JPH1071456A - Tundish for removing slag in hot state and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tundish which can reuse in the hot state at low cost even in a continuous casting equipment for multi-strands having >=3 strands, and a slag removing method in the tundish in the hot state. SOLUTION: In the tundish for multi-strands having >=3 strands are removing the slag in the hot state, a slag removing hole 2 for removing remained molten metal and slag from the tundish 1 is arranged near on the perpendicular bisector in the straight line connecting pouring holes corresponding to the strands at both ends among the pouring holes 3 for pouring the molten metal into a mold. Further, each mutual distance among three positions of the molten metal dropping position from the ladle, the slag removing hole and each pouring hole is made to >=800mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tundish and a hot-draining method for hot-draining a multi-strand in a step of continuously casting a molten metal.

[0002]

2. Description of the Related Art Tundish is being reused hot for the purpose of cost reduction in continuous casting. Hot reuse of the tundish means that at the end of casting, the remaining molten metal and slag of the tundish are discharged in a molten state, and if necessary, the injection system refractories such as the tundish stopper and injection nozzle are exchanged and maintained. This method uses the same tundish continuously for the next casting, and significantly reduces the maintenance time of the tundish compared to the conventional method of once cooling and removing residual molten metal and slag in the tundish. Not only can this be reduced, but also refractory costs can be reduced, and tundish preheating gas and the like can be reduced.

[0003] The most technical point in performing hot reuse of a tundish is how to completely discharge the residual molten metal and slag in the tundish. It has been found that the residual molten metal and slag remaining in the dish may adversely affect the quality of the next casting.

[0004] A conventional tundish on the premise of hot waste is a molten steel injection flow drop region injected from a ladle through a long nozzle as described in Japanese Patent Application Laid-Open No. 4-351251. A slag / metallic inclusion floating area having an injection nozzle is provided downstream of the molten steel injection flow falling area, and a slag cut weir for preventing slag from flowing out from the injection flow falling area to the floating area is provided in both areas. By providing a partition in the partition and providing a concave portion in the injection flow falling area, the area in which the residual molten metal and slag are present in the tundish is narrowed, and a tank having a shape that facilitates hot waste disposal. A dish is disclosed.

[0005]

However, in the case where the strand premised by the present invention is a tundish for hot waste in a continuous casting facility for three or more multi-strands,
Providing a weir or providing a recess at the bottom as in the above-mentioned conventional tundish not only increases the cost because the structure of the refractory of the weir and the tundish becomes complicated, but also, in particular, a tank with three or more strands. In the case of a dish, the weir becomes very large, and the shape of the bottom of the tundish becomes more complicated, which is unsuitable for actual operation.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a tundish which can be applied to hot reuse at low cost even in a continuous casting facility for a multi-strand having three or more strands, and a hot waste of the tundish. It provides a method.

[0007]

The gist of the present invention is as follows. In a multi-strand tundish having three or more strands, the remaining molten metal
A discharge hole for discharging the slag is disposed near a vertical bisector of a straight line connecting the injection holes corresponding to the strands at both ends of the injection hole for injecting the molten metal into the mold, and the molten metal from the pan is disposed. A hot-draining tundish, wherein the distance between each of three positions of a drop position (hereinafter, referred to as a dropping portion), the waste hole, and each of the injection holes is 800 mm or more. Furthermore, in the above-mentioned tundish, the angle (α) formed between the tundish side wall on the side of the waste hole and the rotation axis for tilting the tundish is set to 10 ° or more, and the tundish is inclined toward the waste hole. A tundish characterized by a sloping structure. Also, when discharging the residual molten metal and slag from the tundish using a tundish having a function of tilting the tundish by a rotation axis parallel to a straight line connecting the injection holes of both ends strands or the above-described tundish. In addition, the tundish is tilted by the tilting function, and the waste hole is set at a position lower than the normal position.
This is a hot waste disposal method characterized by discharging slag.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A shows one embodiment of the present invention.
As shown in the embodiment, in the hot-discharge tundish 1, a discharge hole 2 for discharging residual molten metal and slag from the tundish is connected to a straight line L connecting injection holes 3 corresponding to both-end strands. By disposing the molten metal and slag in the vicinity of the vertical bisector at the shortest distance, the entire molten metal and slag in the tundish can be discharged quickly. Also,
The distance l ₁ between the bath 4, the drain hole 2 and each injection hole 3,
l ₂ and l ₃ are each longer than a predetermined distance, preferably 800
mm or more, the silica sand, etc., which has been filled in the waste holes during casting is washed away by the injection flow, and metal is adhered to the waste holes, partially or entirely closing the waste holes. In addition to preventing the waste after casting from malfunctioning, local damage to the injection-type refractory due to the injection flow from the melt-down portion and the injection hole for slag and inclusions caught in the melt-down portion It is possible to prevent the molten metal and slag from adhering to the vicinity of the injection hole at the time of waste disposal.

Further, as shown in FIG. 1 (b), the tundish 1 can be tilted, and at the same time, the tundish side wall on the side of the drain hole is disposed so that the residual molten metal and slag are easily collected in the drain hole. By making the structure of 1a inclined toward the discharge hole at a predetermined angle α or more with respect to the rotation axis A for tilting the tundish, it is more effective in terms of improving the drainage property. This angle α needs to be at least 10 °. Here, in the event that the waste hole becomes inoperative for some reason, a waste gutter (which may also be used as an emergency gutter) may be provided on the tundish side wall on the waste hole side.

FIG. 2 shows the relationship between the distance of the waste hole from the molten metal dropping portion and the amount of silica sand washed out in the waste hole, which was confirmed by a water model test. The method is as follows. A half-scale model of a tundish (15 tons, 4 strands) shown in the following example is created, and 2000 tons of molten steel conversion is performed using pseudo fillings (granular type and clayey material).
A pseudo-injection in an amount corresponding to was performed, and the amount of the pseudo-stuffing washed out was measured. From the experimental results, it was confirmed that when the distance between the slag hole and the molten metal dropping portion was 800 mm or more, the silica sand was almost not washed out, and the slag after casting was completed normally.

Similarly, FIG. 3 also confirms the relationship between the distance between the molten metal dropping portion and the nearest injection hole and the amount of slag inflow using a water model. The method uses the above-mentioned water model tundish, mixes pseudo inclusions (polyethylenes) in water, injects them into the tundish, and in the tundish, makes a pseudo slag (liquid paraffin) exist in the tundish. Casting was performed, and the amount of the pseudo inclusions or pseudo slag flowing out from the injection hole was measured. The experimental results show that the distance between the hot water drop and its nearest injection hole is 80.
At 0 mm or more, it was confirmed that the inclusions and slag almost floated before reaching the injection hole.

[0012]

EXAMPLES The present invention was applied to an actual tundish under the following conditions.・ Heat size: 230 ton / ch ・ Tundish capacity: 15 ton ・ Number of strands: 4 strands ・ Distance l ₃ between the run-off portion and the drain hole: 1100 mm ・ Distance l ₂ between the run-off portion and the nearest injection hole: 1100 mm・ The angle α of the side wall of the tundish toward the waste hole with respect to the tilt axis; 15 ° The average of the tundish with the above specifications is 10 ch / cast and 5 cast
Applied to As a result, it was possible to discharge the residual molten metal and slag from the tundish without particularly hindrance by opening the drain hole within 5 minutes after the end of casting. After the discharge, the vicinity of the tailhole was observed, but no ingot was found near the tailhole,
Filling material that was filled in the waste hole (in this case, use silica sand)
It was confirmed that was not washed away by the injection flow. A quality survey was conducted on the cast slab when the tundish was reused, but no harmful inclusions due to entrained slag were found.

[0013]

According to the present invention, even in a multi-strand tundish with three or more strands, the refractory is inexpensive, the waste is effectively discharged after the casting is completed, and the tundish is smoothly applied to the next casting. It is possible to perform hot reuse without deteriorating the quality of the cast slab.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the distance of a waste hole from a molten metal dropping portion and a silica sand washout index.

FIG. 3 is a diagram showing a relationship between a molten metal dropping portion, its distance from a nearest injection hole, and a slag / inclusion levitation index.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tundish 2 Drainage hole 3 Injection hole 4 Dehydration part

Claims (3)

[Claims] In a multi-strand tundish having three or more strands, a discharge hole for discharging residual molten metal and slag from the tundish is provided at both end strands of an injection hole for injecting molten metal into a mold. Arranged in the vicinity of a vertical bisector of a straight line connecting the corresponding injection holes, a position where the molten metal falls from the pan (hereinafter, referred to as a molten metal dropping portion), the waste hole, and the three positions of the respective injection holes Characterized in that each of the distances is 800 mm or more. 2. An angle (α) between a tundish side wall on the side of a waste hole and a rotation axis for tilting the tundish.
2. The tundish according to claim 1, wherein the angle is set to 10 [deg.] Or more and inclined toward the waste hole. 3. A tundish having a function of tilting the tundish by a rotation axis parallel to a straight line connecting the injection holes of both end strands or a tundish using the tundish according to claim 1 or 2; When discharging the residual molten metal / slag, the tilting function tilts the tundish to set the discharge hole lower than a normal position, and discharges the residual molten metal / slag from the discharge hole. Slag method.