JP6432403B2 - Converter operation method - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a method for operating a converter that performs refining treatment such as degassing P and decarbonization of hot metal, and in particular, a method for operating a converter when refining hot metal using two converters. About.

  The hot metal produced in the blast furnace contains C, P, S and the like as main impurities. Therefore, converter hot metal preliminary treatment is performed in which oxygen is blown into the hot metal in the converter to remove impurities such as C, P, and S as slag.

  In the converter hot metal preliminary treatment, the hot metal is once charged into the converter and the dephosphorization (de-P) and decarburization (de-C) processes are continuously performed. A method, for example, a method called MURC (Multi-Refining Converter) method, and after removing P, the hot metal is once taken out from the converter, and the hot metal is charged again into the converter when de-C is performed. There is a type of converter hot metal preliminary treatment such as a method called LD-ORP (LD converter-Optimized Refining Process).

  The hot metal once charging type converter hot metal pretreatment method is advantageous in that both de-P and de C can be performed in a short time, but compared with the hot metal double charging type converter hot metal pretreatment method, When producing an extremely low P steel having a slightly low P removal effect, for example, with a P content of less than 0.02%, it is necessary to carry out a hot metal double charging type converter hot metal pretreatment method. That is, according to the steel type composition to be manufactured, the ratio of the hot metal once charging type or the hot metal two time charging type converter hot metal pretreatment method is determined.

  As an operation method in which three converters are used and operated in combination with a hot metal once charging type and a hot metal two time charging type converter hot metal pretreatment method, for example, Patent Document 1 discloses three converters. A method in which all furnaces are used in the order of a converter for de-C, a converter for both de-P and de-C, and a converter for de-P, then repaired, and then used and repaired in the same order again Is disclosed. In this method, when any one of the three converters is used as a hot metal double charging type de-C converter, the other one is a hot metal double charging type de-P converter. The remaining one is used as a converter with a single charge of hot metal for both C removal and P removal.

  Further, for example, Patent Document 2 discloses an operation method for efficiently operating with two converters.

JP 2007-113029 A JP 2002-363630 A

  The operating ratio of the hot metal once charging type and the hot metal two time charging type is 1: 2, and based on the method of Patent Document 1, three converters 2a, 2b, 2c are de-P or / and de-C. FIG. 7 shows an example showing the operation schedule for each charge. The horizontal direction in FIG. 7 indicates the length of time, and the operation time proceeds in the right direction in the figure. One cycle of de-P and de-C by the MURC method as a hot metal once charging type converter hot metal pretreatment method is about 35 minutes, and LD- as a hot metal double charging type converter hot metal pretreatment method Each of de-P and de-C by the ORP method takes about 25 minutes. In FIG. 7, the hot metal once charging type converter hot metal pretreatment is described as “de-P, de C”, and the hot metal double charging type converter hot metal pretreatment is “de-P” or “de-free”. C ". In the case of operating three converters, for example, the first converter 2a is a hot metal double charging type de-P converter, and the second converter 2b is a hot metal double charging type de-C. The converter and the third converter 2c are used as a one-time charging type de-P and de-C converter, and the hot metal after de-P in the first converter 2a is sequentially transferred to the second converter 2b. By performing charging and removing C, it is possible to operate efficiently. FIG. 7 shows an operation schedule in which one cycle of the hot metal once charging type 1 charge and two times of the hot metal twice charging type 1 cycle is displayed, and according to this method, 16.7 minutes per charge. It can be operated at.

  However, when one of these three converters 2a, 2b, 2c is stopped for maintenance and operated with two, the converter for de-C and the converter for P are separated, In order to set the operation ratio of the hot metal once charging type and the hot metal two time charging type to 1: 2, for example, as shown in FIGS. Low. FIG. 8 shows the case where the processing performed in the first converter 2a and the third converter 2c in FIG. 7 is performed only in the first converter 2a, that is, the first converter 2a is used as the hot metal 2 In the operation schedule, the second charging furnace 2b is used for the degassing of the hot metal two-time charging type, which is used both for the decharging P of the charging type and for the degassing and decarbonizing of the hot metal one time charging type. is there. In this case, while the first converter 2a operates without a break, the free time of the second converter 2b is long and requires 28.3 minutes per charge. FIG. 9 shows the case where the processing performed in the second converter 2b and the third converter 2c in FIG. 7 is performed only in the second converter 2b, that is, the first converter 2a is used as the hot metal. The operation schedule is for double charge type de-P, and the second converter 2b is used for both hot metal single charge type de-P and de-C and hot metal double charge type de-C. is there. In this case, while the second converter 2b operates without a break, the free time of the first converter 2a is long and requires 28.3 minutes per charge. 8 and 9 also show the operation schedule in two cycles, one cycle of the hot metal once charging type and one time of the hot metal twice charging type two charges, as in FIG.

  Moreover, in patent document 2, it does not mention performing the hot metal 1 time charging type converter hot metal preliminary treatment method.

  An object of the present invention is to provide a converter operating method capable of operating two units efficiently when refining hot metal using two converters.

  In order to solve the above problems, the present invention is a method of operating a converter in which hot metal is refined using two converters, each of the two converters being charged with hot metal once. After the first treatment of the hot metal in which the hot metal is subjected to refining treatment and the first treatment of the refining treatment, the hot metal is once discharged from the converter, and then the hot metal is returned to the converter 2 Provided is a converter operating method characterized in that a hot metal pretreatment is performed in combination with a hot metal double charging type converter hot metal pretreatment for performing the second treatment.

  It is preferable to perform the first treatment and the second treatment of the hot metal double charging type converter hot metal pretreatment before and after the hot metal single charging type converter hot metal pretreatment. In that case, the first treatment is a dephosphorization treatment, the second treatment is a decarburization treatment, and the hot metal is charged twice before and after the hot metal single charge type converter hot metal pretreatment. When performing the converter hot metal preliminary treatment of the mold, the dephosphorization treatment may be performed subsequent to the decarburization treatment, or after the decarburization treatment is continuously performed for a plurality of charges, a plurality of the dephosphorization treatments are performed. You may carry out charge continuously.

  According to the present invention, two converters can be efficiently operated to improve productivity, and reduction of production cost can be realized.

It is explanatory drawing of the converter refining equipment concerning embodiment of this invention. It is a longitudinal cross-sectional view for demonstrating the structure of a converter. It is explanatory drawing of a MURC method. It is explanatory drawing of LD-ORP method, (a) is discharge | emission of molten metal, (b) shows discharge | emission of slag. It is explanatory drawing of the operation schedule concerning 1st embodiment of this invention. It is explanatory drawing of the operation schedule concerning 2nd embodiment of this invention. It is explanatory drawing of the operation schedule of the prior art example by three converters. It is explanatory drawing of the operation schedule of the prior art example by two converters. It is explanatory drawing of the operation schedule of the conventional different example by two converters.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  Drawing 1 is an explanatory view of converter refining equipment 1 concerning an embodiment of the invention. FIG. 2 is a longitudinal sectional view showing the structure of the two converters 2a and 2b provided in the converter refining equipment 1.

  As shown in FIG. 1, in the converter refining equipment 1, two converters 2a and 2b are arranged side by side. These two converters 2a and 2b have the same structure, and as shown in FIG. 2, a structure in which a refractory lining 4 made of brick or the like is attached to the inner surface of a steel converter vessel 3 have. Hereinafter, the converter 2a will be described as a representative.

  The upper end of the converter 2 a has an opening 5 through which hot metal, scrap, slag raw materials, etc. are put into the converter 2 a, and slag is discharged from the converter 2 a through the opening 5. Is done. On the side surface of the converter 2 a, a steel outlet 6 is formed which is located below the opening 5 and closer to the bottom of the converter vessel 3. Through the steel outlet 6, molten metal (molten steel or refined molten steel) is discharged from the converter 2a. The other converters 2b and 2c also have the same configuration, and in the converter refining equipment 1, hot metal, scrap, slag raw materials, etc. are appropriately selected for each converter 2a and 2b. It has become.

  In the present invention, each of the two converters 2a and 2b is a combination of the hot metal once charging type converter hot metal pretreatment method and the hot metal double charging type converter hot metal pretreatment method. Do.

  The single hot metal charging type converter hot metal pretreatment method is a so-called same furnace that performs both dephosphorization (de-P) and decarburization (de-C) in the refining process with a single hot metal charge. As the same furnace refining method, there is a method called a MURC (Multi-Refining Converter) method. First, after removing P in the converter 2a, as shown in FIG. 3, the converter 2a is tilted with the steel outlet 6 facing upward, and only the slag 10 is discarded from the opening 5 (intermediate waste). This is a method of further de-C treatment of the de-P-treated hot metal 11 left in the converter 2a. The MURC method is advantageous in that both de-P and de-C can be performed in a relatively short time, the amount of slag generated can be suppressed, and high-quality steel can be melted.

  Moreover, the hot metal double charging type converter hot metal pretreatment method is a method of first removing P in the converter 2a and then turning the steel outlet 6 downward as shown in FIG. 4 (a). By tilting 2a, the hot metal 11 in the converter 2a is poured out from the steel outlet 6 and once transferred to the ladle 12. Next, as shown in FIG. By tilting the converter 2a with the steel outlet 6 facing upward, the slag 10 remaining in the converter 2a is completely discharged, and then the hot metal 11 transferred to the ladle 12 is put into the empty converter 2a. This is a method of returning and removing C. Such a refining method is called an LD-ORP (LD converter-Optimized Refining Process) method. In general, when performing de-P, the temperature of the hot metal put into the converter 2a is maintained at, for example, about 1300 to 1400 ° C., and when performing de-C treatment, the hot metal put into the converter 2a The temperature rises above 1600 ° C. Although the hot metal pre-treatment method of the hot metal twice charging type requires a longer total time for de-P and de-C compared to the hot iron pre-treatment method of the hot iron once charging type, the amount of impurities such as P is extremely small. There is an advantage that a high-quality low-P steel can be melted.

  Hereinafter, as an embodiment of the present invention, an operation method of the converter when the operation ratio of the hot metal once charging type MURC method and the hot metal two time charging type LD-ORP method is 1: 2 will be described. .

  FIG. 5 is an example of a converter operating method showing the first embodiment according to the present invention, and shows an example of an operation schedule in the converter refining equipment 1 including two converters 2a and 2b. . The horizontal direction in FIG. 5 indicates the length of time, and the operation time proceeds in the right direction in the figure. In order from the upper stage in the figure, the states of the first converter 2a and the second converter 2b are shown, and the operating states of the converters 2a and 2b are shown simultaneously. FIG. 5 shows a part of the operation schedule, and the operation is continuously performed in the same pattern. Similarly to FIGS. 7 to 9 described above, the hot metal one-time charging type converter hot metal preliminary treatment is described as “de-P, de-C”, and the first hot metal double charging type converter hot metal pre-treatment. The dephosphorization process, which is a process, is described as “de-P”, and the decarburization process, which is the second process, is described as “de-C”.

  In the first embodiment shown in FIG. 5, the first converter 2a and the second converter 2b are provided with a hot metal double charging type before and after the hot metal single charging type converter hot metal pretreatment method. The de-P process, which is the first process of the converter hot metal preliminary process, and the de-C process, which is the second process of the converter hot metal pre-treatment of the hot metal twice charging type, are performed alternately for two charges. The hot metal double charging type converter hot metal preliminary treatment is performed in the order of de-P treatment, de-C treatment, and de-P treatment after de-C treatment. That is, after performing 1 charge of de-P and de-C processes by the MURC method, 1 charge of de-C process, 1 charge of de-P process, 1 charge of de-C process, 1 charge of de-P process, and then MURC Repeat the law with 1 charge. In the present embodiment, one cycle from hot metal charging to de-P, intermediate waste, de-C, steel exit, and waste iron by the MURC method as a converter hot metal pretreatment method for a single hot metal charging type. The time required for this is about 35 minutes. Also, de-P (hot metal charging, de-P, hot water, draining) and de-C (hot metal re-charging, de-C) by LD-ORP method as a hot metal double charging type converter hot metal pretreatment method The time required for one cycle each of (steeling, discharging) is about 25 minutes.

  The relative timing of the refining process of the converters 2a and 2b is, for example, as shown in FIG. 5, after 65 minutes from the start time of the de-P and de-C processes by the first converter 2a. The de-P and de-C processes are performed by the above. Moreover, the arrow in a figure shows the movement of the hot metal after a process. For example, in FIG. 5, the hot metal de-P treated in the first converter 2a is charged into the second converter 2b, and de-C treatment is performed in the second converter 2b. The hot metal de-P treated in the second converter 2b is charged into the first converter 2a, and de-C treatment is performed in the first converter 2a. FIG. 5 shows an operation schedule in which each of the converters 2a and 2b is operated with one hot metal charging type 1 charge and two hot metal charging times 2 type, and the same operation is repeated thereafter. . According to this operation method, the hot metal once-insertion type de-P and de-C treatment is 2 charges, the hot metal 2-time charge type de-P and de-C treatment is 4 charges each, and the de-P treatment is 6 charges in total. Both hot metal pretreatments for de-C treatment can be performed in 135 minutes, which is about 22.5 minutes per charge.

  In this embodiment, the hot metal after the completion of de-P of the hot metal double charging type is subjected to de-C treatment in different converters, and more than 10 minutes can be secured from the end of de-P to the start of de-C. . Therefore, while operating the converters 2a and 2b, the ladle containing the molten iron after de-P can be moved and suspended, so the non-operating time of the converters 2a and 2b is omitted. It can operate very efficiently.

  Moreover, in this embodiment, in each converter 2a, 2b, by performing the de-P process after the de-C process, the slag generated by the de-C process can be used for the de-P process that is the next step. . Therefore, the addition of a dephosphorizing agent used for the de-P treatment can be reduced, and the cost can be reduced.

  FIG. 6 is an example of a converter operating method showing a second embodiment according to the present invention. The display method of FIG. 6 is the same as that of FIG.

  In the second embodiment shown in FIG. 6, the first converter 2 a and the second converter 2 b perform the hot metal once charging type de-P and de C processes, and then the hot metal two time charging type. The de-C process, which is the second process of the converter hot metal preliminary process, is continuously performed for two charges, and thereafter, the de-P process, which is the first process of the converter hot metal pre-process of the hot metal two-time charging type, is performed 2 The charging is continuously performed, and then the de-P and de-C processes are repeated.

  The relative timing of the refining process of the converters 2a and 2b in the present embodiment is, for example, as shown in FIG. 6, after 60 minutes from the start time of the de-P and de-C processes by the first converter 2a. The P removal and the C removal treatment by the converter 2b of No. 2 are performed. Moreover, the arrow in a figure shows the movement of the hot metal after a process. For example, in FIG. 6, the hot metal de-P-treated at the first charge of the de-P treatment performed continuously for two charges in the first converter 2a is charged into the second converter 2b, and the second converter The de-C process is performed in 2b. The hot metal de-P-treated in the second charge of the de-P treatment continuously performed in the first converter 2a is removed in the ladle 12 while de-P and de-C treatment are performed in the first converter 2a. It is stored, and after the de-P and de-C processes are completed, it is returned to the first converter 2a, and the de-C process is performed. Similarly, the hot metal de-P-treated at the first charge of the de-P treatment performed continuously for two charges in the second converter 2b is charged into the first converter 2a, and then the first converter 2a De-C processing is performed. The hot metal de-P-treated at the second charge of the de-P treatment continuously performed in the second converter 2b is removed in the ladle 12 while de-P and de-C treatment are performed in the second converter 2b. It is stored, and after the de-P and de-C processes are completed, it is returned to the second converter 2b, and the de-C process is performed. FIG. 6 shows operation schedules in which each of the converters 2a and 2b operates 1 charge of the molten iron 1 charge and 2 charges of the molten metal 2 times, and the same operation is repeated thereafter. . According to this operation method, the hot metal once-insertion type de-P and de-C treatment is 2 charges, the hot metal 2-time charge type de-P and de-C treatment is 4 charges each, and the de-P treatment is 6 charges in total. Both hot metal pretreatments for de-C treatment can be performed in 135 minutes, which is about 22.5 minutes per charge.

  In this embodiment, the hot metal after the completion of de-P of the hot metal double charging type is subjected to de-C treatment in different converters while securing a time of 10 minutes or more until de-C start. The de-C treatment is performed in the same converter after sandwiching the de-P and de-C treatments of the first charging type. Therefore, while operating the converters 2a and 2b, the ladle containing the molten iron after de-P can be moved and suspended, so the non-operating time of the converters 2a and 2b is omitted. It can operate very efficiently.

  In the present embodiment, each converter 2a, 2b performs the de-C treatment continuously for two charges, so that there is very little P remaining in the converter 2a, 2b during the second charge de-C process. Refined in state. Therefore, what carried out the C removal process in the 2nd charge can be made into a high quality ultra low P steel. Furthermore, in this embodiment, in the de-P process performed immediately after the de-C process of the second charge, the slag generated by the de-C process can be used for the de-P process that is the next step. Therefore, the addition of the dephosphorizing agent used for the de-P treatment can be reduced, and the cost can be reduced.

  As described above, according to the first and second embodiments of the present invention shown in FIGS. 5 and 6, compared with the above-described conventional example shown in FIGS. The time is shortened to 5 minutes, and it can be operated more efficiently than the conventional method of operating two converters.

  In the present invention, both of the two converters 2a and 2b are performed by using both the hot metal once charging type converter hot metal pretreatment and the hot metal double charging type converter hot metal pretreatment. Two converters can be operated efficiently to improve productivity. In addition, when the slag is recycled for production cost reduction, or when producing a high quality ultra-low P steel, the operation pattern is changed according to the first embodiment or the second embodiment. By setting as above, it is possible to respond flexibly.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  For example, in the above-described embodiment, the time required for one cycle of the MURC method as the furnace hot metal pretreatment method for the hot metal once charging type is about 35 minutes, and the hot metal double charging type converter hot metal pretreatment method is as follows. The time required for one cycle by the LD-ORP method is about 25 minutes each for de-P and de-C, and the time from the end of de-P treatment to the start of de-C treatment in the hot metal double charging type converter hot metal pretreatment method However, the operation timing of the two converters may be determined in accordance with the time required for each cycle. Further, in that case, the first and second treatments of the hot metal double charging type converter hot metal pretreatment before and after the hot metal single charging type converter hot metal pretreatment are performed as described above. As in the embodiment, the number of charges is not limited to two, but three or more charges may be performed.

  The present invention can be applied to converter refining of hot metal.

DESCRIPTION OF SYMBOLS 1 Converter refining equipment 2a, 2b Converter 3 Converter vessel 4 Refractory lining 5 Opening 6 Steel outlet 10 Slag 11 Hot metal 12 Ladle

Claims (4)

A converter operating method for refining hot metal using two converters,
In each of the two converters, after the first treatment of the hot metal one-time-type converter hot metal processing, in which the refining treatment is performed by charging the hot metal once, and the first treatment of the refining treatment, The hot metal preliminary treatment is performed in combination with the hot metal double charging type converter hot metal preliminary treatment which is once discharged from the furnace, and then the hot metal is returned to the converter to perform the second treatment. Converter operation method.   The two converters are respectively connected to the first treatment of the hot metal double charging type converter hot metal pretreatment and the second treatment before and after the hot metal single charge type converter hot metal pretreatment. The converter operation method according to claim 1, wherein the second treatment is performed.   The first treatment is a dephosphorization treatment, the second treatment is a decarburization treatment, and before and after the hot metal single charging type converter hot metal pretreatment, the hot metal two charging type rolling process. The method for operating a converter according to claim 2, wherein the dephosphorization treatment is performed after the decarburization treatment when the furnace hot metal preliminary treatment is performed.   The first treatment is a dephosphorization treatment, the second treatment is a decarburization treatment, and before and after the hot metal single charging type converter hot metal pretreatment, the hot metal two charging type rolling process. The method of operating a converter according to claim 2, wherein when performing the furnace hot metal preliminary treatment, the decarburization treatment is continuously performed for a plurality of charges, and then the dephosphorization treatment is continuously performed for a plurality of charges. .

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