JPS61246305A - Method and apparatus for removing slag from molten metal - Google Patents

Abstract

PURPOSE:To continuously and efficiently remove slag by blowing a gas carrying treatment material with an immersion lance into the molten metal in the tilted vessel and floating the formed slag by swirling flow. CONSTITUTION:A ladle 12 contg. molten iron 10 is placed on an inclined base 13 and is inclined to a prescribed angle; thereafter the immersion lance 14 is gradually lowered and gas is ejected therefrom. The lance 14 is stopped and the blowing of powder is started when the built-up part of the molten metal surface formed by the ascending gas transfers to the counter slag discharge side. The formed slag is floated and collected to the slag discharge side formed by the swirling flow generated by the blowing of the powder. The collected slag is continuously scraped out by moving a continuous slag scraping device 18 supported by a lifting device 16 to a prescribed position and rotating a scraping plate 20. The integral treatment of the molten iron and slag removal are thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for removing slag from molten metal. In particular, the present invention relates to a method and apparatus for continuously removing slag generated when molten metal such as hot metal is subjected to desiliconization, dephosphorization, and desulfurization treatments.

(Conventional technology) In recent years, there has been a strong demand for ultra-low P steel and ultra-low Swi.
In addition, there are cases where it is necessary to desiliconize hot metal, and as a result, the refining of hot metal has changed from in-furnace refining to outside-furnace refining to treat Si, S, and P in separate processes. It's becoming. The development of such metallurgical pretreatment technology for hot metal is becoming more and more necessary in today's world, where there is a trend toward higher quality steel products.

However, the slag generated in each refining process as described above needs to be removed immediately or simultaneously after the metallurgical treatment is completed in order to proceed with the next metallurgical reaction.

Many technologies have already been proposed for removing slag in such cases, but these include: ■After the metallurgical treatment is completed, containers such as ladles and hot metal cars containing hot metal are sent to a slag removal site. The slag is moved and the slag floating on the surface of the hot metal is scraped off using a scraping plate that moves mechanically in reciprocating motion. There are two main types of methods: 1) and 2) methods that suck up floating slag.

In the above-mentioned reciprocating scraper method, a scraper covered with refractory is attached to the tip of a long arm, and the work of scraping up floating slag and scraping it from the slag end is repeated, but at this time,
Floating slag often escapes to the left and right of the scraping plate, and since the surface of the hot metal is stirred strongly, iron particles are trapped in the floating slag layer and scraped out, increasing efficiency. , the results are very unsatisfactory in terms of yield.

On the other hand, the above-mentioned suction method has the advantage of being able to continuously draw in and suck out floating slag with good fluidity, but it cannot handle slag that has grown into lumps that often occur during metallurgical processing. The size of the suction port is determined by the exhaust capacity, but it is usually 150 to 200 II! ff+) and the distance to the hot metal surface (usually around 10 mm), slag suction is restricted and often cannot be removed.

(Problems to be Solved by the Invention) Thus, an object of the present invention is to provide a system that can efficiently collect floating slag and continuously remove the slag.

Another object of the present invention is to provide a system in which slag generated during desulfurization, dephosphorization, or desiliconization treatment in a hot metal ladle is immediately collected at one location in the ladle and continuously scraped out.

(Means for solving the problem) By the way, it is possible to efficiently (
In order to carry out a metallurgical reaction, it is necessary for the powdered treatment material to enter deeply into the hot metal and at the same time come into uniform contact with the treatment material due to the convection of the hot metal.

Currently, gas-entrained powder injection via submerged nozzles is widely used for this purpose.

Therefore, the inventors of the present invention focused on the possibility of an efficient and continuous slag removal method by integrally combining powder injection technology and slag removal technology, and as a result of various studies, It was discovered that the above-mentioned object can be achieved by combining and arranging one or more diagonally rising and falling powder injection immersion lances, a tilting device for a hot metal container, and a continuous slag scraping device, and based on this invention, the present invention was developed. completed.

Therefore, the gist of the present invention is to generate slag by blowing a gas-entrained treatment material into molten metal in a tilted container through an immersion lance, and to generate slag by the action of air bubbles floating in the molten metal. Forming a swirling flow within the molten metal,
This method of removing slag from molten metal is characterized by scraping the generated slag out of the container while floating and accumulating the generated slag on the swirling flow at one end of the container.

Furthermore, the gist of the present invention is a tiltable molten metal container, an immersion lance for blowing gas-entrained treatment material,
and a continuous slag scraping device, the immersion lance is configured to be freely immersed obliquely into the molten metal at the tilting position of the container, and the slag scraping device is arranged at the end of the container at the lowest point of the tilting position of the container. This is a molten metal slag removal device that is disposed in close proximity to the molten metal.

Preferably, a plurality of two or more immersion lances are provided, but their arrangement and immersion depth are not particularly limited, but in the present invention, one large swirling flow is created in the molten metal by the action of bubbles of blown gas. Therefore, it is preferable that the swirling flow involves the entire molten metal, that is, that the swirling flow reaches from one end of the container to the other.

Specifically, it is preferable that they be arranged parallel to the central axis of the tilting of the container and slightly eccentrically in the upward direction of the tilting, and at equal intervals. By arranging it like this,
Due to the action of the bubbles of the blown gas from each immersion lance, the generated slag accompanies the swirling flow of molten metal to the end of the container at the lowest point of the transfer position, that is, the side opposite to the immersion lance arrangement side with the rolling axis as the center. It floats and accumulates near the edge of the container.

The slag scraping device disposed close to the end of the container is not particularly limited as long as it can be disposed close to the end of the container, but it is more preferable that the slag scraping device be disposed close to the end of the container. It consists of plates attached at regular intervals. This slag scraping plate may have a special shape to increase the separation effect from the molten metal and to prevent excessive stirring, but it is possible to simply attach vertical plates to an endless running body at regular intervals. It may be just for you. According to the present invention, the slag suspended and accumulated by the above-mentioned swirling flow forms a kind of bulge, and is particularly well separated from the molten metal.

Note that the materials of the immersion lance and the slag scraping device may be conventionally known materials, and there are no particular limitations on this point either.

Next, a series of steps of the present invention will be described with reference to the accompanying drawings. In addition, below, explanation will be given using hot metal as an example of molten metal and a "ladle" as a container for storing molten metal.
Those skilled in the art will readily understand that the present invention is not limited thereto.

FIG. 1 is a diagram schematically explaining the state of slag removal according to the present invention, and FIG. 2 is a schematic diagram showing the ladle viewed from above.

In the illustrated example, first, the required amount of hot metal 10 is poured into a ladle 12 and placed on a ladle tilt table 13. The ladle on the tilt table is tilted to the slag discharge side, that is, to the left as viewed in the drawing, until the hot metal inside spills out, and the ladle is stopped at that position.

After the ladle 12 is set in this way, the immersion lance 14 for powder blowing connected to the hose begins to gradually descend, blowing out gas from near the top of the hot metal, and then rushing into the inside of the hot metal. In the illustrated example, three immersion lances are used.

The lance lifting winch (not shown) stops at a position where the raised part of the surface of the hot metal moves to the opposite side of the slag, that is, to the right side as viewed in the drawing, due to the rising gas, and the blowing of powder starts. A swirling flow is generated in the hot metal by the blown gas, and the depth of the immersion lance at this time is the depth that provides the largest swirling flow.

After a while, when the floating slag has accumulated on the slag discharge side, the continuous slag scraping device 18 supported by the lifting device 16 is lowered and extended (sent forward),
Next, the rotation of the scraping plate 20 is started. At this time, the front part of the slag scraping device is adjusted so that it is in a position to scrape out the accumulated slag from the ladle. As a result, the slag accumulated at one end of the ladle is simultaneously and continuously removed during the hot metal pretreatment operation.

The immersion lance for powder blowing continues to eject entrained gas even after blowing a predetermined amount, accumulates slag, and when the slag scraping is finished, it is raised above the ladle and gas supply is stopped.

At the same time, the slag scraping device also begins to rise and contract, returns to the standby position, and stops operating.

Thereafter, the ladle is returned to its original position and transported to the next process.

Next, the present invention will be explained in more detail in connection with examples.

Example Using the apparatus shown in the attached drawings (however, the number of lances was two), desiliconization, desulfurization, and slag removal were performed simultaneously under the conditions shown in Table 1 below. For comparison, powder was blown into a ladle placed horizontally using the same submerged nozzle, and then the slag was scraped out using the conventional method.

Table 2 shows the composition of the hot metal at this time. In addition, in both cases, the amount of slag generated is 3 ton of desiliconized slag per ton of hot metal.
The amount of desulfurization slag was 6 to 7 kg.

In the case of the present invention, the time required for the slag scraping process was the powder injection process + (1 to 3) minutes regardless of the slag fluidity, but in the conventional method, the time required after the powder injection process was determined according to the fluidity. It took 10-20 minutes.

In the case of the present invention, the slag is scraped out even during the powder blowing period, so the 1 to 3 minutes mentioned above is the time from when the powder blowing is stopped to when the slag scraping is finished.

Moreover, the percentage of granulated iron in the scraped slag in that case was 14 to 18% in the present invention, but 20 to 25% in the comparative example.

Table 1 (Note) Q: Carrier gas injection ratio, P: Carrier gas pressure (effect of the invention) As mentioned above, when the present invention is applied to hot metal pretreatment,
The present invention enables hot metal treatment and slag removal to be carried out in an integrated manner, which provides the following advantages in actual operation.

(1) Reducing treatment time: The method of the present invention is a new method that integrally combines the conventional mainstream pretreatment of hot metal by powder blowing and the subsequent process, slag removal treatment. ,
Processing time, including handling, can be reduced. for example,
The conventional slag scraping method using a mechanically reciprocating slag scraping plate or slag suction method takes approximately 20 to 30 minutes, but according to the present invention, the time required is approximately 1 to 3 minutes or less. Become.

(2) Yield improvement: By using DCC morph and freely changing the rotation speed of the slag scraper according to the generation status of floating slag, the entrainment of granular iron into the slag is virtually eliminated and the efficiency of the slag scraper is improved. As the temperature increases, the hot metal yield improves. for example,
While the hot metal yield loss in the above-mentioned conventional slag removal method is approximately 0.4 to 1.0 (%), according to the present invention, the loss is reduced to approximately 1/3 to 1/2.

(3) Improved work efficiency: Hot metal preliminary treatment and slag removal can be performed at the same time in the same place, making it possible to perform the process with fewer personnel.

Scraping methods using mechanical reciprocating motion require the slag scraping plate to be moved along the ladle shape in order to completely remove slag, which is difficult. When using molten metal, it is necessary to strictly control the distance between the suction port and the surface of the hot metal to prevent explosions. In this way, both are difficult to operate. However, the method according to the present invention is not only easy to operate, but also allows accurate control through visual confirmation. Therefore, by being able to easily and accurately control it, it is possible to prevent accidents such as hot metal scattering and small explosions that occur when a large amount of hot metal is accidentally scraped out, and operational safety is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically explaining the state of slag removal according to the present invention; and FIG. 2 is a schematic diagram showing the ladle viewed from above. Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent Attorney Akira Hirose − Qin 2 Dia

Claims (2)

[Claims] (1) A gas-entrained treatment material is blown into the molten metal in the tilted container through an immersion lance to generate slag,
A swirling flow is formed in the molten metal by the action of air bubbles floating in the molten metal, and the generated slag is floated and accumulated at one end of the container on the swirling flow, and the generated slag is scraped out of the container. Features: A method for removing slag from molten metal. (2) Equipped with a tiltable molten metal storage container, an immersion lance for blowing gas-entrained treatment material, and a continuous slag scraping device, and the immersion lance can be tilted and immersed into the molten metal at the tilting position of the container. 2. A molten metal slag removal device, wherein the slag scraping device is arranged so as to be able to approach an end of the container at the lowest point of the tilting position of the container.