JPH05177316A - Tundish and reusing method thereof - Google Patents

Abstract

PURPOSE:To simply carry out the operation and easily and perfectly discharge remained steel, etc., in a tundish. CONSTITUTION:In a method for reusing the tundish 1 by melting and removing the remained steel, etc., 2 in the tundish 1 after completing continuous casting with a burner, in the interval from the step completing the continuous casting till the step melting and removing the remained steel, etc., 2 with the burner, solid additive 3 lowering the m.p. of the remained steel, etc., 2 and/or increasing the fluidity is supplied in the tundish 1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a tundish and a method for reusing it. More specifically, the present invention provides
Especially the steel and slag that remain in the tundish (hereinafter,
In the present specification, "residual steel, etc.")
The present invention relates to a tundish that can be discharged and a method of reusing it.

[0002]

2. Description of the Related Art In continuous casting, molten steel is poured into a tundish after passing through a ladle, and is continuously cast into a mold through a tundish nozzle. If the molten steel is poured directly into the mold from a ladle containing a large amount of molten steel, it becomes difficult to adjust the flow rate and flow rate of the molten steel, so the tundish is an indispensable facility in continuous casting.

Such a tundish is normally used continuously for about 3 to 5 heats. However, if it is reused without repairing the tundish, it will be continuously cast at the initial stage of casting due to residual steel remaining in the tundish. Increasing inclusions and contamination from different components on the piece deteriorates the quality of the slab, and in the worst case, the tundish nozzle part at the start of casting.
There was a risk that (the inside of the tundish inside the tundish nozzle attachment part) would be blocked.

Therefore, the tundish is conventionally repaired by moving the tundish to the repairing place while leaving the molten steel of about 1 to 5 tons and the slag of about 0.1 to 0.5 tons left for several hours. After cooling, the tundish was tilted, and mechanical steel such as a hammer was used to crush and remove the residual steel and the like. At this time, part of the refractory material in the tundish also collapsed, so the collapsed refractory material was repaired, the tundish nozzle was replaced, and the temperature was raised again to prepare for the next operation. ..

Such a repairing method not only increases the cost of the refractory material because the refractory material cannot be reused, but is also a work that involves the scattering of dust and the generation of noise for the operator, which is environmentally friendly. It cannot be said to be preferable, and its improvement has been desired. In recent years, in order to improve the repair work of such a tundish, a method of heating the residual steel and the like in the tundish with a burner and melting and discharging the same has been studied. For example, the methods listed below are known.

(A) Japanese Unexamined Patent Publication No. 62-127146 DISCLOSURE OF THE INVENTION A residual steel or the like in a tundish that has finished casting is heated and melted by a burner and discharged from a nozzle. Is a method of receiving hot water.

(B) Japanese Unexamined Patent Application Publication No. 1-107948 SUMMARY OF THE INVENTION A step of melting and removing residual steel or the like in the nozzle portion after completion of casting with a consumable lance for opening to open the nozzle portion, and the vicinity of the upper surface of the nozzle portion after opening A method comprising the steps of dissolving and removing the residual steel and the like adhered to the nozzle with a burner, and placing the start pipe on the upper surface of the nozzle after the cleaning to prevent the residual steel and the like from flowing into the nozzle. Is.

(C) Japanese Unexamined Patent Application Publication No. 1-107949. A step of tilting the tundish after the completion of casting to discharge residual steel or the like from a discharge hole provided between the upper part of the tundish and the tundish lid. The method comprises the steps of melting and discharging the residual steel and the like adhering in the tundish with the post-discharge preheating gas and oxygen gas.

[0009]

However, these conventional proposals for repairing tundish have the following problems, respectively. In the method of (a), it is difficult to discharge from a small diameter nozzle if the amount of residual steel is relatively large, and if the elapsed time from the end of pouring to the start of heating is relatively long, the temperature of each part drops. However, there is a problem that the residual steel or the like cannot be completely melted and discharged, and some remains in the tundish.

The method (b) has a problem that it can be applied only to a continuous casting method using a start pipe. That is, in this method, since the dissolution and discharge of the residual steel and the like is incomplete, it has been necessary to prevent the residual steel and the like from flowing into the tundish nozzle by the start pipe.

In the method (c), it is necessary to discharge the residual steel, which handles high-temperature substances, in two steps. Therefore, the tundish moving operation, the tilting operation, and the recovery operation of the residual steel are complicated. There is a problem that it will become. further,
If the elapsed time from the end of pouring to the start of heating is relatively long,
There is also a problem that the temperature of each part is lowered and the residual steel or the like cannot be completely melted and discharged, and some residual steel or the like remains in the tundish. This is clear from Table 1 of JP-A-1-107949, in which the weight of the residual steel is 10 kg and the weight of the residual steel slag is 20 kg. To reduce the amount of residual steel, etc., it is necessary to set the time from the end of casting to the start of melting and discharging with preheating gas and oxygen gas within about 10 minutes.
After the lapse of more than a minute, a melting and discharging time of about 30 minutes or more was required due to heating, so that there was a problem in that work was hindered when the remaining steel and the like of a plurality of tundish were sequentially dissolved and removed and reused. Further, FIG. 8 schematically shows the discharge situation of residual steel and the like by this method. FIG. 8 is an explanatory view showing a vertical cross section of the tundish at the time of tilting. In the figure, reference numeral 1 is a tundish, reference numeral 2 is residual steel, reference numeral 5 is a tundish lid, and reference numeral 8 is Exhaust holes, reference numeral 9 respectively indicate a burner, but as is clear from FIG. 8, there is no specific hole for discharging the combustion product gas to the outside of the tundish 1,
There is also a problem that high-load combustion cannot be performed. Further, since the combustion product gas is discharged from the discharge hole 8 of residual steel,
There is also a problem that the high-temperature combustion product gas is highly likely to heat the iron skin of the tundish 1 and the tundish lid 5 to cause a problem such as thermal deformation.

The object of the present invention is to solve many problems in the reuse of the conventional tundish described above,
It is an object of the present invention to provide a tundish that can be relatively easily implemented and that can easily and completely discharge the residual steel and the like in the tundish, and a method for reusing the tundish.

[0013]

SUMMARY OF THE INVENTION Here, the gist of the present invention is to re-use a tundish by melting and removing steel and steel slag remaining in the tundish after continuous casting with a burner. In the step of from the stage of the end of continuous casting to the stage of melting and removing the steel and the slag by the burner, lowering the melting point of the steel or the slag, and /
Alternatively, it is a method of reusing a tundish, which comprises supplying a solid additive that increases fluidity into the tundish.

From another aspect, the present invention provides a tundish in which steel and steel slag remaining in the tundish after completion of continuous casting are melted and removed by a burner and reused. A plurality of burners arranged so that their tips face the inside of the tundish through a plurality of openings provided in the tundish lid so as to face the plurality of tundish nozzles; and (ii) a truck for loading the burner, (iii) ) A tundish characterized by comprising a combustion product gas discharge pipe fitted so as to be inscribed in a molten metal injection hole provided in a tundish lid, and (iv) a discharge hole for discharging molten residual steel, etc. is there.

In the tundish according to the present invention described above, the discharge hole is provided at the joint between the tundish lid and the tundish side wall in the vertical cross section in the width direction of the tundish, and the iron skin or side wall refractory is When the tundish is tilted by 90 degrees in order to dissolve and remove the steel and the steel slag with the burner, the angle of the side wall refractory surface of the tundish with the horizontal toward the discharge hole is 15
It is desirable to be configured so as to be equal to or more than once.

[0016]

The present invention will be described in detail below with reference to the accompanying drawings together with its effects. FIG. 1 is an explanatory diagram for explaining an embodiment of a method according to the present invention, and FIG.
It is explanatory drawing which shows the cross section AA 'shown in FIG.

In the present invention, as shown in FIG. 1, the tundish nozzle portion in the tundish 1 after the continuous casting is finished.
The tundish 1 is obtained by melting and removing the residual steel 2 remaining in 4'with a burner (not shown in FIGS. 1 and 2).
In the method of reusing the steel, the process shown in FIG.
Alternatively, as shown in FIG. 2, a solid additive 3 that lowers the melting point and / or increases the fluidity of the residual steel 2 in the tundish 1 is supplied into the tundish 1.

The method of supplying the solid additive 3 in the present invention may be any method, and may be supplied in any state, without any limitation. But,
For example, as shown in FIGS. 1 and 2, it is desirable to spray the residual steel 2 to completely cover the residual steel 2 in order to lower the melting point and increase the fluidity.

The type of the solid additive 3 may be any solid substance that lowers the melting point and / or increases the fluidity of the residual steel 2 and the like, without any limitation. Examples thereof include soda ash, fluorspar, or solid carbonaceous substances such as coke, bean charcoal, and charcoal.

In the present invention, the solid additive 3 is supplied into the tundish 1 prior to heat removal of the residual steel 2 to reduce the melting point of the residual steel 2 and / or increase the fluidity. As a result, it becomes easy to dissolve and remove the residual steel and the like by the burner, and it is possible to shorten the dissolution and removal time and achieve complete removal of the residual steel and the like. Note that FIG.
2, reference numerals 4a and 4b denote tundish nozzles, reference numerals 5a to 5c denote tundish lids, and reference numerals 6a and 6b denote tundish lids 5, respectively.
Reference numerals 7 are molten metal injection holes provided in the tundish lid 5b.

FIGS. 3 and 4 are explanatory views showing the plane of the tundish 1 according to the present invention. In the example shown in FIG. 3, the discharge holes provided at the joint between the tundish lid and the tundish side wall are shown. The number of installation is one, and the example shown in FIG. 4 is two. Further, FIG. 5 is an explanatory view showing a cross section BB 'shown in FIG. Reference numerals 8, 8a and 8b in FIGS. 3, 4 and 5 are discharge holes for discharging the molten residual steel 2 and the like, respectively.

Further, FIG. 6 is a cross-sectional view showing a state when the tundish according to the present invention shown in FIG. 4 is tilted.
FIG. 7 is a plan view showing a configuration example when the tundish according to the present invention is tilted. Reference numerals in FIGS. 6 and 7 are the same as those in FIG. In FIG. 6, either one of the discharge holes 8a or 8b provided at the joint between the tundish lid 5 and the side wall of the tundish 1 is also indicated by reference numeral 8.

The tundish according to the present invention is a tundish in which residual steel and the like in the tundish after completion of continuous casting are melted and removed by a burner and reused after repair, and as shown in FIG. Tundish nozzle part
4 ', 2 of tundish lids 5a, 5c provided opposite to 4'
The two burners 9a and 9b and the burners 9a and 9b are arranged so that the tips of the two openings 6a and 6b face the inside of the tundish 1.
The trolleys 11a and 11b for loading the gas and the combustion product gas discharge pipe 13 fitted so as to be inscribed in the molten metal injection hole 7 formed in the tundish lid 5b are installed. 6 and 7, reference numeral 10 is a heat insulating plate, which is fixed to the burner in order to prevent the high temperature combustion product gas from being ejected from the opening 6. Reference numeral 12 is a recovery container, which is installed to accommodate the residual steel and the like that have been melted and discharged. In this way, when the inside of the tundish is heated by a plurality of burners provided facing the plurality of tundish nozzles, the residual steel on the tundish nozzle is intensively heated by the burners, and And the like are dissolved and removed extremely efficiently.

In the tundish shown in FIGS. 3 to 7, the discharge hole is installed at the joint between the tundish lid and the tundish side wall, but the present invention is not limited to this embodiment. Absent. The discharge hole may be provided at a position where the melted residual steel or the like can be discharged at the time of tilting.

Further, in the tundish according to the present invention, the residual steel or the like in the tundish after the continuous casting is dissolved and removed by a burner and reused. The side wall refractory of the tundish 1 is constructed such that when the dish 1 is tilted by 90 degrees, the surface of the side wall refractory of the tundish 1 becomes horizontal to the discharge hole 8 at an angle of 15 degrees or more. Is desirable. That is, one or both of the angle α in FIGS. 3 and 4 and the angle β in FIGS. 5 and 6 may be set to 15 degrees or more. In this way, by constructing the sidewall refractory so that the angle between the tundish and the sidewall refractory surface with the horizontal toward the discharge hole 8 is 15 degrees or more, the burner heats and melts the residual steel or the like. At this time, it is desirable that the residual steel that has been melted can be discharged from the discharge hole without stagnation or remaining on the sidewall refractory surface. Furthermore, the present invention will be described in detail with reference to examples, but this is merely an example of the present invention, and the present invention is not limited thereby.

[0026]

[Embodiment 1] In one embodiment of the present invention, FIG.
Using the tundish having the shape shown in FIG. 5, continuous casting of 4 heats was carried out, leaving 4 tons of molten steel and 0.5 tons of steel slag in the tundish at the end of casting. And at the end of the pouring, soda ash in the tundish.
30 kg was sprayed so as to cover the molten steel and the upper part of the steel slag.

The tundish 10 minutes after the completion of casting was tilted by 90 degrees as shown in FIGS. 6 and 7 and heated by two burners. The heating conditions were as follows: the fuel supplied to the burner was coke oven gas at 10 Nm ³ / min, and the combustion-supporting gas was oxygen-enriched air with an oxygen concentration of 50% at 20 Nm ³ / min. After 15 minutes from the start of heating, 4 tons of steel and 0.5 tons of steel slag could be completely discharged without remaining in the tundish.

[0028]

Example 2 Continuous casting of 3 heats was carried out using a tundish having a capacity of 45 tons and having the shape shown in FIGS. 4 and 5, and 5 tons of molten steel was added in the tundish at the end of casting. Left with 0.5 ton of steel slag.

At the tundish residue depositing position, since the residue of the tundish used for another casting was being discharged, 50 kg of coke was supplied, and the tundish 30 minutes after the pouring was completed is shown in FIG. As shown in FIG. 7, it was tilted 90 degrees and heated with two burners. The heating conditions were the same as in Example 1. 5 tons of steel in 22 minutes after starting heating
It was possible to completely discharge 0.5 ton of slag without remaining in the tundish.

[0030]

As described in detail above, according to the present invention,
Remaining steel and the like in the tundish can be relatively easily and completely discharged. The significance of the present invention having such effects is extremely remarkable.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating an example of the present invention.

FIG. 2 is an explanatory diagram illustrating a cross section AA ′ shown in FIG.

FIG. 3 is an explanatory diagram illustrating a plane illustrated in FIG.

FIG. 4 is an explanatory diagram illustrating a plane shown in FIG.

5 is an explanatory diagram illustrating a cross section BB 'shown in FIG. 2. FIG.

FIG. 6 is an explanatory diagram illustrating an example of the present invention.

FIG. 7 is an explanatory diagram illustrating an example of the present invention.

FIG. 8 is an explanatory diagram illustrating an example of a conventional technique.

[Explanation of symbols]

1: Tundish 2: Remaining steel etc. 3: Solid additive 4, 4a, 4b: Tundish nozzle 4 ': Tundish nozzle part 5a-5c: Tundish lid 6a, 6b: Open hole 7: Molten metal injection hole 8, 8a, 8b: Exhaust holes 9, 9a, 9b: Burner 10: Heat shields 11a, 11b: Truck 12: Recovery container 13: Combustion product gas exhaust pipe

Claims (3)

[Claims] 1. A method of reusing the tundish by melting and removing the steel and steel slag remaining in the tundish after the end of continuous casting with a burner, and melting the steel and steel slag with the burner from the stage of the end of continuous casting. The melting point of the steel or steel slag is lowered during the removal stage, and / or
Alternatively, a method for reusing a tundish, which comprises supplying a solid additive that increases fluidity into the tundish. 2. A tundish that is reused after melting and removing steel and steel slag remaining in the tundish after continuous casting with a burner, and further comprising (i) facing a plurality of tundish nozzles. A plurality of burners that are arranged with their tips facing the inside of the tundish through a plurality of openings provided in the tundish lid, (ii) a trolley for loading the burner, and (iii) a tundish lid A tundish provided with a combustion product gas discharge pipe fitted so as to be inscribed in the molten metal injection hole, and (iv) a discharge hole for discharging molten steel and steel slag. 3. The discharge hole is provided at a joint between a tundish lid and a tundish side wall in a vertical cross section in the tundish width direction, and the iron skin or side wall refractory of the tundish is made of steel by a burner. And, when the tundish is tilted by 90 degrees to dissolve and remove the steel slag, the sidewall refractory surface of the tundish forms a horizontal angle toward the discharge hole of 15 degrees or more. The tundish according to claim 2, wherein