KR101821368B1 - Ladle including a turbulent generating part and chromium oxide reduction method using the ladle - Google Patents

Abstract

The present invention relates to a ladle including turbulence generating part and a chromium oxide reduction method using the ladle. Disclosed are a ladle which reduces the chromium oxide by using standby time between each process to improve productivity and reduces the residence time of molten steel in an electric or refining furnace to expand life of a refractory, and the chromium oxide reduction method using the ladle. According to one embodiment of the present invention, the ladle delivers molten metal or molten steel, comprising: a ladle main body in which the molten metal or the molten steel is stored therein; a turbulence generating part protruding from a floor surface of the ladle to generate a turbulence in the molten metal or the molten steel flowing in the ladle.

Description

TECHNICAL FIELD [0001] The present invention relates to a ladle including a turbulent generating portion and a chrome oxide reduction method using the ladle,

The present invention relates to a ladle including a turbulence generating portion and a method of reducing chromium oxide using the ladle. More particularly, the present invention relates to a ladle comprising a turbulent generating portion, And a method of operating the system capable of increasing the reduction of the metal oxide by delaying the rise of the metal oxide by the ladle capable of generating the metal oxide.

The manufacturing process of the stainless steel generally follows an electric furnace-converter / furnace-ladle processing (LT) process. In the electric furnace or the refining furnace process, oxygen is blown to remove impurities such as carbon and phosphorus present in the stainless steel melt or molten steel. At this time, chrome contained in the molten metal or molten steel is also oxidized by oxygen. However, chromium is an intrinsic material of stainless steel and is an expensive raw material, so it is a component that must be recovered as molten steel to reduce the manufacturing cost. Therefore, a reducing agent is added into the molten steel or molten steel to reduce the chromium oxide.

Generally, in an electric furnace, scrap is melted and oxygen is blown to remove carbon and phosphorus in the melt. At this time, since the chrome in the molten metal is also oxidized, the chromium oxide is reduced by using aluminum or silicon. The molten metal which has been reduced is sprinkled with ladle and transferred to the refining furnace. In the refining furnace process, refining is carried out using oxygen and argon to obtain a carbon concentration of 200 to 500 ppm. In this operation, chromium in the molten steel is oxidized by oxygen, and after the molten steel reaches the target carbon content, chromium is reduced using aluminum or silicon. The molten steel having been reduced is moved to the ladle processing (LT) process by introducing into the ladle. As described above, in order to reduce chromium, a separate reducing agent and a reduction time of at least 5 minutes are required. It takes about 5 minutes or longer to transfer molten steel or molten steel into the ladle for transfer, and the desired valuable metal can be reduced in the ladle by using this time.

Of the conventional metal reduction methods in a ladle, Patent Document 1 discloses a method of reducing manganese oxides present in a slag to recover Mn as molten steel, discharging molten steel and slag to a ladle in a converter, introducing a reducing agent into the ladle, Mn can be immediately recovered into molten steel.

In Patent Document 2, a reduction method for recovering valuable metals contained in molten slag and a device for promoting reduction reaction of valuable metals are disclosed. The molten slag discharged from an electric furnace and a converter is separately coated with a carbonaceous material The reducing agent mixture which has a specific gravity higher than that of the molten slag is introduced into the molten slag and precipitated or stirred with a stirrer equipped with a carbon bar capable of moving up and down and promoting the reduction reaction, Recover iron and manganese which are valuable metals.

Patent Document 3 describes a method for recovering manganese from a slag containing manganese. When refining molten steel in a ladle, the molten steel is refined in an inert gas atmosphere to melt the slag added to the molten steel, and manganese And the oxide is reduced and recovered in the molten steel.

The prior art documents described above describe a method for reducing valuable metal oxides in the ladle, which requires excessive facility investment, requires separate refining time for metal reduction, or may require chemical reaction of metal oxide and reducing agent Is not smoothly performed, there is a problem that the recovery rate is lowered.

Korean Registered Patent No. 10-1460661 (Nov. Korean Patent Registration No. 10-1275827 (Jun. 11, 2013) Japanese Laid-Open Patent Publication No. 2006-206957 (2006.08.10.)

The present invention relates to a ladle including a turbulent generation portion and a method for reducing chromium oxide by reducing the chromium oxide by reducing the chromium oxide using the waiting time between processes and reducing the residence time of the steel in the furnace or the refining furnace, We want to improve the life span.

According to one embodiment of the present invention, a ladle for transferring molten metal or molten steel comprises: a ladle main body in which the molten metal or molten steel is accommodated; And a turbulence generator protruding from the bottom surface of the ladle to generate turbulence in the molten steel or molten steel flowing in the ladle.

According to an embodiment of the present invention, the turbulence generating unit may be formed in a hemispherical shape protruding from a bottom surface of the ladle.

According to an embodiment of the present invention, a plurality of the turbulence generators may be provided, and the diameter of the turbulence generator may be 5 to 10% of the diameter of the ladle.

Also, according to an embodiment of the present invention, the distance between the turbulence generating units may be 5 to 15% of the ladle diameter.

The method for reducing the chromium oxide according to an embodiment of the present invention is a method for reducing the amount of chromium oxide in the molten steel from the electric furnace to the refining furnace or from the refining furnace to the LT by feeding the molten steel or molten steel into the ladle, Retarding the rise of chromium oxide.

Further, according to an embodiment of the present invention, before the molten steel or molten steel is imported into the ladle, Al or Si may be introduced into the ladle first.

According to the present invention, as a method for reducing chromium oxide which is a valuable metal in the refining process of stainless steelmaking, the retention time of the chromium oxide in the molten steel is increased by increasing the turbulence characteristic of the ladle flow without investing in expensive facility, , The reduction time during refining necessary for the reduction of chromium oxide is reduced.

In addition, since the chromium oxide is reduced by the carbon in the molten steel and molten steel, the amount of the reducing agent used is reduced. In addition, the total refining time is reduced, so that the melting time of the refractories of the electric furnace and the refining furnace is reduced due to the decrease of the residence time of the molten steel staying in the electric furnace or the refining furnace, thereby increasing the refining replacement period.

With the above effects, the present invention can be expected to improve the productivity and the manufacturing cost of stainless steel.

1 is a schematic diagram of a ladle equipped with a turbulence generating unit according to an embodiment of the present invention.
2 is a schematic view of a flow field in a conventional ladle.
3 is a schematic view of a flow field of a ladle provided with the turbulence generating unit according to the present invention.
4 is a schematic diagram showing a turbulent flow generator according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to fully convey the spirit of the present invention to a person having ordinary skill in the art to which the present invention belongs. The present invention is not limited to the embodiments shown herein but may be embodied in other forms. For the sake of clarity, the drawings are not drawn to scale, and the size of the elements may be slightly exaggerated to facilitate understanding.

1 is a schematic diagram of a ladle equipped with a turbulence generating unit according to an embodiment of the present invention.

Referring to FIG. 1, a ladle 2 according to an embodiment of the present invention may be provided with a turbulent flow generating part 4 on a bottom surface thereof. The molten metal 3 is discharged to the ladle 2 made of refractory bricks for transferring the molten metal 3 from the electric furnace 1 to the refining furnace. The molten metal 3 spouted in the electric furnace 1 strikes the bottom surface of the ladle 2 and gradually fills the inside of the ladle 2. At this time, the molten metal 3 hits the turbulent flow generating unit 4 installed on the bottom surface of the ladle 2. Generally, the molten metal 3 is generated in the electric furnace 1, which chromium oxide is to become the low density of the molten metal (3) than the surface density of 7100kg / m ³ of the molten metal (3) to 5400kg / m ^3. However, the upward flow is obstructed by the turbulent flow generating section 4, and the time for staying in the molten metal 3 of the chromium oxide becomes long.

2 is a schematic diagram of a conventional conventional flow field in a ladle.

Referring to FIG. 2, when molten metal or molten steel flows into the ladle, it forms a large flow flow that moves to the top of the ladle along the bottom surface and the wall of the ladle and then to the bottom of the ladle. At this time, the chromium oxide contained in the molten metal or molten steel moves together with the flow of the molten metal or molten steel. The chromium oxide is floated on the upper surface of the molten steel or molten steel due to the low density when it moves to the upper part of the ladle by the flow, and the mixing into the inside is not easily performed.

3 is a schematic view of a flow field of a ladle equipped with a turbulence generating unit according to an embodiment of the present invention.

Compared with the conventional ladle 2 shown in Fig. 2, the ladle 2 equipped with the turbulence generating part 4 according to the present invention can increase the turbulence in the ladle 2 and delay the rise of the chromium oxide. The molten steel or molten steel 3 that has flowed into the ladle 2 strikes the turbulent flow generating portion 4 provided on the bottom surface of the ladle 2. At this time, the turbulence generating unit 4 may be formed in a hemispherical shape protruding from the bottom surface of the ladle 2, and may be provided in plural. The molten steel or molten steel 3 introduced into the ladle 2 by the turbulence generating unit 4 as described above can not form a uniform flow field as shown in FIG. . Therefore, the velocity of the chromium oxide mixed in the molten steel or molten steel 3 also decreases, and the molten steel 3 or the molten steel 3 is retained. At this time, the carbon contained in the molten steel or molten steel 3 reacts with the chromium oxide to reduce the chromium as shown in Reaction Scheme 1 below.

[Reaction Scheme 1]

Cr ₂ O ₃ + 3C? 2Cr + 3CO

Alternatively, aluminum (Al) or silicon (Si) may be introduced into the ladle 2 before the molten steel or molten steel 3 is imported into the ladle 2 so as to promote the reduction reaction of the chromium oxide.

Thus, the retention time in the molten steel or molten steel (3) of the chromium oxide is increased by providing the turbulence generating part (4) in the ladle (2) used for moving from the refining furnace or the refining furnace in the electric furnace, And the carbon present in the molten steel (3) can be used to reduce the chromium oxide. Therefore, the reduction time in the conventional process can be reduced, and the reducing agent can also be reduced. Further, since the carbon in the molten steel or molten steel 3 is utilized for reducing the chromium oxide, the starting carbon concentration in the subsequent process is lowered, and the time and oxygen amount required for decarburization are also reduced.

4 is a schematic diagram illustrating a turbulent flow generator according to an embodiment of the present invention.

As described above, the turbulence generating section 4 is provided on the bottom surface of the ladle 2 to control the flow velocity and turbulence of the molten metal or molten steel 3, but the range can be limited. The turbulence generating unit 4 may be a hemispherical refractory having a specific diameter and may be installed at regular intervals to generate turbulence. The diameter of each turbulence generating part 4 may be 5 to 10% of the diameter of the ladle 2. A plurality of hemispherical refractories may be arranged at regular intervals on the bottom surface of the ladle 2. The distance between the respective turbulent flow generating portions 4 may be set to be in a range of 5 to 100 mm, 15%. ≪ / RTI >

Hereinafter, the present invention will be described in detail with reference to the following examples. However, the following examples are intended to illustrate the present invention in more detail, but the scope of the present invention is not limited to these examples.

Example

The retention times of chromium oxide in molten steel or molten steel were compared with those of conventional ladders using ladders provided with a plurality of turbulence generating units. The residence time of the chromium oxide was measured by measuring the time until the residual ratio of the chromium oxide in the molten metal or molten steel became 10% or less, and the relative comparison was made based on the conventional method. Table 1 shows the residual ratio and residence time of chromium oxide remaining in the molten metal or molten steel.

The conventional example was measured using existing ladders not provided with the turbulence generating portion and the diameter D of each turbulence generating portion and the distance L therebetween were calculated based on the diameter R of the ladle according to the present invention, Respectively.

division The turbulence generating unit
Diameter (D) The turbulence generating unit
(L) Chromium oxide Residence time (s) Residual ratio Conventional example - - 52 One Comparative Example 1 0.025 * R 0.2 * R 66 1.26 Comparative Example 2 0.15 * R 87 1.67 Comparative Example 3 0.1 * R 100 1.93 Comparative Example 4 0.05 * R 87 1.67 Comparative Example 5 0.05 * R 0.2 * R 81 1.59 Example 1 0.15 * R 133 2.56 Example 2 0.1 * R 152 2.93 Example 3 0.05 * R 133 2.56 Comparative Example 6 0.1 * R 0.2 * R 85 1.64 Example 4 0.15 * R 133 2.56 Example 5 0.1 * R 142 2.74 Example 6 0.05 * R 135 2.59

In the conventional example in which the turbulence generating portion is not provided, the time required for the chromium oxide in the ladle to be 10% or less in the molten steel was 52 seconds. The residual ratios and times of the examples and comparative examples are shown on the basis of this.

Even when the distance between the turbulence generating portions is adjusted to 5 to 20% of the ladle diameter R when the diameter D of the turbulence generating portion is 0.025 times the ladle diameter R as shown in Comparative Examples 1 to 4 2, and the residence time was less than 2 times of the conventional example.

On the other hand, when the diameter D of the turbulence generating portion is 0.05 to 0.1 times the ladle diameter R, that is, 5 to 10% of the ladle diameter R, In the case of 5 to 15% of the diameter (R), the retention time of the chromium oxide was 2.5 times or more as compared with the conventional example. Particularly, when the diameter D of the turbulence generating portion is 5% of the ladle diameter R and the distance L between the turbulence generating portions is 10% of the ladle diameter R, the residence time in the molten steel and the residual ratio Respectively. However, Comparative Examples 5 and 6 have a turbulence generating portion diameter (D) of 5 to 10% of the above-mentioned ladle diameter (R), but exhibit a residual ratio of less than two times that of the conventional example. This is because the distance L between the turbulent generating portions is 20% of the radius of the ladle R and it is judged that the diffusive driving force for turbulent flow is insufficient.

Accordingly, in order for the irregular reflection to be sufficient when the molten metal or the molten steel hits the bottom surface, the diameter D of each turbulent generating portion should be 5% or more of the ladle diameter R, and the distance L between the turbulent generating portions, The effect is halved when the distance is 20% or more of the radius (R) of the ladle, so that it is required to be maintained at 15% or less of the radius (R) of the ladle.

It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims and their equivalents. It is to be understood that the technical idea is included in the scope of the present invention.

1: Electric furnace 2: Ladle
3: molten metal or molten steel 4:

Claims (6)

In the ladle for transferring molten metal or molten steel,
A ladle body in which the molten steel or molten steel is accommodated; And
And a plurality of turbulence generators protruding from a bottom surface of the ladle to generate turbulence in the molten steel or molten steel flowing in the ladle,
The turbulent flow generating unit is formed in a hemispherical shape,
Wherein the diameter of the turbulence generating portion is 5 to 10% of the ladle diameter, and the distance between the plurality of turbulence generating portions is 5 to 15% of the ladle diameter. delete delete delete In the transfer of the molten steel from the electric furnace to the refining furnace or from the refining furnace to the LT,
A method of chromium oxide reduction, wherein the molten steel or molten steel is imported into a ladle including a plurality of hemispherical turbulence generators to delay the rise of chromium oxide by turbulence. 6. The method of claim 5,
Wherein prior to importing the molten steel into the ladle, Al or Si is first introduced into the ladle.

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