Tundish

Abstract

A tundish, wherein a steel passing hole (43) is provided at a lower portion of a gas-curtain weir refractory body (42); an argon duct (46), a gas chamber (45) and a gas-permeable brick (44) are connected to form a gas-curtain generating device, and the gas-curtain generating device is installed at the lower portion of the gas-curtain weir refractory body (42); the gas-permeable brick (44) is provided in association with the position of the steel passing hole (43), and a length of the gas-permeable brick is designed larger than a width of the steel passing hole (43); and a gas-curtain weir plate (4) is provided in a tundish container, the gas-curtain weir refractory body (42) crosses the tundish container horizontally, and divides the tundish container into a first region and a second region.

Claims

1. A method for removing inclusions from molten steel in a tundish comprising injecting molten steel into a first region of a tundish container from a long nozzle; allowing the molten steel in the first region flow into a second region of the tundish container; providing argon by a gas-curtain generating device to form gas curtain without a blind area to gas wash the molten steel that flows through a steel passing hole to promote accumulation and upward floating of inclusions; and wherein working pressure of the argon is selected to be 0.1-0.9 MPa, and an argon blowing rate is 5-50 L/min.

2. The method of claim 1, wherein the tundish comprises the long nozzle, the tundish container, a submerged nozzle, and a gas-curtain weir plate that comprises a gas-curtain weir refractory body, the steel passing hole, a gas-permeable brick, a gas chamber, and an argon duct; wherein the steel passing hole is provided at a lower portion of the gas-curtain weir refractory body, the argon duct is connected to the gas chamber, the gas chamber is connected to the gas-permeable brick to form a gas-curtain generating device, and a gas-curtain generating device is installed at the lower portion of the gas-curtain weir refractory body.

3. The method of claim 2, wherein the gas-permeable brick is provided in association with the position of the steel passing hole, and a length of the gas-permeable brick is larger than a width of the steel passing hole to provide a gas curtain that fully covers all liquid steel flowing to or flowing through the steel passing hole.

4. The method of claim 2, wherein the gas-curtain weir plate is provided in the tundish container, the gas-curtain weir refractory body crosses the tundish container horizontally and divides the tundish container into the first region and the second region.

5. The method of claim 4, wherein molten steel is injected into the first region of the tundish container from the long nozzle, flows into the second region of the tundish container under a diversion of the steel passing hole, and flows out of the tundish container from the submerged nozzle, and wherein the steel passing hole forms a unique flow channel of liquid steel between the first region and the second region.

6. The method of claim 1, wherein the gas-curtain generating device is provided on an entrance side of the steel passing hole of the gas-curtain weir plate, and a position of a top surface of the gas-permeable brick is not higher than a bottom of the steel passing hole.

7. The method of claim 1, wherein from an entrance side to an exit side of the steel passing hole, an inclination of the steel passing hole is designed upward.

8. The method of claim 2, wherein the gas-curtain generating device is provided on the entrance side of the steel passing hole of the gas-curtain weir plate, and a position of a top surface of the gas-permeable brick is flush with a bottom of the entrance side of the steel passing hole.

9. The method of claim 2, wherein the gas-curtain generating device is provided on an entrance side of the steel passing hole of the gas-curtain weir plate, and a top surface of the gas-permeable brick is lower than a bottom of an exit side of the steel passing hole.

10. The method of claim 2, wherein the gas-curtain generating device is provided on an entrance side of the steel passing hole of the gas-curtain weir plate, and a top surface of the gas-permeable brick forms a part of a bottom surface of the steel passing hole.

11. The method of claim 2, wherein the gas chamber and the gas-curtain weir refractory body are integrated or integrally set.

12. The method of claim 2, wherein the gas-curtain weir plate is provided at a position of ½, or ½ to ¼, in a length direction of the tundish, and a length of the first region is less than a length of the second region.

13. The method of claim 2, wherein the gas-curtain weir refractory body crosses horizontally between two vertical inner walls of the tundish refractory working layer, and horizontal distances between the two vertical inner walls is wide upside and narrow downside.

14. The method of claim 1, wherein the steel passing hole is designed rectangular, the size of which is length (50-300 mm)×width (50-300 mm), or circular with a diameter (50-300 mm).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In this disclosure, the same reference signs always indicate the same features, wherein:

(2) FIG. 1 (Prior Art) is a structural diagram of an existing tundish gas-curtain dam;

(3) FIG. 2 is a structural diagram of a device according to embodiment 1 of the present disclosure;

(4) FIG. 3 is a structural diagram of a gas-curtain weir plate according to embodiment 1;

(5) FIG. 4 is an A-A cross-sectional view of the gas-curtain weir plate according to embodiment 1;

(6) FIG. 5 is a structural diagram of a device according to embodiment 2 of the present disclosure;

(7) FIG. 6 is a structural diagram of a gas-curtain weir plate according to embodiment 2;

(8) FIG. 7 is an A-A cross-sectional view of the gas-curtain weir plate according to embodiment 2;

(9) FIG. 8 is a structural diagram of a device according to embodiment 3 of the present disclosure;

(10) FIG. 9 is a structural diagram of a gas-curtain weir plate according to embodiment 3;

(11) FIG. 10 is an A-A cross-sectional view of the gas-curtain weir plate according to embodiment 3.

REFERENCE SIGNS

(12) 1: long nozzle; 2: tundish refractory; 3: tundish shell; 4: gas-curtain weir plate; 5: submerged nozzle; 6: gas-curtain dam; 41: hoist ring; 42: gas-curtain weir refractory body; 43: steel passing hole; 44: gas-permeable brick; 45: gas chamber; 46: argon duct.

DETAILED DESCRIPTION OF EMBODIMENTS

(13) The technical proposals of the present disclosure is described further below with reference to the drawings and embodiments.

(14) A device for removing inclusions by blowing argon with a gas-curtain weir in a tundish, or a tundish, comprises a tundish with a long nozzle 1, a tundish refractory working layer 2, a tundish shell 3, one gas-curtain weir plate 4 that is provided in a middle position of the tundish, a submerged nozzle 5, wherein the tundish refractory working layer 2 and the tundish shell 3 compose a tundish container. It can be seen from FIG. 2 and FIG. 3 that the horizontal distances between the transverse walls (the left and right walls in FIG. 2) or between the vertical walls (the left and right walls in FIG. 3) of the tundish refractory working layer are both wide upside, and narrow downside. The gas-curtain weir plate 4 comprises a hoist ring 41, a gas-curtain weir refractory body 42, steel passing holes 43, gas-permeable bricks 44, a gas chamber 45, and an argon duct 46. The hoist ring 41 is fixedly installed at an upper portion of the gas-curtain weir refractory body 42, while the steel passing holes 43 are provided at a lower portion of the gas-curtain weir refractory body 42. The argon duct 46 is connected to the gas chamber 45, and the gas chamber 45 is connected to the gas-permeable bricks 44 to form a gas-curtain generating device, which is installed at the lower portion of the gas-curtain weir refractory body 42.

(15) The gas-curtain weir plate is provided at a position of ½, or ½ to ¼, in a length direction of the tundish, dividing the tundish container into a first region (the left area) and a second region (the right area) as shown in FIG. 2, FIG. 5 or FIG. 8. As shown in FIG. 8, when the gas-curtain weir plate is at a position that is less than ½ in the length direction of the tundish, a length of the first region is smaller than a length of the second region. The size of the steel passing hole is designed according to the actual steel passing quantity. The steel passing hole is designed rectangular with a size of length (50˜300 mm)×width (50˜300 mm), or circular with a diameter (50˜300 mm), or other shaped. The inclination angle of the steel passing hole is designed upward (0˜80 degrees). The molten steel flows upward under a diversion of the steel passing holes, thereby beneficial to the upward floating of inclusions. The number of the steel passing holes is not limited and may be at least one. The argon duct is equipped with a pressure and flow control device. During a producing process, the argon working pressure is selected to be 0.1˜0.9 MPa, and the argon blowing rate is 5˜50 L/min.

(16) In the embodiment shown in FIG. 2 and FIG. 5, the gas-curtain weir plate 4 is provided in a middle position of the tundish to divide the tundish into a first region (also called as a mixing region) and a second region (also called as a casting region). The molten steel is injected from the long nozzle 1 into the mixing region of the tundish (the left side of the tundish), flows into a stream region of the tundish (the right side of the tundish) under the diversion of the steel passing holes 43 of the gas-curtain weir plate 4, and then flows into a crystallizer from the submerged nozzle 5. A gas-curtain generating device is installed at the entrance of the steel passing holes 43 of the gas-curtain weir plate 4. The gas-curtain generating device is composed of an argon-blowing duct 46, a gas chamber 45 and gas-permeable bricks 44. Since the steel passing holes 43 are the unique flow channel between the first region and the second region, and the length of the gas-permeable bricks 44 is larger than the width of the steel passing holes 43, the positions of which are provided in association to make the gas curtain, formed by the exhaust from the gas-permeable bricks, fully covers all liquid steel that flows through the steel passing holes, the argon blown into thereby forms a gas curtain with no blind area at the entrance of the steel passing holes 43, performing a gas washing to the liquid steel that flows through the steel passing holes 43, so as to promote the accumulation and upward floating of inclusions.

Embodiment 1

(17) Combined with FIG. 2, a 60-ton tundish on site is provided with a long nozzle 1, a tundish refractory layer 2, a tundish shell 3, a gas-curtain weir plate 4, and a submerged nozzle 5. The gas-curtain weir plate 4 is provided at a ½ position of the length of the tundish. Combined with FIG. 3 and FIG. 4, two steel passing holes 43 are provided above a bottom of the gas-curtain weir plate 4. The size of the steel passing holes 43 is 150 mm in length×100 mm in height, with an inclination angle of 45 degrees upward. A gas-curtain generating device is installed at an entrance (the left side) of the steel passing holes 43 of the gas-curtain weir plate 4. The gas-curtain generating device is composed of an argon-blowing duct 46, a gas chamber 45 and gas-permeable bricks 44, wherein the argon duct 46 is connected to the gas chamber 45 and the gas chamber 45 is connected to the gas-permeable bricks 44, a length of gas-permeable brick 44 is designed larger than a length of the steel passing hole 43, and the length of the gas-permeable bricks 44 is designed to be 50˜320 mm. A top surface of the gas-permeable bricks 44 is flush with a bottom of the entrance (the left side) of the steel passing holes 43, while existing at least one variant. For example, the position of the top surface of the gas-permeable brick 44 is lower than the bottom of the entrance side of the steel passing holes 43, or the top surface of the gas-permeable bricks 44 is higher than the bottom of the entrance side of the steel passing holes 43. The position of the steel passing holes 43 can be provided 0˜500 mm above the bottom of the gas-curtain weir plate 4.

(18) Before pouring, the argon of the argon duct 46 of the gas-curtain weir plate 4 is opened. The argon working pressure is 0.5 MPa, and the argon blowing rate is 6 L/min. The blown-in argon forms a gas curtain without a blind area at the entrance (the left side) of the steel passing holes 43.

(19) The starting molten steel is poured into the mixing region of the tundish (the left side of the tundish) from the long nozzle 1, flows into the stream region of the tundish (the right side of the tundish) through the diversion steel passing holes 43 of the gas-curtain weir plate 4, and then flows into the crystallizer from the submerged nozzle 5.

(20) The argon, blown in from the gas-permeable bricks 44 on the gas-curtain weir plate 4, performs a full coverage gas washing to the liquid steel that flows through the steel passing holes 43, to promote the accumulation and upward floating of inclusions. Since the amount of the blown-in argon is little, it will not cause the molten steel churning and exposing that may cause a secondary oxidation of molten steel and a re-entrance of inclusions.

Embodiment 2

(21) Combined with FIG. 5, a 60-ton tundish on site is provided with a long nozzle 1, a tundish refractory layer 2, a tundish shell 3, a gas-curtain weir plate 4, and a submerged nozzle 5. The gas-curtain weir plate 4 is provided at a ½ position of the length of the tundish. Combined with FIG. 6 and FIG. 7, two steel passing holes 43 are provided 0˜500 mm above a bottom of the gas-curtain weir plate 4. The size of the steel passing holes 43 is 150 mm in length×100 mm in height, with an inclination angle of 60 degrees upward. A gas-curtain generating device is provided at a bottom of the steel passing holes 43 of the gas-curtain weir plate 4. The gas-curtain generating device is composed of an argon-blowing duct 46, a gas chamber 45 and gas-permeable bricks 44, wherein the argon duct 46 is connected to the gas chamber 45 and the gas chamber 45 is connected to the gas-permeable bricks 44, a length of the gas-permeable brick 44 is designed larger than a length of the steel passing hole 43, and the length of the gas-permeable bricks 44 is designed to be 50˜320 mm. A top surface of the gas-permeable bricks 44 forms a part of the bottom surface of the steel passing holes 43.

(22) Before pouring, the argon of the argon duct 46 of the gas-curtain weir plate 4 is opened. The argon working pressure is 0.5 MPa, and the argon blowing rate is 3 L/min. The blown-in argon forms a gas curtain without a blind area inside the steel passing holes 43.

(23) The starting molten steel is poured into the mixing region of the tundish (the left side of the tundish) from the long nozzle 1, flows into the stream region of the tundish (the right side of the tundish) through the diversion steel passing holes 43 of the gas-curtain weir plate 4, and then flows into the crystallizer from the submerged nozzle 5.

(24) The argon, blown in from the gas-permeable bricks 44 on the gas-curtain weir plate 4, performs a full coverage gas washing to the liquid steel that flows through the steel passing holes 43, to promote the accumulation and upward floating of inclusions. Since the amount of the blown-in argon is little, it will not cause the molten steel churning and exposing that may cause a secondary oxidation of molten steel and a re-entrance of inclusions.

Embodiment 3

(25) Combined with FIG. 8, a 60-ton tundish on site is provided with a long nozzle 1, a tundish refractory layer 2, a tundish shell 3, a gas-curtain weir plate 4, and a submerged nozzle 5. The gas-curtain weir plate 4 is provided at a ½ position of the length of the tundish. Combined with FIG. 9 and FIG. 10, two steel passing holes 43 are provided 0˜500 mm above a bottom of the weir plate. The size of the steel passing holes 43 is 150×100 mm with an inclination angle of 45 degrees upward. A gas-curtain generating device is provided at an exit (the right side) of the steel passing holes 43 of the gas-curtain weir plate 4. The gas-curtain generating device is composed of an argon-blowing duct 46, a gas chamber 45 and gas-permeable bricks 44, wherein the argon duct 46 is connected to the gas chamber 45 and the gas chamber 45 is connected to the gas-permeable bricks 44, a length of the gas-permeable brick 44 is designed larger than a length of the steel passing hole 43, and the length of the gas-permeable bricks 44 is designed to be 50˜320 mm. A top surface of the gas-permeable bricks 44 is lower than a bottom of the exit side (the right side) of the steel passing holes 43.

(26) Before pouring, the argon of the argon duct 46 of the gas-curtain weir plate 4 is opened. The argon working pressure is 0.5 MPa, and the argon blowing rate is 8 L/min. The blown-in argon forms a gas curtain without a blind area at the exit (the right side) of the steel passing holes 43.

(27) The starting molten steel is poured into the mixing region of the tundish (the left side of the tundish) from the long nozzle 1, flows into the stream region of the tundish (the right side of the tundish) through the diversion steel passing holes 43 of the gas-curtain weir plate 4, and then flows into the crystallizer from the submerged nozzle 5.

(28) The argon, blown in from the gas-permeable bricks 44 on the gas-curtain weir plate 4, performs a full coverage gas washing to the liquid steel that flows through the steel passing holes 43, to promote the accumulation and upward floating of inclusions. Since the amount of blown-in argon is little, it will not cause the molten steel churning and exposing that may cause a secondary oxidation of molten steel and a re-entrance of inclusions.

(29) In the Embodiments 1 and 3, the gas chamber 45 and the gas-curtain weir refractory body 42 are integrated or integrally formed, while existing at least one variant, that is, the gas chamber 45 and the gas-curtain weir refractory body 42 are separate, and the gas chamber 45 can also have a certain nozzle with the gas-curtain weir refractory body 42, at least the gas curtain generated by the gas-permeable bricks 44 provided on the gas chamber 45 can fully cover the liquid steel flowing to or flowing through the steel passing holes.

(30) In summary, by adopting the technical proposals of the present disclosure, according to the embodiments of the present disclosure, the tundish or the device for removing inclusions by blowing argon with a gas-curtain weir in the tundish has the following effects.

(31) (1) By providing a gas-curtain weir plate in the main device to divide the tundish into a mixing region and a stream region, the fluctuation of the liquid surface in the casting region can be made smaller, and less slags from the casting region will be involved. By providing two diversion holes in the middle of the weir plate, the molten steel flows upward through the diversion holes, thereby facilitating the upward floating of inclusions.

(32) (2) By providing a strip-shaped gas-curtain generating device at the position of the entrance of the weir plate, and designing the length of the gas-permeable bricks is larger than the length of the steel passing holes, an effective gas washing is ensured to all molten steel that flows through the steel passing holes of the weir plate, and no blind area of the gas-curtain exists, thereby ensuring the removal efficiency of inclusions in molten steel.

(33) (3) As long as a gas curtain is formed at the entrance of the weir plate, since the area of the steel passing holes of the weir plate is very small, the purging efficiency is improved, which is beneficial to reduce the blowing volume, so as to benefit to reduce the molten steel exposure in the molten steel, thereby beneficial to reduce the secondary oxidation of the molten steel.

(34) (4) During the using process, the steel passing holes guide the liquid steel to flow quickly in a horizontal direction, driving the purging argon also flows horizontally to achieve a more evenly ventilation in the second region of the tundish container, so as to also benefit to reduce the molten steel exposure caused in the molten steel, thereby reducing the secondary oxidation of the molten steel.