Device for reducing converter tapping slag entrapment and use method

Abstract

The device comprises a supporting arm and a refractory cover installed at one end of the supporting arm, the refractory cover is provided with a downward opening, a plurality of side holes distributed in the circumferential direction are formed in the lower end of the side wall of the refractory cover, an argon outlet facing the lower end opening of the refractory cover is formed in the top of the refractory cover, and an argon outlet facing the lower end opening of the refractory cover is formed in the top of the refractory cover. And an argon pipeline communicated with the argon outlet is arranged in the supporting arm in a penetrating manner. Liquid slag on the liquid level is blown away through argon blown out of an argon outlet in the refractory cover, then the refractory cover is covered above a tapping hole area, molten steel enters the cover through a side hole in the lower end of the refractory cover and then flows into the tapping hole, and primary separation of the steel slag, secondary oxidation of the molten steel and nitrogen absorption are achieved. The slag is effectively prevented from entering the tapping hole area in the later tapping period, formation of vortex flow in a molten pool is slowed down, slag entrapment in the later tapping period is restrained, steel slag is prevented from being mixed out, the slag stopping quality and the molten steel quality are improved, and the metal yield is increased.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting technology, and in particular to the treatment of slag coils in the later stages of the steel tapping process, specifically to a device and method for reducing slag coils during converter tapping. Background Technology

[0002] Steel cleanliness is a crucial indicator for measuring the levels of non-metallic inclusions, gas content, and harmful elements in molten steel, directly impacting the mechanical properties, processing performance, and durability of the steel. The cleanliness requirements vary significantly depending on the intended use of the steel. One core indicator of cleanliness is the amount of non-metallic inclusions (oxides, sulfides, etc.). Slag-blocking tapping refers to the operation of releasing molten steel into the ladle (steel ladle) after converter blowing or electric arc furnace oxidative melting, leaving the oxidized slag inside the furnace. Separating the oxidized slag from the molten steel during tapping is a requirement of ladle refining. Secondary refining in the ladle is best carried out under reducing conditions. Using slag-blocking tapping to avoid slag carryover is a crucial guarantee for improving the efficiency of ladle refining.

[0003] During tapping, as the molten steel level drops, a funnel-shaped converging vortex forms above the taphole when the steel depth falls below a certain critical value. Some slag flows out of the taphole before all the molten steel has been tapped, which is the fundamental reason for the incomplete separation of slag and steel. High-temperature, high-oxidizing slag entering the ladle at the converter's end point easily causes phosphorus reversion and reduces the metallurgical effect of ladle refining, lowering alloy yield and steel cleanliness. Therefore, to maximize the effectiveness of ladle refining, improve billet quality, and control the stability of steel composition, slag-blocking operations must be performed during tapping.

[0004] Slag blocking during converter tapping is a crucial step in the steelmaking process. Its core purpose is to reduce the mixing of molten steel and slag, ensuring the purity of the steel and the quality of the product. If slag is not blocked during tapping, the slag will enter the ladle, causing phosphorus and sulfur to return to the molten steel, affecting its quality. Therefore, slag blocking aims to reduce the introduction of these harmful elements and improve the purity of the molten steel.

[0005] Currently, the commonly used methods for slag blocking at steel tapping mainly include slag-blocking balls and sliding plate slag blocking. Slag-blocking balls utilize a sphere made of refractory material wrapped around the iron core to block the tapping opening and prevent slag from flowing out. However, due to their shape, the slag-blocking balls are prone to floating away from the tapping opening with the steel flow, thus losing their slag-blocking effect and causing slag blocking failure. Sliding plate slag blocking refers to installing a sliding valve plate made of refractory material outside the converter tapping opening. Its structure is similar to the sliding nozzle at the bottom of the ladle. When a slag discharge signal is received, the valve is inserted to prevent slag from flowing down. However, because the environmental conditions at the tapping opening are harsher than those at the ladle, the sliding performance of the valve plate is difficult to guarantee, resulting in low reliability. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing a device and method for reducing slag buildup during converter tapping, avoiding the problems associated with slag-blocking balls and sliding plates, and achieving reliable slag blocking.

[0007] The present invention is achieved through the following technical solution, providing a device for reducing slag entrapment during converter tapping, including a support arm and a refractory cover installed at one end of the support arm. The refractory cover opens downward, and a plurality of side holes arranged circumferentially are provided at the lower end of the side wall of the refractory cover. An argon gas outlet is provided at the top of the refractory cover facing the lower port of the refractory cover, and an argon gas pipe communicating with the argon gas outlet is passed through the support arm.

[0008] In use, this solution involves placing the refractory hood into the converter by moving the support arm and positioning it at the converter tapping port to prevent the formation of vortices. Argon gas outlets are used to blow away slag from the molten steel surface below the refractory hood, preventing it from entering the refractory hood. Side holes are located at the lower end of the side wall of the refractory hood, taking full advantage of the characteristic that liquid slag floats on the surface of molten steel to prevent slag from entering the tapping port, thus achieving slag blocking.

[0009] As an optimization, the system also includes a mobile trolley and a support column fixed to the mobile trolley, with the support arm mounted on the support column. This optimized design facilitates the overall movement of the refractory cover, offering flexible operation and greater ease of use.

[0010] As an optimization, the support arm is rotatably connected to the support column via a transverse hinge; a winch device is also installed on the moving trolley, and the wire rope of the winch device is connected to the end of the support arm away from the refractory cover, with the support column located between the refractory cover and the wire rope. This optimized design creates a lever-like structure for the support arm, allowing the winch device to control the raising and lowering of the refractory cover, making it more labor-saving to use.

[0011] As an optimization, the distance from the connection point of the wire rope and the support arm to the support column is less than the distance from the refractory hood to the support column. This optimized design facilitates significant raising and lowering of the refractory hood through short-distance movement of the wire rope, making operation faster and helping to avoid the support column being too close to the converter.

[0012] As an optimization, the support arm includes a cylinder through which an argon gas pipe passes, and a counterweight fixed to the end of the cylinder away from the refractory cover. This optimized support arm uses a cylinder as its main body, allowing for the passage of an argon gas pipe. The addition of a counterweight improves stability and facilitates the hoisting device's control over the lifting and lowering of the support arm.

[0013] As an optimization, a cross-shaped support frame is cast inside the top of the refractory cover. A connecting rod extending upward through the refractory cover is fixed to the cross-shaped support frame, and the upper end of the connecting rod is hinged to the support arm via a horizontal axis. This optimization scheme improves the structural strength of the refractory cover by setting the cross-shaped support frame, and the hinged connection between the connecting rod and the support arm ensures that the refractory cover remains vertical during lifting and lowering.

[0014] This solution also provides a method for using a device to reduce slag coils during converter tapping, including the following steps: a. In the later stage of tapping, start the hoisting device to lower the end of the support arm where the counterweight is located and raise the end where the refractory cover is located to correspond with the converter mouth. b. Start the mobile trolley and send the refractory cover into the converter through the furnace mouth, and position the refractory cover directly above the converter tapping opening, ensuring that the center of the refractory cover is coaxial with the center of the tapping opening; c. The hoisting device releases the rope, and the refractory cover is slowly lowered to the slag surface area above the converter tap hole. Argon gas is supplied through the argon gas pipeline, and the argon gas is blown downward through the argon gas outlet to drive away and blow away the slag on the surface of the liquid below the refractory cover, exposing the molten steel surface. The argon gas flow rate is controlled at 100~120L / min, and the argon gas pressure is controlled at 0.7~0.8MPa. d. Continue to lower the refractory hood to the refractory wall of the converter. Adjust the argon flow rate to 5~10L / min and the argon pressure to 0.25~0.30MPa to ensure positive pressure inside the refractory hood and prevent the molten steel inside the refractory hood from contacting the air. After the refractory hood is lowered, there is no slag on the liquid surface inside the refractory hood. Molten steel flows into the refractory hood from the side hole at the lower end of the side wall and flows out through the tapping port. e. After tapping is completed, remove the refractory cover from the converter and stop the argon gas supply.

[0015] The beneficial effects of this invention are as follows: Argon gas blown out from the argon outlet inside the refractory cover drives away the liquid slag on the surface of the molten steel. Then, the refractory cover is placed over the tapping area. Molten steel enters the cover through the side holes at the lower end and flows into the tapping area, achieving initial separation of steel and slag, secondary oxidation of the molten steel, and nitrogen absorption. In the later stages of tapping, it effectively prevents slag from entering the tapping area, slows the formation of vortex flows in the molten pool, inhibits slag entrapment in the later stages of tapping, avoids slag mixing, improves slag blocking quality and molten steel quality, and increases metal yield. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a top view of the refractory cover. Figure 3 This is a schematic diagram of the refractory cover viewed from below. Figure 4 This is a diagram showing the usage status of the present invention; As shown in the figure: 1. Refractory cover, 2. Cross support frame, 3. Connecting rod, 4. Argon outlet, 5. Side hole, 6. Metal hose, 7. Argon pipeline, 8. Support arm, 9. Connecting lug, 10. Horizontal shaft, 11. Hinge seat, 12. Horizontal hinge shaft, 13. Counterweight, 14. Support column, 15. Moving trolley, 16. Limit switch, 17. Wheel, 18. Travel motor, 19. Winch device, 20. Pipe joint, 21. Converter, 22. Steel tapping port, 23. Slide plate mechanism, 24. Steel slag liquid surface. Detailed Implementation

[0017] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0018] like Figure 1 The device shown is for reducing slag entrapment during converter tapping. It includes a support arm 8 and a refractory cover 1 installed at the front end of the support arm. The refractory cover 1 opens downwards and is cylindrical in shape. A top cover is provided at the upper end of the refractory cover, and several circumferentially arranged side holes 5 are provided at the lower end of the side walls of the refractory cover. In this embodiment, four side holes are provided, and the four side holes are evenly distributed circumferentially for the passage of molten steel.

[0019] A cross-shaped support frame 2 is cast inside the top of the refractory cover. A connecting rod 3, extending upwards through the refractory cover, is fixed to the cross-shaped support frame 2. The connecting rod is perpendicular to the top cover of the refractory cover, and the upper end of the connecting rod 3 is hinged to the support arm via a horizontal shaft 10. For easy connection, a connecting lug 9 is welded to the bottom of the front end of the support arm. The horizontal shaft passes through the connecting lug and the connecting rod in a horizontal direction, achieving the hinge connection between the connecting rod and the connecting lug. The combination of the cross-shaped support frame 2 and the refractory cover ensures structural strength and can withstand the high-temperature corrosion of steel slag, thus improving the service life of the device. In this embodiment, a high-temperature resistant, anti-stick coating is sprayed on the lower end and sides of the refractory cover, which can effectively reduce the adhesion of steel slag and also facilitate the cleaning of some of the slag.

[0020] The top of the refractory shroud is equipped with an argon outlet 4 facing the lower end of the shroud. An argon pipe 7, connected to the argon outlet 4, is threaded through the support arm. In this embodiment, a gas outlet pipe is threaded through the connecting rod 3, and the gas outlet pipe is connected to the argon pipe 7 in the support arm via a metal flexible hose 6. The argon outlet is the lower end of the gas outlet pipe. The argon pipe 7 extends rearward out of the support arm, and a pipe connector 20 is provided at the rear end of the argon pipe for easy connection to an argon delivery pipe. Before the refractory shroud descends, argon is used to disperse the slag. After descending, a slight positive pressure is applied to blow argon, ensuring that only molten steel and no slag are inside the refractory shroud. This achieves the separation of steel and slag inside and outside the refractory shroud, thereby reducing the probability of slag entrapment and steel-slag mixing at the tapping port during the tapping process, and effectively avoiding slag discharge during tapping.

[0021] This embodiment also includes a mobile trolley 15 and a support column 14 fixed on the mobile trolley, with the support arm 8 mounted on the support column. A winch device 19 is also installed on the mobile trolley. The winch device employs existing technology and includes a drum, a wire rope wound on the drum, and a drive motor that drives the drum to rotate, thereby winding and unwinding the rope. In this embodiment, the wire rope of the winch device is connected to the end of the support arm furthest from the refractory cover, and the support column 14 is located between the refractory cover 1 and the wire rope. The support arm includes a cylinder through which an argon gas pipe passes, and a counterweight 13 fixed to the end of the cylinder furthest from the refractory cover. The upper end of the wire rope is connected to the counterweight. The distance from the connection point of the wire rope and the support arm to the support column is less than the distance from the refractory cover to the support column.

[0022] Specifically, the support arm 8 is rotatably connected to the support column 14 via a transverse hinge shaft 12. The bottom of the support arm is welded with a hinge seat 11 through which the transverse hinge shaft 12 passes. The refractory cover is located in front of the support column, and the counterweight is located behind the support column. The distance between the refractory cover and the support column is not less than 5 times the distance between the support column and the counterweight. This facilitates quick adjustment of the height of the refractory cover and ensures that the refractory cover can be lowered to the converter tapping port when the hoisting device releases the rope.

[0023] A limit switch 16 is installed at the front end of the mobile trolley, and a trigger rod adapted to the limit switch is installed on the converter mounting frame. When the limit switch touches the trigger rod, the mobile trolley stops moving, and at this time the refractory cover is directly above the converter tapping opening. The mobile trolley has four rectangularly distributed wheels 17, and a travel motor 18 that drives the wheels 17 to rotate is installed at the bottom of the mobile trolley.

[0024] This embodiment describes a method for using a device to reduce slag coils during converter steelmaking, comprising the following steps: a. After the converter blowing process is completed and the steel is ready to be tapped, the converter 21 is rotated backward to the tapping position, and the sliding plate mechanism 23 is opened to start tapping.

[0025] In the later stages of tapping, the hoisting device is activated, causing the end of the support arm containing the counterweight to descend and the end containing the refractory hood to rise to correspond with the converter opening. That is, the wire rope of the hoisting device pulls down the rear end of the support arm, causing the refractory hood located at the front end of the support arm to rise so that it can enter the converter.

[0026] b. Start the moving trolley and send the refractory cover into the converter through the furnace mouth along the center line of the steel tapping opening, and make the refractory cover directly above the steel tapping opening 22 of the converter, ensuring that the center of the refractory cover is coaxial with the center of the steel tapping opening.

[0027] c. The hoisting device releases the rope, and the refractory cover at the front end of the support arm is slowly placed in the slag molten surface area 24 above the converter tapping port. Argon gas is supplied through the argon gas pipeline, and the argon gas is blown downward through the argon gas outlet to drive away and blow away the slag on the molten surface below the refractory cover, exposing the molten steel surface. The argon gas flow rate is controlled at 100~120L / min, and the argon gas pressure is controlled at 0.7~0.8MPa.

[0028] d. Continue lowering the refractory hood to the converter furnace wall refractory, adjusting the argon flow rate to 5~10L / min and the argon pressure to 0.25~0.30MPa to maintain positive pressure inside the refractory hood and prevent the molten steel inside from contacting the air. After the refractory hood is lowered, there is no slag on the liquid surface inside the refractory hood. Molten steel flows into the refractory hood from the side holes at the lower end of the side wall and flows out through the tapping port. Because the slag is above the molten steel, it effectively prevents slag from entering the refractory hood in the later stages of tapping, reducing the possibility of slag entrapment and slag dripping. At the same time, the slight positive pressure argon blowing inside the refractory hood also prevents the molten steel inside the refractory hood from contacting the air, reducing secondary oxidation and nitrogen accumulation of the molten steel in the later stages of tapping.

[0029] e. During the tapping process, the position of the tapping port changes due to the change in the converter angle. The moving trolley should be adjusted in a timely manner to keep up with the changes and ensure that the center of the refractory cover and the center of the tapping port are always aligned.

[0030] After the refractory hood is lowered, the slag is blocked outside the hood. Argon is blown into the hood under a slight positive pressure to prevent secondary oxidation and nitrogen accumulation in the molten steel, thus ensuring the quality of the molten steel. The design of the refractory hood itself also suppresses the formation of vortex flow in the molten pool during the later stages of tapping. Molten steel flows in through four side holes at the bottom of the refractory hood, preventing and slowing down the formation of vortices and the swirling of molten steel during the tapping process. This effectively reduces slag entrapment, avoids slag mixing, facilitates efficient slag separation, and allows for accurate slag detection at the end of tapping, improving slag blocking efficiency and effectiveness.

[0031] After the slag discharge test determines the end point of steel tapping, the slide gate is closed, and steel tapping ends.

[0032] After tapping is completed, start the hoisting device, pull down the rear end of the support arm again to raise the refractory cover, start the moving trolley to move the refractory cover out of the converter, and stop the argon gas supply.

[0033] In the later stages of converter tapping, the refractory hood, acting as a dedicated vortex suppression device, is placed above the tapping port via a moving trolley and support arm. High-flow-rate, high-pressure argon gas is used to blow away the slag on the molten steel surface before lowering the hood, blocking the slag outside the refractory hood. Molten steel flows in through four side holes at the bottom of the hood, ensuring a slight positive pressure argon blowing inside. This prevents secondary oxidation and nitrogen accumulation in the molten steel, reduces vortex formation, effectively suppresses slag entrapment in the later stages of tapping, avoids slag mixing, and improves the success rate of slag blocking. This device is simple, efficient, economical, and practical, effectively improving work efficiency, metal yield, and steel quality, demonstrating significant economic benefits and broad prospects for wider application.

[0034] Of course, the above description is not limited to the examples above. Technical features not described in this invention can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solutions of this invention and are not intended to limit this invention. This invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention do not depart from the spirit of this invention and should also fall within the scope of protection of the claims of this invention.

Claims

1. A device for reducing the slag entrapment in the tapping of a converter, characterized in that: The application relates to a supporting arm (8) and a refractory cover (1) mounted at one end of the supporting arm, wherein the refractory cover (1) is downwardly open, a plurality of side holes (5) are arranged on the lower end of the side wall of the refractory cover in a circumferential direction, an argon outlet (4) is arranged on the top of the refractory cover and faces the lower end of the refractory cover, and an argon pipeline (7) is arranged in the supporting arm and communicates with the argon outlet (4).

2. A device for reducing the slag entrapment in the tapping of a converter according to claim 1, characterized in that: The application further comprises a moving trolley (15) and a supporting column (14) fixedly arranged on the moving trolley, and the supporting arm (8) is mounted on the supporting column.

3. A device for reducing the slag entrapment in the tapping of a converter according to claim 2, characterized in that: The supporting arm (8) is rotationally connected with the supporting column (14) through a transverse hinge shaft (12), a hoisting device (19) is further mounted on the moving trolley, a wire rope of the hoisting device is connected with one end of the supporting arm away from the refractory cover, and the supporting column (14) is located between the refractory cover (1) and the wire rope.

4. A device for reducing the slag entrapment in the tapping of a converter according to claim 3, characterized in that: The distance from the connecting point of the wire rope and the supporting arm to the supporting column is smaller than the distance from the refractory cover to the supporting column.

5. A device for reducing the slag entrapment in the tapping of a converter according to claim 3, characterized in that: The supporting arm comprises a cylinder in which the argon pipeline is arranged and a counterweight (13) fixedly arranged at one end of the cylinder away from the refractory cover.

6. A device for reducing the slag entrapment in the tapping of a converter according to claim 1, characterized in that: A "cross" supporting frame (2) is cast in the top of the refractory cover, a connecting rod (3) penetrating the refractory cover upwards is fixedly connected to the "cross" supporting frame (2), and the upper end of the connecting rod (3) is hingedly connected with the supporting arm through a transverse shaft (10).

7. A method of using a device for reducing slag entrapment at tapping of a converter as claimed in any one of claims 2 to 6, wherein the device is used in conjunction with a slag skimmer. The application further comprises the following steps: a. starting the hoisting device in the late tapping stage to lower the end of the supporting arm where the counterweight is arranged and to raise the end of the refractory cover to correspond to the converter port; b. starting the moving trolley to send the refractory cover into the converter through the converter port and to make the refractory cover located directly above the tapping hole of the converter; c. releasing the wire rope of the hoisting device to slowly place the refractory cover in the liquid surface area of the steel slag above the tapping hole of the converter, supplying argon through the argon pipeline, and blowing the argon downwards through the argon outlet to drive away and blow open the liquid surface of the slag below the refractory cover to expose the liquid surface of the molten steel; the argon flow is controlled to be 100-120 L / min, and the argon pressure is controlled to be 0.7-0.8 MPa; d. continuously lowering the refractory cover to the refractory of the converter wall, adjusting the argon flow to be 5-10 L / min and the argon pressure to be 0.25-0.30 MPa to ensure the positive pressure in the refractory cover and prevent the molten steel in the refractory cover from contacting with air; after the refractory cover is lowered, there is no slag on the liquid surface in the refractory cover, and the molten steel flows into the refractory cover through the side holes on the lower end of the side wall of the refractory cover and flows out through the tapping hole; e. moving the refractory cover out of the converter after the tapping is completed and stopping the argon supply.

Images