JP5258149B2 - Operation method of converter facilities - Google Patents

Description

  The present invention has a problem in a continuous casting facility that is a subsequent process of the converter facility, and the operation method of the converter facility in a situation where it is impossible to send the molten steel produced in the converter facility to the subsequent process, The present invention also relates to a converter facility capable of realizing this operation method.

As is well known, when producing steel, first, molten iron is first melted from iron ore by a blast furnace, and this molten iron is transferred to a converter while being subjected to a pretreatment by a kneading wheel (toped car). The transferred hot metal is charged into the converter and blown (refined). Molten steel that has been blown and finished with component adjustment is removed from the converter (dispensed) and cast into slabs, blooms, and the like by a continuous casting apparatus.
In the above process, troubles may occur although it is rare. For example, in a converter, molten steel deviating from the setting range of blowing conditions is manufactured, or a prescribed amount of slabs or blooms cannot be cast due to a failure of a continuous casting apparatus.

Conventionally, in such a case, after the molten steel from the converter is taken out into the ladle, it is turned to the ingot making process and poured into a casting mold for waste steel ingots that are always available in the ingot making process. It was a steel ingot (scrap). Thereafter, this steel ingot for raw material was used as a recycled raw material. However, since remelting is necessary to use the steel ingot for raw materials, there is a problem that the heat energy loss is very large.
As a method for solving this problem, for example, there is a technique disclosed in Patent Document 1.
In the technology disclosed in Patent Document 1, based on the occurrence of trouble (unsteady state) in the converter or subsequent continuous casting equipment, the molten steel obtained by blowing in the converter is converted together with the hot metal in the molten state. It is charged into the furnace and reused as the main raw material for blowing. Since the molten steel obtained by blowing is recharged into the converter in the molten state and used as the main raw material, it is possible to utilize unnecessary molten steel while minimizing heat loss in the converter operation. It has become a thing.
JP 2002-212619 A

However, when the technique of Patent Document 1 is applied to an actual steelmaking process, the following problems have been raised as a result of the field.
First, in the conventional converter equipment, even when trying to charge the molten steel discharged from the decarburization furnace (converter) into the decarburization furnace again, the molten steel is transferred from the discharge side of the decarburization furnace to the charging side. There is no means for transferring the ladle that has entered (means for returning the molten steel).
Therefore, as a means for returning molten steel, as shown in FIG. 11, it is conceivable to extend the track 102 conventionally laid under the furnace of the decarburization furnace 100 to the charging side of the decarburization furnace 100. If the extended track 102 and the carriage 101 traveling on the track 102 are used, the ladle 103 having received the molten steel can be transferred to the charging side.

However, when the molten steel is returned using the extended track 102, the time loss required for the decarburization furnace 100 to pass under the furnace as shown by the reference S in the conventional example of FIG. 8 and the Gantt chart shown in FIG. It is clear from the operation results and simulation that (time loss compared to normal operation) occurs about 13 minutes.
The breakdown of the time loss is
(i) When the ladle 103 containing the molten steel to be returned is placed on the steel exit side of the decarburization furnace 100 after the removal, the ladle that was originally installed is carried out. 5 minutes to take out the original ladle
(ii) 3 minutes to lift the ladle 103 containing the molten steel to be returned and place it on the cart 101 on the steel exit side of the decarburization furnace 100 (reference numeral W in FIG. 11)
(iii) About 2 minutes for the cart 101 to pass under the decarburization furnace 100 (reference numeral X in FIG. 11)
(iv) 3 minutes to lift the ladle 103 containing the returned molten steel on the charging side of the decarburization furnace 100 (reference Y in FIG. 11)
It becomes.

In other words, as a means for returning the molten steel, extending the track 102 for “molten steel discharge” that has been conventionally laid under the furnace of the decarburization furnace 100 to the charging side of the decarburization furnace 100 is (i ) To (iv), production inhibition time (13 minutes in total) is generated, which lowers the operating rate of the decarburization furnace 100 and is not preferable.
Furthermore, while the molten steel is being returned, a ladle (molten steel pan) cannot be newly installed, or a slag pan carriage that receives slag from the decarburization furnace 100 cannot enter the bottom of the decarburization furnace 100. A production hindrance situation occurs, and the operation rate of the decarburization furnace 100 further decreases.

  Therefore, in view of the above problems, the present invention reduces the operating status of the decarburization furnace as much as possible when recycling the molten steel in a situation where the molten steel manufactured in the converter equipment cannot be sent to a subsequent process. An object of the present invention is to provide a method for operating a converter facility that is not allowed, and a converter facility.

In order to achieve the above object, the present invention takes the following technical means.
That is, the operation method of the converter equipment without time loss compared with the normal operation according to the present invention accommodates a part or all of the dephosphorization furnace, the decarburization furnace, and the molten steel produced from the decarburization furnace. A ladle, a crane capable of suspending the ladle and provided on the discharge side of the dephosphorization furnace and decarburization furnace, and a ladle capable of suspending the ladle and the dephosphorization furnace and decarburization furnace A crane provided on the charging side, a cart on which a ladle can be placed, and a track capable of transferring the cart from the discharge side of the dephosphorization furnace to the charging side. In the converter facility laid so as to pass under the furnace of the phosphorus furnace, the molten steel in the ladle containing a part or all of the molten steel discharged from the decarburization furnace is used with a crane on the discharge side. Transfer the ladle to the pay-out side of the dephosphorization furnace, and use the trolley on the track. The decarburization furnace continues to operate after passing under the dephosphorization furnace to the charging side of the dephosphorization furnace, and the ladle moved to the charging side of the dephosphorization furnace is moved by a crane on the charging side. Lifting, transporting to the front of the decarburization furnace, charging the molten steel in the ladle into the decarburization furnace again and blowing.
Thereby, even if the situation where the molten steel produced in the converter equipment cannot be sent to the subsequent process occurs, part or all of the molten steel discharged from the decarburization furnace is placed on the charging side of the decarburization furnace. It can be transferred (returning the molten steel), charged again into the decarburization furnace and blown, and can be recycled while minimizing the thermal energy loss of the molten steel. When the molten steel is returned, it passes through the bottom of the dephosphorization furnace next to the decarburization furnace, so that the operation efficiency of the decarburization furnace is not lowered without impeding the operation of the decarburization furnace.

Preferably, when the ladle passes under the dephosphorization furnace, the hot metal in the dephosphorization furnace is added to the molten steel in the ladle, and the mixture of the molten steel and molten iron is charged into the decarburization furnace. .
It has become clear from the actual results of the field that the molten steel discharged from the decarburization furnace has a heat dissipation with time, and when transferred to a continuous casting apparatus, a temperature drop of about 50 to 100 ° C. occurs. It has also been found that when the molten steel is returned to the decarburization furnace due to troubles in the continuous casting apparatus, the temperature of the molten steel further decreases.
Therefore, when a part of the molten steel passes under the furnace of the dephosphorization furnace, if the molten iron in the dephosphorization furnace having a thermal margin is added to the molten steel, the amount of heat of the molten steel increases, Blowing can be performed reliably. In addition, since the hot metal added to molten steel is the hot metal after the dephosphorization treatment, there is no problem even if it is charged in a decarburization furnace and blown.

If the converter equipment has only a decarburization furnace, the ladle containing a part or all of the molten steel produced from the decarburization furnace of the converter equipment is removed through the side of the decarburization furnace. It may be transferred to the charging side of the charcoal furnace, and the molten steel in the ladle may be charged again into the decarburizing furnace and blown.
In this way, even if trouble occurs in the subsequent process, part or all of the molten steel discharged from the decarburization furnace is returned to the charging side of the decarburization furnace and charged again into the decarburization furnace. And can be recycled while minimizing the thermal energy loss of the molten steel. Moreover, when returning molten steel, since it passes through the side of a decarburization furnace, the operation efficiency does not fall, without inhibiting the operation of a decarburization furnace.

The operation method described above includes a dephosphorization furnace, a decarburization furnace, a ladle that accommodates part or all of the molten steel produced from the decarburization furnace, and a carriage on which the ladle can be placed, This can be realized with a converter facility that has a track that can transfer the cart from the steel output side to the charging side of the decarburization furnace, and the track is laid to pass under the dephosphorization furnace. It is.
By this converter equipment, a ladle containing molten steel that cannot be sent to the post-process is placed on a carriage, and the carriage is moved along the track so that the molten steel can be removed from the steel removal side of the decarburization furnace. Can be returned to the charging side. Since the track passes directly under the dephosphorization furnace, the operation of the decarburization furnace is not hindered by the movement of the carriage. Under this configuration, when a part of the molten steel passes under the furnace of the dephosphorization furnace, it is possible to easily add the molten iron in the dephosphorization furnace having a thermal margin to the molten steel.

In addition, the converter equipment includes a decarburization furnace, a ladle that accommodates part or all of the molten steel produced from the decarburization furnace, a cart on which the ladle can be placed, and the cart. The track may have a track that can be transferred from the steel output side to the charging side of the charcoal furnace, and the track may be laid so as to pass through the side of the decarburization furnace.
Even with this converter, a ladle containing molten steel that cannot be sent to the subsequent process is placed on the carriage, and the carriage is moved along the track to remove the molten steel from the decarburizer. It can be returned from the steel side to the charging side. Further, since the track passes through the side of the decarburization furnace, the operation of the decarburization furnace is not hindered by the movement of the carriage.

  ADVANTAGE OF THE INVENTION According to this invention, in the situation where the molten steel manufactured with the converter equipment cannot be sent to a post process, molten steel can be recycled, without raise | generating the operating condition of a decarburization furnace.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best embodiment of a converter facility and its operation method according to the present invention will be described with reference to the drawings.
[First Embodiment]
As shown in FIGS. 1 and 2, the converter facility 1 of this embodiment includes three converters 2 </ b> A, 2 </ b> B, and 2 </ b> C and a plurality of ladles 3 (hot metal ladle) that supply hot metal to these converters 2. And two cranes 4 </ b> A and 4 </ b> B for conveying the ladle 3.
The two cranes 4 </ b> A and 4 </ b> B are capable of traveling on a traveling rail 5 disposed on the upper side of the converter facility 1 so as to cut through the converter facility 1. A wire 6 extends downward from the main body 8 of the crane 4A, 4B, and the ladle 3 can be suspended by a hook 7 provided at the tip of the wire 6. By winding the wire 6 around the crane body 8, the ladle 3 is lifted upward, and when the crane body 8 travels on the traveling rail 5, the ladle 3 can move in the converter 1. It has become.

In addition, the converter equipment 1 has two dispensing stations 10A and 10B (dispensing pits), which are places where the molten iron is transferred from the kneading wheel 9 to the ladle 3, and for the molten iron in the ladle 3 Two desulfurization stations 16A and 16B for performing desulfurization treatment are provided.
The converter equipment 1 is provided with two stripping stations 13A and 13B that are used to scrape the slag floating on the upper surface of the hot metal in the ladle 3 using a scallop 12 (slag dragger). A scrap crane 14 for charging firewood and cold steel is provided. The scrap crane 14 can withdraw two scrap chutes 15 and 15 simultaneously.

The components of the converter facility 1 described above are arranged as follows.
A traveling rail 5 is provided on the upper side of the converter facility 1 so as to run vertically through the converter facility 1. For convenience of explanation, the traveling rail 5 is divided into eight sections (numbers 0 to 7), and numbers are assigned to the sections. One of the two cranes (crane 4A) moves from the dividing numbers 0 to 6 of the traveling rail 5, and the other (crane 4B) moves from the dividing numbers 1 to 7. One division number corresponds to the width of one crane 4A, 4B.
Dispensing stations 10 </ b> A and 10 </ b> B are provided so as to correspond to a substantially lower side of the traveling rail 5 corresponding to the partition numbers 1 and 2 and a side of the traveling rail 5. In the following description, the vertical direction is the same as the vertical direction in FIG. Further, a demolition station 13A and a desulfurization station 16A are provided below the partition number 1 of the traveling rail 5. Similarly, a dedusting station 13B and a desulfurization station 16B are disposed below the partition number 2.

Converters 2A, 2B, and 2C are provided below the traveling rail 5 corresponding to the partition numbers 4, 5, and 6 and on the side of the traveling rail 5 so as to be lined up. In the present embodiment, the converter 2A corresponding to the partition number 4 is the dephosphorization furnace 20, and the converter 2B corresponding to the partition number 5 is the decarburization furnace 21. The converter 2C corresponding to the partition number 6 is the preliminary furnace 22 and is not used.
A scrap crane 14 is arranged at the position of the partition number 7, and this scrap crane 14 can be moved to the partition numbers 4 to 6 (the charging side of each converter) and the partition number 7 of the traveling rail 5. In addition, it is also possible to move to a scrap loading place (scrap yard) (not shown) located on the right side of FIG.

Furthermore, the converter facility 1 of the present embodiment can run on the carriages 23A, 23B, and 23C and the carriages 23A, 23B, and 23C below the dephosphorization furnace 20, the decarburization furnace 21, and the preliminary furnace 22, respectively. Orbits 24A, 24B, and 24C.
The carts 23A, 23B, and 23C can be loaded with ladle 3 that receives hot metal and molten steel discharged from the dephosphorization furnace 20 and decarburization furnace 21, and slag pans that receive slag discharged from the furnace, The ladle 3 and the slag pan can be transferred to a predetermined position by moving on the tracks 24A, 24B, and 24C. The tracks 24A, 24B, 24C are composed of a pair of rails arranged with a width that allows the carriages 23A, 23B, 23C to travel.

  The track 24A is laid in a direction substantially perpendicular to the laying direction of the traveling rail 5 from the hot metal discharge side of the dephosphorization furnace 20 to the charging side. It has been passed. One side of the track 24A (the one extending toward the charging side) is laid to the position immediately below the cranes 4A and 4B (below the traveling rail 5) so that the ladle 3 on the carriage 23A can be lifted by the cranes 4A and 4B. Yes. The other side of the track 24A (the one extending to the payout side) extends directly below the payout crane 19 and to a slag disposal place (both not shown) and ends in the vicinity of the dephosphorization furnace 20. Absent. The carriage 23A moves on the track 24A.

The track 24B is laid in a direction substantially perpendicular to the laying direction of the traveling rail 5 from the bottom of the decarburization furnace 21 toward the molten steel discharge side. One side of the track 24B is terminated immediately below the decarburization furnace 21, and the other side of the track 24B (the one extending to the payout side) extends directly under the crane 19 on the payout side and a slag disposal place. The carriage 23B moves on the track 24B.
The track 24C is laid in a direction substantially perpendicular to the laying direction of the traveling rail 5 from the bottom of the preliminary furnace 22 toward the payout side. One side of the track 24C terminates just below the preliminary furnace 22, and the other side of the track 24C (the one extending to the payout side) extends directly under the crane 19 on the payout side and a slag disposal place. The carriage 23C moves on the track 24C.

Blowing in the converter facility 1 described above is performed according to the following procedure.
First, after the kneading wheel 9 arrives at the converter facility 1, the molten iron is poured from the kneading wheel 9 into the ladle 3 placed on the dispensing station 10 </ b> A or 10 </ b> B. The ladle 3 in which the hot metal is accommodated is transferred by the payout carriage 18 and then lifted by the crane 4A or 4B and is carried into the desulfurization station 16A or 16B.
In the desulfurization station 16A or 16B, the desulfurization process is performed on the hot metal in the ladle 3. After the desulfurization treatment, the ladle 3 is moved to the removal station 13A or 13B by the carriage, and the slag floating on the upper surface of the molten iron is scraped out by the throat oyster 12A or 12B.

The ladle 3 in which the slag scraping has been completed is transferred to the dephosphorization furnace 20 by the crane 4A or 4B, and the ladle 3 is tilted and the ladle 3 is tilted so that the hot metal is put into the dephosphorization furnace 20. Insert.
In the dephosphorization furnace 20 in which the hot metal is charged, a lance is inserted from the furnace port 26 of the dephosphorization furnace 20 and brought close to the upper surface of the hot metal, and oxygen gas is blown at the same time. (Dephosphorization) is started. At the same time, a fouling material such as lime CaO and a cooling material such as iron oxide Fe _x O _y, that is, an auxiliary material, are charged. The phosphorus in the hot metal reacts with the introduced oxygen and shifts to the slag phase, and is laminated in a state of floating above the hot metal.

The hot metal after dephosphorization is discharged from the dephosphorization furnace 20 and then charged into the adjacent decarburization furnace 21. In the decarburization furnace 21, a lance is inserted from the furnace port 26 and oxygen gas is blown close to the hot metal upper surface, and at the same time, decarburization is performed while the hot metal is stirred from the furnace bottom.
The molten steel that has been decarburized is discharged from the decarburization furnace 21 and charged into the ladle 3 on the carriage 23B provided on the discharge side. Thereafter, the carriage 23 moves on the track 24B so as to be separated from the decarburization furnace 21 (the lower side in FIG. 1), and the ladle 3 is transferred to a secondary refining facility or a continuous casting facility which is a subsequent process.

In such converter operation, the following unsteady situation may occur.
For example, the component value of the molten steel after blowing is slightly different from the specified value, and it is a situation where casting cannot be performed by a continuous casting apparatus which is a subsequent process. In addition, troubles occur in the continuous casting apparatus, and a predetermined amount of casting cannot be performed.
In such an unsteady situation, the converter facility 1 performs the following operations.
As shown in FIGS. 3 and 4, the molten steel that has been decarburized in the decarburization furnace 21 is a ladle 3 (a discharge ladle that is mounted on a carriage 23 </ b> B located on the discharge side of the decarburization furnace 21. 3B). Since the molten steel accommodated in the payout ladle 3B cannot be sent to the continuous casting apparatus, which is a subsequent process, it is mounted on the carriage 23A located on the payout side of the dephosphorization furnace 20 using the crane 19 on the payout side. It is transferred to the ladle 3 with a spout (charging ladle 3A).

  After the transfer is completed, the carriage 23A moves on the track 24A to the charging side, so that the charging ladle 3A moves under the dephosphorizing furnace 20 to the charging side of the dephosphorizing furnace 20. . Thereafter, the charging ladle 3A is lifted by the crane 4A or 4B and moved to the front of the decarburization furnace 21, and the molten steel in the charging ladle 3A is charged again into the decarburization furnace 21. That is, the molten steel that was originally scheduled for the subsequent process is returned to the decarburization furnace 21. Blowing conditions such as the amount of oxygen blown in the decarburization furnace 21 are calculated based on the amount of scrap charged, the hot metal transferred from the dephosphorization furnace 20, and the amount of molten steel returned.

FIG. 5 shows a Gantt chart of the operation method according to the present embodiment. The Gantt chart shows the operation status of the payout, molten steel transfer (relay dollar), dephosphorization furnace 20, and decarburization furnace 21 every minute. In addition, the operation status of the cranes 4A, 4B and the scrap crane 14 every minute is shown. The process performed in each work place is indicated by a bar corresponding to the time spent in the process.
In this Gantt chart, when the dephosphorization furnace 20 and the decarburization furnace 21 are being blown, trouble occurs in the continuous casting apparatus which is a subsequent process, and the produced molten steel is brought to the continuous casting apparatus. It is in a state where it cannot go.

Therefore, as described above, the molten steel dispensed at the portion of “denoted A” in “decarburizing blown I” in FIG. 5 is charged into the dispensing ladle 3B and further placed on the carriage 23A. It is transferred to the charging ladle 3A (symbol B). The charging ladle 3A containing molten steel passes under the dephosphorization furnace 20 by the carriage 23A and is transferred to the charging side, and is lifted by the crane 4A and transferred to the decarburization furnace 21. Thereafter, the molten steel in the charging ladle 3A is charged again into the decarburization furnace 21 and blown (reference E).
There are other types of molten steel that cannot be sent to the continuous casting machine. In order to prevent a temperature drop, they are dispensed to a heat retaining pot (a ladle having a heat retaining function). In “Decarburization Blowing III”, the molten steel received in the heat retaining pot is charged.

The molten steel dispensed in the steel removal process of “Decarburization Blowing II” and “Decarburization Blowing III”, if trouble in the post-process continues, is discharged into the heat retaining pot and then the decarburization furnace 21. If the trouble is solved, it will be sent to the continuous casting apparatus (code C, code D).
FIG. 8 shows the production inhibition time of the decarburization furnace 21 generated in the present embodiment. As can be seen from this figure, when returning molten steel through the bottom of the dephosphorization furnace 20,
(i) Since the molten steel in the discharge ladle 3B is transferred to the charging ladle 3A on the carriage 23A during the operation of the decarburization furnace 21, the production inhibition time is 0 minutes.
(ii) 2 minutes for the carriage 23A to pass under the dephosphorization furnace 20
(iii) 3 minutes to lift the charging ladle 3A containing the molten steel to be returned on the charging side of the decarburization furnace 21
(iv) It takes 2 minutes to charge the molten steel into the decarburization furnace 21.

Note that the operations (i) to (iv) described above are also performed in normal operations, and are not different from those in the case where the molten steel is not returned. Therefore, there is no hindrance to steelmaking production by returning the molten steel.
As is clear from the above, even if a situation where the molten steel produced in the converter facility 1 cannot be sent to the subsequent process occurs, the molten steel is directed to the ingot-making process, and the steel ingot (scrap) for raw material is used. This makes it possible to recycle molten steel without having to do so. Moreover, since the bottom of the decarburization furnace 21 is not passed when the molten steel is returned, the operating rate of the decarburization furnace 21 is not lowered.
[Second Embodiment]
A second embodiment of the present invention will be described below.

The second embodiment differs greatly from the first embodiment in that when the charging ladle 3A containing the molten steel being returned passes under the furnace of the dephosphorizing furnace 20, it is dephosphorized in the charging ladle 3A. The hot metal from the furnace 20 (hot metal after dephosphorization treatment) is injected.
The configuration of the converter facility 1 of this embodiment is substantially the same as that of the first embodiment, as shown in FIG.
As shown in FIGS. 3 and 4, half of the molten steel (125 tons) that has been blown in the decarburization furnace 21 is charged into the discharge ladle 3B on the carriage 23B provided on the discharge side of the decarburization furnace 21. Is done. Since the molten steel accommodated in the payout ladle 3B cannot be sent to a continuous casting apparatus, which is a subsequent process, it is mounted on a cart 23A provided on the payout side of the dephosphorization furnace 20 using the crane 19 on the payout side. It is transferred to the charged ladle 3A.

Next, the carriage 23A moves to the bottom of the dephosphorization furnace 20 and temporarily stops. In this position, dephosphorization furnace 20 becomes molten iron payout posture i.e. inclined position, the hot metal 125ton that ended the dephosphorization process of dephosphorization furnace 20 is tapped from the tapping port, mixed into the molten steel in the charging ladle 3A Is done.
Note that the temperature of the molten steel transferred to the bottom of the dephosphorization furnace 20 has dropped significantly since the time when it was discharged from the decarburization furnace 21, so that the normal blowing rate is maintained as it is. It may interfere with smelting. However, by injecting hot metal having a high temperature from the dephosphorization furnace 20 into the charging ladle 3A, the mixture of molten steel and hot metal in the charging ladle 3A becomes a temperature at which blowing can be performed.

After hot metal injection, the charging ladle 3A is moved to the charging side and is lifted by the crane 4A or 4B. The suspended charging ladle 3A is transferred to the front of the decarburization furnace 21 by the crane 4A or 4B, and a mixture (250 ton) of molten steel and hot metal contained therein is charged into the decarburization furnace 21. Is done.
FIG. 6 shows a Gantt chart of the operation method according to the present embodiment. The Gantt chart shows the operation status of the payout, molten steel transfer (relay dollar), dephosphorization furnace 20, and decarburization furnace 21 every minute. In addition, the operation status of the cranes 4A, 4B and the scrap crane 14 every minute is shown. The process performed in each work place is indicated by a bar corresponding to the time spent in the process.

It is assumed that a trouble or the like has occurred in the continuous casting apparatus as a subsequent process during the operation of the dephosphorization furnace 20 and the decarburization furnace 21 shown in the Gantt chart.
Therefore, the molten steel 125ton discharged in the steel removal process indicated by “reference H” of “decarburization blown I” is charged into the discharge ladle 3B and further transferred to the charging ladle 3A (reference numeral I). The charging ladle 3A is moved to the bottom of the dephosphorization furnace 20 by the carriage 23A and stopped. Thereafter, 125 ton of hot metal is charged from the dephosphorization furnace 20 (symbol M).
After the hot metal charging is completed, the charging ladle 3A is transferred to the charging side of the dephosphorization furnace 20. Further, the charging ladle 3A is lifted and inclined by the crane 4A or 4B, and a mixture 250ton of molten steel and hot metal in the charging ladle 3A is charged into the decarburization furnace 21 (reference N). Thereafter, decarburization blowing is performed.

The molten steel delivered in the decarburization blown II or decarburization blown III steelmaking process is returned to the decarburization furnace 21 after being delivered to the heat insulating pot if troubles in the post-process appear to continue. If the trouble is solved, it will be sent to the continuous casting machine.
FIG. 8 shows the production inhibition time of the decarburization furnace 21 in the present embodiment. As can be seen from this figure, when returning molten steel through the bottom of the dephosphorization furnace 20,
(I) The molten steel in the payout ladle 3B is transferred to the charging ladle 3A on the carriage 23A.
Because it is performed during the operation of the decarburization furnace 21, the production inhibition time is 0 minutes (ii) 5 minutes for charging hot metal from the dephosphorization furnace 20 to the charging ladle 3A (iii) charging 1 minute to move the pan 3A to the charging side of the dephosphorization furnace 20 (iv) 3 minutes to lift the charging ladle 3A on the charging side of the decarburization furnace 21 (v) A mixture of molten steel and hot metal It takes 2 minutes to charge the decarburization furnace 21.

The operations (i) to (v) may be performed even in a normal operation from the past, and are not different from the case where the molten steel is not returned. Therefore, the hindrance of the molten steel production by the molten steel return of this embodiment has not generate | occur | produced.
9 and 10 show the state of heat loss of the molten steel in the present embodiment.
When the operating method described in the first embodiment, that is, when the molten steel from the dephosphorization furnace 20 is not added to the molten steel to be returned, the temperature of the molten steel is 1660 ° C., and the molten steel temperature before returning is 1600 ° C. Yes. When this molten steel is transferred to the charging side of the decarburization furnace 21, the molten steel temperature is lowered by 46 ° C., and further, a steelmaking material is introduced into the molten steel, so there is a temperature drop of 24 ° C. Therefore, a temperature drop of 130 ° C. (molten steel temperature compensation amount) occurs as a whole. In order to compensate for this temperature decrease, 26 kg / ton of soil graphite, which is a heating material, or 10 kg / ton of iron alloy (FeSi) is charged. As a result, the temperature of the molten steel is 1554 ° C. when the decarburization furnace 21 is charged.

However, when the hot metal from the dephosphorization furnace 20 is added as in the present embodiment, the temperature rises by 50 ° C. due to the heat compensation by the hot metal added. Therefore, the temperature drop of the entire mixture of molten steel and hot metal is suppressed at 76 ° C., and the soil graphite necessary to compensate for this temperature drop is 15 kg / ton, and the alloy iron (FeSi) is 6 kg / ton. The amount is small compared to the form. The temperature at the time of charging the converter is 1558 ° C.
[ Reference example ]
Reference examples of the present invention will be described below.

As shown in FIG. 7, the converter facility 1 </ b> B of the present embodiment does not include the dephosphorization furnace 20 but includes two decarburization furnaces 21. The dephosphorization process is performed in a kneading vehicle 9 that transports hot metal to the converter facility 1B. The track 24A for returning the molten steel discharged from the decarburization furnace 21 is laid on the side of the decarburization furnace 21 (the left side of the left decarburization furnace 21 in FIG. 7).
The other configuration is substantially the same as that of the first embodiment, and the configuration in which the track 24A extends from the discharge side of the decarburization furnace 21 to the charging side is substantially the same.
In the present embodiment, the following operation is performed.

The molten steel that has been blown in the decarburization furnace 21 is charged into the discharge ladle 3B on the carriage 23B located on the discharge side of the decarburization furnace 21. Payout ladle 3B is transferred to charging ladle 3A on the dolly 23A located on the side out have paid using the payout side of the crane 19.
Next, the carriage 23A passes through the side of the decarburization furnace 21 and moves below the section number 4 of the traveling rail 5, and at this position, the charging ladle 3A is lifted by the crane 4A or 4B, and the decarburization furnace. Then, the molten steel in the charging ladle 3A is charged again into the decarburization furnace 21.

FIG. 8 shows the production inhibition time of the decarburization furnace 21 in this operation method. As can be seen, the production inhibition time when the molten steel is returned through the side of the decarburization furnace 21 is
(i) Since the molten steel in the discharge ladle 3B is transferred to the charging ladle 3A on the carriage 23A during the operation of the decarburization furnace 21, the production inhibition time is 0 minutes.
(ii) 3 minutes to lift the charging ladle 3A containing the returned molten steel on the charging side of the decarburization furnace 21
(iii) It takes 2 minutes to charge the molten steel into the decarburization furnace 21.

Since the production inhibition time of 2 minutes in (iii) also occurs during normal operation of the converter facility, 3 minutes of (ii) is the production inhibition time of the operation method according to this embodiment. However, the advantages of this embodiment are clearly greater than operations that do not recycle molten steel, and the time of 3 minutes is considered to be within an acceptable range.
In addition, you may make it charge the hot metal after the dephosphorization process in the kneading wheel 9 to the charging ladle 3A containing molten steel, for example. Further, when the dephosphorization furnace 20 is constructed on the above-described track 24A (two-dot chain line in FIG. 7), the present embodiment is an operation mode substantially the same as the first embodiment.

The present invention is not limited to the above embodiment.
That is, in FIG. 1, the left converter 2A is used as the dephosphorization furnace 20, the central converter 2B is used as the decarburization furnace 21, and the right converter 2C is used as the preliminary furnace 22, but the operation mode is changed. Accordingly, any converter may be used as the dephosphorization furnace 20. Therefore, it is very preferable to extend the tracks 24A, 24B, 24C under all the converters 2A, 2B, 2C from the paying side to the charging side.

It is a top view of a converter equipment (1st and 2nd embodiment). It is a front view of converter equipment (1st and 2nd embodiment). It is an enlarged plan view of converter equipment (first and second embodiments). It is the figure which showed a mode that molten steel was returned. It is a Gantt chart of a 1st embodiment. It is a Gantt chart of a 2nd embodiment. It is an enlarged plan view of converter equipment ( reference example ). It is the figure which showed the production inhibition time at the time of returning molten steel. It is the figure which showed the temperature change of the molten steel at the time of molten steel return. It is the figure which showed the temperature change of the molten steel at the time of molten steel return It is a top view of the converter equipment concerning a prior art example. It is a Gantt chart which shows an example of the operation of a prior art example (it respond | corresponds to the prior art example of FIG. 8).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Converter equipment 3 Ladle 3A Charging ladle 3B Discharge ladle 4A, 4B Crane 20 Dephosphorization furnace 21 Decarburization furnace 23A, 23B, 23C Carriage 24A, 24B, 24C Track

Claims (2)

A dephosphorization furnace, a decarburization furnace, a ladle containing a part or all of molten steel produced from the decarburization furnace, a ladle capable of being suspended, and the dephosphorization furnace and the decarburization furnace A crane provided on the pay-out side, a crane capable of suspending the ladle and provided on the charging side of the dephosphorization furnace and decarburization furnace, a carriage on which the ladle can be placed, and a carriage A converter facility having a track that can be transferred from the discharge side to the charging side of the dephosphorization furnace, the track being laid so as to pass under the furnace of the dephosphorization furnace,
The ladle of the ladle containing a part or all of the molten steel discharged from the decarburization furnace is transferred to the ladle on the payout side of the dephosphorization furnace using a crane on the payout side,
The ladle where the molten steel has been transferred is moved under the dephosphorization furnace to the charging side of the dephosphorization furnace using a truck on the track,
The decarburization furnace continues to operate,
The ladle moved to the charging side of the dephosphorization furnace is lifted by a crane on the charging side, transferred to the front of the decarburization furnace, and the molten steel in the ladle is charged again into the decarburization furnace and blown. A method for operating converters that does not lose time compared to normal operations . When the ladle passes under the furnace of the dephosphorization furnace, the hot metal in the dephosphorization furnace is added to the molten steel in the ladle, and the mixture of the molten steel and molten iron is charged into the decarburization furnace. The operation method of the converter equipment of Claim 1 to do.

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