JP7111090B2 - Converter refining method and protection device used for converter slag - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a converter refining method for preventing slag from flowing out to a work floor on the front side of a furnace during slag removal in a converter refining process of steelmaking, and a protective device used during slag removal from the converter.

In general, converter equipment consists of a fixed wall having a furnace front side opening provided so as to surround the furnace body of the converter, and a pair of movable walls covering the furnace front side opening of the fixed wall so as to be openable and closable. A partition is provided. This moving wall is called a charging door. The charging door is supported by a carriage below the charging door, and is opened and closed by lateral movement of the carriage. The charging door is opened when hot metal or scrap iron source is charged (hereinafter also simply referred to as charging), and is closed when slag is discharged. The left-right opening/closing direction of the charging door is parallel to the tilting axis direction of the converter. The overlapping portion (joining portion) of the left and right charging doors when the charging doors are closed is called a dividing portion of the charging door.

On the other hand, in the converter refining operation, conventionally, when desiliconization refining and dephosphorization refining are continuously performed in the same converter, the slag is discharged while the hot metal remains in the converter between each refining ( Also called intermediate waste) is being carried out. At that time, the larger the amount of slag discharged from desiliconization refining, the less limestone is used for dephosphorization refining in the next process, which leads to a reduction in refining costs. The slag is discharged by increasing the slag flow velocity by vigorously tilting the slag in the front direction of the furnace. However, at that time, the slag discharged with great force and having a high flow rate may flow out to the furnace front side working floor. Therefore, in order to prevent the slag from flowing out to the front-side work floor, there is a technique in which a converter slag protective member having a protective wall covering the gap between the dividing parts of the charging door is installed on the front-side work floor. (See Patent Document 1) and a technique of displacing the divided portion of the charging door from the center of the converter (See Patent Document 2) has been proposed.

Japanese Patent Application Laid-Open No. 2017-66500 JP 2017-57496 A

However, according to the technique proposed in Patent Document 1, as shown in FIG. It may become a physical obstacle when charging hot metal L into the furnace 11 or when charging a scrap iron source (not shown). In order to avoid this, the height h of the protective wall 31 should be limited to a height that does not interfere with the hot metal ladle 51 during charging, or the protective wall using an overhead crane 45 (only the hook portion shown) should be used during charging. It was necessary to move 31 from the furnace front 20 together with the protective member 39 for converter exhaust slag. Note that the converter slag protection member 39 is provided with a suspension stand 37 for suspension by an overhead crane 45 .

Setting a limit on the height h of the protection wall 31 means setting a limit on the slag flow velocity when slag is discharged, which causes a problem of reducing the amount of slag discharged. Further, if the overhead crane 45 is used to move and re-set the converter slag protection member 39, there is a problem that it takes too much time and the efficiency of the converter refining is lowered.

In addition, according to the technique proposed in Patent Document 2, since the divided portion of the charging door is removed from the collision point of the slag, the slag can be prevented from flowing out from there, but the slag can be prevented from flowing out to places other than the divided portion of the charging door. Since slag collision and adhesion cannot be prevented, there is a risk of water leakage from the piping due to slag collision in the case of a water-cooled charging door using a water-cooled membrane panel, and in the case of a non-water-cooled charging door, There is a risk of thermal deformation of the charging door due to hot slag deposits. Therefore, there is a problem that the slag flow velocity of the slag must be restricted in order to avoid collision of the slag with the charging door.

In view of the problems of the prior art, the present invention provides a converter refining method for preventing slag from flowing out to the front working floor of a converter during intermediate slag removal by means of a protective wall, wherein the height of the protective wall and the It is an object of the present invention to provide a converter refining method and a protective device used when removing converter slag, which can alleviate restrictions on the slag flow velocity of the slag and improve the efficiency and simplification of the work of moving and replacing the protective wall.

In order to solve the above-described problems, the inventors have made intensive studies and made the present invention having the following gist and configuration.
(1) A converter refining method for preventing slag from flowing out to the front working floor when slag is discharged while hot metal remains in the converter, wherein the slag is prevented from flowing out to the front working floor. A step of installing a protective device equipped with a protective wall for preventing from A converter refining method characterized by having
(2) The step of removing the protection device from the carriage of the one charging door includes removing the end of the protection wall of the protection device installed on the carriage of the one charging door and the one charging door. The transfer according to (1), characterized in that it is executed when the durability remaining index of the protective device, defined by the width dimension of the non-overlapping portion with the door in the open state, becomes less than a predetermined threshold. Furnace refining method.
(3) A forklift is used in the step of installing the protection device on the carriage of the one charging door and the step of removing the protection device from the carriage of the one charging door ( The converter refining method according to 1) or (2).
(4) A protective device used at the time of converter slag in the converter refining method according to any one of (1) to (3), wherein the protective device protects the slag from the converter, 1. A protective device for use in removing slag from a converter, comprising a protective wall for preventing outflow to the front working floor, and further, being installed on the carriage of one of the charging doors.
(5) The protective device used for the converter slag discharge according to (4), characterized in that the protective device can be installed on and removed from the carriage of the one charging door by a forklift.
(6) The protection used at the time of converter slag according to (4) or (5), wherein the material constituting the protection device is one or more selected from steel plates, castings, and refractories. Device.

According to the present invention, since the protective device used for discharging the slag from the converter is installed on the carriage of one of the charging doors, the protective device moves integrally with one of the charging doors when charging the hot metal ladle. , etc., thus eliminating the need to limit the height of the protective wall. In addition, by enabling installation on and removal from the truck by a forklift, even if thermal deformation due to collision or adhesion of slag occurs, the protective device can minimize the impact on front-of-furnace work. can be exchanged. As a result, there is no need to limit the slag flow velocity of the slag, and dephosphorization and refining can be performed with the minimum necessary amount of lime.

1 is a schematic diagram illustrating an embodiment of the present invention; FIG. Figure 2 is a schematic view showing the front of the protection device for the converter of Figure 1; 2 is a schematic view showing the rear side of the protection device for the converter of FIG. 1; FIG. FIG. 4 is a schematic view of a partly cutaway side view of a protection device used for converter exhaust slag during replacement by a forklift. FIG. 2 is a schematic diagram showing the connection between a conventional converter slag protection member installed on a work floor on the front side of the furnace and a hot metal ladle when hot metal is charged.

Embodiments of the present invention will be described below with reference to the drawings. Note that the hatched portion indicates a cross section.

FIG. 1 is a schematic diagram showing one embodiment of the present invention. In FIG. A part is a furnace front 20 where hot metal is charged. A furnace front side working floor 21 is provided in the furnace front 20 . FIG. 1 shows the state immediately after desiliconization blowing, and the slag S on the hot metal L is desiliconization slag. In this embodiment, as described above, the converter 11 is tilted in the direction of the arrow A on the front side of the furnace while the hot metal L remains in the converter 11, and the slag S is discharged, that is, the intermediate slag is discharged. will be

At the end of the furnace front 20 on the converter 11 side, there are a pair of charging doors 22 and 27 for isolating the front working floor 21 from the converter 11 during operation, and a charging door carrier supporting them (hereinafter simply referred to as , Also called a trolley.) 23 is provided. The surfaces of the charging doors 22 and 27 on the converter 11 side are called door front surfaces, and the opposite surfaces thereof are called door back surfaces. The carriage 23 is positioned on the rear side of the door. The charging doors 22 and 27 are opened and closed by moving the carriage 23 relative to each other in the direction of arrow B in FIG. 2 (the direction parallel to the tilting axis direction of the converter).

By the step of installing the protective device used for the converter slag according to the present invention on the truck of one of the charging doors 22 (hereinafter also simply referred to as the charging door 22), on the truck 23, the converter exhaust A protection device (hereinafter simply referred to as a protection device) 30 used for slag is installed. (See Figures 1-3)
If the protection device 30 is installed on the carriage 23 as in the present embodiment, the protection device 30 is placed on the carriage 23, and the work of connecting the carriage 23 and the protection device 30 can be omitted. Therefore, it is preferable.

The protection device 30 installed on the carriage 23 is removed from the carriage 23 and replaced with a new device when the replacement of the protection device 30 becomes necessary. This removal is the step of removing the protection device according to the present invention from the carriage of the one charging door 22 .

The protective device 30 is provided with a protective wall 31 arranged on the front side of the charging door 22 so as to cover the portion of the front of the charging door 22 that the slag S scatters and collides with during the intermediate waste discharge, and which is hit by the slag S. is doing. To avoid interference between the charging door 22 and the protective device 30 when the protective device 30 having the protective wall 31 arranged on the door front side is installed on the carriage 23 positioned on the door rear side. In addition, a door notch opening 25 for moving/inserting/inserting the protective device 30 is provided at one portion of the dividing portion of the charging door 22. As shown in FIG. (See Figures 1-3)
Since the protective wall 31 collides with the slag S at the time of intermediate waste disposal, the slag S causes thermal strain (more specifically, the collision and adhesion of the slag S). It may be difficult to prevent the slag S from flowing out to the furnace front side work floor 21 due to Therefore, in the present invention, the step of removing the protection device 30 from the truck 23 is executed when the residual durability index of the protection device 30 installed on the truck 23 becomes less than a predetermined threshold value. This residual durability index is defined by the widthwise dimension (a in FIG. 2) of the non-overlapping portion between the edge of the protection wall 31 and the one charging door 22 in the open state.

If the protective wall 31 deforms such as warping or bending in the thickness direction due to thermal strain, the dimension in the width direction decreases. If a) decreases and becomes too small, the risk of slag flowing behind the protective wall 31 increases. Therefore, a predetermined threshold value is set for the remaining durability index of the protection device 30, and when the remaining durability index of the protection device 30 measured with the charging door 22 open becomes less than the predetermined threshold value, the protection device is removed or replaced. I decided to do Here, if the predetermined threshold value is too large, the number of useless replacements will increase, and if it is too small, the slag S may suddenly flow out behind the protective wall 31. Therefore, from the viewpoint of 10 mm to 50 mm. preferable. As long as the measured thermal strain index is equal to or greater than a predetermined threshold value, it is not necessary to remove the protection device 30 from the truck 23 .

When the protective device 30 is removed from the truck 23 and then replaced with a new one, the entire removed protective device 30 may be replaced with a new one, or only the protective wall 31 of the removed protective device 30 may be replaced with a new one. The remainder includes both cases of reuse.

Moreover, from the viewpoint of strength and heat resistance, the material constituting the protective device 30 is preferably one or more selected from steel plates, castings, and refractory materials.

As a result, when the charging door 22 opens during charging, the protective device 30 on the carriage 23 moves together with the charging door 22 and does not interfere with the hot metal ladle or the like. It can be increased to a height higher than the height that interferes with a pot or the like, and there is no need to set a limit on the slag flow velocity of the slag S.

Further, in the present invention, the protection device 30 is removed from the truck 23 when the residual durability index (a in FIG. 2) of the protection device 30 measured with the charging door 22 open becomes less than a predetermined threshold value. Since the protection device 30 is replaced with a new one at every step, the number of replacements with a new one can be minimized within the service life of the protective device 30.

In this embodiment, a forklift 40 can be used to install the protective device 30 on the carriage 23 or to remove it from the carriage 23, as shown in FIGS.

Although the present invention does not prohibit the use of an overhead crane for the work of installing the protective device 30 on the truck 23 and the work of removing it from the truck 23, the overhead crane is used when the forklift 40 is used. Compared to the case, the work efficiency of the work of installing the protection device 30 on the truck 23 and the work of removing it from the truck 23 can be improved.

As shown in FIG. 4, in the protective device 30, the protective wall 31 is attached to the support base 32 and connected to one end of the base 33. As shown in FIG. A counterweight 34 is provided at the other end of the base 33 for balancing. Further, the base 33 has a nail sticking hole (forklift nail sticking hole) 35 for inserting a nail of the forklift 40 . Therefore, the protective device 30 can be transported by a forklift 40.

Then, for example, as shown in FIG. 3 (rear view) with the charging door 22 closed, the base 33 is positioned at a predetermined position on the carriage 23 of the charging door 22 (more specifically, the door notch on the carriage 23 is opened). 25), the front surface of the protective wall 31 faces the slag flow of the slag S discharged from the converter 11 when the charging door 22 is closed. there is

In the converter equipment configured as described above, the protection device 30 is installed at a predetermined position on the truck 23, molten iron and scrap iron source are charged into the converter 11, and the charging door 22 is closed. Perform desiliconization blowing. After the desiliconization blowing, as shown in FIG. Intermediate slag is performed to remove the silicon removal slag S while leaving L.

However, if the molten iron L is discharged while remaining in the converter 11, the slag is discharged at a shallower tilting angle than when the molten iron is tapped. If there is no slag S, there is a risk that the slag S will come into direct contact with the charging door 22 and flow out to the furnace front work floor 21 through the gap between the dividing parts of the charging door 22 . Furthermore, the desiliconization slag after the desiliconization blowing becomes slag S' in which the melt surface rises as indicated by a double arrow C due to the forming phenomenon, and the melt surface may reach the vicinity of the throat of the converter 11 . In this case, there is a risk that the slag will be discharged at a shallower tilting angle than expected, and the slag will scatter to the front side of the furnace.

Conventionally, as shown in FIG. 5, a protective member 39 for converter slag discharge has been placed on the work floor 21 on the front side of the furnace. Therefore, the height h of the protective wall 31 is limited in terms of the contact with the hot metal ladle 51 when hot metal is charged into the converter 11 .

On the other hand, in the present embodiment, as shown in FIGS. 1 to 3, the protection device 30 is integrated with the charging door 22 when the hot metal or scrap iron source is charged to the opening side in the direction of the double arrow B. (Fig. 2) and cannot interfere with the hot metal ladle for charging. Therefore, it is not necessary to limit the height h of the protection wall 31, and the height h of the protection wall 31 can be increased to a height corresponding to the rise of the silicon removal slag hot water level due to forming.

Moreover, the protective device 30 can be replaced by using a forklift 40 as shown in FIG. 4 without using an overhead crane or the like. , can be replaced with a new product, and the new product can be installed on the truck 23 using the forklift 40. Therefore, the thermal deformation due to the collision and adhesion of the slag to the protection wall 31 increases, and the heat of the protection device 30 increases. When the strain index becomes less than a predetermined threshold value, the protection device 30 can be replaced even in a short time after the hot metal is tapped until the hot metal is charged again.

A work process for replacing the protection device 30, which is performed when the measured value of the thermal strain index of the protection device 30 becomes less than a predetermined threshold value, will be described below.

First, with the charging door 22 closed, the forklift 40 is driven to the furnace front work floor 21, and the claw 41 of the forklift is inserted into the claw sticking hole 35 of the protective device 30 installed at a predetermined position of the truck 23. The vehicle is stopped, and the protection device 30 is lifted up from the truck 23 and supported. The stop position of the forklift 40 at this time is set in advance as the furnace front side stop position.

Next, when the charging door 22 is opened, the charging door 22 and the carriage 23 are withdrawn from the furnace front 20, but the protection device 30 is supported by the forklift 40 and remains in the furnace front 20. - 特許庁

Finally, the protective device 30 is lifted from the furnace front work floor 21, and the forklift 40 is retracted from the furnace front stop position to a retreat location (not shown), thereby completing removal of the protective device 30.

When re-installing a new protective device 30 that replaces the removed protective device 30 or a new protective device 30 that replaces the protective wall 31 at a predetermined position on the truck 23, the above steps are reversed. That is, first, the charging door 22 is opened. At this time, the opening width of the charging door 22 is made wider than the width at which the protection wall 31 is installed in order to facilitate the movement of the protection wall 31 from the door back side to the door front side. Then, the claw 41 of the forklift 40 is inserted into the nail sticking hole 35 of the new protective device 30 or the protective wall 31 placed in the evacuation place (hereinafter referred to as the protective device 30 after replacement). , and the forklift 40 is used to raise the protective device 30 after replacement to a position where it floats above the furnace front work floor 21 and supports it.

Next, the forklift 40 is driven to the front stop position and stopped. Then, when the protection device 30 is set to a height that does not interfere with the carriage 23 and the end of the door notch opening 25 of the charging door 22, and the charging door 22 is closed, a predetermined position on the carriage 23 that has been moved becomes the protective device after the replacement. It is positioned directly below the device 30 . Therefore, the claw 41 of the forklift 40 is lowered to lower the protective device 30 after replacement to a predetermined position on the truck 23 .

Finally, the claws 41 of the forklift 40 are extracted from the claw piercing holes 35 of the protective device 30 after replacement on the carriage 23, and the forklift 40 is evacuated from the front of the furnace 20 to the evacuation location, thereby removing the protective device after replacement. Installation of 30 in place on carriage 23 is completed.

The embodiments of the present invention will be described in more detail below with reference to examples.
In the factory to which the embodiment is applied, the distance between the center of the converter 11 and the front surface of the charging door 22 when closed is 7800 mm. When the slag S′ whose surface rises due to the forming phenomenon is discharged to the furnace front 20 in the absence of the protective wall 31, the charging door 22 is discharged to a maximum height of 2000 mm if the slag discharge is completed in 5 minutes. The slag stream will collide. If the slag is discharged over a period of time exceeding 5 minutes, it becomes rate-limiting for the entire process and production loss occurs, so the slag was discharged in 5 minutes.

On the other hand, in the example of the invention, which is an embodiment of the present invention, when the charging door 22 is opened during charging, the protection device 30 moves together with the charging door 22, and interference with the hot metal ladle 51 is prevented. Since this does not occur, the height h of the protection wall 31 can be increased to a height range that is not limited by the connection with the hot metal ladle 51 (see FIG. 5).

Therefore, in the example of the invention, in FIG. 1, the height h of the protection wall 31 was set to 2000 mm, the maximum height at which the slag stream collides. The protection device 30 except for the protection wall 31 is made of steel plate, and the protection wall 31 is made of casting. The protective wall 31 has a thickness of 25 mm, a width of 2600 mm, and a height h of 2000 mm. The residual life index (a in FIG. 2) of the protective device 30 was measured once every 10 times the charging door 22 was opened. Then, when the measured residual durability index of the protective device 30 becomes less than a predetermined threshold (threshold = 50 mm in the example of the invention), the protective device 30 is replaced by the forklift 40 . The replacement of the protective device 30 by the forklift 40 takes less than 10 minutes.

In the factory to which the embodiment is applied, the conventional technique of Patent Document 1 is applied as a conventional example instead of the invention example. In the conventional example, the height h of the protective wall 31 is limited to 600 mm due to the interface between the converter 11 and the hot metal ladle 51 shown in FIG. Since the height was less than 2000 mm, the slag stream collided with the charging door 22 and the charging door 22 was damaged.

On the other hand, in the example of the invention, since there is no restriction on the height h of the protective wall 31 due to the connection with the hot metal pot 51, the protective wall 31 with a height h of 2000 mm can be adopted, and the charging door 22 can be connected. I was able to avoid the damage.

Furthermore, in the factory to which the embodiment is applied, at the timing when the protective device 30 can be replaced after the blowing of the converter is completed, the overhead crane waits with the hot metal ladle 51 containing hot metal for the next blowing already suspended. there was a case. In the conventional example, when the converter slag protective member 39 is replaced by the overhead crane 45 as shown in FIG. Since the wall 31 was replaced and then the hot metal pot 51 was lifted again, it took more than 20 minutes.

In contrast, in the example of the invention, when the protection device 30 was replaced by a forklift 40 as shown in FIGS. 1 and 4, the time required for replacement was 10 minutes or less. significantly smaller than the

1 Converter equipment
10 Converter placement part
11 Converter
20 Furnace
21 Furnace front work floor
22 One charging door
23 Trolley (charging door trolley)
25 Door cutout opening
27 Other charging door
30 Protection device (Protection device used for converter slag)
31 Protection wall
32 support base
33 base
34 Counterweight
35 Nail stick hole (Forklift nail stick hole)
37 Suspension frame
39 Protective elements for converter slag
40 forklift
41 Forklift Claw
45 Overhead Crane (Hook)
51 Hot metal ladle L Hot metal S, S' Slag

Claims (6)

A converter refining method for preventing slag from flowing out to the front working floor when slag is discharged while molten iron remains in the converter, wherein the slag is prevented from flowing out to the front working floor. a step of installing a protection device having a protection wall for charging on the carriage of one charging door of a pair of charging doors; and a step of removing the protection device from the carriage of the one charging door. A converter refining method characterized by The step of removing the protective device from the carriage of the one charging door includes separating the end of the protective wall of the protective device installed on the carriage of the one charging door and the one charging door. 2. The converter refining method according to claim 1, characterized in that it is executed when the residual durability index of the protective device, which is defined by the width dimension of the non-overlapping portion in the open state, becomes less than a predetermined threshold value. . 2. A forklift is used in the step of installing the protection device on the carriage of the one charging door and the step of removing the protection device from the carriage of the one charging door. 2. The converter refining method according to 2. A protective device used at the time of converter slag in the converter refining method according to any one of claims 1 to 3, wherein the protective device prevents slag from the converter from flowing to the front work floor of the furnace. 1. A protective device for use in removing slag from a converter, comprising a protective wall for preventing outflow and being installed on a carriage of one of the charging doors. 5. The protective device for use in removing slag from a converter according to claim 4, wherein the protective device can be installed on and removed from the carriage of the one charging door by a forklift. 6. The protection device used for removing slag from a converter according to claim 4 or 5, characterized in that the material constituting said protection device is one or more selected from steel plates, castings and refractories.

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