JPH01217187A - Furnace bottom steel taking-out device of melting furnace - Google Patents

Abstract

PURPOSE:To preventing the oxidation of melting steel and the damage of a tap hole by detachably setting a moving cylindrical guide member at the tap hole and equipping a control means for detecting the melting level of a ladle and regulating the length thereof on the guide member while connecting an inactive gas and additive agent supplying means. CONSTITUTION:When a diameter shrinkage part 30 of a guide member 28 is composed of dual structure and an outer pipe is slide, it is moved on the melting level of melting steel 32 which is taken in a ladle 31. A melting surface sensor 34 and a control device 35 are connected to a drive device 33 and form a guide member control means 36. Inactive gas such as Ar and N2 is supplied from a bomb 39 in the guide member 28 and a tap hole as soon as the melting steel is taken in the ladle 31. Additive agent is taken out through a rotary valve 44 from a hopper 43, blown in the guide member 28 by a high pressure gas supply device 45 and added to the melting steel 32.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a bottom tapping device for a melting furnace, and in particular can prevent oxidation of molten steel and wear of the lagoon outlet, and can also prevent dephosphorization and removal. This invention relates to a bottom tapping device for a melting furnace into which additives such as S agent can be introduced.

[Conventional technology] Metal melting furnaces are generally used to melt and melt scrap.
Arc furnaces for refining, converters for refining hot metal tapped in blast furnaces, and the like are known.

In recent years, a bottom tapping type arc furnace 5 as shown in FIG. 2 has been adopted. As shown in the figure, the bottom tapping type arc furnace 5 similarly has a furnace body 2 and a furnace lid 3 made of steel plates and refractory bricks, and a part of the spherical furnace bottom 6 is radially outward. A tapping section 7 is provided extending from the steel tapping section 7, and a lagoon outlet 8 is formed in this tapping section 7. This drying outlet 8 is provided with an opening/opening gate 9 for closing it from below, and a ladle 10 is installed directly below it. This bottom tapping type arc furnace 5 requires only a small inclination angle of the furnace body 2 due to the tilting device 11 provided on the furnace body 2, and since steel is tapped from the furnace bottom 6, slag does not get mixed into the drawer A11. hard.

The opening/closing gate 9 for closing the lagoon outlet 8 employs a flapper gate 12 that rotates as shown in FIG. 3 and a slide gate 13 that moves horizontally as shown in FIG. 4.

The structure of the exhaust port 8 was such that a cylindrical through hole was formed by penetrating the steel plate and refractory bricks of the hearth bottom 6, and a graphite block 14 was placed on the inner wall of the through hole.

[Problems to be Solved by the Invention] By the way, the structure of the conventional drying outlet has the following problems.

The molten steel discharged from the outlet 8 and stored in the drawer wA11 is then subjected to secondary refining to become a product.

However, in the past, no special treatment was performed when tapping steel from the exhaust port 8 formed in the furnace bottom 6, and the molten steel simply fell through an oxidizing atmosphere, resulting in a decrease in yield due to oxidation. there were.

Further, since there is no means for guiding the molten steel from the draining port 8 to the ladle 11, there is a problem that the molten steel is likely to scatter.

Furthermore, since the lower end of the lagoon outlet 8 is exposed to air at high temperatures, there is a problem in that the graphite block 14 of the lagoon outlet 8 is oxidized and worn out.

In view of the above-mentioned problems, the present invention improves yield by preventing scattering and oxidation of molten steel during tapping, and improves refining performance by adding refining additives during tapping. It is an object of the present invention to provide a bottom tapping device for a melting furnace that can prevent the graphite block at the N outlet from being worn out due to oxidation.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an apparatus for tapping molten steel into a ladle from a spout formed at the bottom of a melting furnace, in which a device that can be attached and detached from the spout is provided. A cylindrical guide member that is freely provided and that covers the lower opening of the filtration port and that advances and retreats facing the surface of the molten steel tapped into the ladle, and a guide member that controls the height of the molten steel surface of the ladle. a guide member control means for detecting and adjusting the length of the guide member; an inert gas supply means connected to the lagoon outlet and the guide member to create an inert gas atmosphere therein; and an additive supply means connected thereto for supplying refining additives to the molten steel descending therein.

[Function] When tapping the molten steel housed in the furnace, the guide member is attached to the tap. This guide member is formed into a cylindrical shape, covers the lower opening of the draining port, and moves forward and backward facing the surface of the molten steel to be tapped into the ladle. The guide member control means detects the height of the hot water level in the ladle and adjusts the length of the guide member according to the height. That is, as the hot water level in the ladle rises, the length of the guide member is shortened and its tip is raised. Therefore, the guide member guides the molten steel from the outlet into the ladle and prevents it from scattering.

Moreover, the inside of this guide member and the inside of the exhaust port are made into an inert gas atmosphere by the inert gas supply means. Therefore, the molten steel discharged from the draining port is guided into the ladle without coming into contact with air, thereby preventing the molten steel from oxidizing and improving the yield.

Furthermore, since an additive supply means for injecting refining additives into the molten steel descending inside the guide member is connected to the guide member, impurities can be removed under an inert gas atmosphere during tapping. This improves refining performance.

Furthermore, even if the heat of the molten steel is transferred to the spout during tapping and reaches a high temperature, since the spout is not in contact with air, the graphite block inside the spout will not oxidize and wear out. is to be prevented.

[Example] An example of the bottom tapping apparatus for a melting furnace of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, the furnace body of the melting furnace 20 is formed of a steel plate 21 and refractory bricks 22. FIG. 1 does not show the main part of the furnace bottom 23, and the furnace bottom 23 is formed with a lagoon outlet 24 for tapping the molten steel contained in the furnace. The exhaust port 24 is formed by inserting a graphite block 26 inside a through hole 25 which is opened in a cylindrical shape through the steel plate 21 and the refractory brick 22 . The outer wall of the furnace bottom 23 is provided with a lower opening of the exhaust port 24 at 11
An opening/closing gate 27 such as a flapper gate or a slide gate is provided.

Further, a guide member 28 is detachably provided at the lower end of the evacuation port 24. This guide member 28 is formed into a cylindrical shape, and has a structure in which its upper end is in close contact with the steel plate 21 on the outer periphery of the evacuation port 24. Fixed to a steel plate. The upper part of this guide member 28 has an enlarged diameter, and this enlarged diameter portion 29 covers the outer periphery of the downwardly protruding portion of the evacuation port 24 . Further, the central and lower portions of the guide member 28 are reduced in diameter to have approximately the same diameter as the opening diameter of the tap 24 , and the reduced diameter portion 30 is suspended from the enlarged diameter portion 29 . The reduced diameter portion 30 of this guide member 28 has a double tube structure, and by sliding the outer tube, the
It is designed to advance and retreat while facing the bloodletting of the molten steel 32 that is tapped into the molten steel 31. The reduced diameter portion 30 of this guide member 28 is
A drive device 33 operates, for example, a rack and pinion structure to advance and retreat. In other words, the guide portion vi28 is a cylindrical body formed by integrally molding the enlarged diameter portion 29 and the reduced diameter portion 30 that moves forward and backward in the vertical direction. The guide member 28 covers the lower opening of the hot water spout 24 and moves forward and backward while facing the bloodletting of the ladle 31. The ladle 31 is installed directly below the hot water outlet 24.

At the top of the ladle 31 is a molten metal level sensor 34 for detecting the level of the molten steel 32 using ultrasonic waves or the like, and this molten metal level sensor 34 is connected to a control device 35 such as a microcomputer. This hot water level sensor 34 and 1lI111
11 device 1!35 is connected to the drive device 33, and these constitute a guide member control means 36. An inert gas supply means 37 is connected to the graphite block 26 and the guide member 28. This inert gas supply means 37 includes a gas supply pipe 38 connected to the enlarged diameter portion 29, a cylinder 39 connected thereto for storing an inert gas such as ^r or N2, and a cylinder 39 connected to the gas supply pipe 38. It consists of an on-off valve 40 which is interposed and adjusts the inert gas m. The gas supply pipe 38 is branched into a plurality of parts, including a plurality of circumferential parts of the enlarged diameter part 29 of the guide member 28 and a steel plate 21 of the furnace bottom 23. It passes through the firebrick 22 and the graphite block 26 in order and is connected to several points around the circumference thereof. The reason why the gas supply pipes 38 are arranged at the circumferential locations of the enlarged diameter portion 29 of the guide member 28 and at the circumferential locations of the graphite block 26 is to create a uniform inert gas atmosphere inside these parts. be. still,
The guide member 28 has a structure in which a refractory is placed inside the inner surface of a metal tube or a graphite tube, and the gas supply tube 38 is connected to the metal tube by passing through the tube.

Additionally, an additive supply means 41 is connected above the reduced diameter portion 30 of the guide member 28 . The additive supply means 41 includes an additive supply pipe 42, a hopper 43 connected to the hopper 43 for storing the additive, a rotary valve 44 for cutting out the additive from the hopper 43, and a rotary valve 44 for cutting the additive into the additive supply pipe 42. It consists of a high pressure gas (N2, etc.) supply device 45 for blowing the added additive into the guide member 28 at high pressure.In this embodiment, the additive supply means 41 has two systems. Additives such as a deP/S agent are charged into the hopper 43 of the additive supply means 41 of one system, and molten steel is charged into the hopper 43 of the additive supply means 41 of the other system. An oxidizing exothermic agent such as M is introduced to prevent the temperature from decreasing.The additive supply pipe 42 is penetrated at several points around the circumference of the guide member 28 in order to uniformly supply the additive into the guide member 28. The gas supply pipe 38 of the inert gas supply means 37 and the additive supply pipe 42 of the additive supply means 41 are detachably attached to the guide member 28 by means of a 7-lunge or the like.

Next, we will explain the effect of the above embodiment. Vero.

After the process of melting and refining scrap and the like in the melting furnace 20, the molten steel 32 that has been melted and refined in the furnace is tapped into a draw wA31. At this time, the molten steel 32 tapped from the drying port 24
Because there is no means to guide it from the exhaust port 24 to the drawer 131, it easily scatters and may oxidize when exposed to air. Then, the inner wall of the weeping port 24 becomes hot due to the heat of the molten steel.

Therefore, the lower end of the hot water spout 24 comes into contact with air, oxidizes and wears out. However, in this embodiment, the guide member 28 is provided in the exhaust port 24 in a detachable manner. This guide member 28 is operated by a drive device before opening the opening/closing gate 27 when tapping molten steel stored in the furnace.
Move it directly below the tap hole. Further, the case up to fixed N4 remains unchanged.

Next, the control device 35 of the guide member control means 36 is initialized. At this time, the length of the guide member 28 is in a state where it is extended to the maximum, and its tip end is 5 mm from the bottom of the handle w431.
It is located at a height of ~10α. In this state fFfl
The rfl gate 27 is opened. At this point, the output port 24
The sand filled inside falls and tapping begins. At the same time, the leap valve 40 connected to the gas supply pipe 38 of the inert gas supply means 37 is opened into the guide member 28 and the drainage port 24 to supply inert gas such as ^r or N2 from the cylinder 39. Supply gas to create an inert gas atmosphere. After starting tapping, the additive is cut out from the hopper 43 of the additive supply means 41 by the rotary valve 44, and the high pressure gas supply device 4
The additive cut out in step 5 is blown into the guide member 28 under high pressure to add the additive to the molten steel 32. In this embodiment, two systems of additive supply means 41 are provided for deP and deS.
An oxidizing exothermic agent and an oxidizing exothermic agent for preventing a temperature drop are respectively put into the hopper 43. Then, the drying port 24 and the guide member 2
Since the inside of the guide member 28 is maintained in an inert gas atmosphere, the molten steel being tapped is smoothly refined while descending within the guide member 28 under the inert gas atmosphere without any temperature drop. When tapping starts, the level of the molten steel 32 in the ladle 31 rises. Therefore, this hot water level height is detected by the hot water level sensor 34 of the guide member control means 36, and the value is controlled to zero.
11 into the device 35, and the reduced diameter portion 3 of the guide member 28
The output signal is output to a drive device 33 provided at 0. As a result, the reguide member 28 contracts and rises while maintaining a distance of 5 to 10 α from the hot water level height of the ladle 31. The enlarged diameter part 29 and the reduced diameter part 30 that move forward and backward of this guide member 28 are suspended from the draining port 24 to the inside of the drawer 81131, and guide the molten steel 32 tapped from the tap 24. This will prevent scattering outside the guide member 28. The molten steel 32 descending within the guide member 28 does not come into contact with air and is prevented from oxidizing since the inside of the guide member 28 is made into an inert gas atmosphere by the inert gas supply means 37.

Furthermore, the enlarged diameter portion 29 of this guide member 28 is connected to the spout 24.
Since the reduced diameter part 30 hangs down to the inside of the drawer w431, air does not enter from below, and the lower end of the spout 24 does not come into contact with air at all during tapping. Never.

As a result, the graphite block 2 installed inside the draining port 24
No. 6 is one that does not oxidize even when exposed to the heat of molten steel and reaches high temperatures, thereby preventing its wear and tear.

Further, after tapping the steel, when proceeding to the melting/dosing step 20, the guide member 28 is removed from the tap 24, the opening/closing gate 27 is used as a lever, and the tap 24 is filled with sand.

[Effects of the Invention] In summary, the present invention exhibits the following excellent effects.

(1) A cylindrical guide member that can be attached and detached from the lagoon outlet and covers the lower opening of the outlet and moves forward and backward while facing the bloodletting of the molten steel tapped into the ladle. The guide member is provided with a guide member control means that detects the height of the hot water level in the ladle and adjusts the length of the guide member.
Molten steel discharged from the lagoon outlet is guided by the guide member and accommodated in the ladle, preventing it from scattering and allowing safe work.

(2) Since the inert gas supply means is connected to the guide member provided with the guide member control means, oxidation of the molten steel descending within the guide member can be prevented, and the yield can be improved.

In addition, since the additive supply means is connected to the guide member, the molten steel descending inside the guide member can be successfully refined under an inert gas atmosphere during tapping, improving refining performance and improving product quality. be able to.

Furthermore, it is possible to prevent oxidative wear and tear of the graphite blocks installed on the inner wall of the lagoon outlet, and maintenance can be reduced.

(3) Since it is a simple device, it can be easily applied to existing melting furnaces and is highly versatile.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the main parts showing the bottom tapping device of the melting furnace of the present invention, Fig. 2 is a schematic diagram showing the bottom tapping type arc furnace, and Figs. 3 and 4 show the conventional structure. It is a principal part schematic diagram for explaining. In the figure, 20 is a melting furnace, 23 is a furnace bottom, 24 is a drying port, 2
8 is a guide member, 31 is a ladle, 32 is molten steel, 36 is a guide member control means, 37 is an inert gas supply means, and 41 is an additive supply means.

Claims (1)

[Claims] 1. In a device for tapping molten steel into a ladle from a spout formed at the bottom of a melting furnace, a device is removably installed at the spout, covers the lower opening of the spout, and is detachable. a cylindrical guide member that moves forward and backward facing the surface of the molten steel tapped into the ladle; a guide member control means that detects the height of the hot water surface of the ladle and adjusts the length of the guide member; an inert gas supply means connected to the spout and the guide member to create an inert gas atmosphere therein; and an inert gas supply means connected to the guide member for supplying molten steel refining additives that descend inside the outlet. 1. A bottom tapping device for a melting furnace, comprising an additive supply means.