JP2019094521A - Pellet conveying method and device for discharging pellet to outside of system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain productivity of a reduction furnace even if equipment located downstream of a vibrating screen fails and to transfer it to a reduction furnace through a drying furnace without delay in sieving of the vibrating screen While stably securing the amount of lower pellet, the particle size distribution of the pellet below the sieve is maintained in an appropriate range to enhance the productivity and operation stability of the reduction furnace.
A method of conveying pellets, wherein pellets pelletized by a granulator are transported to a reduction furnace through a vibrating screen and a drying furnace, (i) when equipment downstream of the vibrating screen breaks down, the pellets are excluded from the system And (ii) discharging the pellet out of the system when the pellet particle size distribution deviates from the reference particle size distribution.
[Selected figure] Figure 4

Description

  The present invention relates to a method for transporting pellets to be transported to a rotary hearth type reduction furnace, and an apparatus for discharging pellets out of the system for carrying out the transport method.

  In recent years, reduced iron pellets produced by a rotary hearth reduction furnace (sometimes referred to as "reduction furnace" hereinafter) have been used as one of iron making materials (for example, Patent Documents 1 to 3) ,reference).

  FIG. 1 schematically shows one embodiment of a step of producing reduced iron pellets using a rotary hearth type reducing furnace (hereinafter sometimes referred to as “reduced iron pellet producing step”).

  An iron oxide source (powdery iron ore, converter dust, sintered dust, blast furnace gas dust, etc.) cut out of a storage tank (not shown) and a reducing material (coke, oil coke, coal, etc.) are charged into the ball mill 1 The mixture is mixed and conveyed to the greasey 2 by the conveyor 1a to remove the balls, and then the mixture is kneaded by the kneader 3 to be used as a raw material for producing reduced iron pellets.

  The raw material for producing reduced iron pellets is conveyed and loaded into the granulator 4 by the conveyor 3a to granulate pellets for producing reduced iron (hereinafter sometimes referred to simply as "pellets"). The pellets are conveyed by the conveyor 4 a to the vibrating screen 5, and the unsieved pellets are conveyed by the conveyor 5 a and loaded into the dryer 7 through the swing loading conveyor 6.

  The pellets dried by the dryer 7 are conveyed by the conveyor 7a, charged from the inlet 8a into the rotary hearth type reduction furnace 8, and uniformly spread on the hearth. The pellets are heated to 1000 ° C. to 1500 ° C. by radiant heat of high temperature gas while the hearth of the rotary hearth type reduction furnace 8 rotates once, and the iron oxide source is reduced by the reducing material in the pellets to reduce It becomes an iron pellet.

  The exhaust gas generated in the furnace is collected, for example, in a boiler (not shown) through the exhaust port 8b and then fed to the next step (not shown).

  The reduced iron pellets discharged from the rotary hearth type reduction furnace 8 are cooled by the cooler 9 and conveyed to the next step (not shown).

JP, 2002-194410, A JP 2002-206120 A JP 2008-013797 A

  In the prior art (see FIG. 1), the pellet granulated by the granulator is subjected to a vibrating sieve ("5" in the figure), non-standard pellet of granulation defect, and / or coarse particles of the required particle diameter or more Although the pellets are removed and the sieved pellets are charged into a reduction furnace, there are the following problems in sieving and transporting the pellets.

  (x) When the under-sieve pellets are transported to the reduction oven through the drying furnace, if the equipment downstream from the vibrating sieve breaks down, the under-sieve pellets stay, sometimes overflowing out of the equipment, and the granulator and the vibrator The operation of the sieve has to be interrupted, and it takes a long time to recover from the failure, the operation of the reduction furnace is not stable, and the quality of the reduction pellet is lowered.

  (y) If the pellet granulated by the granulator contains a large amount of non-standard pellet of granulation defect or coarse-grained pellet of the required particle diameter or more, screening with a vibrating sieve (non-standard pellet, The removal of coarse-grained pellets can not keep up, and the amount of pellets below the sieve to be transported to the reduction furnace through the drier can not be secured stably, and the operation of the reduction furnace is not stable.

  (z) When the pellet granulated by the granulator contains a large amount of fine-grained pellets having the required particle diameter or less, the sieved pellets transported to the reduction furnace through the drying furnace contain a large amount of fine-grained pellets Although fine-grained pellets are melted in the reduction furnace and a hard bedrock is formed in the hearth, the wear of the discharge machine (screw) that discharges the reduced iron pellets accelerates and the replacement frequency increases. Furnace productivity is reduced.

  Thus, (A) Failure of the equipment downstream of the vibrating screen greatly affects the operation stability and productivity of the reduction furnace, and (B) particle size distribution of the pellets sifted by the vibrating screen, and / or The particle size distribution of the sieved pellets transferred to the reduction furnace through the drying furnace greatly affects the operation stability and productivity of the reduction furnace.

  SUMMARY OF THE INVENTION In view of the above problems of the prior art, the present invention maintains (a) operation stability and productivity of a reduction furnace even if equipment downstream from the vibrating screen fails, and (b) the vibrating screen While stably securing the amount of sieved pellets to be transported to the reduction furnace through the drying furnace without delaying sieving, the particle size distribution of the sieved pellets is maintained in an appropriate range, and the reduction furnace An object of the present invention is to provide a method for transporting pellets that solves the above problems, and an apparatus for carrying out the method.

  The present inventors diligently studied methods for solving the above problems. As a result, in sieving and conveying of the pellet, the pellet or the particle size distribution deviates from the reference range when equipment downstream of the vibrating sieve breaks down or the particle size distribution of the pellet deviates from the reference range It has been found that the operation stability and productivity of the reduction furnace can be enhanced if the This point will be described later.

  The present invention has been made based on the above findings, and the summary thereof is as follows.

(1) A method of conveying pellets, wherein the pellets granulated by the granulator are transported to the reduction furnace through the vibrating sieve and the dryer,
What is claimed is: 1. A method for conveying pellets, comprising discharging pellets out of the system between a granulator and a reduction furnace when equipment downstream of the vibrating sieve breaks down.

(2) A method of conveying pellets, wherein the pellets granulated by the granulator are transported to the reduction furnace through the vibrating sieve and the dryer,
What is claimed is: 1. A method of conveying a pellet comprising discharging the pellet whose particle size distribution deviates from the reference range out of the system between the granulator and the vibrating sieve when the particle size distribution of the pellet deviates from the reference range.

  (3) The standard range of the particle size distribution of the pellets is characterized in that the pellet having a particle diameter of 30 mm or more: 50% by mass or less and the pellet having a particle diameter of 5 mm or less: 50% by mass or less The method of conveying pellets as described in.

  (4) Discharge of the pellets to the outside of the system is performed by a switching signal between the granulator and the reduction furnace, and an out-system discharge device provided with a damper for moving the discharge position to discharge the pellets out of the system. The pellet according to the above (1), characterized in that the pellet is placed at the required position of the above and the equipment is moved from the retracted position to the discharge position by the switching signal when the equipment downstream from the vibrating screen breaks down. Transport method.

  (5) The discharge of the pellets out of the system is performed by a switching signal between the granulator and the vibrating screen, and an out-system discharge device provided with a damper moving from the retracted position to the discharge position discharging the pellets out of the system. And the damper is moved from the retracted position to the discharge position by the switching signal when the particle size distribution of the pellet deviates from the reference range. How to transport pellets.

  (6) The method for conveying pellets according to any one of (1) to (5), wherein the reduction furnace is a rotary hearth reduction furnace.

(7) An apparatus for discharging pellets out of the system for carrying out the method for transporting pellets according to any one of (1) to (6) above,
A damper is provided to move from the retracted position to the discharge position for discharging the pellet out of the system by the switching signal when the equipment downstream from the vibrating sieve fails or when the particle size distribution of the pellet deviates from the reference range. A system for discharging pellets out of the system.

  (8) The standard range of the particle size distribution of the pellets is characterized in that pellets with a particle size of 30 mm or more: 50% by mass or less and pellets with a particle size of 5 mm or less: 50% by mass or less Out-system discharge device of the pellet as described in.

  (9) The apparatus for discharging the pellets from the system according to (7) or (8) above, wherein the reduction furnace is a rotary hearth reduction furnace.

  According to the present invention, even if equipment downstream of the vibrating screen breaks down, the operation stability and productivity of the reduction furnace can be maintained, and the vibrating sieve is sieved, and the drying furnace is passed to the reduction furnace. It is possible to stably secure the amount of under-sieve pellets to be transported, and maintain the particle size distribution of the under-sieve pellets within an appropriate range, to enhance the operation stability and productivity of the reduction furnace.

It is a figure which shows typically one aspect of the process of manufacturing reduced iron pellets using a rotary hearth type reduction furnace. It is a figure which shows typically one aspect which applied this invention to the process of manufacturing reduced iron pellet using a rotary hearth type reduction furnace. It is a figure which shows typically one another aspect which applied this invention to the process of manufacturing reduced iron pellet using a rotary hearth type reduction furnace. It is a figure which shows typically the one aspect | mode of a system discharge | emission apparatus. (A) shows the aspect which the damper has retracted | saved to the retracted position, (b) shows the aspect which the damper has moved to the discharge position which discharges a pellet out of the system.

The method of conveying pellets according to the present invention (hereinafter sometimes referred to as "the method of conveyance according to the present invention") is a method of conveying pellets which is carried by a granulator into a reduction furnace through vibrating sieves and a dryer. ,
It is characterized in that the pellet is discharged out of the system between the granulator and the reduction furnace when the equipment downstream of the vibrating sieve breaks down.

Further, according to the conveying method of the present invention, the pellet granulated by the granulator is conveyed to the reduction furnace through the vibrating sieve and the drier.
When the particle size distribution of the pellets is out of the standard range, the pellet whose particle size distribution is out of the standard range is discharged out of the system between the granulator and the vibrating sieve.

  Furthermore, in the transport method of the present invention, (a) the reference range of the particle size distribution of the pellets is 50% by mass or less of pellets with a particle size of 30 mm or more and 50% by mass or less of pellets with a particle size of 5 mm or less (B) discharging the pellets out of the system by (b1) a switching signal, comprising: a system discharging device including a dumper moving from the retracted position to a discharging position for discharging the pellets out of the system; It is placed at the required place between the granulator and the reduction furnace, and when the equipment downstream from the vibrating sieve breaks down, or (b2) the above-mentioned system discharge device is placed between the granulator and the vibrating sieve And, when the particle size distribution of the pellet deviates from the reference range, the damper is moved from the retracted position to the discharge position by the switching signal, and (c) the reduction furnace is a rotary hearth type It is characterized by being a reduction furnace.

The system for discharging pellets of the present invention (hereinafter sometimes referred to as “the apparatus for discharging the present invention”) is a system for discharging pellets of the present invention for carrying out the method of transporting the present invention,
A damper is provided to move from the retracted position to the discharge position for discharging the pellet out of the system by the switching signal when the equipment downstream from the vibrating sieve fails or when the particle size distribution of the pellet deviates from the reference range. It is characterized by

  Furthermore, in the discharge device of the present invention, (a) the reference range of the particle size distribution of the pellets is 50% by mass or less of pellets with a particle size of 30 mm or more and 50% by mass or less of pellets with a particle size of 5 mm or less It is characterized in that (b) the reduction furnace is a rotary hearth reduction furnace.

  Hereinafter, the transfer method of the present invention and the discharge device of the present invention will be described based on the drawings.

  FIG. 2 schematically shows an embodiment in which the present invention is applied to the process for producing reduced iron pellets shown in FIG. In the reduced iron pellet production process shown in FIG. 2, between the end of the conveyor 5 a carrying the sieved pellets of the vibrating sieve 5 and the swing loading conveyor 6 uniformly charging the sieved pellets into the dryer 7 In addition, when the equipment downstream from the vibrating screen 5 breaks down, the out-system discharging device 10 for discharging the pellet out of the system is disposed.

  Here, FIG. 4 schematically shows an aspect of the out-system discharge device. FIG. 4 (a) shows a mode in which the damper is retracted to the retracted position, and FIG. 4 (b) shows a mode in which the damper is moved to the discharge position for discharging the pellet out of the system.

  As shown in FIG. 4A, the extraneous discharge device 10 guides the pellets (not shown) falling from the conveyor 5a to the next equipment (see “swing load conveyor 6” in FIG. 2). It is supported by the support shaft 10d at the lower end of the guidance system 10b, the external system guidance system 10c connected to the guidance system 10b, and the external system guidance system 10c side of the guidance system 10b. It is comprised from the damper 12 to which a position (retraction position and discharge position) switches.

  In the out-of-system discharge device 10, the damper 12 of the guiding device 10b is normally at the retracted position, and the pellets conveyed by the conveyor 5a descend the guiding device 10b, and the dryer 7 receives the swing loading conveyor 6 When the monitoring device (not shown) detects a failure of the equipment downstream of the vibrating screen 5, a failure occurrence signal is sent to the control device 11.

  The control device 11 having received the failure occurrence signal transmits a switching signal for switching the position of the damper 12 from the retracted position to the discharge position to a control device (not shown) that controls the drive mechanism 13.

  When the drive mechanism 13 operates and the damper 12 pivots from the retracted position to the discharge position with the support shaft 10d as an axis, the pellet for lowering the guiding device 10b is guided by the damper 12 at the discharge position. It is induced to 10c and discharged out of the system (see FIG. 4 (b)) and is not transported to equipment downstream of the vibrating screen 5 (see FIG. 2). The pellets discharged out of the system are transported to a pellet storage yard by a conveyor 10a (see FIG. 2).

  In the out-of-system discharge device shown in FIG. 4, a damper that rotates about the support shaft 10 d is used. However, when discharging pellets, the damper only needs to abut against the falling pellets. The mechanism for switching the position is not limited to the rotation mechanism. For example, a movable damper may be disposed on the side of the guiding device.

  Thus, when the equipment downstream of the vibrating sieve breaks down, the pellets are not transported to the equipment downstream of the vibrating sieve, so the pellets do not stay in the pellet production process and do not overflow out of the equipment. Therefore, it is not necessary to interrupt the operation of the granulator and the vibrating screen, and it is possible to quickly input the pellets to the reduction furnace after equipment restoration. Furthermore, the pellets discharged to the outside of the system are transported to a pellet storage yard and can be used again as a raw material after recovery from equipment failure.

  Although FIG. 2 shows a mode in which the out-system discharge device 10 is disposed between the end of the conveyor 5a and the swing loading conveyor 6, the arrangement of the out-system discharge device 10 is limited to the arrangement shown in FIG. I will not.

  The extra-system discharge device 10 may be disposed at a location where the pellets can be discharged out of the system between the granulator and the reduction furnace, and may be disposed, for example, between the dryer 7 and the conveyor 7a. It may be disposed between the conveyor 7 a and the reduction furnace 8. Further, the out-system discharge device may be disposed at a plurality of places between the granulator and the reduction furnace.

  FIG. 3 schematically shows another embodiment in which the present invention is applied to the process for producing reduced iron pellets shown in FIG. In the reduced iron pellet production process shown in FIG. 3, when the particle size distribution of the pellet deviates from the reference range between the end of the conveyor 4 a that conveys the pellet granulated by the granulator 4 and the vibrating screen 5, An extra-system discharge device 10 (see FIG. 4) is disposed to discharge the pellet whose particle size distribution is out of the standard range to the outside of the system. In addition, the reference range of the particle size distribution of a pellet is mentioned later.

  In the out-of-system discharge device 10, the dampers 12 of the guiding device 10b are normally at the retracted position, and the pellets conveyed by the conveyor 4a descend the guiding device 10b and are loaded into the vibrating sieve 5 (FIG. 3) If the monitoring device (not shown) that monitors the particle size distribution of the pellets on the conveyor 4a detects that the particle size distribution of the pellets is out of the reference range, the particle size distribution outlier signal controls Sent to 11.

  The control device 11 having received the particle size distribution deviation signal transmits a switching signal for switching the position of the damper 12 from the retracted position to the discharge position to a control device (not shown) that controls the drive mechanism 13.

  When the drive mechanism 13 operates and the damper 12 moves from the retracted position to the discharge position, the "pellet out of the reference range of particle size distribution" which descends the guiding device 10b is outside the system by the damper 12 at the discharge position. It is guided to the induction device 10c and discharged out of the system (see FIG. 4 (b)) and is not inserted into the vibrating screen 5 (see FIG. 3). The pellets discharged out of the system are transported by the conveyor 10a to the pellet storage yard and / or the raw material storage yard.

  In addition, you may use the plate-shaped body which has a mesh | network which can remove the coarse particle pellet more than a required particle size as the damper 12 of the system discharge device 10 (refer FIG. 4). By using this plate-like body as a damper, a required amount of coarse-grained pellets whose particle size distribution deviates from the standard is removed to "pellets whose particle size distribution deviates from the standard range" "pellets with particle size distribution within the standard range" Can be changed to

  As described above, by monitoring the particle size distribution of the pellets conveyed to the vibrating screen and discharging the pellets whose particle size distribution deviates from the reference range to the outside of the system as appropriate, it is possible to avoid the delay of sieving in the vibrating screen. The particle size distribution of the pellets below the sieve transferred to the reduction furnace can be maintained in an appropriate range, and the productivity and operation stability of the reduction furnace can be enhanced.

  In the reduced iron pellet production process shown in FIG. 3, the out-of-system discharge device 10 (see FIG. 4) disposed between the end of the conveyor 4 a for transporting the pellets granulated by the granulator 4 and the vibrating screen 5 It can also be used as an out-system discharge device that discharges pellets out of the system when equipment downstream of the vibrating sieve breaks down.

  Further, in the reduced iron pellet production process shown in FIG. 3, it is added to the out-system discharge device 10 between the end of the conveyor 4 a that conveys the pellet granulated by the granulator 4 and the vibrating screen 5. When the downstream equipment breaks down, an extra-system discharge device for discharging the pellets out of the system may be disposed at an appropriate location between the vibrating screen 5 and the reduction furnace 8.

  That is, the transfer method of the present invention can be implemented by arranging the discharge device of the present invention at an appropriate place in the reduced iron production process.

  Here, the reference range of the particle size distribution of pellets and its monitoring will be described.

  The inventors of the present invention have found that the particle size distribution of the pellets charged in the reduction furnace is reduced: pellets with a particle size of 30 mm or more: 50% by mass or less and pellets with a particle size of 5 mm or less: 50% by mass or less We learned from furnace operation results.

  In the transfer method of the present invention and the discharge device of the present invention, based on this finding, the standard range of particle size distribution of pellets is as follows: pellets with a particle size of 30 mm or more: 50% by mass or less and pellets with a particle size of 5 mm or less It is below mass%.

  If 50% by mass or more of pellets (including non-standard pellets and coarse-grained pellets) having a particle size of 30 mm or more is present in the pellets, screening with a vibrating screen (removal of non-standard pellets and coarse-grained pellets) can not catch up The amount of the sieved pellets to be transported to the reduction furnace through the drier can not be secured stably, and the operation of the reduction furnace is not stable.

  Therefore, the standard range of the diameter distribution of the pellets is 50% by mass or less of pellets having a particle diameter of 30 mm or more. Preferably, it is 40% by mass or less.

  On the other hand, if 50% by mass or more of pellets having a particle size of 5 mm or less is present in the pellets, the under-sieve pellets transported to the reduction furnace through the drier contain a large amount of fine-grained pellets melted in the reduction furnace. . When fine-grained pellets are melted in the reduction furnace, hard bedrock is formed in the hearth, wear of the discharge machine (screw) that discharges reduced iron pellets accelerates and replacement frequency increases, and productivity of the reduction furnace decreases. .

  Therefore, the standard particle size distribution of the pellets is 50% by mass or less of pellets having a particle size of 5 mm or less. Preferably it is 40 mass% or less.

  Next, a method of monitoring whether or not the particle size distribution of the pellet satisfies the reference range will be described.

  According to the inventors' experience, as the coarse-grained pellet increases in the pellet, the layer thickness of the pellet increases, while the fine-grained pellet in the pellet increases, the layer thickness of the pellet decreases. Therefore, usually, the layer thickness of the pellets on the conveyor is constantly monitored by a monitoring device, but the present inventors have observed on the monitoring screen a 50% by mass reference line of pellets having a particle diameter of 30 mm or more, A pellet with a diameter of 5 mm or less set a 50% by mass reference line, and it was monitored whether the layer thickness of the pellet was within the reference line (reference range).

  When the layer thickness of the pellet on the monitoring screen is thick and the pellet with particle size of 30 mm or more exceeds 50% by mass reference line, or the thickness of the pellet on the monitoring screen is thin, the pellet with particle diameter of 5 mm or less When the value falls below the 50% by mass reference line, the monitoring device sends a particle size distribution deviation signal to the control device, and the switching signal from the control device to the out-of-system discharge device switches the damper position from the retracted position to the discharge position. To send out pellets out of the system with particle size distribution outside the standard range.

  Next, although the Example of this invention is described, the conditions in an Example are one condition example employ | adopted in order to confirm the practicability and effect of this invention, and this invention is the one condition example. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the scope of the present invention.

Example 1
In the reduced iron pellet manufacturing process shown in FIG. 2, since the swing loading conveyor 6 broke down, the out-system discharging device 10 was immediately operated to discharge the pellets out of the system to recover from the failure. Since the subsequent pellets were discharged out of the system, recovery work was completed in a short time (conventional one hour) than in the past, and the operation could be resumed.

(Example 2)
In the reduced iron pellet production process shown in FIG. 3, the layer thickness of the pellets on the conveyor 4a is monitored, and the standard range of the particle size distribution (50% by mass of pellets having a particle size of 30 mm or more and a particle size of 5 mm or less When the pellets were out of the 50% by mass reference line), the ex-system discharging device was operated immediately, and the pellets having a particle size distribution outside the standard range were discharged out of the system.

  As a result, pellets having a standard range of particle size distribution can be continuously transported to the reduction furnace, and the operation stability of the reduction furnace is improved. In addition, the frequency of replacement of a discharge machine (screw) for discharging reduced iron pellets decreased, and the productivity of the reduction furnace was improved.

  As described above, according to the present invention, even if the equipment downstream of the vibrating screen breaks down, the operation stability and productivity of the reduction furnace can be maintained, and the vibrating sieve is sieved and dried. Can stably secure the amount of under-sieve pellets to be transported to the reduction furnace through the above, and maintain the particle size distribution of the under-sieve pellets within an appropriate range to enhance the operation stability and productivity of the reduction furnace . Thus, the present invention is highly applicable in the steel industry.

DESCRIPTION OF SYMBOLS 1 ball mill 1a conveyor 2 greaseless 3 kneader 3a conveyor 4 granulator 4a conveyor 5 vibrating sieve 5a conveyor 6 swing loading conveyor 7 dryer 7a conveyor 8 rotary hearth reduction furnace 8a inlet 8b exhaust port 9 cooler 10 system Outer discharge device 10a Conveyor 10b Guidance device 10c External guidance device 10d Support shaft 11 Control device 12 Damper 13 Drive mechanism

Claims (9)

In the method of conveying pellets, the pellets granulated by the granulator are transported to the reduction furnace through the vibrating sieve and the drying furnace,
What is claimed is: 1. A method for conveying pellets, comprising discharging pellets out of the system between a granulator and a reduction furnace when equipment downstream of the vibrating sieve breaks down. In the method of conveying pellets, the pellets granulated by the granulator are transported to the reduction furnace through the vibrating sieve and the drying furnace,
What is claimed is: 1. A method of conveying a pellet comprising discharging the pellet whose particle size distribution deviates from the reference range out of the system between the granulator and the vibrating sieve when the particle size distribution of the pellet deviates from the reference range.   The pellet according to claim 2, wherein the standard range of the particle size distribution of the pellets is a pellet with a particle size of 30 mm or more: 50% by mass or less and a pellet with a particle size of 5 mm or less: 50% by mass or less Transport method.   The discharge of the pellets out of the system is a switching signal, and an extra system discharge device provided with a damper for moving the pellets to a discharge position for discharging the pellets out of the system is required between the granulator and the reduction furnace. The method of transporting pellets according to claim 1, wherein the method is arranged at a location, and when the equipment downstream from the vibrating screen breaks down, the damper is moved from the retracted position to the discharge position by a switching signal.   The discharge of the pellets out of the system is performed by a switching signal, and an out-system discharge device provided with a damper for moving the pellets to a discharge position for discharging the pellets out of the system is disposed between the granulator and the vibrating screen. The method according to claim 2 or 3, wherein, when the particle size distribution of the pellet deviates from the reference range, the damper is moved from the retracted position to the discharge position by a switching signal.   The said reduction furnace is a rotary hearth type reduction furnace, The conveyance method of the pellet of any one of Claims 1-5 characterized by the above-mentioned. An apparatus for discharging pellets out of the system for carrying out the method for transporting pellets according to any one of claims 1 to 6,
A damper is provided to move from the retracted position to the discharge position for discharging the pellet out of the system by the switching signal when the equipment downstream from the vibrating sieve fails or when the particle size distribution of the pellet deviates from the reference range. A system for discharging pellets out of the system.   The pellet according to claim 7, wherein the standard range of the particle size distribution of the pellets is a pellet with a particle size of 30 mm or more: 50% by mass or less and a pellet with a particle size of 5 mm or less: 50% by mass or less Out-of-system discharge device.   The apparatus for discharging the pellets from the system according to claim 7 or 8, wherein the reduction furnace is a rotary hearth reduction furnace.

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