KR20140029663A - Method for treating molten metal - Google Patents

Method for treating molten metal Download PDF

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Publication number
KR20140029663A
KR20140029663A KR1020120094827A KR20120094827A KR20140029663A KR 20140029663 A KR20140029663 A KR 20140029663A KR 1020120094827 A KR1020120094827 A KR 1020120094827A KR 20120094827 A KR20120094827 A KR 20120094827A KR 20140029663 A KR20140029663 A KR 20140029663A
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KR
South Korea
Prior art keywords
molten metal
molten iron
sulfur
molten
desorbent
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KR1020120094827A
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Korean (ko)
Inventor
김광현
김대옥
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주식회사 포스코
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Priority to KR1020120094827A priority Critical patent/KR20140029663A/en
Publication of KR20140029663A publication Critical patent/KR20140029663A/en

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C21C1/025—Agents used for dephosphorising or desulfurising
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D27/00—Stirring devices for molten material

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Abstract

A molten metal processing method according to one embodiment of the present invention includes a step of preparing a container where molten metal is inputted; a step of inputting a desulfurizing agent containing carbon into the container; and a step of inputting the molten metal into the container. In the molten metal inputting step, the molten metal is stirred by gas generated by the reaction of the molten metal and the desulfurizing agent, and a sulfur component of the molten metal is removed. If the sulfur component contained in the molten metal satisfies an aimed value before desulfurizing the molten metal in KR equipment, the molten metal can be directly inputted into a furnace without passing the KR equipment. Therefore, the present invention can reduce processing time.

Description

Treatment method for molten metal {Method for treating molten metal}

The present invention relates to a method for treating molten metal, and more particularly, to a method for treating molten metal that can improve the dewatering efficiency of the molten metal.

Generally, a molten iron produced in a blast furnace contains a large amount of carbon and contains impurities such as phosphorus (P), sulfur (S) and silicon (Si), thus requiring a steelmaking process to reduce the amount of carbon and remove impurities. In this process, a desulfurizing agent such as calcium oxide (CaO) is mainly used to remove components such as sulfur (S) which is an impurity contained in the molten iron.

As such, the molten iron refining process using quicklime is carried out to the refining facility by transferring the molten iron from the blast furnace, and performing mechanical agitation (Kanvara Reactor, hereinafter referred to as “KR process”) in the ladle (L), or transferring to a refining vessel. Carry out the process. At this time, KR process injects quicklime into the molten iron and stirs the molten iron while rotating the impeller coated with refractory on the surface in the molten iron contained in the ladle (L), and the sulfur and quicklime of the molten iron react by the stirring force generated thereby. The dehydration proceeds, after which the molten iron is transferred to the converter.

However, in order to improve the degassing efficiency, it is required to increase the degassing time of the molten iron or increase the stirring performance.

In this case, when the molten iron is treated by increasing the degassing time, the degassing efficiency may be increased, but the process time required in proportion to the increase in the degassing efficiency is required, thereby reducing productivity.

On the other hand, in the case of increasing the degassing efficiency by stirring the molten iron, it is common to change the structure of the impeller of the KR facility or to blow the molten iron by blowing gas into the upper and lower portions of the molten iron. have. In this case, the upper bubbling may inert a gas line inside the impeller to blow gas into the molten iron, and in the case of the lower bubbling, a plug may be installed at the bottom of the ladle in which the molten iron is charged to blow the gas.

However, both of the bubbling methods require facility costs to implement the facility, and in particular, the lower bubbling facility causes a large accident such as leakage of molten iron when equipment trouble occurs, resulting in problems of implementation and stability of the facility. .

KR 2004-0053602 A1 KR 0862803 B

The present invention provides a method for treating a molten metal that can increase the dewatering efficiency of the molten metal.

The present invention provides a method for treating molten metal that can improve productivity by shortening the treating time of molten metal.

The method of treating the molten metal may include preparing a container into which the molten metal is charged, adding a desorbent containing carbon into the container, and introducing the molten metal into the container, and injecting the molten metal into the container. In, the molten metal is stirred by the gas generated by the reaction of the molten metal and the desorbing agent and the sulfur component in the molten metal is removed.

The desorbing agent may include at least one of limestone (CaCO 3) and dolomite (CaMgCO 3).

The gas is CO2, and the solids remaining after the reaction can remove the sulfur component in the molten metal.

The desorbent may be characterized by using a particle having a particle diameter of 10 to 20 mm.

The desorbent may be added 0.7 to 1 kg per ton of the molten metal.

Removing the sulfur component in the molten metal, and mounting the container on the trolley and may include the step of taking a sample from the molten metal and analyzing the sulfur content.

When the content of sulfur in the molten metal satisfies the target value according to the component analysis result of the molten metal, the molten metal is charged into a converter and the content of sulfur in the molten metal does not meet the target value according to the component analysis result of the molten metal. In addition, the molten metal may be additionally discharged and charged into a converter.

In the process of additionally deflowing the molten metal, the molten metal may be stirred by rotating the impeller in the molten metal without additionally adding a dehydrating agent to the molten metal.

The charging of the molten metal into the converter may be performed after excluding the slag remaining on the molten metal of the molten metal.

According to the treatment method of the molten metal according to an embodiment of the present invention, the sulfur component contained in the molten iron and molten steel can be easily removed. For example, a degassing agent that generates gas is introduced into the ladle into which the molten iron is charged for degassing the molten iron transferred from the blast furnace to the converter, and the molten iron is continuously bubbled while the molten iron is discharged and placed in the ladle, thereby degassing the molten iron. The efficiency can be improved.

Since the molten iron is deflowed before performing the KR process for stirring the molten iron using an impeller, if the sulfur value in the molten iron is the target value of the desired steel grade, the KR process may be omitted and the molten iron may be drawn out in the converter. Therefore, the processing time of a process can be shortened.

In addition, the total time required to process the molten iron can be shortened, thereby increasing the productivity of the process.

1 is a view schematically showing a process sequence according to an embodiment of the present invention
2 is a process flow chart showing a method of treating molten iron according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know. Wherein like reference numerals refer to like elements throughout.

1 is a view schematically showing a process sequence according to an embodiment of the present invention. 2 is a process flow chart showing a method of treating molten iron according to an embodiment of the present invention.

In the embodiment of the present invention to remove the sulfur (S) component contained in the molten metal accommodated in the container to process the molten metal, the degassing efficiency is increased through the bubbling of the molten metal using a degassing agent that generates gas. Such a molten metal treatment method can shorten the dewatering time of the molten metal. In this case, the molten metal may be molten iron and molten steel, and the container in which the molten metal is accommodated may be a ladle.

Referring to FIG. 2, in the molten metal treatment method, a process of preparing a ladle L in which molten iron is accommodated (S100), a process of introducing a dehydrating agent M into the ladle L (S120), and a ladle L Including the molten iron furnace (S140), in the molten iron in the process (S140), the molten iron is agitated by the gas generated by the reaction of the molten metal and the desorbent (M) and the sulfur component in the molten iron is removed.

The process of preparing a ladle to accommodate the molten iron (S100) is to prepare a container to be accommodated when the molten iron produced in the blast furnace is embarked. In the overall process, the ladle accommodated in the molten iron is moved to the converter and charged with the molten iron to the converter. Return to accept the molten iron produced in the blast furnace. At this time, the ladle is seated in a Torpedo Ladle Car (TLC) that transports the molten iron.

Next, the molten iron is introduced into the ladle (S120). In the related art, although the molten iron is received in the ladle, the molten metal is introduced into the ladle, but the molten iron is discharged. However, in the embodiment of the present invention, the molten iron is discharged and discharged at the same time. In order to obtain high degassing efficiency in a short time, dehydrating agent is put into ladle before the molten iron is released. At this time, the desorbent may be used as a raw material that is dissociated at high temperature to generate carbon dioxide (CO 2 ), for example, at least one of calcium-based compounds such as limestone (CaCO 3 ) and dolomite (CaMgCO 3 ) may be used.

As such, when a calcium-based compound is used as a desorbent, the compound is dissociated by hot molten iron and the gas component is discharged, and the remaining solids (eg, CaO and CaMgO) act as desorbents to assist the dehydration effect. There is an advantage. In addition, it is preferable to use a desorbent having a particle diameter of about 10 to 20 mm. At this time, when the particle size of the desorbent is 20 mm or more, the reaction of limestone does not easily occur due to the particle size of the gemstone, and when the particle size is 10 mm or less, when the desorbent is added to the ladle, scattering of the desorbent may occur in the atmosphere. The particle diameter of the desorbent is preferably in the above range.

After inputting the desorbent in the ladle (S120), the process of starting the molten iron in the ladle (S140). At this time, the ladle in which the demulsifier is added is transferred to the position where the molten iron is discharged by the topedo ladle car and arranged.

Thereafter, in the process of drawing out the molten iron (S140), the molten iron in the ladle is a process of removing sulfur (S) component in the molten iron while the degassing agent is agitated by a gas (eg, CO 2 ) generated by dissociating with the hot molten iron. S160 is performed.

Specifically, when limestone is used as the desorbent, gas is generated through a reaction as in Scheme 1 below. At this time, the limestone reaction occurs when the temperature of the molten iron is about 900 ℃ or more. Thus produced carbon dioxide (CO 2 ) gas bubbling molten iron to the ladle, and quicklime (CaO) generated together with carbon dioxide (CO 2 ) gas reacts with sulfur in the molten iron as shown in Scheme 2 below to remove sulfur in the molten iron. Can be removed to lower the content.

(Scheme 1)

CaCO 3 → CaO + CO 2 (g)

(Scheme 2)

CaO + S → CaS + O

Limestone decomposed through the reaction scheme as described above is decomposed into the amount of quicklime (CaO) and carbon dioxide (CO 2 ) as shown in Table 1 according to the input amount.

Limestone (CaCO 3 ) Input (㎏) Quicklime (CaO) generation amount (㎏) Carbon Dioxide (CO 2 ) Generation amount (N㎥) 100 54 535 200 108 1069 300 163 1604 400 217 2138 500 271 2673

In this case, since the amount of quicklime and carbon dioxide generated according to the amount of limestone input differs according to various variables such as the shape of the ladle, the working time, and the like, the amount of limestone input for the case where the amount of molten iron is constant is illustrated.

Referring to Table 1, it can be seen that quicklime and carbon dioxide are generated at a substantially constant rate according to the amount of limestone input. At this time, the amount of limestone injected into the molten iron (kg) is preferably 200 to 300 kg, which is preferably 0.7 to 1 kg per ton (ton) of molten iron. If limestone is added below 0.7 kg / ton, it is difficult to stir the molten iron due to less carbon dioxide generated, and when limestone is added above 1 kg / ton, a process time for reacting a large amount of limestone is required. Since the molten iron can float out of the ladle due to an increase in the amount of carbon dioxide generated, the amount of limestone input is preferably in the above range.

After the above process, the ladle containing the molten iron is placed on the trolley (S180) after taking a sample from the molten iron and goes through the process of analyzing the content of sulfur (S200). In general, sampling from the molten iron is called sampling, and in this process, a sampling device for sampling is lowered to the upper part of the ladle at the upper part of the ladle containing the molten iron, using a lance dipping method of the molten iron contained in the ladle. Samples may be taken from the charter. In addition, the temperature of the molten iron can be measured simultaneously with the sampling of the molten iron. At this time, the temperature measurement and sampling may be performed at the same time, or may be provided separately with each device. However, the present invention is not limited to the measuring device for sampling.

As described above, in the process of collecting the sample from the molten iron and analyzing the sulfur content (S200), when the analysis result of the molten iron (that is, the sulfur content in the molten iron) satisfies the target value, the molten iron does not undergo additional dehydration process such as KR process. Without the slag remaining on the hot water surface (S300), the molten iron may be charged into the converter immediately (S400). In this case, the target value may be a case where the content of sulfur in the molten iron before being transferred to the converter satisfies about 80 to 100% of the content of sulfur contained in the steel species produced through the converter process. For example, when the sulfur content of the molten iron in the blast furnace is 0.030ppm, and finally the sulfur content of the steel species produced through the converter process is 0.015ppm, in this embodiment, the sample of the molten iron is collected and the result of analyzing the sulfur content is 0.020 If it is ppm, the molten iron can be charged directly to the converter. This is because about 20 to 30% of the molten iron is further discharged from the converter, so that the sulfur content in the molten iron before charging into the converter is preferably charged when 80% of the molten iron is discharged. Of course, even when 90% of the dehydration proceeds, the charter can be directly charged into the converter.

On the other hand, if the sampling analysis results do not meet the target value, after the additional dehydration process, such as KR degassing process (S220), after the slag excretion process (S300) is charged into the molten iron (S400). At this time, the molten iron is already bubbling by the degreaser introduced into the molten iron, and since the stirring is in progress, no additional desorbent is added.

KR deflow process (S220) is a process of mechanical stirring the molten iron using the impeller 110, and after immersing the impeller 110 in the molten iron can draw the vortex of the molten iron using the rotational force of the impeller 110. . At this time, in order to increase the degassing efficiency in the prior art by increasing the rotational force of the impeller 110 or by modifying the shape of the impeller 110 to increase the degassing efficiency of the molten iron, in the present invention due to the reaction of limestone (M) impeller ( Agitation of 110) and bubbling agitation of carbon dioxide gas increase the degassing efficiency of the molten iron.

Thus, the molten metal treatment method according to an embodiment of the present invention is implemented through a KR process for refining molten iron by stirring the molten iron with a degreaser to improve the degassing efficiency of the molten iron transferred from the blast furnace to the converter with an impeller, It is shown that limestone (CaCO 3 ) is used as an input desorbent, but the treatment method of the molten metal may be used in various processes of the steelmaking process requiring bubbling, and the input desorbent may include various raw materials that may generate gas. Can be used

Table 2 below describes the dehydration effect of the present invention through the examples. In the following embodiments, the amount of molten iron contained in the ladle is 300 ton, and a predetermined amount is received.

Classification Melting line [S] content in blast furnace (ppm) Limestone Input (㎏) Molten iron [S] content (ppm) before KAL process Discharge rate (%) Example 1 0.025 250 0.017 32.0 Example 2 0.028 250 0.018 35.7 Example 3 0.030 300 0.020 33.3 Example 4 0.033 300 0.021 36.4 Example 5 0.035 300 0.022 37.1 ※ About 30 ~ 40% dehydration before KR process

Referring to Table 2, the sulfur contained in the molten iron produced in the initial blast furnace contained sulfur between 0.02 and 0.04. In Examples, when the content of molten iron (S) in the blast furnace was less than 0.03 ppm, 250 kg of limestone was added. When the content of sulfur (S) was more than 0.03 ppm, 300 kg of limestone was added. As such, it can be seen that the molten iron, which has undergone the dehydration due to the limestone input under the above conditions, has undergone about 30 to 40% of the dehydration prior to the dehydration process in the KR process.

As such, the carbon dioxide gas generated by the limestone is bubbled and stirred by the molten iron contained in the ladle, and the molten iron is degassed prior to the KR process to reduce the sulfur content in the molten iron by about 30 to 40% (that is, degassing). Efficiency of about 30 to 40%). In addition, since limestone used as a demineralizing agent is relatively inexpensive compared to quicklime, it is possible to reduce the cost of the process compared to the case where the same amount as the quicklime generated from limestone is dehydrated by only quicklime.

As described above, in the method for treating molten iron according to an embodiment of the present invention, the limestone generates quicklime and carbon dioxide by adding limestone as a desorbing agent for removing sulfur (S) contained in the molten iron. Accordingly, quicklime may react with sulfur contained in the molten iron to proceed with dehydration of the molten iron. Since the degassing is carried out before the KR process, the degassing process can be shortened in the KR process by proceeding with about 30% dehydration prior to degassing the molten iron in the KR process.

In addition, by bubbling molten iron with the gas generated in the desorbent, conventionally, the equipment required for performing the lower bubbling and the upper bubbling is not required, and thus, the equipment cost can be reduced, and in particular, Process accidents caused by troubles can be prevented to increase the safety of the process.

Although the present invention has been described with reference to the accompanying drawings and the preferred embodiments described above, the present invention is not limited thereto but is limited by the following claims. Accordingly, those skilled in the art will appreciate that various modifications and changes may be made thereto without departing from the spirit of the following claims.

L: Ladle M: Desorbent
100: KAL facility 110: impeller
200: converter

Claims (9)

As a method for treating molten metal,
Preparing a container into which the molten metal is charged;
Injecting carbon-containing desorbent into the vessel;
Injecting molten metal into the container; / RTI >
In the process of injecting the molten metal, the molten metal is stirred by the gas generated by the reaction of the molten metal and the desorbing agent and the sulfur component in the molten metal is removed. The method according to claim 1,
The desulfurizing agent treatment method of the molten metal comprising at least one of limestone (CaCO 3 ) and dolomite (CaMgCO 3 ). The method according to claim 1,
The gas is CO 2 , wherein the solid remaining after the reaction removes the sulfur component in the molten metal. The method according to claim 1 to 3,
The desulfurizing agent is a treatment method of the molten metal, characterized in that the one having a particle diameter of 10 to 20 mm. The method according to claim 1 to 3,
The desorbent,
Melting treatment method of injecting 0.7 to 1 kg per ton of the molten metal. The method according to claim 1,
Removal of sulfur components in the molten metal,
Placing the container on the balance; And
Taking a sample from the molten metal and analyzing the sulfur content. The method of claim 6,
According to the component analysis of the molten metal, when the content of sulfur in the molten metal satisfies a target value, the molten metal is charged into a converter.
According to the component analysis of the molten metal, when the content of sulfur in the molten metal does not meet the target value, the molten metal is further deflowed and charged into the converter. The method of claim 7,
The process of additionally dehydrating the molten metal,
A method of treating a molten metal, wherein the molten metal is stirred by rotating the impeller in the molten metal without additionally adding a desorbent to the molten metal. The method of claim 7,
The process of charging the molten metal into the converter,
A method for treating molten metal formed after excluding slag remaining on the molten metal surface of the molten metal.
KR1020120094827A 2012-08-29 2012-08-29 Method for treating molten metal KR20140029663A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20190061800A (en) * 2017-11-28 2019-06-05 주식회사 포스코 Method for treating molten metal
CN112301188A (en) * 2020-09-28 2021-02-02 甘肃酒钢集团宏兴钢铁股份有限公司 Method for efficiently utilizing metallurgical solid waste

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20190061800A (en) * 2017-11-28 2019-06-05 주식회사 포스코 Method for treating molten metal
CN112301188A (en) * 2020-09-28 2021-02-02 甘肃酒钢集团宏兴钢铁股份有限公司 Method for efficiently utilizing metallurgical solid waste

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