JP2002317220A - Method for treating molten stainless steel and molten metal holding container used therefor - Google Patents

Abstract

(57) [Summary] [Problem] The present invention is to simplify the slag discharge work of molten stainless steel and to sufficiently remove slag from Ni-Cr-containing.
Provided is a method for treating a stainless steel capable of re-injecting the molten metal into a converter type refining furnace, and a molten metal holding container used for the method. SOLUTION: A molten metal holding container 24 is composed of a holding container main body 25, a tilting means 26 for drainage, and a tilting means 27 for injecting molten metal. 28 and a molten metal outlet 29 are provided. Molten stainless steel 1 discharged from converter type refining furnace 37
After receiving the slag 17 and the slag 17, the slag 17 is easily and quickly discharged from the discharge port 28, and the discharged stainless steel 16
From the molten metal discharge port 29 as it is
7, and the next step of decarburization refining can be stably refined to produce excellent stainless steel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating molten stainless steel in the case of producing stainless steel using a converter type refining furnace, and a molten metal holding vessel used therefor.

[0002]

2. Description of the Related Art In recent years, in order to reduce the manufacturing cost of stainless steel, inexpensive chromium ore has been directly used instead of the conventionally used high carbon ferrochrome alloy or reduced pellets.

As an example, Japanese Patent Application Laid-Open No. 7-11321 discloses a method for producing stainless steel by smelting reduction using a converter type refining furnace. The converter type refining furnace uses a converter type refining furnace provided with a top blowing oxygen lance, a bottom blowing and / or a side blowing tuyere.

In the converter type refining furnace, a Cr raw material such as Cr ore is charged into a Ni-containing molten metal and reduced by melting to obtain an N-containing melt.
After pouring the i-Cr molten metal into the molten metal holding vessel and discharging the slag floating on the surface of the molten metal, the Ni-Cr-containing molten metal is transferred to a converter type refining furnace to be decarbonized to produce stainless steel. .
A molten metal pot generally called a pelican pot is used for the molten metal holding container, and slag floating on the surface of the molten metal is discharged using a molten metal outlet.

FIG. 5 is a side sectional view showing an example of a molten metal holding container for receiving a molten stainless steel. The molten metal holding container 1 (hereinafter, referred to as a holding container) includes a holding container main body 2 and a tilting means 3. The holding container main body 2 has a lining 4 made of a refractory material. An outlet 5 is provided. The molten metal outlet 5 has a pelican shape.

The holding container 1 is provided with a trunnion ring 18 attached to the side peripheral surface of the holding container body 2, hooked on the trunnion 6 and hung by a ladle crane so that molten stainless steel can be charged into the converter type refining furnace. I have to.

The tilting means 3 has a tilting lever 8a pivotally supported at one end by a fulcrum pin 9a on a flange 7a provided on the outside of the bottom of the holding container main body 2, and at the other end by a pin 11a at a tilting lever 10a. ing. The tilting lever 10a is configured such that a locking pin 22a is attached thereto, and the locking pin 22a is locked to the holding container main body 2 by a locking tool 12a fixed to the outside of the side of the holding container main body 2. ing. A hook receiver 13a is provided at the other end of the tilting lever 10a, and a hook (supplementary winding) 14a is hooked when the holding container 1 is tilted.

According to the holding container 1, after receiving the molten stainless steel 16, the trunnion 6 is hooked, suspended by a ladle crane, and moved to a dumping place where a waste catcher (slag pan) is placed. Is done. Then, the tilting lever 10a is lifted to automatically release the locking pin 22a, and the hook (auxiliary winding) 14a of the auxiliary hoisting crane is hung on the hook receiver 13a of the tilting lever 10a and lifted. Then, the holding container 1 is tilted with the trunnion 6 as a fulcrum, and the slag 17 is discharged from the molten metal discharge port 5 to the waste receptacle 23 using the slag dragger 15 or the like. Reference numeral 36 denotes a sub trunnion.

The slag dragger 15 has a basic structure including a squeezing arm 20 provided with a squeezing plate 19 at a tip thereof and a drive mechanism 21 for driving the squeezing arm 20.

The slag dragger 15 discharges the slag 17 from the holding container 1. After the slag 17 is discharged, the slag 17 is erected and the locking pin 12a of the tilting lever 10a is locked by the locking tool 12a. Reference numeral 35 denotes a fixed base for the slag dragger 15.

The holding vessel 1 is suspended by a ladle crane and moved to an injection position above a converter type refining furnace. Then, the tilting lever 10a is lifted to release the locking pin 22a, and the hook receiver 13a of the tilting lever 10a is hung by hooking the hook 14a of the auxiliary hoisting crane. The holding container 1 is tilted with the trunnion 6 as a fulcrum, and the stainless steel melt 16 The molten metal outlet 5
Into a converter type refining furnace. After the molten stainless steel 16 has been injected, the holding container 1 is erected and the locking pin 12a of the tilting lever 10a is locked by the locking tool 12a.

[0012]

As described above, when producing stainless steel in a converter type refining furnace, it is important to perform a molten metal treatment for separating a slag from a molten stainless steel and discharging the slag. The holding container plays an important role.

However, the holding vessel for processing the Ni-Cr-containing molten metal obtained by smelting and reducing in the converter type refining furnace uses a conventional pelican-type molten metal holding vessel as it is, and the molten metal is discharged through one molten metal discharge port. The slag floating on the surface is drained, and then the molten Ni / Cr-containing metal is injected into a converter type refining furnace to perform a decarburization treatment to produce stainless steel.

Therefore, when the slag is discharged using a slag discharging device such as a slag dragger at a molten metal discharge port having a structure suitable for pouring the molten metal by the pelican type molten metal holding container, particularly when the slag layer becomes thin. In addition, since the slag is completely discharged without loss of the molten metal, the discharging operation is complicated and time-consuming, and the temperature is easily lowered.

[0015] Ni.C containing not sufficiently draining the slag
In the case of decarbonization by re-injecting the molten metal into the converter type refining furnace, the decarburization efficiency decreases with an increase in the amount of slag, which causes a loss of Cr. In addition, a problem of resulfurization occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended to simplify the operation of discharging slag from molten stainless steel and to convert the molten Ni-Cr containing molten slag sufficiently into a converter type. It is an object of the present invention to provide a method for treating molten stainless steel that can be re-injected into a smelting furnace and a molten metal holding container used for the method.

[0017]

The invention according to claim 1 is
In a converter type refining furnace, a Cr raw material such as Cr ore is charged and melt-reduced into a molten Ni-containing metal, and the obtained molten Ni-Cr is discharged into a molten metal holding vessel and slag floating on the surface of the molten metal. After the slag is discharged, the molten metal containing Ni / Cr is transferred to a converter type refining furnace to decarbonize the molten stainless steel, wherein the molten metal holding vessel is provided with a slag port and a molten metal discharge port around the upper end thereof. The molten metal holding container is tilted in one direction by tilting means to discharge the slag from the discharge port into a waste receptacle, and after discharging, the molten metal holding container is tilted in another direction by the tilting means to contain N.
A method for treating stainless steel, characterized by injecting i-Cr molten metal into a converter type refining furnace from the molten metal outlet.

According to a second aspect of the present invention, there is provided a molten metal holding container for use in the first aspect of the present invention, wherein the molten metal holding container has a discharge port and a molten metal discharge port before and after an upper end portion, and the holding container main body is A tilt means for tilting in two directions is provided.

According to the present invention, since the holding container used for treating the molten stainless steel is provided with the discharge port and the molten metal discharge port, the slag can be easily discharged from the discharge port to the waste receptacle.
Therefore, the molten Ni-Cr containing slag sufficiently discharged can be injected into the converter type refining furnace from the molten metal outlet.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a container for holding a molten stainless steel according to the present invention. FIG. 1 is a side sectional view showing one embodiment of a stainless steel molten metal holding container of the present invention,
FIG. 2 is a side view showing an example of slag discharge of molten stainless steel by the molten metal holding container of the present invention. The molten metal holding container has a pelican shape.

The molten metal holding container 24 (hereinafter referred to as a holding container) according to the present invention comprises a holding container main body 25 and a tilting means 26 for waste.
And a tilting means 27 for injecting molten metal. The holding container main body 25 is lined with a refractory material.
And a molten metal outlet 29 are provided.

The molten metal holding container 24 has a trunnion ring 18 attached to the side surface of the holding container main body 25, is hooked on the trunnion 6, and is hung by a ladle crane so that the stainless steel molten metal 16 can be charged into the converter type refining furnace. I have to. Reference numeral 36 denotes a sub trunnion.

The tilting means 26 for discharging the waste is provided with a tilting lever 3 on a flange 30 provided at the lower end on the outer side of the holding container body 25.
1 is supported at one end by a fulcrum pin 32. A hook receiver 33 is provided at the other end of the tilt lever 31 so that the hook 14b is hooked when the holding container 24 is tilted.

The holding container 24 is hooked on the trunnion 6, hung by a ladle crane, and moved to a dumping place. Then, the hook 14 b of the auxiliary hoist crane is hung on the hook receiver 33 of the tilting lever 31 and lifted, and the holding container 24 is tilted with the trunnion 6 as a fulcrum, and the slag 17 floating on the surface of the stainless steel melt 16 is discharged. The slag is discharged to the slag pan 23 at the slag site. When the slag 17 is discharged, a generally known discharging device such as a slag dragger 15 can be used.

As shown in FIG. 2, the slag dragger 15 is basically composed of a scraping arm 20 provided with a scraping plate 19 at the tip thereof, and a driving mechanism 21 for driving the scraping arm 20. Reference numeral 35 denotes a fixed base for the slag dragger.

A holding container 24 using a slag dragger 15
Is performed, the holding container 24 is fixed to the front of the slag dragger 15 and the holding container 24 is tilted so that the surface of the molten stainless steel 16 is flush with the inner edge of the holding container 24. Next, the scraping arm 20 is operated to hold the holding container 2.
The slag 17 is immersed in a depth corresponding to the slag 17 layer toward the back of the slag 4, and the slag 17 is squeezed out by the squeezing plate 19 by moving the squeezing arm 20 toward the front. It is discharged to the slag pan 23 from the discharge port 28. The slag dragger 15 is one in which only the arm based on the basic structure as described above moves forward and backward, and is performed semi-automatically by a human operation, and the slag can be discharged accurately.

On the other hand, as shown in FIG. 5, the tilting means 27 for injecting the molten metal has a tilting lever 8b pivotally supported at one end by a fulcrum pin 9b on a flange 7b provided outside the bottom of the holding container main body 25, and at the other end. And is pivotally supported on the tilting lever 10b by a pin 11b. The tilting lever 10b is configured to be locked to the holding container main body 25 by a locking tool 12b fixed to the outside of the side of the holding container main body 25. A hook receiver 13b is provided at the other end of the tilt lever 10b so that the hook 14b can be hooked when the holding container 24 is tilted.

The holding container 24 is hooked to the trunnion 6 by a hook 34.
And is suspended by a ladle crane and moved to an injection position above a converter type refining furnace. Then, the tilting lever 10b is lifted to release the locking pin 22b from the locking tool 12b, and the hook receiver 13b of the tilting lever 10b is hung by hanging the hook 14b of the auxiliary hoisting crane. The molten metal holding container 24 is tilted, and the molten stainless steel 16 is injected into the converter type refining furnace. After the injection, the holding container 24 is erected and the tilting lever 10b is
Lock pin 22b.

FIG. 3 is a flowchart showing an example of a method for treating molten stainless steel according to the present invention. Step (a) is a smelting reduction step of the Cr raw material. The smelting reduction of the Cr raw material is performed in a converter type refining furnace 37 provided with a top blowing oxygen lance 38 and a bottom blowing and / or side blowing tuyere 39.

In the converter type refining furnace 37, a Cr raw material such as Cr ore is charged from a raw material hopper 40 together with a medium solvent and a carbon material into the dephosphorized / deflowed Ni-containing molten metal obtained or charged in the furnace. .
Thereafter, oxygen is blown from the top blown oxygen lance 38, and a stirring gas such as N ₂ , Ar, or CO is blown and stirred from the bottom blow and / or the side blow tuyere 39 to melt and reduce the Cr raw material.
A molten metal containing Ni.Cr (hereinafter referred to as stainless steel) is obtained. Step (b) is a tapping step of tapping the molten stainless steel obtained in the converter type refining furnace 37 into the holding container 24. Here, the holding container 24 according to FIG. 1 is used. According to the holding container 24, after receiving the molten stainless steel and the slag, the waste metal is easily and quickly subjected to the waste treatment, and poured into the converter type refining furnace 37 in the state of the discharged molten stainless steel as it is, or It can be injected and transferred to a converter type refining furnace. Step (c) is a slag discharge step of the molten stainless steel.
As shown in FIG. 2, the hook 14 b of the auxiliary hoist crane is hung on the hook receiver 33 of the tilting lever 31, and the holding container 24 is tilted with the trunnion 6 as a fulcrum. The floating slag 17 is scraped out by the slag drager 15 and discharged into the slag pan 23 at the slag disposal site, and the molten stainless steel 16 is obtained. Step (d) is a step of injecting the molten stainless steel into the converter type refining furnace and returning it. The holding container 24 containing the molten stainless steel 16 from which the slag has been discharged is attached to the trunnion 6 by the hook 3.
4 and hung with a ladle crane to convert it into a converter type refining furnace 37
Moved up. Then, the hook 14b of the auxiliary hoisting crane is hung on the hook receiver 13b of the tilting lever 10b and lifted, and the holding container 24 is tilted with the trunnion 6 as a fulcrum, and the molten stainless steel 16 is turned into the converter type refining furnace 37.
Is injected into.

In this case, the molten stainless steel 16 can be transferred to another converter type refining furnace of the same system. In the converter type refining furnace 37, the stainless steel 16 is decarburized and refined to produce stainless steel.

FIG. 4 is a schematic view showing an example of a layout for implementing the method of the present invention in an existing converter site.

At the converter site, two converters for ordinary steel and a converter type refining furnace 37 used in the present invention are installed. A raw material yard A, a converter yard B, and a post-processing yard C are provided before and after the converter type refining furnace 37. In the raw material yard A, a crane facility 42 for transporting a molten metal or the like is installed. A crane facility 43 is also installed in the post-processing yard C.

The crane facilities 42, 43 are operated for two converters for ordinary steel and a converter type refining furnace 37. Conventionally, an empty space was found at one corner on the left side in the traveling direction of the traveling path of the crane of the raw material yard A, and a dumping place 41 was installed there. However, the crane in raw material yard A occupies a higher operating rate than the crane in post-processing yard C. For that purpose, it was examined to set up a waste disposal site in the post-processing yard C, but it was used for post-processing of the converter, and there was only a site for the waste disposal site 44 on the left side in the traveling direction of the traveling path of the crane.

In such a case, the conventional molten metal holding container 1 shown in FIG. 5 is provided with only a so-called pelican-type molten metal outlet 5, and the position of the molten metal outlet 5 of the molten metal holding container 1 is the converter. Since it is suspended by a crane so that it can be injected into the mold refining furnace 37, the molten metal discharge port 5 of the molten metal holding container 1 is on the opposite side to the waste dump 44 on the crane traveling path of the post-processing yard C. become. Therefore, the waste disposal site 44 cannot be used, and the waste disposal site 41 provided in one corner of the raw material yard A is used.
Can only be used.

On the other hand, the molten metal holding container 24 used in the present invention is a molten metal holding container provided with the molten metal discharge port 29 and the slag discharge port 28. Can be used.

Therefore, when the molten metal holding container 24 used in the present invention receives the stainless steel molten metal 16 and the slag to carry out the waste treatment, the crane in the post-processing yard C, which generally has a lower operation rate than the crane equipment 42 in the raw material yard A, Since the equipment 43 can be used, there is no waste work using a crane in the raw material yard A as compared with the conventional molten metal holding container 1, so the crane in the raw material yard A is used for other transport work and the like. it can.

As is clear from the above embodiment, when the molten stainless steel 16 and the slag discharged from the converter type refining furnace 37 are received using the molten metal holding container 24 according to the present invention and the slag is discharged, the waste is easily and quickly processed. The molten stainless steel 16 that has been subjected to the slag treatment and the slag
Therefore, the decarburization refining in the next step can be performed stably, and an excellent stainless steel can be produced. As an example, the approximate component of the molten stainless steel is Cr18.
%, Ni 8%, and C 5%, and the approximate components of the stainless steel after decarburization and refining are Cr 18%, Ni 8%, and C 0.3%.
The bottom was obtained stably.

Further, according to the molten metal holding container of the present invention, the molten stainless steel from which slag has been sufficiently discharged is injected into the converter type refining furnace 37 and returned or injected into another converter type refining furnace and transferred. Therefore, chromium loss due to slag mixing is small, and resulfurization does not occur. Therefore, the decarburization rate can be improved.

Further, when stainless steel is manufactured using a converter type refining furnace utilizing the existing converter site, etc., it is easy to select a slag site for slag discharge from molten stainless steel. is there.

[0041]

As described above, according to the present invention, slag can be drained from molten stainless steel using a molten metal holding container provided with a discharge port and a molten metal discharge port and provided with a tilting means for tilting in two directions. Therefore, the slag discharge operation can be performed simply and quickly, so that the molten Ni-Cr containing slag sufficiently discharged can be re-injected into the converter type refining furnace.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing one embodiment of a molten metal holding container of the present invention.

FIG. 2 is a side view showing one example of slag discharge of molten stainless steel by the molten metal holding container of the present invention.

FIG. 3 is a flowchart showing an example of a method for treating a molten stainless steel according to the present invention.

FIG. 4 is a schematic view showing an example of a layout for implementing the method of the present invention in an existing converter site.

FIG. 5 is a side sectional view showing an example of a conventional holding container used for discharging molten stainless steel.

[Explanation of symbols]

 Reference Signs List 1 molten metal holding container (conventional) 2 holding container main body (conventional) 3 tilting means (conventional) 4 lining 5, 29 molten metal outlet 6 trunnion (conventional) 7a, 7b flange 8a, 8b tilt lever 9a, 9b fulcrum pin 10a, 10b Tilting lever 11a, 11b Pin 12a, 12b Locking device 13a, 13b Hook receiver 14a, 14b Hook (supplementary winding) 15 Slug dragger 16 Stainless steel melt 17 Slug 18 Trunnion ring 19 Scraper plate 20 Scrape arm 21 Drive mechanism 22a 22b Locking Pin 23 Waste Receptor 24 Molten Metal Holding Container (Invention) 25 Main Body of Holding Container (Invention) 26 Tilting Means for Draining (Invention) 27 Tilting Means for Injecting Molten Metal (Invention) 28 Discharge Port ( Present invention) 30 flange (for waste) 31 tilting lever (for waste) 32 fulcrum pin (for waste) 33 foot Receiving (waste slag for) 34 (for trunnion) hook 35 Suragudoragga fixing base 36 Sabutoranion 37 rolling furnace type refining furnace 38 above 吹酸 containing lance 39 birds port 40 raw material hopper 42, 43 crane equipment 41, 44 Haikasujo

Claims (2)

[Claims] In a converter type refining furnace, a Cr raw material such as Cr ore is charged and melt-reduced in a Ni-containing molten metal.
The method for treating a stainless steel melt in which the molten Cr is discharged into a molten metal holding vessel, slag floating on the surface of the molten metal is discharged, and then the Ni-Cr-containing molten metal is transferred to a converter type refining furnace for decarburization. A discharge port and a molten metal discharge port are provided before and after the upper end of the holding container, and the molten metal holding container is tilted in one direction by a tilting means, and slag is discharged from the discharge port to a waste receptacle and discharged. A method for treating molten stainless steel, comprising: tilting the molten metal holding container in another direction by a tilting means to inject the molten Ni / Cr molten metal into the converter type refining furnace from the molten metal discharge port. 2. The molten metal holding container according to claim 1, wherein the molten metal holding container has a discharge port and a molten metal discharge port before and after an upper end portion, and a tilting means for tilting the holding container body in two directions is provided. A molten metal holding container for a molten stainless steel.