JPH02284751A - Tundish refining device - Google Patents

Abstract

PURPOSE:To quickly execute the stirring of molten steel and to efficiently execute tundish refining by injecting gas from both lances while mutually facing to alloy adding position in the tundish and providing a stirring device for stirring the molten metal. CONSTITUTION:The prescribed molten alloy from a melting furnace 5 is poured and as necessary, the molten steel is heated with an induction heater and also inert gas, etc., is blown from a bottom blow bubbling device 3 and jet lances 6. Since the molten steel is stirred while circulating along inner peripheral face of the tundish 1 by blowing the inert gas with the jet lances 6, the poured molten alloy is quickly and uniformly mixed. By this method, the stirring of molten metal can be quickly executed and casting start with good efficiency is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a tundish refining device used, for example, in continuous casting equipment.

[Conventional technology and its issue a] Tundishes generally used in continuous casting equipment are:
A distributor placed between the ladle and the mold that stabilizes the flow of molten steel from the ladle and pours it into the mold for continuous casting, and in the case of multiple strands, distributes the molten steel to the mold corresponding to each strand. plays the role of

By the way, one of the difficulties of continuous casting equipment is the production of a wide variety of small ronds, and in order to solve this difficulty, it has recently been proposed to provide a refining function to the tundish. According to the publication, a tundane is divided into two chambers by a sinking weir, an immersion nozzle for injecting malt is attached to the bottom of one chamber, and the other chamber is constructed as follows. In other words, this chamber faces the sliding nozzle attached to the lower surface of the ladle, and also contains additive alloys (for example, AI, Ti, V, Nt, Cr, Mo, Cu, Nb, etc.) for adjusting the composition of the steel material. ), which is connected to a melting furnace that holds the melted material in advance, and is also equipped with a bottom-blowing bubbling device and an inductor heater for reheating.

Therefore, the molten alloy is added to the molten steel poured from the ladle and stirred to adjust the composition of the molten steel.

The adjusted molten steel then overflows the sinking weir and is cast into malt.

Furthermore, when w4g4 is varied by changing the amount of alloy added, the injection speed of the molten alloy in the feeder is adjusted. As a result, it is said that a wide variety of steel products with small ronds can be produced.

However, according to the tests conducted by the present inventors, in such a tanditsu refining apparatus, unlike the ladle refining carried out in -i, the shape of the tanditsu is rectangular.
It has been found that when a molten alloy is added to molten steel, it takes a long time for the alloy to be uniformly mixed throughout the tundish.

In other words, the quality of recent steel materials has improved in grade, and for this reason, molten steel is transferred to a ladle and then refined.
So-called ladle refining is generally carried out, but since the ladle refining ladle is generally formed in a cylindrical shape and bottom-blown bubbling is performed, the alloy must be added to the center of the ladle. In this case, the alloy is diffused in all directions and mixed quickly and uniformly. On the other hand, since the tanditshu is rectangular, it can only stir the molten steel near the bottom-blowing bubbling gas inlet (=j), and it takes a long time for the alloy to uniformly diffuse to the molten steel in the corners far from the bubbling device. Therefore, since tanditshu has a small capacity, refining tanditshu, which takes a lot of time, was considered inefficient.

[Means for Solving the Problems] Therefore, the present invention was created in order to eliminate such problems, and the gist thereof is that in a tanditsu refining device, the positions of alloy addition in the tanditsu are placed facing each other. A tanditsu refining apparatus is characterized in that it is equipped with a stirring device for blowing out gas and stirring molten steel.

〔Example〕

The structure and operation of the present invention will be described in detail with reference to first and second embodiments shown in the accompanying drawings.

Fig. 1 is a plan view showing the first embodiment of the present invention, Fig. 2 is a vertical sectional view of Fig. 1, Fig. 3 is an enlarged view of the main parts of the jet lance, and Fig. 4 is the second embodiment. 5 is a plan view showing the 4th
FIG.

These embodiments are tundishes 1 used in multi-strand continuous casting equipment, and the tundishes 1 have, for example, two pouring holes (not shown) symmetrically sandwiching a bubbling device, which will be described later. It is provided.

(First embodiment) In FIGS. 1 and 2, a rectangular tanditsh l
An induction heater (not shown) is attached to the side wall of the molten metal, and the molten metal is circulated through the induction heater through the communication hole 2 to heat the molten metal as necessary. Further, a bottom-blowing bubbling device 3 is attached to the center of the bottom of the tundish 1. Furthermore, the upper surface of the tandish 1 is sealed with a lid 4.
A melting furnace 5 containing molten alloy is installed in the upper center.

Here, in this embodiment, a part of the opposite corner of the tundish 1, with the alloy addition position as the center, is
At an 80° symmetrical position, apply an inert gas such as Ar or a reducing gas toward the alloy addition position, either horizontally or
A jet lance 6.6 is installed that blows air slightly diagonally upward. The gas inlet of this jig lance 6.6 is opened at a predetermined height h from the bottom surface of the tundish 1. In the case of a tundish in the 6 to B ton class, the height h was set to 400 m or less for effective stirring. Note that if h=400 mm or more, a vortex may occur, and this vortex may involve the slab on the upper surface of the molten steel into the molten steel. In addition, when the blowing angle α of the jet lance 6 was set upward from the horizontal direction, it was effective for stirring when it was set to α-30° or less, as shown in FIG.

Next, the operation of this embodiment will be described. Molten steel from the ladle
Molten metal is poured into a tundish 1 with a tundish nozzle (not shown) closed, and the tundish 1 is moved to a refining zone. Therefore, a predetermined amount of molten alloy is injected from the melting furnace 5, heated by an induction heater as needed, and an inert gas or the like is blown from the bottom blow bubbling device 3 and the jet lance 6. At that time, flux is blown in and the generated harmful gas is degassed using a vacuum processing device (not shown). In particular, by blowing inert gas through dientrance 6? Since the 8 steel is circulated and stirred along the inner peripheral surface of the tundish as shown by the arrow in FIG. 2, the injected molten alloy is quickly and uniformly mixed.

Next, the results of the mixing test of the additive alloy in the tundish refining test of this example conducted by the present inventors will be explained with reference to FIG. FIG. 6 is a bar graph comparing the stirring according to this example with the conventional stirring without stirring or using only a bubbling device as the stirring means, using the diffusion rate (time required for uniform mixing) as an index. In this graph, the stirring by the jet lance of this example is referred to as horizontal stirring, and as is clear from this graph, horizontal stirring very effectively contributes to uniform mixing of the added alloy.

(Second Embodiment) In FIGS. 4 and 5, a rectangular tundish 1 equipped with an induction heater, a bottom-blowing bubbling device 3, etc. is used, which is similar to the first embodiment. However, in this example, 18
A vane lower 7 for blowing out inert gas, etc. is installed on the 0° symmetrical side wall.

This lining 7.7 is provided within a predetermined height ho from the bottom surface of the tundish l. This height ho is 5~
For Bton class tanditshu, h'=400
When the temperature was less than .aug, stirring was effective. In addition,
When h'-400 mm or more, a vortex may occur, and this vortex may involve the slag on the upper surface of the molten steel. In addition, this vane lower may be configured to eject a small amount of inert gas to constantly generate an upward flow in the molten steel and promote the floating of inclusions even when refining or strong stirring of the molten steel is not performed. .

The operation of this embodiment is similar to that of the first embodiment described above, but
Describing the test results of this example 0 The mixing test results of the additive alloy in the tundish refining test of this example conducted by the present inventors are as shown in Figure 7, and the cleanliness in the steel material is shown in Figure 8. It was as shown in Figure 7 is a bar graph comparing the stirring according to this embodiment and the conventional stirring using only a bubbling device as the stirring means, using the time required for uniform mixing, that is, the diffusion rate, as an index, and it is clear from this graph. As can be seen, in this example, the stirring time was significantly shortened and the refining efficiency was significantly improved. Furthermore, Fig. 8 is a bar graph comparing the cleanliness in the steel material according to this example with the cleanliness in the steel material when only a bubbling device is used as the conventional stirring means. As can be seen, in this example, the cleanliness of the steel material was significantly improved.

This is because inert gas is constantly ejected from the blade lower 7, which is considered to have contributed to promoting the floating of nonmetallic inclusions.

Note that the tundish refining of the present invention can be applied to systems other than continuous casting equipment, and when used in continuous casting equipment, it can be performed not only in the refining zone but also in the casting zone.

(Effects of the Invention) According to the present invention, molten steel can be rapidly stirred by a stirring device such as a jet lance or tuyere that blows inert scum etc. into a rectangular tundish. Although there is a pre-entry window that makes it inefficient, it is possible to eliminate such a pre-entry window and improve the efficiency of tanditsu refining. In addition, the quality of the tomb slab at the beginning of casting is improved, so there is less wastage of material and it is possible to economically produce a wide variety of small lots. can.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the first embodiment of the present invention, Fig. 2 is a vertical sectional view of Fig. 1, Fig. 3 is an enlarged view of the main parts of GenoTrans, and Fig. 4 is the second embodiment. 5 is a plan view showing the 4th
The longitudinal sectional views in the figure and FIGS. 6 to 8 are comparison graphs with the conventional example. l... Tanditshu, 5... Melting furnace, 6... Jet lance, 7... Tuyere. Sub-Agent Patent Attorney Yoshihiko Okabe Figure 4 Figure 5 (a) (b) Figure 6 Figure 1 Figure 2 Figure 7 Figure 8!7

Claims (1)

[Claims] (1) A tundish refining device, characterized in that stirring devices for spouting gas and stirring molten steel are provided facing each other at alloy addition positions in the tundish.