JP2005281723A - Method for detecting stuck metal quantity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for detecting stuck metal quantity by which the removal work of the stuck metal in a vacuum vessel can be performed at a suitable timing by accurately detecting the stuck metal quantity in a vacuum vessel. <P>SOLUTION: Circulating-flow treatment (V-treatment) of molten metal is successively performed ≥3 times by using the same vacuum vessel, and in the V-treatment performed after 3 times, based on the difference of the stuck metal quantities in the vacuum vessel before starting the ascent and after completing the descent of a molten metal vessel, the stuck metal quantity stuck in the vacuum vessel when the V-treatment is performed at one time, is obtained and the stuck metal quantity in the vacuum vessel is detected from the sum total of this assumed stuck metal quantities. When the detected stuck metal quantity reaches a prescribed stuck metal quantity, it is judged to be a suitable timing for performing the removal work of the stuck metal in the vacuum vessel, and the removal work of the stuck metal in the vacuum vessel is performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for detecting the amount of adhesion of a bullion in a vacuum tank in a decarburization process of molten metal.

Conventionally, in the steelmaking process, as shown in Patent Document 1, the carbon component contained in the molten metal is removed by introducing the molten metal into a vacuum chamber disposed above the molten metal container and circulating it. Decarburization processing is performed.
The decarburization process includes a first process that is mainly a process for producing an ultra-low carbon steel and a second process that is a process for mainly producing a low and medium carbon steel. The process and the second process may be selectively performed using the same vacuum chamber. Here, in the first treatment, since it is necessary to accelerate the decarburization reaction of the molten metal and remove a large amount of carbon components, the vacuum chamber is made to have a higher vacuum environment than the second treatment, and the vacuum chamber The molten metal is circulated while blowing oxygen from above toward the inner molten metal. On the other hand, in the second treatment, since the decarburization load is lower than that in the first treatment, the molten metal is circulated without blowing oxygen to the molten metal in the vacuum chamber.

When the first treatment or the second treatment is performed, the metal is attached to the inside of the vacuum chamber, and the metal that has adhered to the vacuum chamber is dropped to a certain extent and falls into the molten metal being decarburized. At this time, if the decarburization process is not sufficiently performed on both the dropped metal and the molten metal being decarburized, a defective component is generated in the molten metal after the decarburization process.
In addition, when decarburization treatment is continuously performed on different types of molten metal using the same vacuum tank, the metal that has adhered to the vacuum tank in the decarburization process performed earlier is removed later. If it falls during the charcoal treatment and is mixed into the molten metal, a component defect may occur in the molten metal that has been decarburized later.

These problems can be solved by frequently removing the bullion that has adhered to the vacuum chamber, but it is expensive to remove the bullion, and during the bullion removal work, a work line in the steelmaking process is required. Since it is necessary to stop, the working efficiency of the steelmaking process is reduced.
Therefore, it is important in terms of quality control of the molten metal and work efficiency of the steel making process to remove the metal in the vacuum chamber at an appropriate time. On the other hand, conventionally, regardless of the content of the decarburization process, when the number of decarburization processes reaches a predetermined number of times, the amount of metal in the vacuum chamber is expected to fall. It is determined that the predetermined amount of bullion adhesion has been reached, and bullion removal work is performed.
JP 56-79915 A

However, the conventional method described above does not reflect the difference in the amount of metal in the vacuum chamber between the first treatment and the second treatment. For this reason, when the number of decarburization processes reaches a predetermined number, the amount of metal in the vacuum chamber does not reach the predetermined amount of metal or exceeds the amount of metal Is assumed.
If the amount of metal in the vacuum chamber does not reach the predetermined amount of metal, the number of metal removal operations will increase more than necessary, and the work efficiency of the steelmaking process will decrease. In addition, if the amount of metal in the vacuum chamber exceeds the specified amount of metal, the metal will drop and mix with the molten metal being decarburized before removing the metal. As a result, defective components occur in the molten metal after the decarburization treatment.
The present invention has been made paying attention to the above-mentioned problems, and by accurately detecting the amount of metal in the vacuum chamber, the removal work of the metal in the vacuum chamber can be performed at an appropriate time. It is an object of the present invention to provide a method for detecting the amount of adhesion of a bare metal that can be performed in a simple manner.

In order to solve the above-mentioned problems, the invention described in claim 1 is a first aspect in which the molten metal is circulated while blowing oxygen to the molten metal in the vacuum tank using the same vacuum tank. Detecting the amount of metal in the vacuum chamber where the molten metal is decarburized by sequentially selecting one of the processes or the second process of circulating the molten metal without blowing oxygen to the molten metal in the vacuum chamber A method,
Based on the estimated amount of metal adhesion that is estimated to adhere to the vacuum chamber when the first treatment is performed once, and the number of times the first treatment is performed, the amount of metal adhesion in the vacuum chamber Is detected.
According to the present invention, since the amount of metal adhesion in the vacuum chamber is detected based on the estimated amount of metal adhesion and the number of times related to the first process, the detection accuracy of the amount of metal adhesion in the vacuum chamber is improved.

The reason will be described below.
When the first treatment performed in a higher vacuum environment than the second treatment is performed on the bare metal attached to the inside of the vacuum vessel by the second treatment, the molten metal in the vacuum vessel is at a position where the molten metal surface height is high. In order to become, a part of the attached metal is removed. On the other hand, in the first treatment, oxygen is blown onto the molten metal in the vacuum chamber, so that spitting occurs in the molten metal. The metal that scatters and adheres to the vacuum chamber due to spitting of the molten metal is attached to a higher position than the metal that adheres to the vacuum chamber when the second treatment is performed. Since this bullion is not removed by the molten metal during the decarburization process and is not removed by the second treatment, it is possible to accurately determine the estimated bullion adhesion amount by measuring the adhesion amount of this bullion. It becomes.

Next, the invention described in claim 2 is the invention described in claim 1, wherein the estimated amount of adhesion of the ingot is determined before and after the first process every time the first process is performed. It calculates | requires based on the difference of the mass of the vacuum chamber after a process, It is characterized by the above-mentioned.
According to the present invention, it is possible to determine the estimated metal adhesion amount more accurately.
In addition, it is preferable to use what calculated | required the estimation metal adhesion amount only about the 1st process performed after the 1st process was performed several times. The reason will be described below.

  When the first treatment is performed after performing the second treatment, the first treatment has a higher molten metal surface height in the vacuum chamber than the second treatment. The bare metal adhering to the inside of the vacuum chamber is removed (see FIG. 5). For this reason, it is possible to accurately obtain the estimated metal adhesion amount by obtaining the estimated metal adhesion amount for the first process performed after the metal in the vacuum chamber is removed by the second treatment. It becomes possible.

  According to the present invention, it is possible to perform the operation of removing the metal attached in the vacuum chamber at an appropriate time.

A first embodiment according to the present invention will be described with reference to the drawings.
First, the molten metal decarburization process will be described with reference to FIG. In addition, the 1st process which circulates the said molten metal while blowing oxygen to the molten metal in a vacuum chamber is hereafter described as V process, and demonstrates the 2nd process performed without spraying oxygen as L process.
As shown in FIG. 1, the decarburization treatment of the molten metal S removes the carbon component contained in the molten metal S by introducing the molten metal S in the molten metal container 30 into the vacuum chamber 20 and circulating it. To do. In addition, the detection apparatus 1 mentioned later other than the vacuum chamber 20 and the molten metal container 30 is shown in the figure. In the decarburization process of the molten metal S, a V process for circulating the molten metal S while blowing oxygen to the molten metal S in the vacuum tank 20, and a molten metal S without blowing oxygen to the molten metal S in the vacuum tank 20. And L treatment for refluxing.

  The vacuum chamber 20 is provided with a lance 24 at the top, a rise pipe 26 and a down pipe 28 are connected to the bottom, and a vacuum exhaust pipe (not shown) is connected to the side wall. A support frame 22 is provided on the outer periphery of the vacuum chamber 20. The lance 24 is movable in the vertical direction, and the distance from the molten metal S can be set to an arbitrary distance. The lance 24 is supplied with oxygen from an oxygen supply unit (not shown), and blows oxygen from above toward the molten metal S in the vacuum chamber 20 only when V treatment is performed. The ascending pipe 26 and the descending pipe 28 communicate the inside of the vacuum chamber 20 with the outside. The vacuum exhaust pipe is connected to a vacuum pump (not shown), and the vacuum pump can adjust the degree of vacuum in the vacuum chamber 20. In addition, when performing V process, the vacuum degree in the vacuum chamber 20 is made higher than when performing L process.

  The molten metal container 30 includes a moving mechanism and an elevating mechanism (not shown), and can move in the left-right direction and elevate in the vertical direction. When the molten metal container 30 is raised, the ascending pipe 26 and the descending pipe 28 are immersed in the molten metal S in the molten metal container 30, and the inside of the vacuum chamber 20 is set to a high vacuum environment by a vacuum pump, The molten metal S rises in the ascending pipe 26 and flows into the vacuum chamber 20. Then, the molten metal S that has flowed into the vacuum chamber 20 descends through the downcomer 28 and is discharged into the molten metal container 30. When the degree of vacuum in the vacuum chamber 20 is lowered by the vacuum pump and the molten metal container 30 is lowered, all of the molten metal S flowing into the vacuum chamber 20 is discharged into the molten metal container 30.

Next, an example of a method for detecting the adhesion amount of the metal A in the vacuum chamber 20 and performing the metal A removal work at an appropriate time in this embodiment will be described.
In this method, when the L process and the V process are sequentially selected and performed, each time the V process is performed, the estimated bullion estimated to be attached to the vacuum chamber 20 when the V process is performed once. The amount of adhesion of the metal in the vacuum chamber 20 is detected by calculating the amount of adhesion and calculating the sum of the estimated amount of adhesion of the calculated metal.

Then, when the detected amount of metal in the vacuum chamber 20 reaches a predetermined amount of metal in which the metal A is expected to fall, the metal A attached in the vacuum chamber 20 is removed. Therefore, it is determined that it is an appropriate time, and the metal A attached to the vacuum chamber 20 is removed.
According to this embodiment, since the detection accuracy of the amount of metal in the vacuum chamber 20 is improved, it is possible to appropriately know that the amount of metal in the vacuum chamber 20 has reached the predetermined amount of metal. Thus, the removal work of the metal A attached to the vacuum chamber 20 can be performed at an appropriate time. For this reason, it becomes possible to prevent the work efficiency of the steel making process from being lowered and the defective component of the molten metal S after the decarburization treatment.

As an example of a method for obtaining the estimated amount of metal adhesion, there is a method of obtaining each time the V treatment is performed based on a difference in mass of the vacuum chamber 20 before the V treatment and after the V treatment. The reason for obtaining the estimated amount of metal adhesion using this method will be described below.
In FIG. 2, the change of the metal adhesion amount in the vacuum chamber 20 when V process is performed once is shown. In the vacuum chamber 20 during the V treatment, since the metal A attached to the vacuum chamber 20 before the V treatment is removed by the molten metal S, as shown in FIG. The amount of attached metal in 20 decreases.

Accordingly, as indicated by I in the figure, the V metal treatment is obtained by obtaining the estimated metal adhesion amount based on the difference between the metal adhesion amount in the vacuum chamber 20 before the molten metal container 30 starts to rise and after the descent is completed. It is possible to accurately determine the estimated metal adhesion amount without being affected by the change in the metal adhesion amount in the inside vacuum chamber 20.
Moreover, when calculating | requiring an estimated metal adhesion amount using said method, it is preferable to perform V process continuously 3 times or more, and to obtain | require only in the V process performed after the 3rd time. The reason will be described below.

FIG. 3 shows a state in the vacuum chamber 20 during the L treatment. The metal A _L adheres in the vacuum chamber 20 during the L treatment. Note that the molten metal S surface height H in the vacuum chamber 20 is proportional to the degree of vacuum in the vacuum chamber 20.
On the other hand, FIG. 4 shows the state of the vacuum chamber 20 during the V treatment. Since the vacuum chamber 20 in the V processing high vacuum than the vacuum chamber 20 in the L process, the molten metal surface height H _V of the molten metal S in V processing the melt surface of the molten metal S in L process It becomes higher than the height H _L. For this reason, if V processing is performed after L processing using the same vacuum tank 20, the metal A _L adhering in the vacuum chamber 20 during the L processing is removed by the molten metal S during V processing.

Also, within the vacuum chamber 20 in the V process, since the blowing oxygen from above toward the molten metal S, spitting occurs in the molten metal S, bullion A _V is attached to the high position of the vacuum chamber 20 To do. Bullion A _V adhering to the high position of the vacuum chamber is not to be removed by the molten metal S in V process, adhering to the vacuum chamber 20 after exiting the V process.

  FIG. 5 shows a change in the amount of metal adhesion in the vacuum chamber 20 when the V treatment is performed several times continuously after performing the L treatment using the same vacuum chamber 20. As shown in the drawing, in the V treatment performed for the first time and the second time, the metal A attached to the vacuum chamber 20 during the L processing is removed, so the metal in the vacuum chamber 20 is removed. The amount of adhesion is decreasing. In addition, in the V treatment performed after the third time, the metal A attached in the vacuum chamber 20 during the L treatment is removed, so the metal A attached in the vacuum chamber 20 by one V treatment. The amount of metal adhesion in the vacuum chamber 20 is increased on average. Therefore, the V treatment is continuously performed three or more times, and the mass of the metal A attached to the vacuum chamber 20 in the V processing performed after the third time accurately represents the estimated metal adhesion amount.

Next, as a method of obtaining the estimated amount of metal adhesion based on the difference between the amount of metal adhesion in the vacuum chamber 20 before the start of rising of the molten metal container 30 and after completion of the lowering, a case where a detection device equipped with a load cell is used is used. An example will be described.
First, the configuration of this detection apparatus will be described with reference to the drawings.
As shown in FIG. 1, the detection device 1 includes a load cell 4 attached to a support base 2, a conversion unit 6, a calculation unit 8, and a detection unit 10. The support 2 supports the vacuum chamber 20 from below via a support frame 22 provided in the vacuum chamber 20.

The load cell 4 is attached to a position where the support base 2 is interposed between the support base 2 and the support frame 22 when the support base 2 supports the vacuum chamber 20 via the support frame 22. The downward pressure received from the tank 20 is detected, and the detected pressure is output to the converter 6.
The conversion unit 6 converts the pressure input from the load cell 4 into the total mass of the bare metal A and the vacuum chamber 20 attached in the vacuum chamber 20, and outputs this total mass to the calculation unit 8. The calculation unit 8 stores the mass of only the vacuum chamber 20, and calculates the mass of the metal A attached to the vacuum chamber 20 based on the total mass input from the conversion unit 6 and the mass of only the vacuum chamber 20. The calculated mass of the metal A is output to the detection unit 10.

  The detection unit 10 includes a sensor 12 and a storage unit 14. The sensor 12 detects the rise and fall of the molten metal container 30, and the storage unit 14 is attached to the inside of the vacuum chamber 20 input from the calculation unit 8. The mass of gold A is memorized. Moreover, the detection part 10 is the mass of the metal A attached to the vacuum chamber 20 before the molten metal container 30 starts to rise, and the mass of the metal A attached to the vacuum tank 20 after the molten metal container 30 is lowered. From this, the estimated amount of attached metal is obtained, and the obtained estimated amount of attached metal is displayed on a display.

Next, how to determine the estimated amount of attached metal using the detection device 1 will be described.
First, the pressure applied to the load cell 4 from the vacuum chamber 20 is detected before the molten metal container 30 starts to rise, and the detected pressure is output to the conversion unit 6, and the metal A and the vacuum chamber adhered to the vacuum chamber 20. Convert to a total mass of 20. Then, the total mass is output to the calculation unit 8, the mass of the metal A attached in the vacuum chamber 20 is calculated and output to the detection unit 10, and the calculated mass is stored in the storage unit 14.

Next, after the lowering of the molten metal container 30 is completed, the mass of the metal A attached in the vacuum chamber 20 is calculated and output to the detection unit 10 using the same method as before the rising of the molten metal container 30. The calculated mass is stored in the storage unit 14.
And, from the mass of the metal A attached in the vacuum tank 20 after the completion of the lowering of the molten metal container 30, by removing the mass of the metal A attached in the vacuum tank 20 before starting the rise of the molten metal container 30, The estimated amount of attached metal is obtained, and the obtained estimated amount of attached metal is displayed on a display or the like.

Next, a description will be given with reference to a second embodiment based on the present invention. In addition, about the same structure as what was demonstrated in 1st embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.
In the present embodiment, unlike the first embodiment, the estimated ingot adhesion amount obtained in advance is used without obtaining the estimated ingot adhesion amount every time V processing is performed.
First, the estimated metal adhesion amount that adheres in the vacuum chamber 20 when the V treatment is performed once is obtained in advance.

Next, the number of times of performing the V process in the actual decarburization process is counted, and the present amount of metal adhesion in the vacuum chamber 20 is detected by multiplying this number by the estimated amount of metal adhesion.
Then, when the detected amount of attached metal reaches the predetermined amount of attached metal, it is determined that it is an appropriate time to remove the metal A attached to the vacuum chamber 20, and the vacuum chamber 20 The removal work of the metal A attached inside is performed.

According to this embodiment, it is possible to obtain the amount of metal in the vacuum chamber simply by counting the number of times V processing is performed and multiplying it by the estimated amount of metal in the vacuum chamber, thus preventing a reduction in work efficiency. It becomes possible to do.
In addition, when calculating | requiring estimated amount of bullion beforehand, you may obtain | require by the method similar to 1st embodiment, However, It is not limited to this, For example, the state in which bullion A was removed completely You may obtain | require using the vacuum chamber 20 of.

The estimated amount of metal adhesion was determined by a method similar to that described in the present embodiment, and the amount of metal adhesion in the vacuum chamber was detected by multiplying the estimated amount of metal adhesion by the number of times V processing was performed. . Then, when the detected amount of attached metal reached the predetermined amount of attached metal, the removal work of the metal attached in the vacuum chamber was performed. In addition, the predetermined metal adhesion amount was 25 t.
When the estimated amount of metal adhesion was determined by the same method as described in the present embodiment, the estimated amount of metal adhesion was determined to be 0.5 t. Therefore, when the V treatment is performed 50 times, the amount of metal in the vacuum tank reaches a predetermined amount of metal, and it is an appropriate time to perform the removal work of the metal in the vacuum tank. Judging, the removal work of the metal which adhered in the vacuum chamber was done.

  And when removing the bullion, when we measured the mass of the bullion actually attached to the vacuum chamber, the mass of the bullion actually adhered to the vacuum chamber was It was confirmed that the amount was almost equal to the amount of adhesion. Therefore, it was confirmed that the detection accuracy of the amount of attached metal in the vacuum chamber is improved by using the method for detecting the amount of attached metal of the present invention.

It is a side view of the detection apparatus of the metal adhesion amount which concerns on embodiment of this invention. It is a figure which shows the change of the metal adhesion amount in a vacuum chamber when V process is performed once. It is a figure which shows the state in the vacuum chamber in L process. It is a figure which shows the state in the vacuum chamber in V process. It is a figure which shows the variation | change_quantity of the metal adhesion amount in a vacuum chamber when V process is performed several times.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Detection apparatus 2 Support stand 4 Load cell 6 Conversion part 8 Calculation part 10 Detection part 12 Sensor 14 Memory | storage part 20 Vacuum tank 22 Support frame 24 Lance 26 Rising pipe 28 Lowering pipe 30 Molten metal container A Ingot S Molten metal I Ingot adhesion Difference in amount H

Claims (2)

Using the same vacuum tank, a first treatment for circulating the molten metal while blowing oxygen to the molten metal in the vacuum tank, or a first process for circulating the molten metal without blowing oxygen to the molten metal in the vacuum tank A method for detecting the amount of adhesion of a metal in a vacuum chamber in which one of the two treatments is sequentially selected and decarburization of the molten metal is performed,
Based on the estimated metal adhesion amount estimated to adhere to the vacuum chamber when the first treatment is performed once and the number of times the first treatment is performed, the metal adhesion amount in the vacuum chamber A method for detecting the amount of metal adhesion.   The estimated amount of metal adhesion is determined based on a difference in mass between vacuum chambers before and after the first treatment every time the first treatment is performed. Method for detecting the amount of attached metal.

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