JP5790608B2 - Hot metal desulfurization apparatus and hot metal desulfurization method - Google Patents

Description

  The present invention relates to a hot metal desulfurization apparatus and a hot metal desulfurization method for performing desulfurization treatment of hot metal.

  In the steelmaking process, the hot metal discharged from the blast furnace is desulfurized in the hot metal pretreatment process. As a typical desulfurization apparatus used for the desulfurization treatment, there is a KR desulfurization apparatus. The KR desulfurization apparatus includes an impeller that stirs the hot metal in the hot metal ladle, and the impeller can be moved in the vertical direction by an elevating mechanism.

  When performing hot metal desulfurization with the KR desulfurizer, the impeller is immersed in the hot metal in the hot metal ladle during the desulfurization process. When the desulfurization process is finished, the impeller is raised by the lifting mechanism and pulled up from the hot metal. Thereafter, the hot metal ladle after the desulfurization treatment is completed is transported to a subsequent process. At this time, since the hot metal ladle has been transported, the space below the impeller becomes an atmospheric atmosphere, so the impeller is deprived of heat by the atmosphere, and the temperature of the impeller rapidly decreases. The state where the impeller waits in such an air atmosphere continues until the hot metal ladle for performing the desulfurization process is conveyed below the impeller.

  In general, the surface of the impeller is covered with a refractory, but the refractory is thermally contracted due to a rapid temperature change of the impeller, and as a result, the refractory is cracked. If the desulfurization treatment is performed in such a state, the impeller may be melted or lost, and the impeller must be replaced. In addition, the shorter the impeller replacement period, the longer the time spent on the replacement work and the lower the throughput. Therefore, in order to prevent thermal contraction of the refractory covered with the impeller, it is necessary to suppress a rapid temperature change of the impeller.

  As a method for suppressing a rapid temperature change of the impeller, for example, there is an impeller cooling method described in Patent Document 1. This allows air to pass through the impeller to suppress the temperature rise of the impeller during the desulfurization process. Thereby, the temperature difference between the impeller and the air atmosphere after the desulfurization treatment can be reduced, and a rapid temperature drop can be suppressed.

JP 2010-116583 A

  However, even with the impeller cooling method described in Patent Document 1, the impeller cannot be sufficiently cooled, and cracking of the refractory on the impeller surface due to a rapid temperature change may still occur. There is.

  An object of the present invention is to provide a hot metal desulfurization apparatus capable of suppressing the occurrence of cracks in the refractory coated on the surface of the impeller by keeping the impeller in a standby state during the desulfurization process in order to solve the above-mentioned problem. It is to provide a hot metal desulfurization method.

  In order to solve the above problems, according to the present invention, an impeller coated with a refractory and a dust collector that collects dust generated during the desulfurization treatment are provided, and a desulfurizing agent is introduced into the hot metal in the hot metal ladle. A hot metal desulfurization apparatus for performing a desulfurization process by stirring with an impeller, wherein the dust collector is provided with a dust collection hood that covers an upper portion of the hot metal pan, and the dust collection hood includes a dust collection hood fixing portion And a plurality of dust collection hood movable parts, the inner surface of the dust collection hood fixed part and each dust collection hood movable part is coated with a heat storage refractory, each dust collection hood movable part, There is provided a hot metal desulfurization apparatus provided with a movable mechanism that selectively moves in a state of covering the upper side of the hot metal ladle and a state of covering the impeller.

  The movable mechanism has a rotation shaft that is pivotally supported at an overlapping portion between the dust collection hood fixing portion and each dust collection hood movable portion, and rotates each dust collection hood movable portion around the rotation shaft. It is good also as a structure. In addition, a suspension holding mechanism that suspends and holds each dust collection hood movable portion is provided at the peripheral portion of each dust collection hood movable portion, and the suspension retention mechanism is in a state of hanging and holding. It is good also as a structure which can be switched. The suspension holding mechanism may include a chain or a wire that can be wound, and an attachment portion that is provided at a peripheral portion of each dust collection hood movable portion and to which the chain or the wire is attached.

  Further, a hydraulic cylinder that can be expanded and contracted in a direction in which the bottom surfaces of the peripheral portions of each dust collection hood movable part are pressed against each other, and a hydraulic cylinder mounting part to which the hydraulic cylinder is mounted are provided, and the hydraulic cylinder mounting part is Below the shaft, it may be provided on the side surface of the peripheral edge of each dust collection hood movable part.

  Moreover, the raising mechanism which raises and rotates each dust collection hood movable part may be provided, and the location which raises each dust collection hood movable part may be provided under the said rotating shaft. In addition, the pulling mechanism is provided on the surface of each pullable pulling chain or pulling wire, and on the surface of each dust collecting hood movable part, and the pulling chain or pulling wire is attached to the mounting part. And may be provided.

  Moreover, in order to solve the above-mentioned problem, according to the present invention, a hot metal desulfurization method for performing a desulfurization treatment by adding a desulfurizing agent to hot metal in a hot metal ladle and stirring with an impeller coated with a refractory, The dust collection hood that covers the top of the hot metal ladle is divided into a dust collection hood fixed part and a plurality of dust collection hood movable parts that are covered with heat-storing refractory on the inner surface. There is also provided a hot metal desulfurization method characterized by moving a dust hood moving part to cover the impeller.

  Further, an overlapping portion of the dust collection hood fixing part and each dust collection hood movable part may be pivotally supported, and each dust collection hood movable part may be rotated about the pivotal axis that is pivotally supported. Further, each dust collection hood movable part may be suspended and held during the desulfurization process, and each dust collection hood movable part may not be suspended and held during the standby state during the desulfurization process. Moreover, it is good also as pressing the bottom face of the peripheral part of each dust collection hood movable part mutually below with a hydraulic cylinder below the said rotating shaft. Moreover, it is good also as rotating each dust collection hood movable part by pulling up each dust collection hood movable part below the said rotating shaft.

  According to the present invention, each dust collection hood movable part which covered the upper part of the hot metal ladle can be moved, and the impeller in the standby state during the desulfurization process can be covered. Thereby, an impeller can be heat-retained with the heat radiation from the heat storage refractory material coat | covered by the inner surface of each dust collection hood movable part. For this reason, the rapid temperature change of the impeller in the standby state between desulfurization processes can be suppressed, and the crack generation of the refractory on the impeller surface can be suppressed. As a result, it is possible to reduce the frequency of occurrence of implosion damage and defects of the impeller, and to extend the life of the impeller.

1 is a schematic front view of a hot metal desulfurization apparatus according to an embodiment of the present invention. 1 is a schematic plan view of a hot metal desulfurization apparatus according to an embodiment of the present invention. It is a side view showing rotation operation of a dust collection hood movable part concerning an embodiment of the invention. It is a figure which shows the desulfurization process process which concerns on embodiment of this invention. It is a side view showing rotation operation of a dust collection hood movable part concerning a modification of the present invention.

  Hereinafter, an embodiment of the present invention will be described based on a KR desulfurization apparatus 1 which is a kind of hot metal desulfurization apparatus. 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.

  As shown in FIGS. 1 and 2, the KR desulfurization apparatus 1 includes an impeller 3 for stirring the hot metal 2 in the hot metal ladle, an impeller drive device 4 for moving the impeller 3 up and down, dust generated during the desulfurization process, and the like. It is comprised from the dust collector 5 which collect | recovers. Also, below the KR desulfurization apparatus 1, a hot metal ladle 7 conveyed by the hot metal ladle transport vehicle 6 is disposed. After the hot metal 2 in the hot metal ladle has been desulfurized, the hot metal hot pot 7 is transported to a subsequent process by the hot metal ladle transport vehicle 6.

  As shown in FIG. 1, a shaft 8 that extends downward protrudes from the lower center surface of the substantially cylindrical impeller driving device 4, and the impeller 3 is attached to the tip of the shaft 8. The shaft 8 and the impeller 3 are configured to be movable up and down and rotatable by the impeller driving device 4.

  The dust collector 5 includes a rectangular discharge path 9 for discharging dust, a dust collection hood 10 that covers the top of the hot metal pan 7, and a dust collection skirt 11 that covers the upper outer edge of the hot metal pan 7. As shown in FIG. 2, an opening 12 through which the ascending / descending impeller 3 can pass is provided at the center of the dust collection hood 10. Further, the dust collecting hood 10 is provided with a desulfurizing agent charging port 13 so that the desulfurizing agent can be dropped into the hot metal ladle from a desulfurizing agent charging hopper (not shown). Moreover, the heat storage refractory 14 is coat | covered by the inner surface of the dust collection hood 10, and the heat | fever of the hot metal 2 in the desulfurization process can be heat-stored.

  Further, the dust collection hood 10 is divided into three along a predetermined direction, and includes a single dust collection hood fixing part 15 and two dust collection hood movable parts 16. The predetermined direction is, for example, a direction connecting the center point of the opening 12 and the intersection of diagonal lines in the rectangular discharge path 9 with a straight line, and corresponds to the X-axis direction in FIG. The dust collection hood 10 in the present embodiment is divided into three along the X-axis direction, and an opening 12 and a discharge path 9 are included in the divided area of the dust collection hood fixing portion 15. Of the three divided dust collection hoods 10, a part other than the dust collection hood fixing part 15 is a dust collection hood movable part 16. The dust collection hood fixing portion 15 and each dust collection hood movable portion 16 partially overlap each other (shaded portion in FIG. 2), and in the overlapping portion D, the dust collection hood movable portion 16 is fixed to the dust collection hood. Covered by the part 15. In addition, the overlapping portion D is provided with a pin 17 that pivotally supports the X-axis direction of each dust collecting hood movable portion 16 so as to penetrate each overlapping portion D. Note that the Y-axis direction in FIG. The direction perpendicular to the X-axis direction in plan view.

  As shown in FIG. 2, a mounting portion 18 of a movable chain 19 that moves each dust collection hood movable portion 16 is provided on the upper surface of the peripheral edge portion 16 a of each dust collection hood movable portion 16. The movable chain attaching portion 18 is provided at two places on the upper surface of each peripheral edge portion 16a. Each movable chain 19 is configured to be wound up or down by a movable chain winding mechanism (not shown) provided on the upper portion of the dust collector 5.

  When each movable chain 19 is wound up, each movable chain 19 is stretched against the peripheral edge portion 16a of each dust collection hood movable portion 16, and each dust collection hood movable portion 16 is suspended and held. On the other hand, when each movable chain 19 is lowered, each movable chain 19 becomes loose, and each dust collection hood movable portion 16 is not suspended and held. For this reason, each dust collection hood movable part 16 has the pin 17 as an axis due to the weight of each dust collection hood movable part 16 and the weight of the heat storage refractory 14 coated on the inner surface of each dust collection hood movable part 16. Rotates downward. The dust collection hood fixing portion 15 is suspended and held by a suspension mechanism (not shown) provided above the dust collector 5.

  Further, as shown in FIG. 3A, a pressing hydraulic cylinder 20 for pressing the bottom surfaces of the peripheral edge portions 16 a to each other is provided on the side of each dust collection hood movable portion 16. Further, among the side surfaces of the peripheral edge portion 16a of each dust collection hood movable portion 16, the pressing hydraulic cylinder mounting portion 21 is provided on the side surface portion where the distance in the Y-axis direction from the center point of the opening portion 12 is farthest. Is provided. The pressing hydraulic cylinder 20 is attached to the pressing hydraulic cylinder mounting portion 21. In the present embodiment, as shown in FIG. 3 (b), each of the dust collection hood movable parts 16 is obtained by extending the pressing hydraulic cylinders 20 in the Y-axis direction while the movable chains 19 are loosened. Can be pressed against each other. At this time, the impeller 3 is covered with each dust collection hood movable part 16. In other words, in the present embodiment, each dust collection hood movable portion 16 is moved, so that each dust collection hood movable portion 16 selectively covers a state where the hot metal pan 7 is covered and a state where the impeller 3 is covered. Can be switched. Note that the dust collecting skirt 11 is not shown in FIGS.

  As shown in FIG. 2, the dust collection skirt 11 is disposed so as to cover the outer periphery of the peripheral edge of the dust collection hood. However, as shown in FIG. 1, a portion of the dust collecting skirt 11 is notched so as to avoid the hydraulic cylinder mounting portion 20 where the hydraulic cylinder mounting portion 20 of the dust collecting hood movable portion 16 is provided. 22 is inserted. Further, on the upper surface of the dust collection skirt 11, a mounting portion 24 for a lifting chain 23 for raising and lowering the dust collection skirt 11 is provided. There are four lifting chain attachment portions 24 provided on the upper surface of the dust collection skirt 11. Each lifting / lowering chain 23 is configured to be wound or unwound by a lifting / lowering chain winding mechanism (not shown) provided above the dust collector 5.

  Further, four guides 25 are provided on the upper surface of the dust collection skirt 11 so that the dust collection skirt 11 can be moved up and down along the dust collection hood 10. The four guides 25 are provided so that the two guides 25 face each other, and are arranged so that the two straight lines are orthogonal to each other when the opposing guides 25 are connected by straight lines. Further, a caster 26 is attached to each guide 25, and the caster 26 is in contact with the dust collection hood 10. By providing such a guide 25, the caster 26 can always move so as to follow the surface of the dust collection hood 10 when the dust collection skirt 11 is raised and lowered.

  A hot metal desulfurization method using the KR desulfurization apparatus 1 configured as described above will be described.

  First, the hot metal ladle 7 containing the hot metal 2 is conveyed below the KR desulfurization apparatus 1 by the hot metal ladle conveying vehicle 6 (FIG. 4A). And the raising / lowering chain 23 is wound down by the raising / lowering chain winding mechanism which is not shown in figure, and the dust collection skirt 11 descend | falls along the dust collection hood 10 (FIG.4 (b)). Then, the impeller 3 is lowered by the impeller driving device 4, and the impeller 3 is immersed in the hot metal 2 (FIG. 4C). Next, the desulfurizing agent is dropped into the hot metal ladle from the desulfurizing agent inlet 13 provided in the dust collecting hood 11, and the impeller 3 is rotated. Thereby, the hot metal 2 is desulfurized. Note that dust generated during the desulfurization process is discharged from the discharge path 9 of the dust collector 5. Further, during the desulfurization process, heat generated from the hot metal 2 is stored in the heat storage refractory 14 provided on the inner surface of the dust collection hood 10.

  After completion of the desulfurization process, the impeller 3 is raised by the impeller driving device 4 (FIG. 4D). And the raising / lowering chain 23 is wound up and the dust collection skirt 11 raises along the dust collection hood 10 (FIG.4 (e)). Thereafter, the hot metal ladle 7 subjected to the desulfurization treatment is transported to a subsequent process by the hot metal ladle transporting vehicle 6 (FIG. 4E).

  After the hot metal ladle 7 is conveyed, each movable chain 19 attached to the upper surface of the peripheral edge portion 16a of each dust collecting hood movable portion 16 is unwound by a movable chain winding mechanism (not shown). Thereby, each dust collection hood movable part 16 of each dust collection hood 10 of each dust collection hood movable part 16 is weighted by the weight of heat storage refractory 14 coated on the inner surface of dust collection hood movable part 16, etc. The pin 17 provided in the overlapping part D starts to rotate downward about the rotation axis. At this time, the dust collection skirt 11 is maintained in a suspended state.

  Thereafter, as shown in FIG. 3B, the pressing hydraulic cylinder 20 is extended, and the bottom surfaces of the peripheral edge portions 16 a of the dust collection hood movable portions 16 are pressed against each other. Thereby, the space below the impeller 3 is covered by the two dust collection hood movable parts 16. At this time, the heat of the hot metal 2 stored during the desulfurization process is radiated from the heat storage refractory 14 coated on the inner surface of each dust collection hood 10. The rapid temperature drop of the impeller 3 can be suppressed by the heat. This state is maintained until the next hot metal ladle 7 requiring desulfurization treatment is conveyed to the KR desulfurization apparatus 1 (FIG. 4 (f)). Thereby, even if the impeller 3 is in a standby state during the desulfurization process, the impeller 3 can be prevented from being cooled, and the thermal contraction of the refractory coated on the surface of the impeller 3 can be suppressed. Note that the dust collecting skirt 11 is not shown in FIGS.

  And when the hot metal ladle 7 which performs a desulfurization process approaches the KR desulfurization apparatus 1, the peripheral part 16a of each dust collection hood movable part 16 pressed against each other by contracting the hydraulic cylinder 20 for pressing. Are separated from each other. Thereafter, the movable chain 19 attached to the upper surface of the peripheral edge portion 16a of each dust collecting hood movable portion 16 is wound up. Thereby, each dust collection hood movable part 16 rotates upwards by using the pin 17 provided in the overlap part D of the dust collection hood 10 as a rotating shaft.

  After the movable chain 19 is wound up until the bottom surface of each dust collection hood movable portion 16 becomes horizontal, the hot metal ladle 7 to be desulfurized next is conveyed (FIG. 4A). By repeating the above steps, the hot metal 2 is desulfurized by the KR desulfurization apparatus 1.

  As described above, according to the present invention, the space below the impeller in the standby state during the desulfurization process can be covered with the dust collection hood movable portion whose inner surface is coated with the heat storage refractory. For this reason, the impeller can be kept warm by the heat of the hot metal stored in the heat storage refractory during the desulfurization treatment. Thereby, the thermal contraction of the refractory material coat | covered by the impeller surface resulting from the rapid temperature fall of an impeller can be suppressed. As a result, it is possible to reduce the occurrence frequency of cracks generated in the refractory, and it is possible to reduce the occurrence frequency of impeller melting and defects. Accordingly, the replacement frequency of the impeller can also be reduced, so that the throughput can be improved.

  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 embodiment of the present invention, two dust collection hood movable parts are provided. However, the present invention is not limited to this, and a plurality of dust collection hood movable parts may be provided. Moreover, although each dust collection hood movable part was moved by raising or lowering the movable chain, it is not limited to using a chain, and a wire or the like may be used. You may combine. Further, the number of chains and the attachment locations are appropriately changed according to the shape and size of the dust collector. Further, in the embodiment of the present invention, each dust collection hood movable part is pivotally supported using pins, but may be pivotally supported by other parts. Further, in the embodiment of the present invention, the peripheral portion of each dust collection hood movable portion is pressed by a hydraulic cylinder, but other devices, mechanisms, etc. may be used as long as each peripheral portion can be pressed. It may be adopted. That is, it can be said that it belongs to the technical scope of this invention if it is the structure which moves a part of dust collection hood and covers an impeller.

  Further, as a modification of the present invention, as shown in FIG. 5A, instead of the pressing hydraulic cylinder 20, a lifting chain 27 that pulls up and rotates each dust collecting hood movable portion may be provided. On the surface of each dust collection hood movable portion 16, a lifting chain attachment portion 28 to which the lifting chain 27 is attached is provided. The pull-up chain mounting portion 28 is provided below the pin 17 of each dust collection hood movable portion. Further, the lifting chain 27 is wound up or lowered by a lifting chain winding mechanism (not shown) provided above the dust collector 5. Further, a pulley 29 is provided above each pull-up chain mounting portion 28 to guide the lifting or lowering operation of each pull-up chain 27. Further, these pulleys 29 are provided so that the positions in the Y-axis direction are between the pins 17 that pivotally support the dust collection hood movable portions 16. In this modification, in each overlapping portion D, the dust collection hood fixing portion 15 is covered with the dust collection hood movable portion 16. Other configurations are the same as those of the embodiment of the present invention.

  As shown in FIG. 5B, in such a configuration, when each lifting chain 27 is wound up, each dust collection hood movable portion 16 rotates downward about the pin 17 as a rotation axis. When each lifting chain 27 is wound up until the bottom surfaces of the peripheral edge portions 16a of the respective dust collection hood movable portions 16 come into contact with each other, the bottom surfaces of the peripheral edge portions 16a of the respective dust collection hood movable portions 16 are pressed against each other. The space below the impeller 3 is covered with a dust collection hood movable portion 16.

  Using the KR desulfurization apparatus according to the present invention and the conventional KR desulfurization apparatus, the hot metal desulfurization process was repeatedly performed, and the number of desulfurization processes until the impeller had to be replaced was compared. As a result, the number of desulfurization treatments was 166 times in the conventional KR desulfurization apparatus, whereas it was 192 times in the KR desulfurization apparatus according to the present invention. That is, according to the present invention, the occurrence of cracks in the refractory due to the temperature change of the impeller can be suppressed, and the life of the impeller can be extended.

  The present invention can be applied to a hot metal desulfurization apparatus and a hot metal desulfurization method for performing desulfurization treatment of hot metal.

DESCRIPTION OF SYMBOLS 1 KR desulfurization apparatus 2 Hot metal 3 Impeller 4 Impeller drive device 5 Dust collector 6 Hot metal ladle conveyance vehicle 7 Hot metal ladle 8 Shaft 9 Discharge path 10 Dust collection hood 11 Dust collection skirt 12 Opening part 13 Desulfurization agent inlet 14 Thermal storage refractory 15 Dust collection hood fixing part 16 Dust collection hood movable part 16a Peripheral part 17 of dust collection hood movable part 18 Pin 18 Movable chain mounting part 19 Movable chain 20 Pressing hydraulic cylinder 21 Pressing hydraulic cylinder mounting part 22 Dust collection skirt notch 23 Lifting chain 24 Lifting chain mounting part 25 Guide 26 Caster 27 Lifting chain 28 Lifting chain mounting part 29 Pulley D Duplicated part

Claims (12)

It has a refractory-coated impeller and a dust collector that collects dust generated during the desulfurization process. The desulfurization process is performed by adding a desulfurizing agent to the hot metal in the hot metal ladle and stirring with the impeller. A desulfurization device,
The dust collector includes a dust collection hood that covers the top of the hot metal pan,
The dust collection hood is divided into a dust collection hood fixing part and a plurality of dust collection hood moving parts,
The inner surface of the dust collection hood fixing part and each dust collection hood movable part is covered with a heat storage refractory,
A hot metal desulfurization apparatus, comprising: a movable mechanism for selectively moving each dust collection hood movable part between a state covering the hot metal ladle and a state covering the impeller.   The movable mechanism has a rotation shaft that is pivotally supported at an overlapping portion of the dust collection hood fixing portion and each dust collection hood movable portion, and rotates each dust collection hood movable portion around the rotation shaft. The hot metal desulfurization apparatus according to claim 1, wherein the hot metal desulfurization apparatus is provided.   A suspension holding mechanism for suspending and holding each dust collection hood movable portion is provided at the peripheral edge of each dust collection hood movable portion, and the suspension retention mechanism is in a state of being suspended and not suspended. The hot metal desulfurization apparatus according to claim 2, wherein the hot metal desulfurization apparatus is configured to be switchable. The suspension holding mechanism includes a chain or a wire that can be wound,
The hot metal desulfurization apparatus according to claim 3, further comprising an attachment portion provided at a peripheral portion of each dust collection hood movable portion to which the chain or the wire is attached. A hydraulic cylinder that can be expanded and contracted in the direction in which the bottom surfaces of the peripheral portions of each dust collection hood movable part are pressed against each other;
A hydraulic cylinder mounting portion to which the hydraulic cylinder is mounted;
5. The hot metal desulfurization apparatus according to claim 2, wherein the hydraulic cylinder mounting portion is provided on a side surface of a peripheral portion of each dust collection hood movable portion below the rotating shaft.   5. A lifting mechanism for lifting and rotating each dust collection hood movable part is provided, and a location for lifting each dust collection hood movable part is provided below the rotation shaft. Hot metal desulfurization apparatus according to the above. The pulling mechanism includes a winding chain or a pulling wire that can be wound;
The hot metal desulfurization apparatus according to claim 6, further comprising: an attachment portion provided on a surface of each dust collection hood movable portion to which the pulling chain or the pulling wire is attached. A hot metal desulfurization method in which a desulfurizing agent is put into hot metal in a hot metal ladle and desulfurized by stirring with an impeller coated with a refractory.
The dust collection hood that covers the top of the hot metal pan is divided into a dust collection hood fixed part and a plurality of dust collection hood movable parts whose inner surface is coated with a heat storage refractory,
A hot metal desulfurization method comprising: moving each dust collection hood movable part to cover the impeller during a standby state between desulfurization treatments.   9. The dust collection hood movable portion is pivotally supported around an overlapping portion of the dust collection hood fixing portion and each dust collection hood movable portion, and the pivotally supported rotation shaft is used as an axis. Hot metal desulfurization method.   The dust collection hood movable part is suspended and held at the time of desulfurization treatment, and the dust collection hood movable part is not suspended and held at the standby state during the desulfurization process. Hot metal desulfurization method.   11. The hot metal desulfurization method according to claim 9, wherein the bottom surfaces of the peripheral portions of the dust collection hood movable portions are pressed against each other by a hydraulic cylinder below the rotating shaft. The hot metal desulfurization method according to claim 9 or 10, wherein each dust collection hood movable portion is rotated by pulling up each dust collection hood movable portion below the rotation shaft.

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