KR20200005848A - Manufacturing method of molten steel - Google Patents

Abstract

The present invention relates to a method for manufacturing molten steel, which comprises the following processes of: preparing first molten iron; preparing first molten steel having manganese content higher than manganese content of the first molten iron; manufacturing second molten iron by mixing the first molten iron with the first molten steel; and manufacturing second molten steel by refining the second molten iron. Moreover, liquidity of a slag can be secured to suppress base metal attached to a lance.

Description

Manufacturing method of molten steel

The present invention relates to a method for producing molten steel, and more particularly, to a method for manufacturing molten steel that can suppress adhesion of a lance to a lance due to a defective product during a converter operation.

In general, the furnace operation involves charging hot metal and scrap as main raw materials into the converter, injecting oxygen into the converter and simultaneously adding subsidiary raw materials such as carbon (C), silicon (Si), A series of operations for removing manganese (Mn), phosphorus (P), sulfur (S), titanium (Ti) and the like by oxidation refining are collectively referred to. Here, the blowing operation uses slag to remove impurities (for example, phosphorus, sulfur, carbon and titanium) from molten iron by blowing oxygen gas into the converter, and slag is required for stable removal of impurities. It is possible to obtain a molten steel that can produce the desired steel species by removing impurity elements by the subsidiary materials introduced during the drilling.

By the way, the molten iron or slag is scattered due to the injection pressure of the gas injected from the lance during the operation of the converter is a phenomenon that now forms in the lance. As such, when the lance is attached to the lance, a load is generated in the driving means for moving the lance in the up and down direction by the current load, or a supporting member such as a wire supporting the lance by the current load is broken. In addition, in the process of moving the lance in the up and down direction, there is a problem in that an accident occurs in the collision with the peripheral equipment such as the exhaust duct or the lance falls.

KR 2016-0077328 A KR 2003-0052913 A

The present invention provides a molten steel manufacturing method that can prevent the current is attached to the lance by making the goods smoothly during the converter operation.

The present invention provides a method for producing molten steel that can facilitate maintenance of the lance and improve its service life.

The molten steel manufacturing method which concerns on embodiment of this invention is a process of providing a 1st molten iron | metal; Providing a first molten steel having a higher manganese content than that of the first molten iron; Manufacturing a second molten iron by mixing the first molten steel with the first molten iron; And refining the second molten iron to produce a second molten steel.

The process of preparing the first molten iron, the process of manufacturing the molten iron in the melting furnace; And a process of manufacturing the first molten iron by desulfurizing the molten iron; and excluding the process before and after the process of manufacturing the first molten iron.

The first molten steel may contain 1% by weight or more of manganese based on the total weight of the first molten steel.

The first molten steel may include a residual water that is injected into the tundish of the casting facility and remains in the ladle.

The process of manufacturing the second molten iron, the process of transferring the first molten iron to a casting facility; And charging the first molten steel remaining in the ladle to the first molten iron.

In the process of manufacturing the second molten iron, the first molten steel may be mixed such that the second molten iron contains 0.2% by weight or more of manganese based on the total weight of the second molten iron.

In the process of manufacturing the second molten iron, 1 to 10% by weight of the first molten steel may be mixed with respect to the total weight of the second molten iron.

The process of manufacturing the second molten steel by refining the second molten iron may include: charging a second molten iron into a converter; Charging scrap into the converter; And injecting an oxygen-containing gas into the second molten iron, wherein the scrap may contain 1% by weight or more of manganese based on the total weight of the scrap.

According to the embodiment of the present invention, when the manganese operation is performed by adjusting the content of manganese contained in the molten iron, manganese can promote slag production and suppress the occurrence of low melting point compounds. This ensures that the slag fluidity can be prevented from forming now in the lance even if the slag is attached to the lance due to the injection pressure of the oxygen-containing gas injected through the lance. This extends the work cycle of removing the now debris attached to the lance, thereby facilitating maintenance and improving the life of the lance.

In addition, since the manganese content in the molten iron is adjusted using the residual water generated during casting, it is possible to reduce the cost incurred by adding manganese ferroalloy.

1 schematically shows a typical converter installation.
Figure 2 is a photograph showing the state is now attached to the lance used in the converter refining.
Figure 3 is a flow chart showing a molten steel manufacturing method according to an embodiment of the present invention in sequence.
Figure 4 is a view schematically showing a state that is now attached to the lance when refining molten iron in the molten steel manufacturing method according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you.

1 is a view schematically showing a typical converter equipment, Figure 2 is a photograph showing the state is now attached to the lance used in the converter refining.

Referring to FIG. 1, the converter may include a converter 100 having an open top and a space in which a melt is accommodated, and a lance 110 that blows oxygen-containing gas into the melt through an upper portion of the converter 100. have. In addition, an upper portion of the converter 100 includes an exhaust duct 120 that sucks and discharges exhaust gas generated in the converter 100, and the exhaust duct 120 communicates with the exhaust duct 120 and is included in the exhaust gas discharged through the exhaust duct 120. An exhaust gas treatment device (not shown) for treating dust and the like 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. And a tapping hole 102 for tapping the molten steel produced by refining the molten iron is formed on the upper side of the converter 100, a stirring gas for stirring the molten iron, for example inert gas and oxygen at the bottom of the converter 100 Blowable nozzles (not shown) may be formed that can be blown.

When the oxygen-containing gas is blown into the molten iron by using the converter equipment, that is, the molten iron is blown, the molten iron is contained in the molten iron by blowing the oxygen-containing gas into the molten iron contained in the converter 100 through the lance 110. Impurities such as carbon can be removed.

On the other hand, steel mills are equipped with a plurality of melting furnaces capable of producing molten iron. Some of them are blast furnaces for melting molten iron ore to produce molten iron, and some are molten gasifiers for melting molten iron reduced in molten iron ore to produce molten iron.

Since the raw materials (iron ore) used in the blast furnace and the melt gasification furnace is different, and the method of manufacturing the molten iron using the same, there are some differences in the components of the molten iron produced. For example, molten iron produced in a melt gasifier has a higher manganese (Mn) concentration and silicon (Si) concentration than the molten iron produced in a blast furnace. As such, the molten iron produced in the blast furnace and the melt gasifier is used in the converter operation by mixing the molten iron produced in the blast furnace and the molten iron produced in the melt gasifier if necessary.

Among the components contained in the molten iron, manganese has the property of improving slag production, that is, goods in the converter operation. When slag is not produced smoothly during the converter operation, a large amount of low melting point compounds are generated, thereby decreasing the flowability of slag. Thus, as shown in (a) and (b) of FIG. 2, a slag containing a large amount of a low melting point compound is attached to a lance for injecting an oxygen-containing gas into a molten iron during a converter operation, thereby forming a current.

Table 1 below shows the relationship between the manganese content of the molten iron used in the converter operation, and thus the number of times the rust is removed from the lance and the lance life.

Manganese content in molten iron (% by weight, average) Percentage of manganese content of 0.1% by weight or less Recall Now Removed Lance Life expectancy (Ch) Operation Example 1 0.17 2.9 93 29.9 Operation Example 2 0.16 4.9 133 16.5 Operation Example 3 0.16 3.8 91 24.8 Operation Example 4 0.14 10.5 124 22.2 Operation Example 5 0.12 24.9 147 16.7 Operation Example 6 0.14 10.8 152 17.9 Operation Example 7 0.14 9.9 169 16.5 Operation Example 8 0.13 17.6 204 13.8

Referring to Table 1, it can be seen that as the manganese content in the molten iron decreases, the number of times of removal is increased and the lance life expectancy is shortened. In particular, when the ratio of the manganese content of the molten iron is 0.1% by weight or less, it can be seen that the number of times of removal and lance life are now shortened.

Therefore, during the converter operation, additives containing manganese are added or mixed with molten iron with a high manganese content and molten iron with a relatively low manganese content.

However, the molten iron produced in the melt gasifier has a higher manganese content than the molten iron produced in the blast furnace. However, since the manganese content changes with the aging process, a method of injecting additives containing manganese is mainly used in the converter operation. Therefore, there is a problem in that the cost of manufacturing molten steel increases.

Thus, the embodiment of the present invention provides a molten steel manufacturing method that can prevent the current is attached to the lance by allowing the slag to be generated smoothly during the converter operation by increasing the manganese content of the molten iron to provide to the converter operation.

Figure 3 is a flow chart showing a molten steel manufacturing method according to an embodiment of the present invention in sequence, Figure 4 schematically shows a state that is now attached to the lance when refining molten iron in the molten steel manufacturing method according to an embodiment of the present invention. Drawing.

Referring to Figure 3, the molten steel manufacturing method according to an embodiment of the present invention, the process of preparing a first molten iron (S110) and the process of preparing a first molten steel having a higher manganese content than the manganese content of the first molten iron (S114)) and mixing the first molten steel with the first molten iron (S116) and a second molten iron by blowing the second molten iron (S118) may be included.

The process of preparing the first molten iron can be performed as follows.

First, when the first molten iron is manufactured in a melting furnace such as a blast furnace and a melt gasification furnace, the first molten iron is repaired in a container, for example, topedoca. At this time, the manufactured first molten iron may contain less than 0.2% by weight of manganese.

The topedoca is moved to the place where the charter preliminary treatment process is performed. When Topedoca arrives at the place where the charter preliminary treatment process is performed, the first chartered ship in Topedoca is ladleed.

When the first molten iron is embarked on the ladle, the slag floating on the upper portion of the first molten iron is removed, for example, totally distributed. The ladle is transferred to a desulfurization apparatus to desulfurize the first molten iron.

Thereafter, the sulfur component in the first molten iron may be removed by mechanically stirring the first molten iron using an stirrer such as an impeller while adding a desulfurization agent to the first molten iron (S112).

When the desulfurization treatment is completed, the slag generated during the desulfurization treatment is excreted, for example, post-discharged.

When the first molten iron is provided in this way, the ladle in which the first molten iron is accommodated may be transferred to the casting facility.

Next, the process of preparing the first molten steel can be performed as follows.

A ladle containing molten steel, for example, primary molten steel, which has undergone converter refining, secondary refining, or the like can be transferred to a casting facility. In this case, the first molten steel may be adjusted to about 1 wt% or more or 1 to 25 wt% of manganese alloy by introducing manganese ferroalloy during the tapping and the second refining of the converter. Such first molten steel may be used to manufacture welding rods, high tensile strength steels, high strength steels for automobiles, LNG tank steels, and the like that require manganese in an amount of 1% by weight or more.

The ladle may be seated on a ladle turret provided above the tundish. Thereafter, the nozzle unit including the shroud nozzle may be connected to the outlet of the lower ladle, and the first molten steel accommodated in the ladle may be injected into the tundish through the nozzle unit. At this time, if most of the first molten steel accommodated in the ladle is injected into the tundish, it can be replaced with a new ladle leaving some first molten steel in the ladle to prevent the slag from flowing into the tundish. At this time, the first molten steel remaining in the ladle, for example, the residual water may be about 5 to 15 tons.

Thus the first molten steel remaining in the ladle can be used to mix with the first molten iron.

When the ladle containing the first molten iron is transferred to the casting facility, the second molten iron may be manufactured by injecting and mixing the first molten steel into the first molten steel by tilting the ladle containing the first molten steel.

The second molten iron prepared as described above may have a higher manganese content than the first molten iron, and may contain about 0.2 wt% or more, preferably about 0.3 wt% to 1 wt% of the total weight of the second molten iron. At this time, when the manganese content in the second molten iron is about 0.2% by weight, it is possible to suppress the present formation in the lance, and when the manganese content is higher than this, it is possible to more effectively suppress the present formation in the lance. And the upper limit of the manganese content is set to 1% by weight because the amount of residual water generated in the casting process is limited, and because the amount of the first molten steel mixed with the first molten iron is relatively small, it is difficult to increase the content of manganese in the second molten iron. to be.

When the first molten steel is added to the first molten iron, the amount of the first molten steel may be adjusted according to the manganese content in the first molten steel. The first molten steel may be added in an amount of about 1 wt% to about 10 wt% based on the total weight of the first molten steel and the first molten iron, that is, the total weight of the second molten iron. For example, when the manganese content in the first molten steel is very high, about 25% by weight, the first molten steel may be added in an amount of about 1% by weight based on the total weight of the second molten iron, and the manganese content in the first molten steel may be about 1% by weight. In this case, about 10% by weight of the first molten steel may be added to the total weight of the second molten iron.

If the amount of the first molten steel secured is too small, i.e., less than the suggested range, the second molten iron may be adjusted to have the target manganese content by adding a high manganese scrap when charging the second molten iron into the converter. have. In this case, the input scrap may include high manganese steel, for example, scrap generated from the cast cast in the above-described casting facility.

When the second molten iron is provided in this way, the ladle in which the second molten iron is accommodated can be transferred to the converter facility.

Subsequently, the second molten iron is charged into the converter, and the oxygen-containing gas is blown through the lance to form carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), and titanium. (Ti) etc. can be removed and a 2nd molten steel can be manufactured.

As such, when the manganese operation is performed by adjusting the content of manganese contained in the molten iron, manganese can promote slag generation and suppress the generation of low melting point compounds. Thus, even if the slag is attached to the lance due to the injection pressure of the oxygen-containing gas injected through the lance to ensure the fluidity of the slag can be formed to form a coating layer on the surface of the lance as shown in FIG. As a result, it is possible to prevent the occurrence of facility accidents such as damage to the exhaust duct or fall of the lance.

In addition, since the manganese content in the molten iron is adjusted using the residual water generated during casting, it is possible to reduce the cost incurred by adding manganese ferroalloy. In addition, since the molten residue is poured into the molten iron instead of the solid manganese ferroalloy, the temperature drop of the molten iron can also be prevented.

Although the technical spirit of the present invention has been described in detail according to the above embodiment, it should be noted that the above embodiment is for the purpose of description and not for the purpose of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

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

Claims (8)

Preparing a first charter ship;
Providing a first molten steel having a higher manganese content than that of the first molten iron; And
Manufacturing a second molten iron by mixing the first molten steel with the first molten iron; And
Refining the second molten iron to produce a second molten steel;
Molten steel manufacturing method comprising a. The method according to claim 1,
The process of preparing the first molten iron,
Manufacturing molten iron in a melting furnace; And
Desulfurization of the molten iron to prepare a first molten iron; includes,
Molten steel manufacturing method comprising the; process before and after the process of manufacturing the first molten iron. The method according to claim 2,
The first molten steel,
A molten steel production method containing manganese at least 1% by weight based on the total weight of the first molten steel. The method according to claim 3,
The first molten steel is molten steel manufacturing method comprising the residue in the ladle and injected into the tundish of the casting equipment. The method according to claim 4,
The process of manufacturing the second molten iron,
Transferring the first molten iron to a casting facility; And
And charging the first molten steel remaining in the ladle to the first molten iron. The method according to claim 5,
The process of manufacturing the second molten iron,
The molten steel manufacturing method of mixing the said 1st molten steel so that a said 2nd molten iron may contain 0.2 weight% or more of manganese with respect to the total weight of the 2nd molten iron. The method according to claim 6,
The process of manufacturing the second molten iron,
A molten steel manufacturing method for mixing 1 to 10% by weight of the first molten steel relative to the total weight of the second molten iron. The method according to claim 7,
The process of manufacturing the second molten steel by refining the second molten iron,
Charging a second charterer to the converter;
Charging scrap into the converter; And
And blowing an oxygen-containing gas into the second molten iron.
And said scrap contains at least 1% by weight manganese relative to the total weight of said scrap.

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