KR20200020129A - Manufacturing method of molten material - Google Patents

Abstract

The present invention relates to a method for manufacturing a molten material, which comprises the following steps of: preparing first molten metal; preparing first molten iron with a higher silicon (Si) content than the first molten metal; and manufacturing second molten iron by mixing the first molten metal with the first molten iron. Accordingly, large slopping can be prevented from being generated due to an excessive oxidation reaction during a converter refining process.

Description

MANUFACTURING METHOD OF MOLTEN MATERIAL}

The present invention relates to a melt production method, and more particularly, to a melt production method that can suppress the occurrence of large slopes due to excessive oxidation during the converter refining process.

In general, the converter refining process involves charging molten iron, which is the main raw material, and scrap metal (called 'scrap') into the converter, and injecting various secondary raw materials while injecting oxygen gas into the converter, thereby adding carbon (C) and silicon (Si), which are impurities in the molten iron. , A series of operations to remove manganese (Mn), phosphorus (P) and titanium (Ti) and the like. Appropriate amount of slag is required for stable removal of impurity elements.

On the other hand, the molten iron is manufactured in a blast furnace and a melt gasification furnace, there is a case that the starting amount and the component ratio of the molten iron is outgoing for each blast furnace. At this time, the content of silicon in the five components of molten iron such as carbon (C), silicon (Si), manganese (Mn), phosphorus (P) and sulfur (S) should be 0.65% by weight or less based on the total weight of the molten iron. No slope occurs.

During the converter refining process, when slagging occurs, a large amount of visible dust is generated, and there is a problem in that the present invention is fused to the converter refining process equipment.

The background art of this invention is published in the following patent document.

KR 10-2015-0002094 A KR 10-2001-0047206 A

The present invention provides a melt production method that can suppress the occurrence of large slopes due to excessive oxidation during the converter refining process.

Melt production method according to an embodiment of the present invention, the process of providing a first molten steel; Preparing a first molten iron having a higher content of silicon (Si) than the first molten steel; And mixing the first molten steel with the first molten iron to produce a second molten iron.

The second molten iron may have a lower silicon content than the first molten iron and a higher silicon content than the first molten steel.

The first molten steel may include Al-Killed steel or enamel steel.

The first molten steel may contain more than 0 and less than 0.10% by weight of silicon relative to the total weight of the first molten steel.

The first molten steel may contain 0 to 0.02 wt% of silicon based on the total weight of the first molten steel.

The process of preparing the first molten steel may include preparing a return molten steel or ladle residue in the casting process as the first molten steel.

The first molten iron may include molten gas furnace molten iron, or blast furnace molten iron and mixed molten iron of the molten gas furnace molten iron.

The first molten iron may contain 0.7 to 1.40 wt% of silicon based on the total weight of the first molten iron.

In the process of manufacturing the second molten iron, the first molten steel may be mixed with the first molten iron such that a mixing ratio of the first molten steel and the first molten iron becomes a ratio of 1: 1 to 1: 0.9.

In the process of manufacturing the second molten iron, the first molten steel may be mixed with the first molten iron such that the second molten iron contains 0.50 to 0.65 wt% of silicon based on the total weight of the second molten iron.

After the process of manufacturing the second molten iron, the process of refining the second molten iron, manufacturing a second molten steel; may include.

The melt which concerns on embodiment of this invention contains the melt manufactured with the said melt manufacturing method.

According to embodiment of this invention, the silicon content in molten iron can be adjusted using the return molten steel or ladle remnant which generate | occur | produces in a casting process. For example, a return molten steel or ladle scald produced in a casting process using aluminum-killed steel with a strictly controlled silicon content of 0.02% by weight or less is combined with a molten iron having a silicon content of 1.20% by weight or more. This can then be used to carry out the converter refining process. Therefore, it is possible to suppress the occurrence of large-sized slopes due to excessive oxidation during the subsequent converter refining process.

Therefore, it is possible to prevent the converter refining process equipment from being damaged by large-sized slopes, and to suppress the current fusion to the equipment. As a result, the maintenance cycle of the equipment can be lengthened, and the life of the equipment can be improved. In addition, it is possible to suppress the generation of visible dust during the process. Thus, environmental pollution can be reduced. In addition, since the return molten steel or ladle remnant generated in the casting process can be utilized for the production of molten steel, the cost can be reduced and the error rate can be increased.

1 is a process diagram showing an example of a converter refining process equipment used in the melt production method according to an embodiment of the present invention.
2 is a photograph showing a state in which a large slope occurs due to the rapid oxidation reaction due to the high silicon content in the converter refining process.
3 is a flowchart illustrating a melt manufacturing method according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, it will be described an embodiment of the present invention; However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. Only embodiments of the present invention are provided to complete the disclosure of the present invention and to fully inform the scope of the invention to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS The drawings may be exaggerated to illustrate embodiments of the invention, and like reference numerals designate like elements in the drawings.

1 is a process diagram showing an example of a converter refining process equipment used in the melt manufacturing method according to an embodiment of the present invention, Figure 2 is a large slope due to the rapid oxidation reaction due to high silicon content during the converter refining process This picture shows the status.

First, the converter refining process equipment (referred to as "converter equipment") will be described in order to facilitate understanding of the embodiment of the present invention.

Referring to FIGS. 1 and 2, the converter facility includes a converter 100 having an open top and a space in which a melt is received, and a lance for blowing oxygen-containing gas into the melt through an upper portion of the converter 100. 110). The converter 100 has an exhaust duct 120 for sucking and discharging exhaust gas generated in the converter 100 at an upper portion thereof, and dust contained in the exhaust gas communicated with the exhaust duct 120 and discharged through the exhaust duct 120. A flue gas treatment device (not shown) for treating the back may be provided.

The converter 100 may have a space in which a melt, for example, molten iron, is accommodated, and a furnace port 104 may be formed in the upper portion of the converter 100. The converter 100 may be formed with a tap hole 102 for tapping the molten steel on one side. The converter 100 may be provided with a low odor nozzle (not shown) capable of blowing a stirring gas, for example, an inert gas and oxygen, for stirring molten iron in the bottom.

When the oxygen-containing gas is blown into the molten iron contained in the converter 100 through the lance 110 and the molten iron is refined (referred to as 'blown'), impurities such as carbon contained in the molten iron can be removed. Thus, molten steel is produced.

On the other hand, the molten iron is manufactured in at least one of the blast furnace equipment and the melt gasification furnace equipment, the steel mill is equipped with a number of blast furnace equipment and melt gasification furnace equipment. These are collectively called molten iron manufacturing equipment.

Here, the melt gasifier may include a Corex facility and a Finex facility. Hereinafter, one example of a Finex plant as a melt gasifier, but the melt manufacturing method according to an embodiment of the present invention can be applied to Korex facilities.

The silicon content of the molten iron by molten iron manufacturing equipment varies widely. In particular, in the case of blast furnace equipment can control the silicon content at a stable level, such as less than 0.30 to 0.50% by weight relative to the total weight of the molten iron, while the melting gasifier equipment is far beyond the stable level of silicon in the molten iron. For example, the molten iron drawn out of the molten gasifier may have a silicon content of 1.55 to 1.85% by weight, or 1.73 to 1.94% by weight, based on the total weight of the molten iron.

This is because raw materials and molten iron manufacturing processes used in the blast furnace facility and the melt gasification furnace facility are different.

If the silicon content in the molten iron exceeds 0.65% by weight relative to the total weight of the molten iron, the slag goods are abnormally promoted during the converter refining process, so that slope occurs.

Therefore, the molten iron drawn out from each molten iron manufacturing facility may be mixed as needed and used for the converter refining process. However, this method has the following problems.

Blast furnace plants, for example, have thousands of tons of lead than melt gasifiers. When both the blast furnace facility and the melt gasifier are operating normally, the blast furnace molten iron produced in the blast furnace facility and the melt gasifier (Finex) molten iron produced in the molten gasifier can be smoothly mixed and used at an appropriate ratio. However, when some of the blast furnace facilities are under maintenance, blast furnace molten iron cannot be drawn out, and since the molten iron having a relatively low silicon content is insufficient, it is not possible to adjust the required silicon content of the molten molten iron. That is, a sufficient amount of high silicon molten iron (melting gas furnace molten iron) is secured, but since a low silicon molten iron (blast furnace molten iron) cannot be secured in a sufficient amount, the silicon content of the molten molten iron cannot be adjusted. For example, even when the two molten irons are mixed, the silicon content of the molten iron is 1.0 wt% or more, or 0.7-1.40 wt%.

Accordingly, when the blast furnace facility is partially under maintenance, the converter refining process is inevitably performed as a molten molten iron having a high ratio of high silicon molten iron, and large slitting occurs frequently due to excessive oxidation reaction during the process. This is illustrated in FIG. 2.

Thus, the embodiment of the present invention provides a molten steel manufacturing method that can prevent the occurrence of the slope during the converter refining process by lowering the silicon content in the molten iron to provide a converter refining process.

Specifically, the embodiment of the present invention provides a molten steel manufacturing method that can control the silicon content of the molten iron to a target level by incorporating the molten iron or ladle residue in the casting process of the aluminum-kilted steel to the molten iron. In this case, the aluminum-kilted steel is a steel grade in which the silicon content is strictly managed in an amount of 0.02% by weight relative to the total weight of the aluminum-kilted steel. Aluminum-kilted steel may also be referred to as WW steel.

3 is a flow chart of a melt manufacturing method according to an embodiment of the present invention.

1 and 3, a melt manufacturing method according to an embodiment of the present invention will be described in detail.

Melt production method according to an embodiment of the present invention, the process of preparing the first molten steel, the process of preparing a first molten iron having a silicon content higher than the first molten steel, by mixing the first molten steel and the first molten iron, the second molten iron It includes the process of manufacturing.

The melt production method may further include a step of refining the second molten iron after the process of manufacturing the second molten iron to produce a second molten steel.

The process of preparing the first molten steel and the process of preparing the first molten iron may be performed independently, together or simultaneously or sequentially. The order of these processes is not particularly limited. Hereinafter, the process of preparing the first molten iron will be described first, and then the process of preparing the first molten steel will be described.

Perform the process of preparing the first charter. Here, the first molten iron may have a higher silicon content than the first molten steel. The first molten iron may include molten gas furnace molten iron, or may include mixed molten iron of the blast furnace molten iron and molten gas furnace molten iron.

Prepare the first charterer through the following process.

The blast furnace molten iron and the melt gasification furnace molten iron is manufactured using the blast furnace equipment and the melt gasification furnace equipment, and the first molten iron is manufactured by mixing them (S110). Alternatively, molten iron is prepared by melting gasification, and the molten iron is prepared as the first molten iron. The first molten iron may comprise from 0.70 to 1.40 wt% or greater than 0.65 up to 2.50 wt% of silicon relative to the total weight of the first molten iron. The numerical value of the silicon content in the molten iron described above can be determined by the process environment of the blast furnace plant and melt gasification plant, for example.

Next, the first molten iron is preliminarily processed. Take out the first molten iron from the melt gasifier. Alternatively, the first molten iron may be prepared by drawing and mixing the blast furnace molten iron and the molten gasifier in the blast furnace facility and the melt gasification furnace facility. Thereafter, the first molten iron is accommodated in topedoca, for example. When the starting work is completed, the toppedoca is moved to the workshop where preliminary processing is performed.

When Topedoca arrives at the workshop, the first molten iron in Topedoca is embarked on a ladle, and then the slag of the upper part of the first molten iron is excluded. This is called pre-discharge treatment.

Thereafter, KR (Kal) treatment of the first molten iron is performed (S120). For example, a desulfurizing agent is added to the first molten iron in the ladle, and the first molten iron is mechanically stirred using an agitator such as an impeller. In this process, the sulfur component in the first molten iron may be removed. Thereafter, the slag generated on top of the first molten iron is excluded. This is called post-treatment.

In this way, the first charter is prepared. Thereafter, the ladle in which the first molten iron is accommodated may be transferred to a facility in which a casting process is performed (called a 'casting facility').

Next, to prepare a first molten steel (S130).

The first molten steel is, for example, aluminum-kilted steel, and may have a strictly controlled content of silicon to contain 0 to 0.02% by weight or less of silicon relative to the total weight of the first molten steel. Aluminum-kilted steel can also be called W steel. Aluminum-kilted steel is a kind of steel that is made of wire rods and is used in various applications for manufacturing machines such as automobile parts.

Alternatively, the first molten steel may be, for example, an enamel steel, in which the content of silicon is controlled to contain more than 0 and less than 0.10 wt% of silicon based on the total weight of the first molten steel. Enameled steel refers to a variety of steels used for manufacturing, for example, household, medical and sanitary steel products.

Of course, in addition to the aluminum-kilted steel and the enamel steel described above, the first molten steel may be prepared using various molten steels whose components are controlled to contain silicon in an amount lower than the upper limit of silicon content required in the second molten iron, for example, 0.65 wt%. have.

The first molten steel, which has undergone the previous refining process and the second refining process, is transferred to the casting facility. The ladle containing the first molten steel is seated on the ladle turret, the shroud nozzle is connected to the ladle collect nozzle, and the first molten steel is tapped with a tundish disposed under the shroud nozzle. At this time, when most of the first molten steel accommodated in the ladle is tapped into the tundish, some first molten steel is left in the ladle to prevent the slag from flowing into the tundish. Thereafter, the new ladle containing the first molten steel can be replaced and the injection of the first molten steel can be continued at the tundish. At this time, the first molten steel left in the ladle is called ladle retreat. For example, ladle scald can be on the order of 5 to 30 tonnes.

On the other hand, when the ladle containing the first molten steel is transferred to a casting facility, the temperature may be lower than a predetermined temperature suitable for casting. In this case, the first molten steel is returned without being supplied at tundish. This is called return molten steel.

Alternatively, the casting process cannot be continued if nozzle clogging occurs, slab rupture occurs, or abnormality occurs in other casting facilities while the first molten steel is injected into the tundish. At this time, the molten steel remaining in the ladle is returned. This is also called return molten steel.

That is, the return molten steel means the first molten steel which is transferred to the casting process but cannot be cast for various reasons.

The process of preparing the first molten steel may include preparing the return molten steel or the ladle remnant generated in the casting process as the first molten steel as described above.

Next, by mixing the first molten iron and the first molten steel, a process of manufacturing the second molten iron (S200) is performed. That is, the first molten iron is transferred to the casting facility, and the first molten steel provided from the casting facility is mixed with the first molten iron. For example, the ladle containing the first molten steel is tilted to tap the first molten steel with the ladle containing the first molten iron. Thus, the first molten iron and the first molten steel are melted in the ladle containing the first molten iron. Thus, the second molten iron can be produced.

The process of mixing the first molten iron and the first molten steel based on the mixing ratio will be described.

The first molten steel may be mixed with the first molten iron so that the mixing ratio of the first molten steel and the first molten iron becomes a ratio of 1: 1 to 1: 0.9. For example, the second molten iron may be manufactured by mixing 135 tons of the first molten iron with 150 tons of the first molten steel. That is, the first molten steel having a relatively low silicon content is mixed and the first molten iron having a relatively high silicon content is mixed.

At this time, the higher the mixing ratio of the first molten steel can lower the silicon content in the second molten iron. However, the reason for limiting the above numerical range is that the amount of the first molten steel is limited. On the other hand, if the mixing ratio of the first molten steel and the first molten iron is outside the above-described numerical range, it is difficult to control the silicon content of the second molten iron within the desired content.

The process of pooling the first molten iron and the first molten steel based on the silicon content will be described.

The first molten steel is mixed with the first molten iron such that the second molten iron contains 0.50 to 0.65 wt% of silicon based on the total weight of the second molten iron. Preferably, the first molten steel is mixed with the first molten iron such that the silicon content of the second molten iron is 0.50 to 0.60 wt% based on the total weight of the second molten iron. At this time, the smaller the silicon content of the first molten steel can be easily matched to the silicon content required in the second molten iron by adding a small amount of the first molten steel to the first molten iron.

If the silicon content of the second molten iron is less than 0.50% by weight, the silicon content is too small in the subsequent process of manufacturing the second molten steel, which is disadvantageous for temperature rise and slag goods. If the silicon content of the second molten iron is more than 0.65% by weight, a large slope may occur due to excessive oxidation reaction in the converter in the process of manufacturing the second molten steel. When the silicon content of the second molten iron is 0.50 to 0.60% by weight relative to the total weight of the second molten iron, it is advantageous to control the basicity in the subsequent process, and the input of the coolant may be reduced.

The second molten iron prepared by the above-described process may have a lower silicon content than the first molten iron and a higher silicon content than the first molten steel.

Thereafter, the second molten iron is refined to prepare a second molten steel (S300).

That is, the second molten steel is transferred to a facility in which a converter refining process is performed, a second molten steel is charged into the converter, an oxygen-containing gas is blown into the converter, and the second molten steel is refined. Accordingly, the second molten steel may be manufactured by removing carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), titanium (Ti), and the like from the second molten iron.

In this way, by adjusting the silicon content of the molten iron and performing the converter refining process, it is possible to suppress or prevent the slag from slipping.

Hereinafter, a specific example of preparing the first molten iron by mixing the blast furnace molten iron with the molten gas furnace molten gas and mixing the return molten steel with the first molten iron will be described.

150 tons of return molten steel generated in the casting process of aluminum-kilted steel is prepared, and 135 tons of molten iron of molten iron is added. At this time, the return molten steel contains 0.02% by weight of silicon relative to the total weight of the return molten steel, and the molten molten iron contains 1.35% by weight of silicon based on the total weight of the molten molten iron. A second molten iron is prepared by mixing the molten iron and the molten molten iron together. Thus, the second molten iron contains 0.65% by weight of silicon with respect to the total weight of the second molten iron. Thereafter, the second molten steel is manufactured using the second molten iron.

As a result of repeating this series of processes (ch) a number of times, the occurrence of visible dust was reduced from 5 times / 1 year to 0 times / 1 year as the slope was prevented, and the output was increased by 10 charges per year. An estimated $ 400 million has been saved, and damage to converter facilities has been avoided, saving about $ 1 billion annually.

Hereinafter, a melt according to an embodiment of the present invention will be described. The melt according to the embodiment of the present invention is a melt prepared by the melt manufacturing method according to the embodiment of the present invention described above, and includes, for example, the second molten iron described above.

The second molten iron may contain from 0.50 to 0.65% by weight of silicon relative to the total weight of the second molten iron, as described above. Therefore, during the refining treatment of the second molten iron, there is little silicon component in the converter, so that a sudden increase in temperature can be prevented, thereby preventing slipping and reducing the introduction of a coolant such as sintered ore. In addition, the basicity can be easily adjusted to, for example, 3.5 or more even with a small amount of quicklime as a side material.

The above embodiment of the present invention is for the description of the present invention, not for the limitation of the present invention. It is to be noted that the configurations and manners disclosed in the above embodiments of the present invention will be modified in various forms by combining or crossing each other, and such modifications can also be regarded as the scope of the present invention. That is, the present invention will be implemented in various forms that are different from the scope of the claims and equivalent technical idea, and various embodiments are possible within the scope of the technical idea of the present invention for those skilled in the art corresponding to the present invention. You will understand.

100: converter 102: exit
104: Nogu 110: Lance
120: exhaust duct

Claims (12)

Preparing a first molten steel;
Preparing a first molten iron having a silicon content higher than that of the first molten steel; And
And mixing the first molten steel with the first molten iron to produce a second molten iron. The method according to claim 1,
The second molten iron has a lower silicon content than the first molten iron and a higher silicon content than the first molten steel. The method according to claim 1,
The first molten steel is an aluminum-killed (Al-Killed) steel or enamel steel manufacturing method. The method according to claim 3,
And the first molten steel contains more than 0 and no more than 0.10 wt% of silicon based on the total weight of the first molten steel. The method according to claim 3,
And the first molten steel contains 0 to 0.02 wt% of silicon based on the total weight of the first molten steel. The method according to claim 1,
The process of preparing the first molten steel,
And preparing a return molten steel or ladle residue in the casting process as the first molten steel. The method according to claim 1,
The first molten iron includes a molten gas furnace molten iron, or a molten iron production method comprising a blast furnace molten iron and a mixed molten iron of the molten gas furnace molten iron. The method according to claim 1,
The first molten iron is a molten steel manufacturing method containing 0.7 to 1.40% by weight of silicon relative to the total weight of the first molten iron. The method according to claim 1,
In the process of manufacturing the second molten iron,
The molten steel manufacturing method for mixing the first molten steel so that the mixing ratio of the first molten steel and the first molten iron is a ratio of 1: 1 to 1: 0.9. The method according to claim 1,
In the process of manufacturing the second molten iron,
And melting the first molten steel into the first molten iron such that the second molten iron contains 0.50 to 0.65 wt% of silicon based on the total weight of the second molten iron. The method according to claim 1,
After the process of manufacturing the second molten iron,
And refining the second molten iron to produce a second molten steel. The melt manufactured by the manufacturing method of any one of Claims 1-11.

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