KR100544422B1 - Method for Manufacturing Molten Steel - Google Patents

Abstract

The present invention relates to a method for recycling the slag and molten steel remaining in the ladle which is terminated in the steelmaking process, or stopped in the middle of the continuous casting, it is more economical and more efficient to recycle the performance ladle slag and scald To provide a method of manufacturing molten steel that can be, the purpose is.

The present invention is a method of manufacturing molten steel comprising the step of taking the secondary refined molten steel to the performance ladle, and then transported to a continuous casting machine to supply molten steel until the slag and residual water remaining in the ladle, The slag and the molten metal in the performance ladle generated in the continuous casting process are poured into a dedicated ladle containing molten iron in advance, and then the molten iron, the ladle slag, and the molten metal in the dedicated ladle are solidified and the slag solidifies. The main point shall be a method of manufacturing molten steel, which is charged as a main raw material into a converter and blown to manufacture molten steel.

According to the present invention, not only can the molten steel manufacturing cost be lowered, the productivity can be improved, and waste generation can be reduced.

Molten steel, scald, slag, ladle, recycling, converter

Description

Method for Manufacturing Molten Steel

1 is a process chart showing a typical steelmaking industry

 2 is a process chart showing a process for recycling ladle slag and scum according to the conventional method.

 3 is a process diagram showing a process for recycling ladle slag and scald according to the present invention.

 4 is a process flow diagram illustrating one embodiment of the present invention.

The present invention is a slag (hereinafter referred to as "ladle slag") remaining in the ladle (hereinafter referred to as "playing ladle") that terminated the continuous casting in the steelmaking process, or stopped casting during the continuous casting (hereinafter referred to as "ladle slag") ), And more specifically, ladle slag and tang left in the playing ladle are collected in a ladle containing a certain amount of molten iron, and the water is solidified. It relates to a method of manufacturing molten steel by charging the converter as it is not molten state.

In general, the steelmaking industry consists of a charter preliminary treatment → converter refining → secondary refining → continuous casting process as shown in FIG. The molten iron produced by melting iron ore in the blast furnace removes sulfur and phosphorus in the molten iron preliminary treatment process. Since the molten iron has a very high carbon content, carbon is removed from the molten iron by a certain amount (0.04% by weight) by placing molten iron in a converter to blow carbon and injecting pure oxygen (hereinafter referred to as "blowing"). Molten iron from which carbon has been removed is called molten steel. After the conversion process, the molten steel is transferred to RH or LADLE FURNACE, which is a secondary refining facility, in a container called ladle, to uniform molten steel and temperature, or to remain in the molten steel. After removing the gas component or raising the temperature of the molten steel, it is solidified in a continuous casting process to produce a cast product, the final product of the steelmaking step. This steelmaking process is shown in FIG.

In the continuous casting process, the molten steel contained in the ladle is supplied to the continuous casting machine through the outlet of the bottom of the ladle, and when the majority of the molten steel in the ladle is supplied to the casting machine or the casting is stopped due to unavoidable circumstances in the ladle, Casting is completed by closing the outlet of the bottom.

The reason why slag and molten steel remain inside the ladle after casting is as follows. During casting, molten steel is placed in the ladle and lighter slag is in the upper portion. However, as the casting progresses, the height of the hot water surface gradually decreases to the bottom of the ladle, so that slag may be mixed into the casting machine at the end of the casting, and slag quality other than molten steel may be mixed into the casting machine. In order to prevent this from happening, casting is terminated when an appropriate amount of molten steel remains.

In addition, when the casting is stopped in the middle due to unavoidable circumstances, molten steel is present in the lower part of the ladle and slag is present in the upper part.

In general, ladle slag and scum of the performance ladle are received using a separate container such as a slag pot (SLAG POT) and a fan (PAN), and then disposed of in a slag yard (SLAG YARD) as shown in FIG. 2.

2 shows a recycling process of the conventional ladle slag and jangtang, which will be described in detail with reference to the following.

In the steelmaking process, ladle slag and tang in the ladle are poured into the slag pot, transported the container to the slag yard, scattered the ladle slag and tang in the slag port, and then cools it. Using a device of crushing to a certain size, slag and iron (鐵: STEEL) is separated. The separated slag is landfilled or used for various purposes, and iron is charged into the converter along with scrap iron to supplement the molten steel output.

 As described above, in the conventional method of recycling the ladle slag and the tang, the ladle slag and the tang are cooled and solidified in the slag port unless the ladle slag and the tang in the slag port are transferred to the slag yard and not scattered and cooled. It becomes a large, bulky mass that makes it impossible to transport, crush, or separate.

Therefore, in the conventional recycling method, there is a problem in that separate slag yards for cooling the ladle slag and the residual water and separate devices for crushing and separating solidified ladle slag and the residual water must be installed.

In addition, iron charged in the converter has a problem that heat loss by lowering the temperature of the molten iron, resulting in a decrease in productivity due to the increase in manufacturing cost for the additional heat supply and delay in the converter blow time.

The present inventors have conducted research and experiments to solve the above-mentioned problems of the prior art, and based on the results, the present invention proposes the present invention. The present invention is a ladle slag and a ladle in the process of recycling the ladle. By collecting them in separate ladles (hereafter referred to as "dedicated ladles") and using them as raw materials, without separate places for solidifying the wild slag and hot water, or separate equipment for crushing and separating them, The purpose is to provide molten steel manufacturing method that can recycle the performance ladle slag and smelt economically and efficiently.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention is a pretreatment process of the molten iron, the converter refining process of charging the molten steel with the pretreated molten iron in the converter, a process of secondary refining of the molten steel for the converter, and the second refined molten steel in the playing ladle In the manufacturing method of the molten steel comprising the step of transporting the molten steel until the slag and residual water remaining in the ladle is transferred to the continuous casting machine, the slag and the residual liquid in the performance ladle generated in the continuous casting process The molten steel is poured into a dedicated ladle containing molten iron in advance, and then molten iron, ladle slag and molten metal in the dedicated ladle are molten without solidification. It relates to a molten steel manufacturing method.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention is a pretreatment process of the molten iron, the converter refining process of charging the molten steel with the pretreated molten iron in the converter, a process of secondary refining of the molten steel for the converter, and the second refined molten steel in the playing ladle After that, it is transferred to a continuous casting machine and applied to the manufacturing method of molten steel including the step of continuous casting by supplying molten steel until the slag and residual water in the ladle, and the slag in the playing ladle generated in the continuous casting process It is a characteristic of recycling the residing water.

In order to recycle the residual slag and the residue according to the present invention, the molten iron must be filled in a dedicated ladle to receive the residual slag and the residue.

If the molten iron is filled after collecting a certain amount of ladle slag and tang in a dedicated ladle, the oxygen component ((O)) of the ladle slag and the carbon component ([C]) of the molten iron react as shown in the following Reaction Formula (1). By generating the carbon monoxide gas (CO) it is impossible to apply the present invention because the slag foaming (SLAG FOAMING) phenomenon due to the rapid gas generation and slag boils may occur.

Scheme 1

(O) in slag + [C] in iron = CO (g)

Furthermore, the ladle slag and scum of the performance ladles alone cannot satisfy the loading criteria required for one-time production in the converter, and if the ladle slag and scalding are poured into the ladle without filling the molten iron in advance, If you try to fill, the ladle slag and tang in the ladle coagulate due to excessive time, it can not be charged into the converter.

As described above, in the present invention, the molten iron must be filled in the dedicated ladle before the residual slag and the remaining hot water are received in the dedicated ladle.

 In the present invention, when charging the slag mixed with the slag in the ladle and the molten iron and molten iron in the converter, it is necessary to solidify all slag remaining in the converter beforehand.

This is also true when the slag of ladle slag in the ladle and the molten metal and molten iron are charged into the converter while the liquid slag in the converter remains in the furnace. This is because the carbon component of the molten metal reacted with each other may cause explosion and slag forming.

 In addition, in the present invention, the slag mixed with slag, molten metal and molten iron in the ladle should be charged into the converter in a molten state that is not solidified.

This is because when the molten water is cooled and solidified in the ladle, charging into the converter is not possible, and heat loss for dissolving the molten water increases, which impedes productivity.

3 shows an example of a process for producing molten steel according to the present invention.

As shown in Fig. 3, when some or all of the molten iron mixed with slag, molten metal and molten iron in the ladle is solidified, they must be dissolved and charged in a molten state by a heating apparatus.

For example, if there is some solidified slag on top of the waste in a dedicated ladle, some solidified slag on the top of the molten slag must be dissolved in a ladle furnace or the like and then charged into the converter.

Hereinafter, the present invention will be described in detail through examples.

(Example)

The operation was performed in the following manner for recycling the ladle slag and the tang in the playing ladle, this process was performed according to the flow chart as shown in FIG.

In Fig. 4, ① is a step of placing the molten iron in the dedicated ladle (LADLE) in the molten iron preparation building, ② is a step of transferring the dedicated ladle containing the molten iron to the dockyard, ③ is a lai remaining in the performance ladle Pouring slag and tang into dedicated ladles, ④ heats the molten slag in a ladle furnace (LADLE FURNACE: LF), melts the solidified slag on the upper side of the molten iron, and ⑤ transfers the dedicated ladles to the converter. Step 6 and ⑥ show the steps of charging the ladle of the dedicated ladle into the converter and then moving to the molten iron preparation building.

As shown in FIG. 4, first, the dedicated ladles were transferred to the molten iron preparation ridge to contain the molten iron (①), and then transferred to the docking station to receive ladle slag and residual water from the performing ladle.

At this time, the chemical composition of the molten iron contained in the dedicated ladle is shown in Table 1.

Chemical composition (% by weight) Temperature (℃) Weight (ton) C Mn Si P S S.Al Ti 4.50 0.13 0.16 0.095 0.004 0.000 0,019 1300 170

Next, 2 tons of ladle slag and 8 tons of boiling water at 1500 ° C. were poured into the dedicated ladles from the finished playing ladles, and in the same manner, 12 playing ladles were poured into one dedicated ladle in the same manner. (③)

At this time, the chemical composition, temperature, weight and ladle slag weight of the residue in each playing ladle are shown in Table 2 below.

division Bantang Residual slag Chemical composition (% by weight) Temperature (℃) Weight (ton) Weight (ton) C Mn Si P S S.Al Ti Ladle 1 0.19 0.15 0.00 0.011 0.007 0.036 0.000 1530 8 2.0 Ladle 2 0.35 0.22 0.00 0.013 0.005 0; 038 0.000 1539 9 2.0 Ladle 3 0.76 0.41 0.46 0.096 0.006 0.034 0.004 1525 9 2.0 Ladle 4 0.44 0.25 0.01 0.015 0.007 0.022 0.001 1539 10 2.0 Ladle 5 0.49 1.57 0.22 0.010 0.001 0.025 0.025 1530 10 1.5 Ladle 6 0.36 0.24 0.00 0.013 0.008 0.033 0.001 1537 8 1.5 Ladle 7 0.45 0.24 0.01 0.011 0.010 0.027 0.001 1541 8 2.0 Ladle 8 0.40 0.24 0.01 0.014 0.008 0.036 0.000 1538 10 2.5 Ladle 9 0.43 0.24 0.00 0.014 0.010 0.036 0.001 1538 8 2.5 Ladle 10 0.25 0.19 0.00 0.010 0.006 0.043 0.001 1539 10 2.0 Ladle 11 0.26 0.18 0.00 0.008 0.006 0.036 0.000 1531 12 2.0 Ladle 12 0.37 0.22 0.00 0.013 0.008 0.024 0.000 1534 11 3.0

The molten iron and the molten metal received in the dedicated ladle showed a temperature drop rate of 0.5 ° C. per minute, and the average time for supplying one performance ladle was 16 minutes, for a total of 192 minutes. The temperature of the water in the dedicated ladle measured by transferring the dedicated ladle containing the water to the ladle furnace (LADLE FURNACE), a secondary refining facility, is about theoretical solidification temperature when the carbon content of molten iron is 2.72% by weight. Higher than 1280 ° C.

Using the electrode heating device installed in the ladle furnace, the partially solidified slag covered on the upper part of the ladle was uniformly melted to allow smooth operation when charging the converter. (④)

At this time, the final chemical composition of the metal in the dedicated ladle is shown in Table 3.

Chemical composition (% by weight) Temperature (℃) Weight (ton) C Mn Si P S S.Al Ti 2.72 0.22 0.12 0.065 0.005 0.013 0,013 1369 283

Next, ladle slag 2ton and a bath of 1500 degreeC from the performance ladle which completed casting

The dedicated ladles were transferred to the converter via the ladle furnace and charged. (⑤)

After charging the converter, empty ladles were transferred to the molten iron preparation building (①). (⑥)

By repeating the above steps 1 to 6, it was possible to continuously recycle ladle slag and scum of the performance ladle.

As described above, the present invention increases the real rate of molten steel by pouring the ladle slag and the residue remaining on the playing ladle into the dedicated ladle containing the molten iron and charging it into the converter as it is in the molten state without solidifying it. It does not require a separate place or facility for recycling ladle slag and tang, and also recycles ladle slag and tang as it is in the hot molten state, thereby reducing the cost of producing molten steel and increasing productivity. In addition to improving the quality of waste, it is possible to reduce waste generation.

Claims (3)

Pretreatment process of molten iron, converter refining process of refining molten steel into molten steel and refining molten steel, secondary refining molten steel, and secondary refined molten steel in the ladle A method of manufacturing molten steel comprising the step of transferring the molten steel until the slag and the molten metal remain in the ladle and continuously casting the molten steel, wherein the slag and the molten metal in the playing ladle generated in the continuous casting process are preliminarily molten. The molten steel manufacturing method characterized by pouring the molten iron, ladle slag and tang in the dedicated ladle as a raw material into the converter to which the slag solidified, and then melted to manufacture molten steel The molten steel manufacturing method according to claim 1, wherein the molten iron, the ladle slag, and the molten metal in the dedicated ladle are heated in a heating apparatus and charged into the converter in a molten state before charging the converter into the converter. The molten steel manufacturing method according to claim 2, wherein the temperature raising device is a ladle furnace.

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