Method for charging reduced iron and method for operating a blast furnace using the same

Abstract

This invention provides a method for charging reduced iron that can avoid wear and tear on the furnace body and enable stable operation of the blast furnace. [Solution] A method for charging reduced iron is employed, in which iron-based raw materials and coke are transported to the top of a blast furnace by a conveyor belt, and an ore layer composed of iron-based raw materials containing reduced iron and sintered ore, and a coke layer composed of coke are charged into the blast furnace using a bellless charging method and deposited alternately, characterized in that 90 mass% or more of the reduced iron to be mixed in the iron-based raw materials per ore charge placed on the conveyor belt is placed behind the dimensionless position 0.5 on the conveyor belt.

Description

[[Technical Field]]

[0001] The present invention relates to a method for charging reduced iron and a method for operating a blast furnace using the same. [[Background Art]]

[0002] In the steel industry, the blast furnace process dominates the pig iron manufacturing process. In the blast furnace process, iron-based raw materials and coke are alternately and layeredly charged into the blast furnace from the top of the blast furnace as an ore layer and a coke layer respectively, while hot air is blown into the blast furnace from tuyeres at the lower part of the blast furnace. Here, the "iron-based raw material" refers to a raw material containing iron oxide, and is mainly sintered ore. Hereinafter, the "iron-based raw material" is also simply referred to as "ores". Further, the ores include at least one of sintered ore, lump ore, pellets, carbon-containing agglomerated ore and the like.

[0003] The hot air reacts with pulverized coal blown together with the hot air and coke in the blast furnace to generate high-temperature reducing gas (mainly CO gas herein). That is, the hot air gasifies the coke and the pulverized coal. The reducing gas ascends in the blast furnace and reduces the iron-based raw material while heating the same. The iron-based raw material descends in the blast furnace and is heated and reduced by the reducing gas. Thereafter, the iron-based raw material is melted and drips down in the blast furnace while being further reduced by coke. The iron-based raw material is finally stored in a hearth as molten iron (pig iron) containing slightly less than 5% by mass of carbon. The molten iron stored in the hearth is taken out from a taphole and supplied to the subsequent steelmaking process. As described above, in the blast furnace process, carbonaceous materials such as coke and pulverized coal are used as reducing agents.

[0004] Incidentally, in recent years, there has been a growing call to prevent global warming, and a reduction in emissions of carbon dioxide (CO2 gas), one of the greenhouse gases, is desired. As mentioned above, the blast furnace method uses carbon as a reducing agent, which generates a large amount of CO2 gas. Therefore, the steel industry is one of the major industries in terms of CO2 gas emissions, and it is desired that it respond to the social demand to reduce CO2 emissions. Specifically, there is an urgent need to further reduce the reducing agent ratio (amount of reducing agent used per ton of molten iron) in blast furnace operations.

[0005] In blast furnace operation, the mixing and charging of reduced iron is being promoted with the aim of reducing the reducing agent ratio (RAR) and improving the permeability of the ore layer. However, reduced iron generally has a higher density and much higher strength than ore raw materials such as sintered ore and coke. Therefore, if reduced iron is repeatedly charged into the furnace in a way that it directly hits the ore receiving hardware installed at the furnace opening, it may wear down the hardware. In addition, reduced iron charged close to the furnace wall may wear down the staves during its subsequent descent into the furnace. For this reason, when charging reduced iron into a blast furnace, it is being considered to reduce the amount charged near the furnace wall in order to protect the furnace body.

[0006] Here, Patent Document 1 describes a method for operating a blast furnace in which iron ore and coke are charged from the top of the furnace and hot air is blown in from the tuyeres to produce pig iron, characterized in that small-particle reduced iron is charged only to the periphery of the furnace in the radial direction.

[0007] Patent Document 2 describes a pig iron manufacturing method using a blast furnace having tuyeres, comprising the steps of alternately stacking a first layer containing ore raw materials and a second layer containing coke in the blast furnace, and reducing and dissolving the stacked ore raw materials in the first layer while blowing auxiliary fuel into the blast furnace with hot air blown from the tuyeres, wherein aggregate for allowing the hot air to pass to the center of the blast furnace is mixed in the first layer, and the aggregate includes a reduced iron molded body obtained by compression molding of reduced iron.

[0008] Patent Document 3 describes a method for charging raw materials into a blast furnace using a bellless charging device, in which iron sources and carbon materials are deposited in layers as raw materials into the blast furnace, characterized in that a portion of the raw materials is designated as a specific raw material, the remaining raw materials other than the specific raw material are charged so as to form recesses in the radial range of 0.2R to 0.9R, with the furnace opening radius of the deposited surface being R, and then the specific raw material is charged into the recesses.

[0009] Patent Document 4 describes a method for charging iron ore and coke along with iron raw materials such as reduced iron and scrap into a blast furnace, characterized in that the particle size of the iron raw materials is adjusted to be larger than the particle size of the charged iron ore but smaller than the particle size of the charged coke, and the timing of charging the iron raw materials is before charging the iron ore after charging the coke. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 11-315308 [Patent Document 2] Japanese Patent Publication No. 2022-042774 [Patent Document 3] Japanese Patent Publication No. 2001-064705 [Patent Document 4] Japanese Patent Publication No. 2001-271104 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The inventions described in Patent Documents 1 and 2 involve a method of charging reduced iron into the furnace wall, which carries the risk of wear and tear on the furnace wall inside the blast furnace, specifically the staves and ore receiving hardware. When the staves wear down, the loading of raw materials along the furnace wall becomes uneven, resulting in fluctuations in gas flow and making it impossible to maintain stable operation. Furthermore, if the wear progresses and damages the internal cooling water piping, water will enter the blast furnace, severely degrading operations. Regarding the ore receiving hardware, wear and tear increases the frequency of replacement, leading to disadvantages such as increased downtime and higher costs. In addition, the way the charged raw materials bounce off upon impact changes, which may prevent the formation of the desired deposit shape, potentially making it impossible to maintain stable operation. Furthermore, in the inventions described in Patent Documents 3 and 4, reduced iron was not mixed into the ore raw material, resulting in insufficient reduction of the reducing agent ratio (RAR). Based on these findings, there was room for further reduction in the reducing agent ratio during blast furnace operation.

[0012] The present invention has been made in view of the above circumstances, and aims to provide a method for charging reduced iron and a method for operating a blast furnace using the same, which can avoid wear and tear on the furnace body and enable stable operation of the blast furnace. [Means for solving the problem]

[0013] To solve the above problems, the present invention adopts the following configuration. (1) Iron-based raw materials and coke are transported to the top of the blast furnace by a conveyor belt. An ore layer composed of the iron-based raw materials including reduced iron and sintered ore, A coke layer composed of the aforementioned coke, A method for charging reduced iron, wherein reduced iron is charged into the furnace of the blast furnace by a bellless charging method and deposited alternately, A method for charging reduced iron, characterized in that 90 mass% or more of the reduced iron contained in the iron-based raw material per ore charging, which is placed on the conveying conveyor, is placed behind the dimensionless position 0.5 on the conveying conveyor. (2) Iron-based raw materials and coke are conveyed to the top of a blast furnace by a conveying conveyor, an ore layer composed of said iron-based raw material containing reduced iron and sintered ore; a coke layer composed of said coke; a method for charging reduced iron, wherein said layers are charged into the blast furnace by a bell-less charging method and alternately deposited, the method comprising: when charging said reduced iron into the blast furnace with a rotating chute, a method for charging reduced iron, characterized in that the reduced iron is charged at a charging position located closer to the center than a dimensionless radius 0.9 of the blast furnace. (3) conveying said iron-based raw material and said coke to the top of the blast furnace by said conveying conveyor, said ore layer composed of said iron-based raw material containing said reduced iron and said sintered ore; said coke layer composed of said coke; a method for charging reduced iron, wherein said layers are charged into the furnace by a bell-less charging method and alternately deposited, the method comprising: when charging said reduced iron into the blast furnace with a rotating chute, when the time required for charging the iron-based raw material in one charging operation is defined as dimensionless charging time 1, the method for charging reduced iron according to (1), characterized in that charging at a position closer to the center than the dimensionless radius 0.9 of the blast furnace is performed after dimensionless charging time 0.3. (4) A method for operating a blast furnace, characterized in that the reduced iron is charged into the blast furnace by the method for charging reduced iron according to any one of (1) to (3). Effects of the Invention

[0014] According to the present invention, it is possible to provide a method for charging reduced iron capable of avoiding wear of the furnace body and realizing stable blast furnace operation, and a method for operating a blast furnace using the same. Brief Description of the Drawings

[0015] [Figure 1] A schematic diagram of the blast furnace according to the present embodiment. [Figure 2] A schematic diagram of the packaging of reduced iron on a conveyor belt according to this embodiment. [Figure 3] A schematic diagram of the packaging of reduced iron on a conveyor belt, which is a comparative example to this embodiment. [Figure 4] A schematic diagram of the test apparatus used in the embodiments of the present invention. [Figure 5] This figure shows the evaluation results of a method for transporting reduced iron, which is one embodiment of the present invention. [Figure 6] This figure shows the evaluation results of a method for transporting and charging reduced iron, which is one embodiment of the present invention. [Figure 7] This figure shows the evaluation results of a method for transporting and charging reduced iron, which is one embodiment of the present invention. [Figure 8] This figure shows the evaluation results of a method for transporting and charging reduced iron, which is one embodiment of the present invention. [Figure 9] This figure shows the evaluation results of a comparative example of the present invention: a method for transporting reduced iron and a method for charging iron. [Modes for carrying out the invention]

[0016] Previously, in blast furnace operations where reduced iron was mixed with iron-based raw materials and charged into the furnace, the reduced iron was first mixed with the iron-based raw materials to form a mixture, which was then transported to the top of the furnace and charged into it. The inventors of this invention have diligently studied a method for charging reduced iron and iron-based raw materials into a furnace such that the reduced iron does not directly collide with the ore receiving hardware and that the reduced iron accumulates while avoiding the vicinity of the furnace wall.

[0017] As a result, the inventors discovered that when transporting iron-based raw materials containing reduced iron by a conveyor, the arrangement of reduced iron on the conveyor should be set such that reduced iron is not charged into the furnace in the initial stages of charging, and more is charged in the latter half of the charging process. Furthermore, they found that, as a condition for the rotating chute during charging, the furnace body can be avoided by controlling the position where the raw material falls away from the wall when the reduced iron is charged into the furnace. The following describes an embodiment of the present invention: a method for charging reduced iron and a method for operating a blast furnace using the same.

[0018] The method for charging reduced iron according to this embodiment involves transporting iron-based raw materials and coke to the top of a blast furnace by a conveyor belt, and charging an ore layer composed of iron-based raw materials containing reduced iron and sintered ore, and a coke layer composed of coke, into the blast furnace using a bellless charging method and stacking them alternately. The method is characterized in that 90 mass% or more of the reduced iron contained in the iron-based raw materials per ore charge placed on the conveyor belt is positioned behind a dimensionless position of 0.5 on the conveyor belt. Furthermore, the method for charging reduced iron in this embodiment involves transporting iron-based raw materials and coke to the top of the blast furnace by a conveyor belt, and charging an ore layer composed of iron-based raw materials including reduced iron and sintered ore, and a coke layer composed of coke, into the blast furnace using a bellless charging method and stacking them alternately. The method is characterized in that when charging the reduced iron into the blast furnace using a swirling chute, the charging position of the reduced iron is positioned on the side of the blast furnace's dimensionless radius of 0.9.

[0019] There are two main methods for charging blast furnace materials into a blast furnace: the bell-type and the bell-less type. The bell-type charging method involves dropping the blast furnace materials, held on an umbrella-shaped buffer device, all at once. The bell-less charging method involves charging the materials while rotating a chute-shaped device inside the furnace. In this embodiment, reduced iron is charged using the bell-less method. With the bell-type charging method, the controllability of the amount and position of iron-based materials and coke charged into the blast furnace is inferior to that of the bell-less method.

[0020] Figure 1 shows the top charging device 20 used in blast furnace operation according to this embodiment. The furnace top charging device 20 according to this embodiment is attached to the top of the blast furnace 10. The furnace top charging device 20 includes a transport conveyor 25, a switching chute 26, a pair of furnace top hoppers 27, a collection hopper 28, and a swivel chute 30. The blast furnace 10 is equipped with an ore receiving fitting 32 and a stave 35 on its interior. In the following description, the ore receiving fitting 32 and the stave 35 may be collectively referred to as the "furnace wall" of the blast furnace.

[0021] Blast furnace raw materials, including iron-based raw materials and coke, are transported to the switching chute 26 by a conveyor belt 25. After being stored in a pair of furnace top hoppers 27 from the switching chute 26, they are transported through a collection hopper 28 to the swivel chute 30.

[0022] The rotating chute 30 rotates around a pivot axis R, as indicated by arrow A, and the pivot axis R coincides with the center of the blast furnace. While the rotating chute 30 is rotating, the iron-based raw materials and coke supplied to the rotating chute 30 from the collection hopper 28 accumulate inside the blast furnace 10.

[0023] Iron-based raw materials and coke are charged from the swivel chute 30, and inside the blast furnace 10, layers of ore and coke are formed alternately. One charge of blast furnace raw materials (supplying a predetermined weight of blast furnace raw materials from the hopper to the swivel chute 30 and charging it into the blast furnace 10) is called a dump, and the unit of repeated charging that forms a pair of layers, an ore layer and a coke layer, by accumulating blast furnace raw materials inside the furnace is called a charge. When forming a coke layer, coke may be charged by multiple dumps, and when forming an ore layer, iron-based raw materials may be charged by multiple dumps.

[0024] When blast furnace raw materials are charged into the blast furnace 10, the rotating chute 30 rotates around the rotation axis R and changes the angle θ at which the rotating chute 30 is tilted with respect to the rotation axis R (called the tilt angle).

[0025] (Method of charging reduced iron using a conveyor belt) The method for charging reduced iron into the blast furnace 10 will be described below. Figure 2 shows a schematic diagram of iron-based raw materials arranged on a conveyor belt 25. In Figure 2, the direction of conveyance F is considered the front or forward side, and the opposite direction is considered the rear. In the method for charging reduced iron 1 according to this embodiment, 90 mass% or more of the reduced iron contained in the iron-based raw materials per ore dump placed on the conveyor is placed behind the dimensionless position 0.5 on the conveyor, and the reduced iron is charged.

[0026] When iron-based raw materials are charged into the blast furnace 10, there is a concern that they may collide with the furnace wall, especially in the initial stages of charging. When transporting the iron-based raw materials for each layer of ore, the arrangement of reduced iron 1 is as described above, so that the sintered ore 2 is charged into the blast furnace 10 first, followed by the reduced iron 1. This charging method prevents the reduced iron 1 from colliding with the furnace wall of the blast furnace 10. If the arrangement of 90 mass% or more of the reduced iron 1 contained in the iron-based raw materials per dump is not located 0.5 rear from the front of the conveyor belt 25 at a dimensionless position, there is a risk that reduced iron 1 will be mixed in during the initial stages of charging the iron-based raw materials, and that reduced iron 1 will accumulate near the furnace wall. This may cause wear on the ore receiving hardware 32 and staves 35, potentially accelerating the wear of the blast furnace 10.

[0027] In Figure 2, the iron-based raw materials for each ore dump are arranged continuously, but the iron-based raw materials do not necessarily have to be arranged continuously on the conveyor belt 25. That is, in Figure 2, the sintered ore 2 at the front 0.5 min of the dimensionless position may be charged into the top hopper 27 first, and then the sintered ore 2 and reduced iron 1 at the rear 0.5 min may be charged into the top hopper 27, and the combined product in the top hopper 27 may be charged into the blast furnace 10. Alternatively, the transport of iron-based raw materials for each ore dump to the blast furnace 10 as shown in Figure 2 may be divided into three or more transports to the top hopper 27, and then all of them may be charged into the blast furnace 10.

[0028] Furthermore, although Figure 2 shows reduced iron 1 and sintered ore 2 separated into two layers, they may also be transported in a mixed state. That is, the reduced iron 1 and sintered ore 2 may be transported in a mixed state from 0.5 rearward at a dimensionless position on the transport conveyor 25 and then charged into the blast furnace 10.

[0029] (Method of charging reduced iron using a rotating chute) The above describes the method of charging reduced iron by conveying it using the conveyor belt 25. The following describes the method of charging reduced iron 1 into the blast furnace 10 using the rotating chute 30.

[0030] The method for charging reduced iron 1 into a blast furnace 10 according to this embodiment is characterized in that, when charging the reduced iron into the blast furnace using a rotating chute, the charging position of the reduced iron is located on the side of the blast furnace's dimensionless radius of 0.9.

[0031] The iron-based raw materials and coke transported to the top of the furnace pass through the collection hopper 28, move to the swirling chute 30, and are charged into the blast furnace 10.

[0032] When charging blast furnace materials into the blast furnace 10, the tilt angle θ of the rotating chute 30 is varied. This operation allows control of the charging position of the blast furnace materials in the dimensionless radial direction within the blast furnace 10. In this embodiment, when the dimensionless radial direction of the horizontal cross-section of the blast furnace 10 is defined as 0 to 1 (0: center of the blast furnace 10 to 1: furnace wall inside the blast furnace 10), when charging reduced iron 1 into the blast furnace 10, the reduced iron 1 is charged at a position less than 0.9 in the dimensionless radial direction.

[0033] The above-described charging method prevents reduced iron from accumulating near the furnace wall of the blast furnace 10, thereby suppressing wear and tear on the blast furnace 10. If the charging position of reduced iron 1 is greater than 0.9 in the dimensionless radial direction, the reduced iron 1 may accumulate near the furnace wall of the blast furnace 10, potentially accelerating the wear of the furnace wall.

[0034] The above describes the method for transporting reduced iron 1 to the blast furnace 10 according to this embodiment. By satisfying either the transport method or the charging method described above, the accumulation of reduced iron 1 near the furnace wall inside the blast furnace can be suppressed, and wear and tear on the furnace body can be avoided. Furthermore, it is more preferable to operate the blast furnace by combining the transport method and the charging method described above.

[0035] Furthermore, when applying the above-described configuration of reduced iron 1 on the conveyor belt 25, a modified version of the method for charging reduced iron 1 using the swivel chute 30, as shown below, may be used instead of the above-described method for charging reduced iron 1 using the swivel chute 30.

[0036] (A modified method of charging reduced iron using a swivel chute) The method for charging reduced iron 1 in this embodiment may also be modified as described below. A modified version of the reduced iron 1 charging method of this embodiment is a reduced iron charging method in which iron-based raw materials and coke are transported to the top of the furnace by a conveyor belt, and an ore layer composed of iron-based raw materials including reduced iron and sintered ore, and a coke layer composed of coke are charged into the furnace by a bellless charging method and deposited alternately, characterized in that of the reduced iron contained in the iron-based raw materials for each ore charge placed on the conveyor belt 25, 90 mass% or more of the reduced iron is placed behind the dimensionless position 0.5 of the conveyor belt, and when the reduced iron is charged into the blast furnace by a swivel chute, when the time required to charge the iron-based raw materials in one charging operation is defined as the dimensionless charging time 1, the charging position from the dimensionless charging time 0.3 onwards is charged to the center of the dimensionless radius 0.9 of the blast furnace.

[0037] This modified method involves charging sintered ore 2 to the furnace wall side of the blast furnace 10, and then charging reduced iron 1 towards the center of the furnace, which can more effectively suppress the deposition of reduced iron 1 on the furnace wall. When 90 mass% or more of the reduced iron mixed with the iron-based raw materials per ore charge on the conveyor belt 25 is placed behind the dimensionless position 0.5 on the conveyor belt, and the reduced iron is transported in this manner, almost no reduced iron is mixed into the iron-based raw materials charged into the blast furnace 10 until the dimensionless time reaches 0.3. This allows for the charging of reduced iron while further suppressing wear on the furnace walls of the blast furnace 10. As described above, the method of charging reduced iron 1 according to this embodiment reduces the amount of reduced iron 1 charged near the furnace wall, thereby protecting the furnace body of the blast furnace 10. This avoids wear and tear on the furnace body, resulting in a stable blast furnace operation method while reducing the reducing agent ratio. [Examples]

[0038] The present invention will be specifically described below with reference to examples. Figure 4 shows 5000m 3 This shows a 1 / 3 scale test apparatus of a blast furnace. The test apparatus is equipped with a blower pipe 15 at the bottom of the blast furnace body 10 and a cutting device 16 at the very bottom. The blower pipe 15 and cutting device 16 can simulate the gas flow inside the blast furnace and the loading of the charged material. In this embodiment, iron-based raw materials containing reduced iron and sintered ore were transported to the furnace top hopper using two types of transport methods, transport A and transport B, as shown below. Subsequently, the iron-based raw materials for each ore layer were charged into the blast furnace using two types of charging methods, charging A and charging B. The outlines of each transport and charging method are as follows. After charging, the reduced iron 1 deposited in the furnace was divided into seven radial sections and sampled to confirm the amount of reduced iron 1 deposited at each location. The conditions for each charging location and charging method are shown in Table 1. Conveying A: As shown in Figure 2, the reduced iron is transported with the conveyor positioned behind the dimensionless position 0.5. Conveying method B: As shown in Figure 3, the reduced iron is transported with the conveyor positioned ahead of the dimensionless position 0.5 during transport. Charge A: The iron-based raw materials are charged in one layer of ore on the side of the dimensionless radius of 0.9 inside the blast furnace. Charge B: After a dimensionless charging time of 0.3 during the charging of iron-based raw materials, the charging is carried out towards the center of the blast furnace, beyond the dimensionless radius of 0.9.

[0039] Note that "dimensionless radius = 1" refers to the furnace wall of blast furnace 10. "Dimensionalless radius of charging position > 1" indicates that if there were no furnace wall of blast furnace 10, the iron-based raw materials would be charged outside the furnace wall. In other words, the condition that the charging position of the iron-based raw materials is greater than a dimensionless radius of 1 is the condition that the iron-based raw materials are charged by colliding with the furnace wall.

[0040] [Table 1]

[0041] First, as a comparison between transport A and transport B, when the reduced iron 1 transported by each method was charged into the furnace, the reduced iron 1 and sintered ore 2 being charged were periodically sampled to confirm the change in the amount of reduced iron at the time of furnace loading. The results are shown in Figure 5. As in the present invention, under the condition that reduced iron 1 is transported to the blast furnace 10 by transport A, it can be confirmed that almost no reduced iron 1 is charged into the furnace within a dimensionless charging time of less than 0.3. On the other hand, as in the comparative example, when reduced iron 1 is transported to the blast furnace 10 by transport B, there is a concern that reduced iron 1 will be charged into the furnace from the initial stage of charging, and that the reduced iron 1 will directly collide with the furnace wall.

[0042] Figure 6 shows the radial accumulation of reduced iron 1 in the blast furnace 10 in an example where reduced iron 1 is transported by transporter A and charged into the blast furnace by charger A. The vertical axis shows the amount of reduced iron 1 charged at each sampling position, with the total radial sampling amount set to 1. The horizontal axis shows the dimensionless radial position within the blast furnace 10, where 0 is the center of the blast furnace 10 and 1 is the furnace wall of the blast furnace 10. As a result, it can be confirmed that there is almost no reduced iron 1 present in the furnace wall in the radial direction from 0.8 to 1.

[0043] Figure 7 shows the amount of reduced iron 1 deposited radially within the blast furnace in an example where reduced iron 1 was transported by transporter A and charged into the blast furnace 10 by charging B. This result also confirms that there is almost no reduced iron 1 near the furnace wall in the radial direction 1. Furthermore, during testing with this test apparatus, visual observation of the charged material falling from the rotating chute 30 confirmed that the charged material that collided with the furnace wall fell almost straight down after impact. That is, the charged material located at the dimensionless position 0.8 in the radial direction within the blast furnace did not bounce off the furnace wall, but rather was charged at the dimensionless position 0.8 in the radial direction within the blast furnace. In other words, it has been confirmed that by evaluating the deposition position of reduced iron 1, it is possible to indirectly evaluate whether or not reduced iron 1 collided with the furnace wall.

[0044] Figure 8 shows the amount of reduced iron 1 deposited radially in the blast furnace in an example where reduced iron 1 was transported by transporter B and charged into the blast furnace 10 by charger A. This result also confirms that there is almost no reduced iron 1 near the furnace wall in the radial direction 1.

[0045] Figure 9 shows the amount of reduced iron 1 deposited radially in the blast furnace in a comparative example where reduced iron 1 was transported by transporter B and charged into the blast furnace 10 by charger B. In the comparative example, it can be seen that a large amount of reduced iron 1 is deposited near the furnace wall in the radial direction 1. From the above, it is suggested that the method of charging reduced iron 1 according to the present invention can prevent the accumulation of reduced iron 1 near the furnace wall inside the blast furnace 10, and that operation can be carried out without damaging the ore receiving hardware or staves.

[0046] Based on the above results, it was found that the method of charging reduced iron according to the present invention enables superior blast furnace operation with a further reduction in the reducing agent ratio. [Explanation of symbols]

[0047] 1. Reduced iron 2. Sintered Ore 10 blast furnace 15. Air supply piping 16 Cutting equipment 20 Top charging device 25 Conveying device 26 Switch Shot 27. Top Hopper 30. Swinging Shot 32. Ore holding hardware 35 Steve F Conveying direction R rotation axis A Turning direction θ Tilt angle

Claims

1. Iron-based raw materials and coke are transported to the top of the blast furnace by a conveyor belt. An ore layer composed of the iron-based raw materials including reduced iron and sintered ore, A coke layer composed of the aforementioned coke, A method for charging reduced iron, wherein reduced iron is charged into the furnace of the blast furnace by a bellless charging method and deposited alternately, A method for charging reduced iron, characterized in that 90 mass% or more of the reduced iron contained in the iron-based raw material per ore charging, which is placed on the conveying conveyor, is placed behind the dimensionless position 0.5 on the conveying conveyor.

2. Iron-based raw materials and coke are transported to the top of the blast furnace by a conveyor belt. An ore layer composed of the iron-based raw materials including reduced iron and sintered ore, A coke layer composed of the aforementioned coke, A method for charging reduced iron, wherein reduced iron is charged into the furnace of the blast furnace by a bellless charging method and deposited alternately, When the reduced iron is charged into the blast furnace using a rotating chute, A method for charging reduced iron, characterized in that the charging position of the reduced iron is located on the side of the dimensionless radius of the blast furnace that is 0.

9.

3. The iron-based raw materials and the coke are transported to the top of the blast furnace by the conveyor. The ore layer is composed of the iron-based raw materials, including the reduced iron and the sintered ore, The coke layer, which is composed of the aforementioned coke, A method for charging reduced iron, which involves charging it into a furnace using a bellless charging method and stacking it alternately, When the reduced iron is charged into the blast furnace using a rotating chute, When the time required to charge the iron-based raw material in one charging operation is defined as the dimensionless charging time of 1, The method for charging reduced iron according to claim 1, characterized in that the charging position after a dimensionless charging time of 0.3 is located on the central side of the dimensionless radius of the blast furnace of 0.

9.

4. A method for operating a blast furnace, characterized in that the reduced iron is charged into the blast furnace by the method for charging reduced iron described in any one of claims 1 to 3.

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