Equipment and method for feeding easily oxidized alloy screw rod into molten steel directly in tundish

Abstract

The invention discloses equipment and a method for feeding easily oxidized alloy in a tundish into molten steel directly through a screw rod, belongs to the technical field of metal smelting, and solves the technical problem that materials do not make contact with a slag layer in the process of adding special alloy into the tundish. The feeding auger penetrates through the high-temperature-resistant feeding pipe in the vertical direction; alloy easy to oxidize stored in the hopper is fed into the high-temperature-resistant feeding pipe from the feeding port through the feeding auger, an air inlet is formed in the position, located above the surface of the slag layer, of the lower portion of the side wall of the high-temperature-resistant feeding pipe, the air inlet is communicated with a shielding gas pump station through an air pipe, and shielding gas is blown into the high-temperature-resistant feeding pipe from the air inlet. And the protective gas is discharged through the feeding auger and the feeding auger in sequence, that is, the flowing direction of the protective gas is opposite to the feeding direction of the easily oxidized alloy. Due to the fact that the system is protected by the protective atmosphere in the feeding process and is prevented from making contact with a slag layer in the feeding process, materials can be effectively prevented from being oxidized, and the yield of the materials is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of metal smelting, and particularly relates to equipment and a method for feeding an easily oxidizable alloy screw directly into molten steel in a tundish. Background Art

[0002] During the alloying process of continuous casting, the following two methods are usually used: 1. Mold alloying method: The cored wire is fed into the mold. However, the cored wire is easily burned and oxidized when in contact with the molten steel surface. Since the molten steel flow rate in the mold is fast and the temperature is low, inclusions cannot be completely removed, which easily leads to inclusions in the subsequent casting. 2. Use the tundish alloying method: directly put metal blocks into the tundish or directly feed the cored wire. When the material is highly active and the slag is highly oxidizing, the material will react violently with the slag layer, resulting in low material yield, oxygenation of the molten steel and other adverse consequences. Summary of the Invention

[0003] The main purpose of the present invention is to overcome the shortcomings of the existing technology and provide an apparatus and method for feeding easily oxidized alloys directly into molten steel through a screw in a tundish. During the process of adding special alloys into the tundish, the materials do not come into contact with slag and can be added directly to the molten steel, which greatly reduces the oxidation of the materials by the slag and the violent reaction between the steel and the slag, and reduces the probability of defects such as slag rolling.

[0004] The present invention is achieved through the following technical solutions: The equipment uses a screw to feed easily oxidized alloy directly into the molten steel in the tundish. It includes a motor, a feeding auger, a hopper and a feeding auger. The hopper is set above the far end of the feeding auger, wherein: A high-temperature resistant feeding pipe is vertically inserted into the tundish, the upper end of the high-temperature resistant feeding pipe is a sealed end, and the lower end of the high-temperature resistant feeding pipe extends below the liquid level of the molten steel; The feeding auger passes through the high-temperature resistant feeding pipe in a vertical direction, the upper end of the feeding auger extends above the high-temperature resistant feeding pipe, the feeding auger outside the high-temperature resistant feeding pipe is connected to the rotor of the motor, and the lower end of the feeding auger is provided with a stirring paddle, which is located below the liquid level of the molten steel; A feeding port is provided at the upper part of the side wall of the high-temperature resistant feeding pipe, and the proximal end of the feeding auger is connected to the feeding port. The easily oxidized alloy stored in the hopper is fed into the high-temperature resistant feeding pipe from the feeding port through the feeding auger; an air inlet is provided at the lower part of the side wall of the high-temperature resistant feeding pipe, which is located above the surface of the slag layer. The air inlet is connected to the protective gas pump station through an air pipe. The protective gas is blown into the high-temperature resistant feeding pipe through the air inlet and is discharged in sequence through the feeding auger and the feeding auger, that is, the flow direction of the protective gas is opposite to the feeding direction of the easily oxidized alloy.

[0005] Furthermore, the air inlet is arranged to be inclined upward.

[0006] Furthermore, the high temperature resistant feeding pipe is configured as a Venturi tube, and a negative pressure zone is formed on the upper portion of the high temperature resistant feeding pipe.

[0007] The present application improves the structure of the high-temperature resistant feeding pipe so that the protective gas blown into the high-temperature resistant feeding pipe flows quickly to the upper part of the high-temperature resistant feeding pipe. On the one hand, the air in the feeding system can be blown out quickly, thereby protecting the easily oxidized alloys in the feeding auger, the feeding auger and the hopper, preventing the easily oxidized alloys from carrying excessive oxygen when entering the molten steel, thereby ensuring the oxygen content of the molten steel during the smelting process; on the other hand, the air flow forms a slight suction force on the surface of the molten steel, so that the surface of the molten steel in the high-temperature resistant feeding pipe is slightly higher than the surrounding slag layer. This not only reduces the feeding distance of the easily oxidized alloy in the height direction, but also when the protective gas pump station stops working, the surface of the molten steel in the high-temperature resistant feeding pipe drops, preventing the slag layer from flowing into the high-temperature resistant feeding pipe.

[0008] Furthermore, to ensure the smoothness of feeding, the inner diameter of the high-temperature resistant feeding pipe is 100-200mm; to ensure the temperature stability inside the high-temperature resistant feeding pipe, the wall thickness of the high-temperature resistant feeding pipe is 20-30mm; the feeding auger, feeding auger, high-temperature resistant feeding pipe and stirring paddle are all made of refractory materials.

[0009] Furthermore, in order to reduce the impact of molten steel impact on the device, the distance between the lower end of the high-temperature resistant feeding pipe and the bottom surface of the ladle is higher than 1 / 3 of the depth of the ladle.

[0010] The method of feeding an easily oxidizable alloy screw directly into molten steel in a tundish comprises the following steps: S1. Before the molten steel is transferred to the tundish, the high-temperature resistant feeding pipe is vertically inserted into the tundish to a predetermined height; S2. Start the protective gas pump station and blow protective gas into the high-temperature resistant feeding pipe from the air inlet until the air in the system is completely exhausted; S3. Continuously blow in protective gas to transfer the molten steel from the ladle to the tundish. When the surface of the molten steel is above the bottom of the feeding pipe, start the motor and the feeding auger simultaneously. The feeding auger feeds the easily oxidized alloy in the hopper into the high-temperature resistant feeding pipe from the feeding port. The motor drives the feeding auger to spirally feed the easily oxidized alloy downward directly into the bottom of the molten steel surface. During the process of the easily oxidized alloy entering the molten steel, the stirring paddle continues to stir, completing the screw feeding of the easily oxidized alloy in the tundish directly into the molten steel.

[0011] Furthermore, in step S3, the feeding speed of the feeding auger is equal to the feeding speed of the feeding auger, and the relationship between the feeding speed V of the feeding auger and the molten steel flow rate Q of the tundish is: V = ρQn; (1) In formula (1), V is the feeding speed, unit is kg / s; Q is the molten steel flow rate in the tundish, unit is m 3 / s; ρ is the density of the easily oxidizable alloy, in kg / m 3 ; n is the target content of alloy in molten steel, unit is wt%; The rotation speed a of the stirring paddle is: a = 45×(V / 2Q)×(lnμ) / (μ L -1); (2) In formula (2), V is the feeding speed, in kg / s; Q is the molten steel flow rate in the tundish, in m 3 / s; a is the rotation speed of the stirring blade (6), the unit is r / s, and the value of a is not higher than 60r / s; μ is the diffusion coefficient of the target element in the molten steel, the unit is m 2 / s; L is the length of the intermediate package, in meters.

[0012] The beneficial effects of the present invention are as follows: Because the feeding system is protected by a protective atmosphere during the feeding process and avoids contact with the slag layer during feeding, oxidation of the material can be effectively prevented, significantly improving the material yield. Furthermore, by controlling the speed of the screw feeder, the amount of material added can be precisely controlled. Due to the stable internal environment of the feeding system, it is applicable to most easily oxidized metals, effectively reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the overall structure of the present invention, where the dotted line indicates the direction of movement of the shielding gas.

[0014] In the figure, 1 is the motor, 2 is the feeding auger, 3 is the hopper, 4 is the feeding auger, 5 is the high temperature resistant feeding pipe, 6 is the stirring paddle, 7 is the air pipe, and 8 is the protective air pump station. DETAILED DESCRIPTION

[0015] The present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0016] like Figure 1 The device shown in the figure is a device for feeding molten steel directly into a tundish through an easily oxidized alloy screw, which includes a motor 1, a feeding auger 2, a hopper 3 and a feeding auger 4. The hopper 3 is arranged above the distal end of the feeding auger 2, wherein: A high-temperature resistant feeding pipe 5 is vertically inserted into the tundish. The upper end of the high-temperature resistant feeding pipe 5 is a sealed end, and the lower end of the high-temperature resistant feeding pipe 5 extends below the liquid level of the molten steel. The distance between the lower end of the high-temperature resistant feeding pipe 5 and the bottom surface of the tundish is greater than 1 / 3 of the depth of the tundish. The high-temperature resistant feeding pipe 5 is configured as a Venturi tube, and a negative pressure zone is formed at the upper portion of the high-temperature resistant feeding pipe 5. The inner diameter of the high-temperature resistant feeding pipe 5 is 100-200 mm, and the wall thickness of the high-temperature resistant feeding pipe 5 is 20-30 mm. The feeding auger 2 passes through the high-temperature resistant feeding pipe 5 in the vertical direction, and the upper end of the feeding auger 2 extends above the high-temperature resistant feeding pipe 5. The feeding auger 2 outside the high-temperature resistant feeding pipe 5 is connected to the rotor of the motor 1. The lower end of the feeding auger 2 is provided with a stirring paddle, and the stirring paddle 6 is located below the liquid level of the molten steel; the feeding auger 2, the feeding auger 4, the high-temperature resistant feeding pipe 5 and the stirring paddle 6 are all made of refractory materials; A feeding port is provided at the upper part of the side wall of the high-temperature resistant feeding pipe 5, and the proximal end of the feeding auger 4 is connected to the feeding port. The easily oxidized alloy stored in the hopper 3 is fed into the high-temperature resistant feeding pipe 5 from the feeding port through the feeding auger 4; an air inlet is provided at the lower part of the side wall of the high-temperature resistant feeding pipe 5, which is located above the surface of the slag layer. The air inlet is inclined upward, and the air inlet is connected to the protective gas pump station 8 through the air pipe 7. The protective gas is blown into the high-temperature resistant feeding pipe 5 from the air inlet, and is discharged through the feeding auger 2 and the feeding auger 4 in sequence, that is, the flow direction of the protective gas is opposite to the feeding direction of the easily oxidized alloy.

[0017] The method for feeding the easily oxidizable alloy screw directly into the molten steel in the tundish using the above-mentioned equipment comprises the following steps: S1. Before the molten steel is transferred to the tundish, the high-temperature resistant feeding pipe 5 is vertically inserted into the tundish to a predetermined height; S2, the protective gas pump station 8 is started, and the protective gas is blown into the high-temperature resistant feeding pipe 5 from the air inlet until the air in the system is completely exhausted; S3. Continuously blow in protective gas to transfer the molten steel from the ladle to the tundish. When the surface of the molten steel is above the bottom of the feeding pipe, start the motor 1 and the feeding auger 4 synchronously. The feeding auger 4 feeds the easily oxidized alloy in the hopper 3 into the high-temperature resistant feeding pipe 5 from the feeding port. In this example, the easily oxidized alloy is a Zr alloy. In traditional technology, the Zr alloy block is usually directly fed into the tundish. However, the Zr element is very active and easily reacts violently with the slag layer. However, in the present invention, the motor 1 drives the feeding auger 2 to spirally feed the easily oxidized alloy (in a protective atmosphere) downward directly below the surface of the molten steel to avoid contact with the slag layer and overcome the slag rolling phenomenon. During the process of the easily oxidized alloy entering the molten steel, the stirring paddle 6 continues to stir, and the rotation speed of the stirring paddle 6 is not higher than 60r / s, completing the screw feeding of the easily oxidized alloy in the tundish directly into the molten steel.

[0018] Furthermore, in step S3, the feeding speed of the feeding auger 2 is equal to the feeding speed of the feeding auger 4. The relationship between the feeding speed V of the feeding auger 4 and the molten steel flow rate Q of the tundish is: V = ρQn; (1) In formula (1), V is the feeding speed, unit is kg / s; Q is the molten steel flow rate in the tundish, unit is m 3 / s; ρ is the density of the easily oxidizable alloy, in kg / m 3; n is the target content of alloy in molten steel, unit is wt%; The rotation speed a of the stirring paddle 6 is: a = 45×(V / 2Q)×(lnμ) / (μ L -1); (2) In formula (2), V is the feeding speed, in kg / s; Q is the molten steel flow rate in the tundish, in m 3 / s; a is the rotation speed of the stirring blade 6, the unit is r / s, and the value of a is not higher than 60r / s; μ is the diffusion coefficient of the target element in the molten steel, the unit is m 2 / s; L is the length of the intermediate package, in meters.

[0019] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An apparatus for feeding molten steel directly into a tundish through an easily oxidizable alloy screw, comprising a motor (1), a feeding auger (2), a hopper (3) and a feeding auger (4), wherein the hopper (3) is provided above the distal end of the feeding auger (2), and characterized in that: A high-temperature resistant feeding pipe (5) is vertically inserted into the tundish, the upper end of the high-temperature resistant feeding pipe (5) is a sealed end, and the lower end of the high-temperature resistant feeding pipe (5) extends below the surface of the molten steel; The feeding auger (2) passes through the high-temperature resistant feeding pipe (5) in a vertical direction, the upper end of the feeding auger (2) extends above the high-temperature resistant feeding pipe (5), the feeding auger (2) outside the high-temperature resistant feeding pipe (5) is connected to the rotor of the motor (1), and a stirring paddle (6) is provided at the lower end of the feeding auger (2), and the stirring paddle (6) is located below the liquid surface of the molten steel; A feeding port is provided at the upper portion of the side wall of the high-temperature resistant feeding pipe (5), and the proximal end of the feeding auger (4) is connected to the feeding port. The easily oxidized alloy stored in the hopper (3) is fed into the high-temperature resistant feeding pipe (5) from the feeding port through the feeding auger (4); an air inlet is provided at the lower portion of the side wall of the high-temperature resistant feeding pipe (5) above the surface of the slag layer, and the air inlet is connected to the protective gas pump station (8) through the air pipe (7). The protective gas is blown into the high-temperature resistant feeding pipe (5) through the air inlet and is discharged through the feeding auger (2) and the feeding auger (4) in sequence, that is, the flow direction of the protective gas is opposite to the feeding direction of the easily oxidized alloy.

2. The equipment for feeding molten steel directly through a screw of an easily oxidizable alloy in a tundish according to claim 1, characterized in that: The air inlet is arranged obliquely upward.

3. The equipment for feeding molten steel directly through a screw of an easily oxidizable alloy in a tundish according to claim 1, characterized in that: The high-temperature resistant feeding pipe (5) is configured as a Venturi tube, and a negative pressure zone is formed on the upper portion of the high-temperature resistant feeding pipe (5).

4. The equipment for feeding molten steel directly through a screw of an easily oxidizable alloy in a tundish according to claim 1, characterized in that: The inner diameter of the high-temperature resistant feeding pipe (5) is 100-200 mm, and the wall thickness of the high-temperature resistant feeding pipe (5) is 20-30 mm; the feeding auger (2), the feeding auger (4), the high-temperature resistant feeding pipe (5) and the stirring paddle (6) are all made of refractory materials.

5. The equipment for feeding molten steel directly through a screw of an easily oxidizable alloy in a tundish according to claim 1, characterized in that: The distance between the lower end of the high-temperature resistant feeding pipe (5) and the bottom surface of the tundish is greater than 1 / 3 of the depth of the tundish.

6. A method for feeding an easily oxidizable alloy screw directly into molten steel in a tundish using the device as claimed in claim 1, characterized in that: The following steps are involved: S1. Before the molten steel is transferred to the tundish, the high temperature resistant feeding pipe (5) is inserted vertically into the tundish to a predetermined height; S2, the protective gas pump station (8) is started, and the protective gas is blown into the high temperature resistant feeding pipe (5) from the air inlet until the air in the system is completely exhausted; S3. Continuously blow in protective gas to transfer the molten steel from the ladle to the tundish. When the surface of the molten steel is above the bottom of the feeding pipe, the motor (1) and the feeding auger (4) are started synchronously. The feeding auger (4) feeds the easily oxidized alloy in the hopper (3) from the feeding port into the high-temperature resistant feeding pipe (5). The motor (1) drives the feeding auger (2) to spirally feed the easily oxidized alloy downward directly into the bottom of the molten steel surface. During the process of the easily oxidized alloy entering the molten steel, the stirring paddle (6) continuously stirs it, completing the screw feeding of the easily oxidized alloy in the tundish directly into the molten steel.

7. The method of feeding molten steel directly through a screw of an easily oxidizable alloy in a tundish according to claim 6, characterized in that: In the step S3, the feeding speed of the feeding auger (2) is equal to the feeding speed of the feeding auger (4), and the relationship between the feeding speed V of the feeding auger (4) and the molten steel flow rate Q of the tundish is: V = ρQn; (1) In formula (1), V is the feeding speed, unit is kg / s; Q is the molten steel flow rate in the tundish, unit is m 3 / s; ρ is the density of the easily oxidizable alloy, in kg / m 3 ; n is the target content of alloy in molten steel, unit is wt%; The rotation speed a of the stirring paddle (6) is: a = 45×(V / 2Q)×(lnμ) / (μ L -1); (2) In formula (2), V is the feeding speed, in kg / s; Q is the molten steel flow rate in the tundish, in m 3 / s; a is the rotation speed of the stirring blade (6), the unit is r / s, and the value of a is not higher than 60r / s; μ is the diffusion coefficient of the target element in the molten steel, the unit is m 2 / s; L is the length of the intermediate package, in meters.

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