JP4991370B2 - Treatment method for molten steel - Google Patents

Description

  The present invention relates to a method for treating molten steel.

In the secondary refining process for producing high-grade steel and the like, it is performed in a ladle (outside the furnace) refining process that uses a ladle that transports the molten steel discharged from the converter. In such a ladle refining process, alloy elements such as nickel, chromium, molybdenum and vanadium are dissolved in molten steel for the purpose of desulfurization, deoxygenation and the like to obtain alloy steel. The ladle refining is performed by the ASEA-SKF method, the LF (Ladle Furnace) method, the RH method, or a combination thereof. The ladle refined molten steel is usually transferred to the next continuous casting and cast.
In recent years, the production amount of steel has increased, and in order to increase the production capacity, it is desirable to increase the casting speed of the continuous casting machine to the upper limit of the capacity. If the casting speed of the continuous casting machine is increased, the amount of molten steel to be processed must be increased also in the secondary refining process, which is the previous process of the continuous casting process. In other words, it is necessary to shorten the ladle refining cycle time and increase the supply frequency of supplying molten steel to the continuous casting machine.

By the way, in ladle refining by the ASEA-SKF method and the LF method, in order to dissolve the added alloy element in the molten steel or to discharge the molten steel to the next process (continuous casting process) at a predetermined temperature, Is heated. In ordinary ladle refining, the ladle charged with molten steel in the converter process is placed in a specific place where the arc heating equipment, alloy addition equipment, etc. are installed after being placed on a truck traveling on the track. While being transported and placed on the carriage, the ladle is installed and processed at a predetermined place from the carriage by a crane or the like (Patent Document 1).
In such ladle refining, conventionally, the cycle time of the molten steel accommodated in the ladle is reduced by efficiently handling the ladle sent from the converter process at regular intervals. It has been tried.

For example, in Patent Document 2, in order to efficiently handle the ladle, the ladle loading place, the ladle heating device and the degassing device are arranged on an annular closed loop, and the ladle containing the ladle is placed on the closed loop. An invention is disclosed in which heating, degassing processing, and the like are performed while moving in order to simultaneously improve productivity and reduce equipment costs by shortening the total processing time (cycle time).
Patent Document 3 discloses an invention for efficiently treating hot metal using a plurality of carts, although it is not a refining treatment for treating molten steel.
That is, in Patent Document 3, the transfer position of the hot metal ladle cart is laid so as to intersect with the hot metal treatment position, and at least the work position at which the hot metal ladle is reloaded at two positions on the transfer path sandwiching the hot metal treatment position, respectively. The laying is disclosed.
JP 2001-87852 A Japanese Patent Publication No. 2-9084 Japanese Patent Laid-Open No. 4-17610

In the technique shown in Patent Document 2, since a plurality of molten steel containing ladles are configured to move continuously on a closed loop, some molten steel containing ladles that have been processed are replaced with other molten steel containing ladles. As long as the processing for is not completed, there is a problem that it cannot be moved to the next processing location. That is, there is a problem that all the molten steel containing ladle cannot be transported to the next processing place until the processing with the longest processing time is completed in each processing.
In the technique shown in Patent Document 3, the hot metal ladle can be reloaded at two positions on the transfer path across the hot metal treatment position, and the hot metal hot pot can be transported to the hot metal treatment position using a carriage, so that efficiency can be expected. . However, the hot metal treatment and ladle refining have different treatment forms and the treatment procedures are completely different. That is, in reality, it is impossible to apply the technique of Patent Document 3 to ladle refining in which an alloy is added or molten steel is heated.

  This invention is made in view of the above-mentioned problem, and it aims at providing the processing method of the molten steel which can shorten the cycle time of the ladle refining which performs the component adjustment of the molten steel by heating and alloy addition. .

The technical means of the present invention includes a first position for adding an alloy to the molten steel accommodated in the ladle, and heating and alloy addition to the molten steel accommodated in the ladle adjacent to the first position. It is possible to move independently between the second position to be performed and the third position to add the alloy to the molten steel accommodated in the ladle on the side opposite to the first position and adjacent to the second position. While the ladle is moved to each position by the first transport cart and the second transport cart, the molten steel is heated and the alloy is added to the molten steel in the following procedure.
(1) The first transport cart is positioned at the first position, and the second transport cart is positioned at the third position.
(2) The first ladle in which the molten steel is accommodated is installed on the first transport carriage at the first position.
(3) After installing the first ladle, the first transport cart is moved to the second position.
(4) Heating and adding an alloy to the molten steel in the first ladle at the second position to perform coarse adjustment of the molten steel components.
(5) After completion of heating and alloy addition to the first ladle at the second position, the first transport carriage is moved to the first position.
(6) The alloy is added to the molten steel in the first ladle at the first position to finely adjust the molten steel components.
(7) During the processes (3) to (6), the second ladle is installed on the second transport carriage at the third position.
(8) After the first transport carriage has moved to the first position, the second transport carriage at the third position is moved to the second position.
(9) The molten steel in the second ladle at the second position is heated and alloyed to roughly adjust the molten steel components.
(10) After the addition of the alloy to the molten steel in the first ladle at the first position, if the temperature of the molten steel in the first ladle is within the target range, the first ladle is carried out.
(11) After the heating and alloy addition to the second ladle at the second position, the second transport carriage is moved to the third position.
(12) Fine adjustment of the molten steel components is performed by adding an alloy to the molten steel in the second ladle at the third position.
(13) A third ladle in which molten steel is accommodated is installed in the first transport carriage at the first position.
(14) After installing the third ladle, the first transport carriage is moved to the second position.
(15) The molten steel in the third ladle at the second position is heated and alloyed to roughly adjust the molten steel components.
(16) After the addition of the alloy to the molten steel in the second ladle at the third position, if the temperature of the molten steel in the second ladle is within the target range, the second ladle is carried out.
(17) After the heating and alloy addition to the third ladle at the second position, the first transport carriage is moved to the first position.
(18) Fine adjustment of the molten steel component is performed by adding an alloy to the molten steel in the third ladle at the first position.
(19) During the processing of the third ladle, the fourth ladle is placed on the second transport cart at the third position.
(20) Thereafter, the third ladle is used as the first ladle and the fourth ladle is used as the second ladle, and the process is repeated according to the procedures (8) to (19).

The inventor verified the method of shortening the cycle time in the treatment of molten steel, that is, ladle refining, from various angles. Specifically, the inventor first sets the position (place) where the molten steel is processed at the first position where the alloy is added, the second position where the heating and the alloy are added, and the opposite side of the first position. By dividing into the third position where the alloy is added, the processing of molten steel can be divided and the processing speed is increased.
In addition, the carriage that transports the ladle was moved independently so that the ladle containing molten steel was quickly transported to each position, and the procedure for shortening the cycle time was verified. As a result, according to the procedure described above, the cycle time can be significantly shortened as compared with the prior art.

When the temperature of the molten steel in the first ladle is outside the target range in the procedure (10), it is preferable to perform at least the following procedure.
(10-1) The first transport carriage is moved to the second position, and the molten steel in the first ladle at the second position is heated.
(10-2) When the molten steel in the first ladle is heated to the target range, the first transport carriage is moved to the first position.
(10-3) Unload the first ladle on the first transport carriage at the first position.

When the temperature of the molten steel in the second ladle is outside the target range in step (16), it is preferable to perform at least the following procedure.
(16-1) The second transport carriage is moved to the second position, and the molten steel in the second ladle at the second position is heated.
(16-2) When the molten steel in the second ladle is heated to the target range, the second transport carriage is moved to the third position.
(16-3) Unload the second ladle on the second transport carriage at the third position.

  In addition, the description of "1st ladle"-"4th ladle" in the above is an expression for the convenience of prescribing the ladle to which attention is paid, and the processing according to the above procedure is taken from the converter process. It is performed continuously on the pan and is not limited to processing on a specific ladle.

  ADVANTAGE OF THE INVENTION According to this invention, the processing method of the molten steel which can shorten the ladle refining cycle time can be provided in the component adjustment of the molten steel by heating and addition of alloy materials.

The processing method of the molten steel of this invention is demonstrated.
The method for treating molten steel of the present invention is suitable for treating molten steel in a secondary refining facility (ladder refining device), for example, from the steel converted from a converter.
As shown in FIG. 1, the secondary refining equipment 1 includes a track 2, two carriages 3 a and 3 b movable on the track 2, and a ladle 4 placed on the carriages 3 a and 3 b, It has an alloy addition device 5 for adding an alloy, a heating device 6 for heating the molten steel in the ladle 4, and a stirring device 7. Hereinafter, for convenience of explanation, the carriage 3a is referred to as a first conveyance carriage, and the carriage 3b is referred to as a second conveyance carriage.

In the secondary refining equipment 1, three positions at which the first transport cart 3a and the second transport cart 3b moving on the track 2 stop are determined in advance. Specifically, each stop position is determined so that the first transport cart 3a and the second transport cart 3b stop on each track 2 obtained by dividing the laid track 2 into three. Hereinafter, for convenience of explanation, each stop position may be referred to as a first position, a second position, and a third position in order from the left side of FIG.
The first position and the second position are adjacent to each other, and the third position is on the opposite side of the first position across the second position and is adjacent to the second position. The alloy addition device 5 and the stirring device 7 are disposed in each of the first position, the second position, and the third position, and the heating device 6 is disposed in the center second position. In a 1st position, while adding an alloy to the molten steel accommodated in the ladle 4 with the alloy addition apparatus 5, the ladle 4 is carried in and out. In the second position, the molten steel accommodated in the ladle 4 is heated and an alloy is added. At the third position, the alloy addition device 5 adds an alloy to the molten steel accommodated in the ladle 4 and carries the ladle 4 in and out.

  The 1st conveyance cart 3a and the 2nd conveyance cart 3b are for conveying the ladle 4 to each 1st position, 2nd position, and 3rd position stably, and the 1st conveyance cart 3a is 1st position. The second transport carriage 3b can move between the second position and the third position. The 1st conveyance trolley 3a and the 2nd conveyance trolley 3b can each move independently. The heating device 6 is of an electrode heating type in which the electrode 6a is brought close to the bath surface of the molten steel and is discharged, and is disposed above the second position so as to be movable up and down. The stirring device 7 is an electromagnetic device that forms an alternating magnetic field to flow the molten steel in the ladle 4 and performs stirring by Lorentz force, and is disposed on the side of each of the first position, the second position, and the third position. Has been. The agitator 7 is movable in a direction perpendicular to the track 2, and the first transport cart 3a and the second transport cart 3b stop at each of the first position, the second position, and the third position and are mounted on the cart. When the alloy is added to the molten steel in the ladle 4, it moves from the side of each of the first position, the second position, and the third position toward the ladle 4 (the first conveyance carriage 3 a and the second conveyance carriage 3 b). Then, the molten steel is stirred in the vicinity of the molten steel 4 in the ladle 4. Further, the agitator 7 is moved (retracted) in a direction away from the track 2 when the first transport cart 3a and the second transport cart 3b travel on the track.

The alloy addition device 5 is used to add various alloys for adjusting the molten steel components into the ladle 4 installed in the first transport cart 3a and the second transport cart 3b, from a device such as a hopper or a shooter. It is configured.
As shown in FIG. 2, each alloy adding device 5 is connected to an alloy conveying device 8, and the ladle 4 is moved from above the first position, the second position, and the third position of the alloy conveyed from the alloy conveying device 8. It is supposed to be thrown towards The alloy conveying device 8 includes a plurality of storage hoppers 10 in which alloys are stored for each type, a weighing hopper 11 that weighs various alloys supplied from the respective storage hoppers 10, and a plurality of materials that are used to convey the various alloys weighed. A conveyor 12 and a three-way distribution chute 13 for distributing the various alloys being conveyed to the respective alloy addition devices 5 are provided.

According to the alloy conveying device 8, when the alloy is added to the molten steel for processing, the alloy supplied from the storage hopper 10 to the weighing hopper 11 is appropriately selected according to the molten steel to be processed, and the alloy necessary for processing. Is weighed by a weighing hopper 11, and the alloy is conveyed by a conveyor 12. And an alloy is divided by the three-way distribution chute 13 so that it may be added to the molten steel to process, and is conveyed by each conveyor 12 which conveys an alloy toward each position.
A crane 14 is disposed above the secondary refining equipment 1. With this crane 14, the ladle 4 can be installed on the first transport carriage 3a stopped at the first position, or the ladle 4 of the first transport carriage 3a stopped at the first position can be carried out. Further, the ladle 4 can be installed on the second transport carriage 3b stopped at the third position, or the ladle 4 of the second transport carriage 3b stopped at the third position can be carried out by the crane 14.

Hereinafter, a method for treating molten steel (a ladle refining method) will be described with reference to FIG.
FIG. 3 shows a ladle refining procedure. The processing procedure proceeds from the top to the bottom on the left side of the paper, and then proceeds from the top to the bottom on the right side of the paper. In the description of FIG. 3, the ladle placed on the first transport carriage 3a is referred to as a first ladle 4a or a third ladle 4c. Let the ladle 4 mounted in the 2nd conveyance trolley 3b be the 2nd ladle 4b or the 4th ladle 4d. In the description of FIG. 3, the numerical values in parentheses indicate procedure numbers.
When ladle refining is performed in the secondary refining facility 1, first, as shown in FIG. 3A, the first transport cart 3a is positioned at the first position, and the second transport cart 3b is positioned at the third position. (1), the first ladle 4a in which the molten steel is accommodated is installed in the first transport carriage 3a in the first position (2).

As shown in FIG.3 (b), after installing the 1st ladle 4a, the 1st conveyance trolley 3a is moved to a 2nd position (3), and with respect to the molten steel of the 1st ladle 4a in a 2nd position Coarse adjustment of the molten steel components is performed by heating and alloy addition (4).
As shown in FIG.3 (c), after the heating with respect to the 1st ladle 4a and completion | finish of alloy addition in a 2nd position, the 1st conveyance trolley 3a is moved to a 1st position (5).
As shown in FIG. 3D, the molten steel components are finely adjusted by adding an alloy to the molten steel of the first ladle 4a at the first position (6). In addition, the 2nd ladle 4b is installed in the 2nd conveyance trolley 3b in a 3rd position during the process of FIG.3 (b)-(d) (7).

As shown in FIG. 3 (e), after the second ladle 4b is installed on the second transport cart 3b and the first transport cart 3a is moved to the first position, the second transport cart 3b in the third position. Is moved to the second position (8).
As shown in FIG. 3 (f), the molten steel components are roughly adjusted by heating and alloy addition to the molten steel of the second ladle 4b in the second position (9).
As shown in FIG. 3 (g), after the addition of the alloy to the molten steel in the first ladle 4a is completed at the first position, if the temperature of the molten steel in the first ladle 4a is within a target range, the first ladle 4a is moved. Unload (10).

As shown in FIG. 3 (h), after heating and addition of the alloy to the second ladle 4b at the second position, the second transport carriage 3b is moved to the third position (11), and the second position at the third position is reached. Fine adjustment of the molten steel component is performed by adding an alloy to the molten steel in the two ladle 4b (12).
As shown in FIG. 3 (i), another third ladle 4c different from the first ladle 4a in which the molten steel is accommodated is installed in the first transport carriage 3a in the first position (13).
As shown in FIG. 3 (j), after the third ladle 4c is installed, the first transport carriage 3a is moved to the second position (14).

As shown in FIG. 3 (k), the molten steel components are roughly adjusted by heating and adding alloy to the molten steel of the third ladle 4c in the second position (15), and at the third position. After the addition of the alloy to the molten steel in the second ladle 4b, if the temperature of the molten steel in the second ladle 4b is within the target range, the second ladle 4b is unloaded (16).
As shown in FIG. 3 (l), after heating and addition of the alloy to the third ladle 4c at the second position, the first transport carriage 3a is moved to the first position (17).
As shown in FIG. 3 (m), fine adjustment of the molten steel component is performed by adding an alloy to the molten steel of the third ladle 4c in the first position (18). In addition, during the process of the 3rd ladle 4c, the 4th ladle 4d is installed in the 2nd conveyance trolley 3b in a 3rd position (19).

As shown in FIG. 3, thereafter, the third ladle 4c is used as the first ladle 4a, and the fourth ladle 4d is used as the second ladle 4b, and the process is repeated according to the procedures (8) to (19). (20).
In said procedure (10), when the temperature of the molten steel of the 1st ladle 4a is not a target range, it progresses to a procedure (11) through the following process.
As shown to Fig.4 (a), when there is no 2nd conveyance trolley 3b in a 2nd position, the 1st conveyance trolley 3a is moved to a 2nd position, and with respect to the molten steel of the 1st ladle 4a in a 2nd position (10-1).

As shown in FIG.4 (b), if the temperature of the molten steel of the 1st ladle 4a is heated up to a target range, the 1st conveyance trolley 3a will be moved to a 1st position (10-2).
As shown in FIG.4 (c), the 1st ladle 4a on the 1st conveyance trolley 3a in a 1st position is carried out (10-3).
As shown in FIG. 4 (d), in the procedure (10-1), when the second transport carriage 3b is in the second position when the first transport carriage 3a is moved to the second position, The coarse adjustment at the position is interrupted, and the second transport carriage 3b is moved (retracted) to the third position (10-4).

As shown in FIG.4 (e), after the 2nd conveyance trolley 3b moves to a 3rd position, the 1st conveyance trolley 3a is moved to a 2nd position, and it heats with respect to the molten steel of the 1st ladle 4a ( 10-5).
As shown in FIG.4 (f), if the temperature of the molten steel of the 1st ladle 4a is heated up to the target range, the 1st conveyance trolley 3a will be moved to a 1st position (10-6).
As shown in FIG. 4 (g), after moving the first transport carriage 3a after the heat treatment at the second position to the first position, the second transport carriage 3b is returned to the second position, and the molten steel component The coarse adjustment is resumed (10-7). In addition, the 1st ladle 4a which returned to the 1st position after completion | finish of a heating is carried out by the crane 14. FIG.

In said procedure (16), when the temperature of the molten steel of the 2nd ladle 4b is not a target range, it progresses to a procedure (17) through the following process.
As shown in FIG. 4 (h), when the first transfer carriage 3a is not in the second position, the second transfer carriage 3b is moved to the second position, and the molten steel of the second ladle 4b in the second position is And heating (16-1).
As shown in FIG. 4 (i), when the temperature of the molten steel in the second ladle 4b is raised to the target range, the second transport carriage 3b is moved to the third position (16-2).

As shown in FIG.4 (j), the 2nd ladle 4b on the 2nd conveyance trolley 3b in a 3rd position is carried out (16-3).
As shown in FIG. 4 (k), when the second transport carriage 3b is moved to the second position in the procedure (16-1), if the first transport carriage 3a is at the second position, The coarse adjustment at the position is interrupted, and the first transport carriage 3a is moved (retracted) to the first position (16-4).
As shown in FIG. 4 (l), after the first transport cart 3a has moved to the first position, the second transport cart 3b is moved to the second position, and the molten steel in the second ladle 4b is heated ( 16-5).

As shown in FIG. 4 (m), when the temperature of the molten steel in the second ladle 4b is raised to the target range, the second transport carriage 3b is moved to the third position (16-6).
As shown in FIG. 4 (n), after moving the second transport carriage 3b after the heat treatment at the second position to the third position, the first transport carriage 3a is returned to the second position, and the molten steel component The coarse adjustment is resumed (16-7). In addition, the 2nd ladle 4b which returned to the 3rd position after completion | finish of heating is carried out by the crane 14. FIG. In the description of FIG. 4, numerical values in parentheses indicate procedure numbers.
In the explanation of the above procedure, when the alloy addition is performed at the first position, the second position, and the third position, the stirring device 7 comes close to the ladle 4 and stirs the molten steel in the ladle 4. Yes.

  5-9 shows the Gantt chart of the process of the Example which processed with the processing method of the molten steel of this invention, and the comparative example which was not processed with the processing method of the molten steel of this invention. In the Gantt charts of FIGS. 5 to 9, “molten steel heating” indicates an operation of heating the molten steel in the heating device 6 at the second position. The time for heating the molten steel is 20 minutes. 5 to 9, “component adjustment” means adding an alloy to molten steel (alloy addition) and stirring the molten steel (molten steel stirring) in the alloy addition device 5 at the first position, the second position, and the third position. This shows the work of adjusting the components of the molten steel. The alloy addition time is 20 minutes. Between each 1st position, 2nd position, and 3rd position, the movement time of the 1st conveyance trolley 3a and the 2nd conveyance trolley 3b is 150 sec / time. The time for reheating the molten steel at the second position is 5 minutes.

The installation and unloading time of the ladle 4 by the crane 14 is 10 minutes / time, and the time from unloading the ladle 4 to installing another ladle 4 requires at least 20 minutes. For example, after unloading the ladle 4 at the first position, it takes 20 minutes to install the other ladle 4 on the first transport carriage 3a at the first position. Moreover, when adding an alloy with respect to molten steel by the following description, the molten steel in the ladle 4 is stirred with the stirring apparatus 7. FIG.
As shown in FIG. 5, when the installation of the first ladle 4a on the first transfer carriage 3a is completed at the first position (# 11), the first transfer carriage 3a moves to the second position and stops (# 12). ). After the stop of the first transport carriage 3a, the electrode 6a of the heating device 6 is inserted into the first ladle 4a at the second position, and the molten steel in the first ladle 4a is heated (# 13). The alloy is added by an adding device almost simultaneously with the heating of the molten steel, and the component adjustment of the molten steel (adjustment of the molten steel component) is performed. The component adjustment of the molten steel at the second position is a rough component adjustment (coarse adjustment), and fine adjustment (fine adjustment) of the component is performed at the first position or the third position. In other words, the component adjustment of the molten steel in the secondary refining can be completed by two adjustments of the coarse adjustment and the fine adjustment.

When the heating and component adjustment (coarse adjustment) of the first ladle 4a at the second position are completed, the installation of the second ladle 4b is completed on the second transport carriage 3b at the third position (# 14). ). After heating and rough adjustment of the first ladle 4a at the second position, the first transport cart 3a moves from the second position to the first position (# 15). When the 1st conveyance trolley 3a is moving toward the 1st position, the 2nd conveyance trolley 3b in the 3rd position moves toward the 2nd position (# 16).
After the 1st conveyance trolley 3a stops at a 1st position, an alloy is added in the 1st ladle 4a in a 1st position, and the molten steel component of the 1st ladle 4a is finely adjusted (# 17). When the fine adjustment to the molten steel of the first ladle 4a is performed at the first position, the second transport cart 3b moved to the second position stops at the second position, and the second ladle is at the second position. The electrode 6a of the heating device 6 is inserted into 4b, and the molten steel in the second ladle 4b is heated (# 18). An alloy is added by the alloy addition device 5 substantially simultaneously with the heating of the second ladle 4b to the molten steel, and the molten steel components are adjusted.

When the molten steel in the second ladle 4b is heated and the alloy is added (component adjustment) at the second position, the fine adjustment of the molten steel component with respect to the molten steel in the first ladle 4a is performed at the first position. If completed and the temperature of the molten steel in the first ladle 4a is within the target range, the first ladle 4a is carried out by the crane 14 (# 19).
After heating and rough adjustment of the molten steel in the second ladle 4b, the second transport carriage 3b moves from the second position to the third position (# 20). After the second transport carriage 3b stops at the third position, the alloy is added into the second ladle 4b at the third position, and the molten steel component of the second ladle 4b is finely adjusted (# 21). When the molten steel component of the second ladle 4b is finely adjusted at the third position, the third ladle 4c is placed on the first transport carriage 3a at the first position by the crane 14 (# 22). Thereafter, the first transport carriage 3a moves to the second position and stops (# 23), and heating and alloy addition (component adjustment) are performed on the molten steel of the third ladle 4c at the second position (# 24). ).

When the process is performed on the molten steel in the third ladle 4c, the fine adjustment to the molten steel in the second ladle 4b, which has been performed at the third position, is completed, and the temperature of the molten steel in the second ladle 4b is increased. If it is within the target range, the second ladle 4b is carried out by the crane 14 (# 25). After the second ladle 4b is carried out, the fourth ladle 4d is installed on the second transport carriage 3b at the third position. Hereinafter, in Example 1, if the 3rd ladle 4c is considered similarly to the 1st ladle 4a and the 4th ladle 4d is considered similarly to the 2nd ladle 4b, # 14- # 25 process will be performed repeatedly. .
As shown in FIG. 5, in Example 1, the ladle 4 can be carried out at a pace of once every 67.5 minutes from the first position and the third position, respectively, and is 33 when viewed from the secondary refining equipment 1. It is possible to supply molten steel for which the ladle refining has been completed toward the continuous casting machine once every 75 minutes. That is, the ladle refining cycle time in Example 1 is 33.75 minutes.

FIG. 6 shows Example 2 in which the temperature of the molten steel has not reached the target temperature when the first ladle 4a and the second ladle 4b are carried out. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
After the fine adjustment to the molten steel of the 1st ladle 4a performed at the 1st position is completed, when the temperature of the molten steel of the 1st ladle 4a is not a target range, the 1st conveyance trolley | bogie 3a is toward the 2nd position. Move (# 30). When the first transport carriage 3a stops at the second position, the electrode 6a is inserted into the first ladle 4a, and the molten steel is reheated (# 31). When the first ladle 4a is reheated at the second position and the temperature of the molten steel reaches the target temperature, the first transport carriage 3a moves toward the first position (# 32).

After the fine adjustment to the molten steel of the 1st ladle 4a performed at the 3rd position is completed, when the temperature of the molten steel of the 2nd ladle 4b is not a target range, the 2nd conveyance trolley | bogie 3b is directed toward the 2nd position. Move (# 35). When the second transport carriage 3b stops at the second position, the electrode 6a is inserted into the second ladle 4b, and the molten steel is reheated (# 36). When the second ladle 4b is reheated at the second position and the temperature of the molten steel reaches the target temperature, the second transport carriage 3b moves toward the third position (# 37).
As shown in FIG. 6, in Example 2, the ladle 4 can be carried out at a pace of once every 77.5 minutes from the first position and the third position, respectively, and 38 when viewed from the secondary refining equipment 1. It is possible to supply molten steel for which the ladle refining has been completed toward the continuous casting machine once every 75 minutes. That is, the ladle refining cycle time in Example 2 is 38.75 minutes.

FIG. 7 shows Comparative Example 1 in which the molten steel was processed at two positions. In Comparative Example 1, molten steel heating and alloy addition (component adjustment) were performed at the second position. In the second position, alloy addition was performed to perform both coarse and fine adjustments of the molten steel. The component adjustment time is 40 minutes. The cart is one of the first transport carts 3a.
As shown in FIG. 7, after the installation of the first ladle 4a on the first transfer carriage 3a at the first position is finished (# 40), the first transfer carriage 3a moves to the second position and stops (#). 41). In the second position, heating and alloy addition (component adjustment) are performed on the molten steel of the first ladle 4a (# 42). After completion of alloy addition (after fine adjustment), the first transport carriage 3a moves to the first position, and the first ladle 4a is carried out at the first position (# 43).

As shown in FIG. 7, in Comparative Example 1, the ladle 4 is carried out at a pace of once every 65 minutes from the first position, and when viewed from the secondary refining equipment 1, it is continuously cast at a pace of once every 65 minutes. We will supply the molten steel for which the ladle refining has been completed. That is, the ladle refining cycle time in Comparative Example 1 is 65 minutes.
FIG. 8 shows a comparative example 2 in which the molten steel is processed at three positions with respect to the comparative example 1 shown in FIG. In Comparative Example 2, the same parts as in Comparative Example 1 are denoted by the same reference numerals, and the description thereof is omitted. Two carts, a first transport cart 3a and a second transport cart 3b, were used.

As shown in FIG. 8, when the heating and component adjustment of the first ladle 4a at the second position are completed, the installation of the second ladle 4b on the second transport carriage 3b at the third position is completed. (# 50). After heating the molten steel in the first ladle 4a and adjusting the components at the second position, the first transport carriage 3a moves from the second position to the first position, and after the movement, the first ladle 4a is carried out from the first position. (# 51). When the 1st conveyance trolley 3a is moving toward the 1st position, the 2nd conveyance trolley 3b in a 3rd position moves toward a 2nd position (# 52).
After the second transport carriage 3b stops at the second position, heating and alloy addition (component adjustment) are performed on the molten steel of the first ladle 4a at the second position (# 53). When the heating and component adjustment of the second ladle 4b at the second position are completed, the installation of the third ladle 4c on the first transport carriage 3a at the first position is completed (# 54). After heating the molten steel in the second ladle 4b and adjusting the components at the second position, the second transport carriage 3b moves from the second position to the third position, and after the movement, the second ladle 4b is carried out from the first position. (# 55). After the second ladle 4b is carried out, the fourth ladle 4d is installed on the second transport carriage 3b at the third position. When the second transfer carriage 3b is moving toward the third position, the first transfer carriage 3a located at the first position is moved toward the second position (# 57).

Thereafter, in Comparative Example 2, when the third ladle 4c is considered in the same manner as the first ladle 4a and the fourth ladle 4d is considered in the same manner as the second ladle 4b, the operations described above are repeatedly performed.
As shown in FIG. 8, in Comparative Example 2, the ladle 4 is transported from the first position or the third position at a pace of once every 87.5 minutes and is 43.75 minutes when viewed from the secondary refining equipment 1. At one pace, the molten steel for which the ladle refining has been finished is supplied to the continuous casting machine. That is, the ladle refining cycle time in Comparative Example 2 is 43.75 minutes.
FIG. 9 shows Comparative Example 3 in which molten steel was processed at three positions. In Comparative Example 3, alloy addition was performed to perform both coarse adjustment and fine adjustment of the molten steel at the first position and the third position. The component adjustment time is 40 minutes. Two carts, a first transport cart 3a and a second transport cart 3b, were used.

  As shown in FIG. 9, when the installation of the first ladle 4a on the first transfer carriage 3a is completed at the first position (# 60), the first transfer carriage 3a moves to the second position and stops (# 61). ). After the stop of the first transport carriage 3a, the electrode 6a of the heating device 6 is inserted into the first ladle 4a at the second position, and the molten steel in the first ladle 4a is heated (# 62). After the heating of the molten steel in the first ladle 4a at the second position, the first transport carriage 3a moves from the second position to the first position (# 63). After the 1st conveyance trolley 3a stops at a 1st position, an alloy is added in the 1st ladle 4a in a 1st position, and adjustment of the molten steel component of the 1st ladle 4a is performed (# 64).

  When the component adjustment for the molten steel of the first ladle 4a is performed at the first position, the installation of the second ladle 4b on the second transport carriage 3b at the third position is finished (# 65). The second transport carriage 3b at the third position moves toward the second position (# 66). The electrode 6a of the heating device 6 is inserted into the second ladle 4b in the second position, and the molten steel in the second ladle 4b is heated (# 67). After the molten steel in the second ladle 4b is heated, the second transport carriage 3b moves from the second position to the third position (# 68). After the second transport carriage 3b stops at the third position, the alloy is added into the second ladle 4b at the third position, and the molten steel component of the second ladle 4b is adjusted (# 69).

When the molten steel component of the second ladle 4b is adjusted at the third position, the component adjustment of the first ladle 4a is completed and the first ladle 4a is carried out of the first position by the crane 14. (# 70). While the adjustment of the molten steel component of the second ladle 4b is performed at the third position, the third ladle 4c is installed on the first conveyance carriage 3a at the first position, and the first conveyance carriage 3a is the first conveyance carriage 3a. The position has been moved to the second position (# 71). Further, the molten steel of the third ladle 4c is heated at the second position (# 72).
When the molten steel of the third ladle 4c is heated at the second position, the adjustment of the molten steel component of the second ladle 4b is completed at the third position, and the second ladle 4b is It is carried out from position 3 (# 73). After the second ladle 4b is carried out, the fourth ladle 4d is installed on the second transport carriage 3b at the third position.

Thereafter, in Comparative Example 3, when the third ladle 4c is considered in the same manner as the first ladle 4a and the fourth ladle 4d is considered in the same manner as the second ladle 4b, the above-described operation is repeatedly performed.
As shown in FIG. 9, in the comparative example 3, the ladle 4 is carried out at a pace of once every 103 minutes from the first position or the third position, and 1 in 51.5 minutes when viewed from the secondary refining equipment 1. The molten steel that has been smelted in the ladle will be supplied to the continuous casting machine at a pace. That is, the ladle refining cycle time in Comparative Example 3 is 51.5 minutes.
Table 1 summarizes the cycle times (unloading pitch) of the molten steel in Examples 1 and 2 and Comparative Examples 1 to 3.

表１の実施例１、２に示すように、溶鋼に対する合金添加を第１位置、第２位置、第３位置のぞれぞれの位置で行うと共に、溶鋼の加熱を第２位置で行うことにより、溶鋼の処理のサイクルを低減することができる。しかも、実施例１及び２では、第２位置において合金添加と加熱とを同時（加熱をしながら合金添加を行う）に行うと共に、１つの取鍋４に対する成分調整を２回に分けているので、合金添加と加熱とにかかるトータル時間が非常に短くなり、溶鋼の処理のサイクルタイムを大幅に低減することができる。言い換えれば、第２位置において溶鋼に対する加熱と合金添加との処理を同じ時間帯で開始及び終了すると共に、合金添加を２回に分けてそれぞれ異なる位置で行っているので、取鍋精錬における処理を早くすることができる。

As shown in Examples 1 and 2 in Table 1, alloy addition to the molten steel is performed at each of the first position, the second position, and the third position, and the molten steel is heated at the second position. Thereby, the cycle of the treatment of molten steel can be reduced. Moreover, in Examples 1 and 2, alloy addition and heating are performed simultaneously (adding the alloy while heating) in the second position, and the component adjustment for one ladle 4 is divided into two times. The total time required for alloy addition and heating becomes very short, and the cycle time of the molten steel can be greatly reduced. In other words, at the second position, the process of heating and alloy addition to the molten steel starts and ends at the same time zone, and the alloy addition is performed at two different positions, so the process in ladle refining is performed. Can be fast.

On the other hand, in Comparative Examples 1 to 3 in which the treatment of the molten steel of the present invention was not performed, the cycle time was longer by at least 5 minutes or more than in the Examples, and the productivity was low.
As mentioned above, according to the processing method of the molten steel of this invention, since the cycle time in ladle refining is shortened, it becomes possible to shorten the casting time per charge in continuous casting. Therefore, when the production amount in the casting process is limited by the molten steel processing capacity in the ladle smelting process, an effect of increasing production by increasing the casting speed can be obtained.
In addition, a reduction in power cost and a reduction in carbon dioxide generation can be achieved by shortening the ladle refining treatment time, shortening the casting time, and reducing heat loss by eliminating the waiting time after receiving the molten steel in the ladle.

It is a schematic plan view of the place where ladle refining is performed. It is a figure explaining an alloy addition apparatus and an alloy conveyance apparatus. It is a figure explaining the processing method of molten steel. It is another figure explaining the processing method of molten steel. 2 is a Gantt chart of molten steel processing in Example 1. 6 is a Gantt chart of molten steel processing in Example 2. 5 is a Gantt chart for molten steel processing in Comparative Example 1. 6 is a Gantt chart of molten steel processing in Comparative Example 2. 10 is a Gantt chart of molten steel processing in Comparative Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Secondary refining equipment 3a 1st conveyance trolley 3b 2nd conveyance trolley 4 Ladle 4a 1st ladle 4b 2nd ladle 4c 3rd ladle 4d 4th ladle

Claims (3)

A first position for adding an alloy to the molten steel accommodated in the ladle; a second position for heating and alloy addition to the molten steel accommodated in the ladle adjacent to the first position; A first transport carriage and a second carriage that can move independently from each other between a third position adjacent to the second position on the side opposite to the first position and where the alloy is added to the molten steel accommodated in the ladle. A method for treating molten steel, comprising heating the molten steel and adding an alloy to the molten steel according to the following procedure while moving the ladle to each position by a transport carriage.
(1) The first transport cart is positioned at the first position, and the second transport cart is positioned at the third position.
(2) The first ladle in which the molten steel is accommodated is installed on the first transport carriage at the first position.
(3) After installing the first ladle, the first transport cart is moved to the second position.
(4) Heating and adding an alloy to the molten steel in the first ladle at the second position to perform coarse adjustment of the molten steel components.
(5) After completion of heating and alloy addition to the first ladle at the second position, the first transport carriage is moved to the first position.
(6) The alloy is added to the molten steel in the first ladle at the first position to finely adjust the molten steel components.
(7) During the processes (3) to (6), the second ladle is installed on the second transport carriage at the third position.
(8) After the first transport carriage has moved to the first position, the second transport carriage at the third position is moved to the second position.
(9) The molten steel in the second ladle at the second position is heated and alloyed to roughly adjust the molten steel components.
(10) After the addition of the alloy to the molten steel in the first ladle at the first position, if the temperature of the molten steel in the first ladle is within the target range, the first ladle is carried out.
(11) After the heating and alloy addition to the second ladle at the second position, the second transport carriage is moved to the third position.
(12) Fine adjustment of the molten steel components is performed by adding an alloy to the molten steel in the second ladle at the third position.
(13) A third ladle in which molten steel is accommodated is installed in the first transport carriage at the first position.
(14) After installing the third ladle, the first transport carriage is moved to the second position.
(15) The molten steel in the third ladle at the second position is heated and alloyed to roughly adjust the molten steel components.
(16) After the addition of the alloy to the molten steel in the second ladle at the third position, if the temperature of the molten steel in the second ladle is within the target range, the second ladle is carried out.
(17) After the heating and alloy addition to the third ladle at the second position, the first transport carriage is moved to the first position.
(18) Fine adjustment of the molten steel component is performed by adding an alloy to the molten steel in the third ladle at the first position.
(19) During the processing of the third ladle, the fourth ladle is placed on the second transport cart at the third position.
(20) Thereafter, the third ladle is used as the first ladle and the fourth ladle is used as the second ladle, and the process is repeated according to the procedures (8) to (19). When the temperature of the molten steel of a 1st ladle is outside a target range in a procedure (10), the following procedure is performed at least, The molten steel processing method of Claim 1 characterized by the above-mentioned.
(10-1) The first transport carriage is moved to the second position, and the molten steel in the first ladle at the second position is heated.
(10-2) When the molten steel in the first ladle is heated to the target range, the first transport carriage is moved to the first position.
(10-3) Unload the first ladle on the first transport carriage at the first position. 3. The molten steel processing method according to claim 1, wherein when the temperature of the molten steel in the second ladle is outside the target range in the procedure (16), at least the following procedure is performed.
(16-1) The second transport carriage is moved to the second position, and the molten steel in the second ladle at the second position is heated.
(16-2) When the molten steel in the second ladle is heated to the target range, the second transport carriage is moved to the third position.
(16-3) Unload the second ladle on the second transport carriage at the third position.

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