casting ladle turret to lower the height of the ladle 1, make the lower end face of the long nozzle 7 150mm below the lower surface of the middle ladle cover 3, and the distance between the end of the long nozzle 7 and the protective slag surface 4 is 380mm, so that there is space between the end of the long nozzle 7 and the protective slag surface 4 for the operation of blocking and draining sand, to ensure that the bearing structure 11 does not contact the slag surface.

[0041] 3. Lower the column 20 of the supporting structure 11 and insert the cross arm 19 of the supporting structure 11 into the tundish 2 through the opening of the tundish cover 3 until the highest point of the ejection disk 12 is lower than the end of the shroud 7. Then rotate the column 20 of the supporting structure 11 so that the ejection disk 12 on the cross arm 19 is directly below the shroud 7. The ejection disk 12 installed on the cross arm 19 of the supporting structure 11 has a cone top angle of 120° and a cone bottom diameter of 150mm. The carbon content of the refractory material is 15%. The distance from the upper surface of the ejection disk 12 to the end of the shroud 7 is 50mm.

[0042] 4. The argon gas source is turned on. The gas enters protective housing 16 through pressure-resistant hose 21, cooling the cables, drive unit 18, and drive unit protective housing 16. The gas is then discharged through opening 24 of protective housing 16 into tundish 2. The temperature of drive unit 18 (motor) and its cables is kept below 70°C by the insulation provided by thermal blanket 17 and the cooling effect of the argon flow. Drive unit 18 is then started, and the projectile disc 12 is rotated at 50 rpm.

[0043] 5. The ladle slide is opened to release drainage sand and molten steel. The drainage sand and a small amount of molten steel fall onto the ejection disk 12, where they are struck and projected in all directions by the rapidly rotating disk 12, scattering onto the mold slag surface 4. The drainage sand particles and the broken-up molten steel droplets are deposited on the mold slag's sintered layer. Oxygen and nitrogen in the drainage sand and its pores are removed from the molten steel 5, preventing it from contaminating it.

[0044] 6. After the drainage sand is completely drained (approximately 2 seconds after the ladle slide is opened), the molten steel flows into the ejection disk 12. The built-in sensor of the rotary lifting mechanism 23 measures the impact force on the ejection disk 12. When it reaches the response value, the column 20 of the supporting structure 11 is automatically rotated to separate the ejection disk 12 from the molten steel flowing from the shroud. The column 20 of the supporting structure 11 is then raised, raising the ejection disk 12 above the tundish cover 3. The gas source connected to the electrical circuit pressure hose 21 is switched from argon to compressed air.

[0045] 7. After the current ladle 1 is poured, operate the shroud manipulator to separate from the ladle 1 and move it to the cleaning position. Clean the shroud 7 and the surface of the ejection disk 12 at the same time. Prepare to pour the next ladle until the continuous casting is completed.

[0046] The average total oxygen content (purity index) of the continuous casting slabs in this casting was 0.0011%, while the average total oxygen content of the continuous casting slabs without the drainage sand removal operation was 0.0013%, which increased the purity of the steel by 15.4%. In addition, the nitrogen content of the molten steel was reduced by 0.0002%.

[0047] Example 2:

[0048] Continuous casting of household appliance plate steel, a total of 7 tanks, ladle capacity of 180 tons. Figures 1 to 4 As shown, the pouring drainage sand blocking method includes the following:

[0049] 1. Before changing ladle 1, blow argon into the tundish to form a protective atmosphere.

[0050] 2. Before the ladle 1 starts pouring, operate the long nozzle manipulator on the middle ladle platform 8, install the long nozzle 7 on the lower nozzle of the ladle 1, adjust the continuous casting ladle turret to lower the height of the ladle 1, make the lower end face of the long nozzle 7 150mm below the lower surface of the middle ladle cover 3, and the distance between the end of the long nozzle 7 and the protective slag surface 4 is 400mm, so that there is space between the end of the long nozzle 7 and the protective slag surface 4 for the drainage sand blocking operation to ensure that the bearing structure 11 does not contact the slag surface.

[0051] 3. Lower the column 20 of the supporting structure 11 and insert the cross arm 19 of the supporting structure 11 into the tundish 2 through the opening of the tundish cover 3 until the highest point of the ejection disk 12 is lower than the end of the shroud 7. Then rotate the column 20 of the supporting structure 11 so that the ejection disk 12 on the cross arm 19 is directly below the shroud 7. The ejection disk 12 installed on the cross arm 19 of the supporting structure 11 has a cone top angle of 130° and a cone bottom diameter of 120 mm. The carbon content of the refractory material is 20%, and the distance from the upper surface of the ejection disk 12 to the end of the shroud 7 is 60 mm.

[0052] 4. The argon gas source is turned on. The gas enters the protective housing 16 through the pressure-resistant hose 21, cooling the cables, drive unit 18, and the drive unit's protective housing 16. The gas is then discharged through the opening 24 of the protective housing 16 into the tundish 2. The insulation provided by the thermal blanket 17 and the cooling effect of the argon flow keep the temperature of the drive unit 18 (motor) and its cables below 65°C. The drive unit 18 is then started, and the projectile disc 12 is rotated at 45 rpm.

[0053] 5. The ladle slide is opened to release drainage sand and molten steel. The drainage sand and a small amount of molten steel fall onto the ejection disk 12, where they are struck and projected in all directions by the rapidly rotating disk 12, scattering onto the mold slag surface 4. The drainage sand particles and the broken-up molten steel droplets are deposited on the mold slag's sintered layer. Oxygen and nitrogen in the drainage sand and its pores are removed from the molten steel 5, preventing it from contaminating it.

[0054] 6. After the drainage sand is completely drained (approximately 2 seconds after the ladle slide is opened), the molten steel flows into the ejection disk 12. The built-in sensor of the rotary lifting mechanism 23 measures the impact force on the ejection disk 12. When it reaches the response value, the column 20 of the supporting structure 11 is automatically rotated to separate the ejection disk 12 from the molten steel flowing from the shroud. The column 20 of the supporting structure 11 is then raised, raising the ejection disk 12 above the tundish cover 3. The gas source connected to the electrical circuit pressure hose 21 is switched from argon to compressed air.

[0055] 7. After the current ladle 1 is poured, operate the shroud manipulator to separate from the ladle 1 and move it to the cleaning position. Clean the shroud 7 and the surface of the ejection disk 12 at the same time. Prepare to pour the next ladle until the continuous casting is completed.

[0056] The average total oxygen content (purity index) of the continuous casting slabs in this casting was 0.0010%, while the average total oxygen content of the continuous casting slabs without the drainage sand removal operation was 0.0014%, which increased the purity of the steel by 21%. In addition, the nitrogen content of the molten steel was reduced by 0.00018%.

[0057] It should be noted that the above embodiments are only for illustrating the technical concept and features of the present invention and are not intended to limit the present invention. Any equivalent replacement or modification that does not depart from the essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for removing pouring drainage sand, characterized in that: Includes the following: 1) Before the ladle starts pouring, lower the shroud so that the end of the shroud is below the lower surface of the tundish cover, and leave space between the end of the shroud and the surface of the protective slag for removing the drainage sand; 2) Move the ejection disc connected to the driving device to the position directly below the long shroud, and start the driving device to rotate the ejection disc; 3) Open the ladle slide, and the drainage sand and a small amount of molten steel fall onto the ejection disk in succession. They are thrown around by the rotating ejection disk. In a relatively closed space, the drainage sand particles and the broken small droplets of molten steel are scattered on the sintering layer of the protective slag surface. 4) After the drainage sand is drained, remove the ejection disc from the molten steel flow out of the long water outlet.

2. A method for removing pouring drainage sand according to claim 1, characterized in that: The end of the long nozzle is located 10 to 300 mm below the lower surface of the tundish cover, and the distance between the end of the long nozzle and the protective slag surface is greater than 100 mm; the distance from the upper surface of the ejection disk to the end of the long nozzle is 50 to 150 mm, and the number of revolutions of the ejection disk is 10 to 150 r / s.

3. A method for removing pouring drainage sand according to claim 1, characterized in that: Before changing the ladle, inert gas is blown into the tundish to form a protective atmosphere; the descending shroud is achieved by lowering the height of the ladle through the continuous casting ladle turret.

4. A device for implementing the method for removing pouring drainage sand according to any one of claims 1 to 3, characterized in that: The invention comprises a projection disc (12), a driving device (18) and a bearing structure (11) for fixing the driving device. The projection disc (12) has a conical body, a surface made of refractory material, and a disc shaft (14) connected to the driving device (18) is provided at the bottom.

5. A pouring sand removal device according to claim 4, characterized in that: The conical body of the projectile disc (12) has a support frame inside, and the disc shaft (14) is fixedly connected to the support frame; or the conical body of the projectile disc (12) is solid, and the disc shaft (14) and the conical body are an integrated structure.

6. A pouring sand removal device according to claim 4, characterized in that: The cone bottom diameter of the projection disk (12) is 100-300 mm, the top angle is 60°-170°, and the carbon content of the surface refractory material is greater than 5%.

7. The pouring sand removal device according to claim 4, characterized in that: The projectile disc (12) has 3 to 15 scattering grooves (13) on its conical surface from the top to the bottom of the cone.

8. The pouring sand removal device according to claim 4, characterized in that: The bearing structure (11) is installed on the cantilever (9) of the long nozzle manipulator, and its lifting and rotation are controlled by the rotary lifting mechanism (23).

9. The pouring sand removal device according to claim 4, characterized in that: The bearing structure (11) is L-shaped, the column (20) of the L-shaped component is installed on the long nozzle manipulator cantilever (9), the driving device (18) is installed on the cross arm (19) of the L-shaped component, and the cross arm (19) and the column (20) close to the cross arm (19) are provided with a refractory guard plate (22).

10. The pouring sand removal device according to claim 4, characterized in that: A protective shell (16) is provided around the driving device (18), an opening (24) is left at the position of the output shaft (15) of the driving device (18), and a heat-insulating felt (17) is added around the protective shell (16); an electric and gas pressure-resistant hose (21) is laid in the bearing structure (11), the pressure-resistant hose (21) is connected to the protective shell (16), a high-temperature resistant cable is passed through the pressure-resistant hose (21), and argon gas is passed as a cooling gas, and the gas is discharged from the opening (24) of the protective shell (16).

11. The pouring sand removal device according to claim 8, characterized in that: The rotary lifting mechanism (23) includes a motor, a transmission mechanism, and a sensor. The motor is started and stopped by a detection signal from the sensor. The started motor drives the transmission mechanism and drives the bearing structure (11) to move along a predetermined trajectory.

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