JPH091321A - Equipment for removing non-metallic inclusions in molten steel - Google Patents

Abstract

(57) [Summary] [Object] To provide a non-metallic inclusion removing device for efficiently removing non-metallic inclusions in molten steel and improving the quality of cast slabs. [Structure] A weir 4 made of a porous brick is provided at a portion through which molten steel flows, and particles 5 to which non-metallic inclusions 3 are easily adsorbed are suspended upstream of the weir, or two weirs are provided, This is a non-metallic inclusion removing device for molten steel in which particles 5 in which non-metallic inclusions are easily adsorbed are suspended between the weirs. It is desirable that the particle size is 0.5 cm or more, the specific gravity is 6 or more and 8 or less, and the ratio of the particles to the total volume is 0.5 or less. Further, stirring by gas injection or electromagnetic force can be added to further improve the removal efficiency. You can [Effect] Since it is a method of adsorbing to suspended particles, it does not clog, it can be used for a long time, and high removal efficiency becomes possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is intended to efficiently remove non-metallic inclusions generated in molten steel, reduce defects caused by non-metallic inclusions, and improve the quality of cast slabs. The present invention relates to the field of steelmaking, which is a steel manufacturing process.

[0002]

2. Description of the Related Art Many devices for removing non-metallic inclusions in molten steel have been proposed (Japanese Patent Laid-Open Nos. Sho 60-221158 and Sho 6).
1-74611, JP-A-61-261417, JP-A-6
3-213616, JP-A-1-162563).
Although these have some differences, they generally have a configuration as shown in FIG. That is, the molten steel 2 is passed through the substance 1 having a gap such as a porous brick, the non-metallic inclusions 3 are captured in the gaps, and the non-metallic inclusions of the molten steel are removed.

[0003]

However, in the above-mentioned conventional apparatus, when the size of the gap is small (FIG. 3 (a)), the non-metallic inclusions 3 are well captured in the gap and high removal efficiency is obtained. However, since the non-metallic inclusions 3 block the gaps and the passage of the molten steel 2 is also hindered, they cannot be used for a long time.

If the size of the gap is large (see FIG. 3)
In (b), the nonmetallic inclusions 3 pass through the gap, and the removal efficiency of the nonmetallic inclusions 3 is low. In any case, the conventional apparatus cannot remove non-metallic inclusions with high efficiency over a long period of time.

The present invention is an apparatus for removing non-metallic inclusions in molten steel capable of eliminating the obstruction of molten steel passage, high removal efficiency, and smooth passage of molten steel in such a conventional apparatus. It is intended to provide.

[0006]

The gist of the present invention is as follows. (1) A non-metallic inclusion of molten steel characterized in that a weir made of a porous brick is provided at a portion where the molten steel flows through, and particles on which the non-metallic inclusion easily adsorbs are suspended on the upstream side of the weir. Removal device. (2) Non-metallic inclusions in molten steel, characterized in that two weirs made of porous bricks are provided in a region where molten steel flows through, and particles easily adsorbed by non-metallic inclusions are suspended between the weirs. Removal device. (3) The particle size is 0.5 cm or more, and the weir is made of a porous brick having a function of not being blocked by non-metallic inclusions and preventing the particles from flowing out (1) or (2). Non-metallic inclusion removing device for molten steel. (4) A device such as an electromagnetic force or gas injection is provided at the portion where the molten steel flows and the molten steel flows at a flow rate of 12
The apparatus for removing non-metallic inclusions in molten steel according to (1) or (2), characterized in that stirring is performed in a range of 0 cm / s or less. (5) The apparatus for removing non-metallic inclusions in molten steel according to (1) or (2), characterized in that the particle specific gravity is in the range of 6 or more and 8 or less. (6) The apparatus for removing non-metallic inclusions in molten steel according to (2), characterized in that the ratio of particles to the volume between weirs is 0.5 or less.

According to the present invention, as shown in FIG. 1 (a), a weir 4 made of porous brick is provided at a portion of the molten steel 2 through which the non-metallic inclusions are easily adsorbed upstream of the weir 4. The particles 5 are suspended and the non-metallic inclusions 3 are adsorbed to the particles 5 to remove the inclusions. The apparatus of the present invention is a method of adsorbing non-metallic inclusions to the particles floating in molten steel, and is not a method of capturing non-metallic inclusions in the gap of the porous body in the conventional apparatus, Non-metallic inclusions cannot close the gap and prevent the passage of molten steel.

In order to increase the probability of adsorption, it is effective that a large amount of the particles are suspended in a constant molten steel. FIG.
As shown in (b), weirs 4 made of porous bricks are provided at two places at intervals in a region where molten steel flows through, and particles 5 to which nonmetallic inclusions are easily adsorbed are suspended between the weirs. This makes it possible to suspend a large number of the particles 5 in the constant molten steel. At this time, if the ratio of the particles to the volume between the weirs (hereinafter referred to as the solid fraction) is extremely increased,
When the particles adsorb non-metallic inclusions and become huge, the gaps between the particles may become narrow and impede the passage of molten steel. Therefore, the solid phase ratio is preferably 0.5 or less.

In order that the particles do not pass through the weir, the size of the porous gap must be at least the particle size or less. However, if the size of the gap of the porous brick is less than 0.5 cm, there is a high possibility that the porous brick will be blocked by the non-metallic inclusions. That is, the particle diameter is preferably 0.5 cm or more in order that the weir does not have the function of blocking the non-metallic inclusions and preventing the particles from passing through the weir.

Further, the particles are floated or settled so that the probability of adsorption of non-metallic inclusions is higher when the particles are uniformly dispersed in the molten steel than locally distributed in the molten steel. In order to uniformly disperse the particles in the molten steel, the specific gravity of the particles is preferably 6 or more and 8 or less.

Further, stirring the molten steel between the weirs by electromagnetic force, injection or the like is very effective in increasing the removal efficiency. By stirring, the probability that the non-metallic inclusions and the particles collide with each other increases, and the particles easily adsorb. However, if the molten steel flow rate is higher than 120 cm / s, the particles may be crushed by collision of the particles, and fine particle fragments may flow out of the weir and contaminate the molten steel. A stirring flow rate of s or less is desirable. If the flow rate of the molten steel passing through is large, the particles will be agitated and the removal efficiency will be increased, but for the same reason, 120 cm / s or less is desirable.

By using the apparatus of the present invention as described above, it is possible to obtain a high nonmetal removal efficiency for a long time without the weir being blocked by nonmetal inclusions.

[0013]

[Experimental example] A conventional device using porous bricks having a gap size of 1 mm and 5 mm, an electromagnetic force as a stirring power, and a diameter in which alumina is coated around chromium as particles for adhering nonmetallic inclusions. Molten steel was passed through the apparatus of the present invention using particles of 5 cm, and the T.O. The O value (oxygen content in molten steel) was investigated. Table 1 shows the results. Compared to the conventional device, the device of the present invention does not occlude the T.S. It was confirmed that the range of decrease in O value was increased and the alumina-based inclusions were efficiently removed.

[0014]

[Table 1]

[0015]

As described above, the non-metallic inclusion removing device for molten steel of the present invention can improve the removal efficiency of non-metallic inclusions without blocking.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a non-metallic inclusion removing device according to the present invention as viewed from the side, where (a) shows a case where particles that easily adsorb non-metallic inclusions are suspended upstream of a weir, and (b) shows It shows a configuration in which particles that easily adsorb non-metallic inclusions are suspended between both weirs.

FIG. 2 is a cross-sectional view of a conventional non-metal inclusion removing device as viewed from the side, showing the configuration and principle of the device.

FIG. 3 is a cross-sectional view of a conventional non-metal inclusion removing device as viewed from the side, where FIG.
(B) shows a problem when the size of the gap is large.

[Explanation of symbols]

 1 Substance with a gap such as porous brick 2 Molten steel 3 Non-metallic inclusions 4 Weir made of porous bricks 5 Particles to which non-metallic inclusions are easily adsorbed

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication C21C 7/00 C21C 7/00 P (72) Inventor Shingo Katayama 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Nippon Steel Corporation Advanced Technology Research Center

Claims (6)

[Claims] 1. A nonmetal of molten steel characterized in that a weir made of porous brick is provided at a portion where the molten steel flows and flows, and particles on which the nonmetallic inclusions are easily adsorbed are suspended on the upstream side of the weir. Inclusion removal device. 2. A nonmetal of molten steel, characterized in that two weirs made of porous bricks are provided in a region where molten steel flows through, and particles easily adsorbed by nonmetallic inclusions are suspended between the weirs. Inclusion removal device. 3. The porous brick having a particle diameter of 0.5 cm or more, the weir not blocking with non-metallic inclusions, and having a function of preventing the particles from flowing out, according to claim 1 or 2. Non-metallic inclusion removing device for molten steel. 4. The molten steel according to claim 1 or 2, wherein a device such as electromagnetic force or gas injection is provided at the portion where the molten steel flows and flows, and the molten steel is stirred at a flow rate of 120 cm / s or less. Non-metallic inclusion removing device. 5. The apparatus for removing non-metallic inclusions in molten steel according to claim 1 or 2, wherein the particle specific gravity is in the range of 6 or more and 8 or less. 6. The apparatus for removing non-metallic inclusions in molten steel according to claim 2, wherein the ratio of the particles to the volume between the weirs is 0.5 or less.