JP6135622B2 - Blast furnace raw material charging method - Google Patents

Description

  The present invention relates to a method for charging coke and ore, which are blast furnace raw materials, into a bellless blast furnace having a center feed type bellless raw material charging device.

Coke and ore, which are blast furnace raw materials, are generally charged alternately into a bellless blast furnace from a raw material charging apparatus provided at the top of the bellless blast furnace. In this case, in recent years, from the viewpoint of environmental problems, it has been required to operate the blast furnace while reducing the amount of coke used in the blast furnace as much as possible.
There are two methods for reducing the amount of coke used in the blast furnace: a method of increasing the amount of ore charged per charge and a method of decreasing the amount of coke charged per charge. However, the method of increasing the amount of ore charge increases the layer thickness of the ore charged in the blast furnace, which reduces the ore reducibility and leads to a decrease in furnace heat due to the direct reaction of unreduced ore at the bottom of the blast furnace. It becomes a factor to worsen the blast furnace condition. On the other hand, the method of reducing the amount of coke charged is a factor that deteriorates the air permeability at the bottom of the blast furnace because the thickness of the coke charged in the blast furnace becomes thinner in the cohesive zone (the region where the ores soften and fuse together). become.

The technology to stabilize the blast furnace condition by maintaining the air permeability and liquid permeability of the blast furnace well, after charging coke into the blast furnace, charging ore and coke at the same time and mixing the coke layer and coke into the blast furnace. Techniques for alternately forming ore layers are known (see, for example, Patent Documents 1 and 2).
However, in the techniques described in Patent Documents 1 and 2, since the particle size of coke charged at the same time as the ore is made small in order to promote the melting of the ore, the ore starts to melt until it drops. It is considered that coke disappears in the region (softened cohesive zone), the air permeability in the softened cohesive zone becomes insufficient, and the effect of reducing the amount of coke charged, that is, the effect of reducing the coke ratio with respect to the ore is small.

  Therefore, when the coke mixed ore layer is formed in the bell-less blast furnace, the coke particle size is set to 1.3 times or more than the ore particle size, the ore is introduced into the upper bunker, and then the ore and coke are mixed. Patent Document 3 discloses a technique for transferring a raw material in an upper bunker to a lower bunker after charging, and forming a coke mixed ore layer in the blast furnace through a turning chute for the raw material discharged from the lower bunker. .

According to the technique disclosed in Patent Document 3, the coke charged simultaneously with the ore is prevented from disappearing in the softening cohesive zone of the blast furnace, and the coke caused by the difference in particle size between the ore and the coke is suppressed. Although the effect of segregation on the coke mixing ratio has improved somewhat, the mixing ratio distribution of coke and ore in the radial direction of the blast furnace has not been made uniform.
That is, the coke mixing ratio increases from the beginning to the middle of charging, and changes with time such that the coke mixing ratio decreases at the end stage. When the raw material is charged into the blast furnace through the swirl chute with such a discharge mixture ratio distribution, an improvement effect of air permeability cannot be expected in the lower part of the furnace in the region charged at the end of discharge.

  Moreover, in the technique described in Patent Document 3, in order to prevent the distribution in the furnace of coke charged at the same time as the ore from becoming uneven in the radial direction of the blast furnace, on the furnace top conveyor of the raw material charging apparatus. The timing of supplying coke from the raw material tank is adjusted, but segregation of coke occurs due to the particle size difference between the ore and coke, so as long as the ore and coke are mixed and charged, the segregation of coke It is difficult to suppress the change with time of the coke discharge ratio.

Japanese Patent Laid-Open No. 08-283804 JP-A-10-183210 JP 2010-133008 A

  The present invention has been made in view of the above-mentioned problems, and it is possible to charge a blast furnace raw material into a bell-less blast furnace having a center-feed type bell-less raw material charging device while maintaining a substantially constant mixing ratio of ore and coke. It aims at providing the charging method of the blast furnace raw material which can be performed.

  In order to solve the above-mentioned problems, the present inventors have made use of the fact that the upper bunker and the lower bunker are connected by a plurality of ports, which is a feature of the center-feed type bellless raw material charging device. By properly charging ore and coke into each port of the port, when the raw material is dropped and transferred to the lower bunker, the mixing ratio of coke and ore when discharged from the lower bunker is almost constant. The present invention has been completed by confirming that it can be maintained.

The present invention
(1)
There is a center feed type bellless raw material charging device in which a lower bunker provided at the top of the furnace and an upper bunker provided above the lower bunker and connected by a plurality of ports are arranged in two upper and lower stages. A method of charging a blast furnace raw material in a bell-less blast furnace, in which coke is charged only in a part of the plurality of ports, and the coke is deposited in the part of the ports,
Charging ore onto the deposited coke, causing the ore to flow into another port of the plurality of ports, and depositing the ore at the other port;
Transferring the coke and ore deposited in the upper bunker to the lower bunker;
Charging the coke and the ore transferred to the lower bunker into the bell-less blast furnace to form a coke mixed ore layer.
(2)
The blast furnace according to (1), wherein in the step of depositing the coke, the position of the tip of the chute provided in the upper bunker is fixed above the part of the ports and the coke is charged. Raw material charging method.
(3)
In the step of depositing the ore in the other port, the ore is charged through the chute, and the blast furnace raw material charging method according to (2),
(4)
The method for charging a blast furnace raw material according to (1) or (2), wherein the chute is a turning chute.
(5)
The amount of coke mixed in the coke mixed ore layer is 10% by mass or more and 50% by mass or less with respect to the total amount of coke charged from the top of the furnace (1) to ( 4) The blast furnace raw material charging method according to any one of 4).
It is.

  Therefore, according to the blast furnace raw material charging method of the present invention, when the coke and ore are charged into the bell-less blast furnace to form a coke mixed ore layer in the blast furnace, the mixing ratio of the coke and ore is made substantially constant. The blast furnace raw material can be charged into the bell-less blast furnace while maintaining it.

It is a schematic diagram which shows the furnace top part of the bell-less blast furnace to which the charging method of the blast furnace raw material which concerns on embodiment of this invention is applied. It is a figure explaining the state when coke is thrown into the upper bunker among the upper and lower two-stage furnace top bunker arranged at the top of the bellless blast furnace shown in FIG. It is a figure explaining a state when ore is thrown into the upper bunker shown in FIG. It is sectional drawing seen from the IV-IV direction of FIG. It is a figure explaining the state of a lower bunker when ore is discharged from an upper bunker to a lower bunker in a state where all raw material discharge ports formed in the upper bunker are opened. It is sectional drawing seen from the VI-VI direction of FIG. It is a figure which shows typically the discharge ratio of the ore discharged | emitted from a lower bunker, and coke. FIG. 8A is a diagram showing a temporal change in the mixing ratio of ore and coke discharged from the lower bunker when the charging method of the blast furnace raw material according to the comparative example is used, and FIG. ) Is a diagram showing a temporal change in the mixing ratio of ore and coke discharged from the lower bunker when the method for charging a blast furnace raw material according to the embodiment of the present invention is used.

  Hereinafter, a method for charging a blast furnace raw material according to an embodiment of the present invention will be described with reference to the drawings. First, the bell-less blast furnace 1 to which the blast furnace raw material charging method according to the embodiment of the present invention is applied includes a furnace top bunker 4 at the furnace top as shown in FIG. The furnace top bunker 4 is a raw material charging device for charging the bellless blast furnace 1 with coke 2 and ore 3 as blast furnace raw materials, and includes a lower bunker 6 and a lower bunker 6 provided above the lower bunker 6. This is a two-stage structure.

Further, the blast furnace raw material stored in the raw material tank 7 for the coke 2 and the raw material tank 8 for the ore 3 is supplied to the upper charging port of the furnace top bunker 4 via the furnace top conveyor 9. From the upper turning chute 10 arranged at the top of the upper bunker 5.
The upper bunker 5 has a plurality of ports that can be opened and closed at the bottom. For example, as shown in FIG. 4, the upper bunker 5 can employ a structure having four ports 51, 53, 55, 57 for discharging the raw material. The four ports 51, 53, 55, and 57 are provided at equal intervals in the circumferential direction at the bottom of the upper bunker 5, and the four ports 51, 53, 55, and 57 have gates that open and close each port, respectively. It is attached. In FIG. 1, two ports 51, 53 among the four ports 51, 53, 55, 57 of the upper bunker 5 shown in FIG. 4, and respective gates 52, 54 that open and close the two ports 51, 53, Is illustratively shown. The number of ports of the upper bunker 5 is not limited to four, and may be changed as appropriate, such as two, three, five or more.

On the other hand, at the bottom of the lower bunker 6, one port 61 for discharging the blast furnace raw material transferred from the upper bunker 5 is provided. The port 61 has a gate 62 that opens and closes the port 61. The blast furnace raw material discharged from the port 61 of the lower bunker 6 is charged into the bellless blast furnace 1 from the in-furnace turning chute 11 disposed below the lower bunker 6.
Next, the blast furnace raw material charging method according to the embodiment of the present invention used when the coke mixed ore layer 13 is formed in the raw material charging portion of the bell-less blast furnace 1 using the furnace top bunker 4 shown in FIG. explain. First, as shown in FIG. 2, the position of the tip 10 a of the upper turning chute 10 is fixed on an arbitrary port of the upper bunker 5. In the embodiment of the present invention, one of the four ports 53 is set as a port for fixing the position of the tip 10a of the upper turning chute 10 upward. All the gates 52, 54, 56 and 58 of the four ports 51, 53, 55 and 57 (see FIG. 4) of the upper bunker 5 are closed.

  Next, the coke 2 stored in the raw material tank 7 is conveyed to the upper charging port of the furnace top bunker 4 by the furnace top conveyor 9, and is charged into the upper bunker 5 from the upper turning chute 10. The state of the upper bunker 5 at this time is shown in FIG. In the upper bunker 5, the coke 2 is deposited in the space inside and above the set one port 53, and a coke mountain 2 a having a top is formed on the tip 10 a side of the upper turning chute 10. In the case of the upper bunker 5 according to the embodiment of the present invention, the coke 2 forming the coke mountain 2a does not exist in the other three ports adjacent to the port 53 as shown in FIG. It does not prohibit coke 2 from flowing into it.

  Next, the ore 3 stored in the raw material tank 8 is transported to the top of the bellless blast furnace 1 by the furnace top conveyor 9 while the position of the tip 10a of the upper turning chute 10 is fixed on one port 53 (see FIG. 1). Then, as shown in FIG. 3, the ore 3 conveyed to the top of the bell-less blast furnace 1 is put into the upper bunker 5 from the upper turning chute 10. At this time, the charged ore 3 flows from the top of the coke mountain 2 a deposited on one port 53 to the three surrounding ports. The state of the upper bunker 5 at this time is shown in FIGS.

  Specifically, a part of the input ore 3 is further piled up on the coke mountain 2a, and the other ore 3 falls from the top of the coke mountain 2a and is located on the skirt side of the coke mountain 2a, that is, It moves mainly to the other three ports 51, 55, 57 side. The ore 3 dropped from the top of the coke 2a is deposited inside and above the other three ports 51, 55, 57. At this time, in the upper bunker 5, an ore mountain 3a is formed which simultaneously straddles the coke mountain 2a and the other three ports 51, 55, and 57, respectively.

  That is, the coke 2 and the ore 3 are charged and deposited in this order in the upper bunker 5 so that the coke 2 is first unevenly distributed on the port 53 that exists below the position of the tip 10 a of the upper turning chute 10. Thereafter, the ore 3 is unevenly distributed on the inner side of each of the other three ports 51, 55, 57 and on the upper side of all four ports 51, 53, 55, 57. The operation of unevenly distributing the coke 2 and the operation of unevenly distributing the ore 3 are performed continuously, and processing such as opening any port of the upper bunker 5 is not performed between the two operations.

  By fixing the position of the tip 10 a of the upper turning chute 10 on one port 53, the coke 2 can be reliably deposited on one port 53. Further, since the upper turning chute 10 used at the time of charging the coke 2 is used as it is for charging the ore 3 without rotating, the raw material charging operation in one batch can be made efficient. Further, the upper turning chute 10 only needs to fix the tip 10a at a predetermined position in one batch, and it is not necessary to make the turning, so that the raw material charging operation can be made more efficient.

  Next, the gates 52, 54, 56, and 58 of the four ports 51, 53, 55, and 57 of the upper bunker 5 are all opened at the same time, and as shown in FIG. The ore 3 is transferred to the lower bunker 6. That is, the opening operation of the plurality of ports provided in the upper bunker 5 is performed at a single timing, and the coke 2 and the ore 3 are simultaneously dropped onto the lower bunker 6. At this time, in the lower bunker 6, a layer in which the coke 2 and the ore 3 are separated from each other in the circumferential direction in the horizontal plane is indicated by a linear bidirectional arrow in FIG. As described above, the layers are stacked from the position of the gate 62 of the port 61 of the lower bunker 6 to the position near the upper surface in the deposited blast furnace raw material layer.

  FIG. 6 shows a layer of a blast furnace raw material that appears in a circular shape when the blast furnace raw material deposited in the substantially cylindrical lower bunker 6 is viewed in a plan view in a horizontal section. In the blast furnace raw material layer where the coke 2 and the ore 3 are separated, a state where the coke 2 and the ore 3 are separated in the circumferential direction is formed as shown by two arc-shaped two-way arrows in FIG. Is done. In the case of the embodiment of the present invention, the region formed by the coke 2 in the separated layer is a fan-shaped region having a central angle of 90 degrees. Therefore, the region formed by the ore 3 is a fan-shaped region having a central angle of 270 degrees. appear.

  The center angle of 90 degrees and the area of the fan formed by the coke 2 is about one-fourth of the entire perfect circle. Of the four ports 51, 53, 55, and 57 of the upper bunker 5, only one port 53 is used. This is because the coke 2 falls. Of course, the mixing ratio of the coke 2 and the ore 3 separated from each other in the circumferential direction varies depending on the number of all ports provided in the upper bunker 5.

Thereafter, the port 61 provided at the bottom of the lower bunker 6 is opened, the coke 2 and the ore 3 transferred to the lower bunker 6 are dropped to the bellless blast furnace 1 side, and charged into the bellless blast furnace 1 from the furnace turning chute 11. Then, the coke mixed ore layer 13 is formed inside the bell-less blast furnace 1.
In addition, it is preferable that the quantity of the coke 2 mixed with the coke mixed ore layer 13 shall be 10 mass% or more and 50 mass% or less with respect to the total coke amount charged from a furnace top. That is, the amount of coke 2 to be charged for each batch is 10% by mass or more and 50% by mass or less with respect to the total amount of coke existing in the bellless blast furnace 1 as the coke layer 12 and the coke mixed ore layer 13. Set. When the ratio of the amount of coke 2 to the total amount of coke is less than 10% by mass, the amount of coke mixed with the ore layer is less than 10%, so the coke 2 in the coke mixed ore layer 13 reaches the cohesive zone. This is because the gasification reaction completely eliminates the air permeability and the air permeability improvement effect cannot be expected. When the ratio of the amount of coke 2 to the total amount of coke exceeds 50% by mass, the thickness of the coke layer laminated in the blast furnace is thinned so that the air permeability is deteriorated in the cohesive zone, and mixing is caused by charging. This is to offset the effect of improving the air permeability of the ore layer. Further, the port 53 for fixing the position of the tip 10a of the upper turning chute 10 upward is preferably changed for each batch in order to eliminate the circumferential deviation of the blast furnace raw material in the upper bunker 5.

  As shown in FIGS. 2 to 6, when the deposition state of the coke 2 and the ore 3 in the furnace top bunker 4 is formed, the coke 2 and the ore 3 of the lower bunker 6 are discharged at a discharge ratio as shown in FIG. 7, for example. Then, it is discharged from the lower bunker 6 and charged into the bell-less blast furnace 1. FIG. 7 shows the completion of the discharge of the raw material deposited at each position with respect to the total time when all the raw materials are discharged after opening the port 61 in the storage facility formed to reduce the diameter downward. The percentage of time until is shown. As shown in FIG. 7, the blast furnace raw material located almost directly above the port 61 is discharged first, then the blast furnace raw material around the first dropped blast furnace raw material is discharged second, and then dropped second. The blast furnace raw material around the blast furnace raw material is discharged.

  Therefore, in the embodiment of the present invention, the coke 2 charged into the upper bunker 5 is transferred from the single port 53 to the lower bunker 6. A part of the ore 3 put into the upper bunker 5 is transferred to the lower bunker 6 from the port 53 and most of the ore 3 is transferred from the other three ports 51, 55, 57. In the lower bunker 6, the coke 2 and the ore 3 can be deposited in a state separated in the circumferential direction. Therefore, when the coke 2 and the ore 3 are charged into the bell-less blast furnace 1 from the lower bunker 6, the coke 2 and the ore 3 are discharged in the order shown in FIG. The mixing ratio between the coke 2 and the ore 3 becomes constant. In this way, when the coke 2 and the ore 3 are charged into the bellless blast furnace 1 from the furnace top bunker 4 arranged at the top of the bellless blast furnace 1, the coke mixed ore layer 13 is formed in the blast furnace. The blast furnace raw material can be charged into the bell-less blast furnace 1 while keeping the mixing ratio of the coke 2 and the ore 3 substantially constant.

  The present inventors investigated the temporal change of the coke mixing ratio in the ore discharged from the lower bunker 6. The survey results are shown in FIG. FIG. 8A shows a case where coke 2 and ore 3 are simultaneously charged into a raw material tank to form a mixed raw material, and then a mixed raw material of coke 2 and ore 3 is charged into an upper bunker 5 from a lower bunker 6. The time change of the coke mixing rate in the blast furnace raw material when discharged (comparative example) is shown. FIG. 8B shows a temporal change in the coke mixing ratio in the blast furnace raw material discharged from the lower bunker 6 when the embodiment of the present invention is applied (Example).

  In the comparative example, although the coke mixing ratio in the blast furnace raw material discharged from the lower bunker 6 is as large as about 0.15 to 0.12 at the initial stage of discharging, it decreases to 0.10 or less from the middle discharging stage and discharged. It can be seen from FIG. 8 (a) that at the end stage, it drops to about 0.07. On the other hand, in the embodiment of the present invention, the coke mixing ratio in the blast furnace raw material discharged from the lower bunker 6 is generally within the range of about 0.09 to 0.12, and does not change greatly from the initial discharge to the final discharge. It can be seen from FIG.

  Therefore, as in the above-described embodiment of the present invention, with the position of the tip 10a of the upper turning chute 10 fixed, the raw material is charged into the upper bunker 5 in the order of coke 2 and ore 3, and the upper bunker 5 When the raw material is transferred to the bunker 6, the coke 2 and the ore 3 are charged into the bellless blast furnace 1 from the lower bunker 6 and the coke mixed ore layer 13 is formed in the blast furnace. The blast furnace raw material can be charged into the bell-less blast furnace 1 while maintaining the mixing rate substantially constant from the beginning to the end of charging. Moreover, the influence of the segregation in the lower bunker 6 due to the difference in particle size of the blast furnace raw material can be reduced.

  Moreover, when the coke 2 and the ore 3 are charged into the bell-less blast furnace 1 by the method according to the comparative example and the method according to the embodiment of the present invention, the ventilation resistance index and gas utilization rate of the blast furnace are measured. The results are shown in Table 1.

  When coke 2 and ore 3 were charged into the bellless blast furnace 1 by the method according to the comparative example, as shown in Table 1, the airflow resistance index was 2.35, and the gas utilization rate was 47.9%. Indicated. The coke ratio was 389, and the reducing material ratio was 499. On the other hand, when the coke 2 and the ore 3 were charged into the bell-less blast furnace 1 by the method according to the embodiment of the present invention, the ventilation resistance index was 2.31, and the gas utilization rate was 48.3%. The coke ratio was 386, and the reducing material ratio was 496.

When it was charged by the method according to the embodiment of the present invention, the gas resistance was increased while the ventilation resistance index was lowered. Moreover, coke ratio and reducing material ratio became a lower value than the method which concerns on a comparative example. From the results of Table 1, it was confirmed that the method according to the embodiment of the present invention is effective for stable operation of a blast furnace and can be used as a low reducing material ratio operation technique.
As mentioned above, although the charging method of the blast furnace raw material which concerns on embodiment of this invention has been demonstrated, the charging method of the blast furnace raw material which concerns on this invention is not limited to described embodiment, The summary of this invention is obtained. It is possible to change appropriately without changing. For example, although there is only one tip 10a of the upper turning chute 10 according to the embodiment of the present invention, the tip on the exit side may be branched into two. If the angle between the two tips of the chute is set so that one port is located under each of the two branched tips, the same effect as the embodiment of the present invention can be obtained. .

  In the present invention, the coke was charged and deposited only on some of the plurality of ports of the upper bunker, and then ore was further poured on the deposited coke and flowed into the other ports. Above, all the ports of the upper bunker may be opened and the coke and ore may be transferred to the lower bunker.

1 Belleless Blast Furnace 2 Coke 3 Ore 4 Top Bunker 5 Upper Bunker 6 Lower Bunker 7 and 8 Raw Material Tank 10 Upper Turning Chute 10a Tip 12 Coke Layer 13 Coke Mixed Ore Layer 51, 53, 55, 57 Ports 52, 54, 56, 58 gate

Claims (3)

There is a center feed type bellless raw material charging device in which a lower bunker provided at the top of the furnace and an upper bunker provided above the lower bunker and connected by a plurality of ports are arranged in two upper and lower stages. A method for charging a blast furnace raw material in a bell-less blast furnace,
The position of the tip of the chute provided in the upper bunker is fixed above a part of the ports of the plurality of ports, and the coke is thrown into only the part of the ports through the chute , the part of the ports Depositing the coke on
On the deposited coke, the ore is poured through the chute while the position of the chute at the time of the coke charging is fixed, and the ore flows into the other ports of the plurality of ports, and the other Depositing the ore on a port of
Transferring the coke and ore deposited in the upper bunker to the lower bunker;
Charging the coke and the ore transferred to the lower bunker into the bell-less blast furnace to form a coke mixed ore layer. The blast furnace raw material charging method according to claim 1 , wherein the chute is a turning chute. The coke quantity of coke mixture is mixed into the ore layer, the furnace with respect to the total amount of coke which is charged from the top, according to claim 1 or 2, characterized in that at least 10 wt% 50 wt% or less The charging method of the blast furnace raw material described in 1.

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