Method for charging raw material into blast furnace

Abstract

To provide a method for charging a raw material into a blast furnace, capable of achieving an intended particle size distribution of the raw material in a furnace top bunker, and thereby obtaining a desired particle size distribution of the raw material in the blast furnace.SOLUTION: The method includes controlling, for each selected furnace top bunker, a charging direction of a raw material from a raw material charging furnace top bunker switching device into the furnace top bunker.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a method for charging raw materials into a blast furnace. [Background technology]

[0002] As shown in Figure 1, a top bunker is installed at the top of a bell-less blast furnace to temporarily store raw materials transported by a belt conveyor (hereinafter also referred to as a charging belt conveyor or charging BC) from a raw material storage tank installed on the ground. Note that ore raw materials such as sinter, pellets, and lump ore, as well as coke, are collectively referred to as raw materials. A blast furnace with two or more top bunkers arranged in parallel, as shown in Figure 2, is generally called a parallel bunker blast furnace. In such a parallel bunker blast furnace, a raw material charging top bunker switching device is installed above the top bunker. The raw materials transported by the belt conveyor are then charged into one of the top bunkers selected by the raw material charging top bunker switching device via the raw material charging top bunker switching device, and the raw materials are stored in that top bunker. The raw materials stored in the top bunker are discharged from the top bunker as appropriate and charged into the blast furnace according to the operation of the blast furnace. In the figure, reference numeral 1 denotes a charging belt conveyor, 2 denotes a raw material charging furnace top bunker switching device, 3 denotes a casing, 4 denotes a raw material flow passage, 5 denotes a movable control plate, and 6 denotes a furnace top bunker.

[0003] In blast furnace operation, the flow of reducing gas within the blast furnace affects the reduction efficiency of ore raw materials and the amount of heat dissipated outside the blast furnace. Raw material particle size varies to a certain extent, and the particle size distribution of the raw materials within the blast furnace can cause uneven flow of reducing gas within the blast furnace. Therefore, technologies have been investigated that intentionally segregate the raw materials by particle size when storing them in the furnace top bunker, thereby changing the particle size of the raw materials over time when they are discharged from the furnace top bunker, thereby achieving the desired particle size distribution of the raw materials within the blast furnace.

[0004] For example, Patent Document 1 states: "A raw material charging method for a blast furnace using a bell-less type charging device equipped with a rotating chute and bunkers arranged in parallel at the furnace top, When charging raw materials into a blast furnace through a furnace top bunker that temporarily stores the raw materials and discharges them into a rotating chute installed below, A tiltable movable plate is provided within the top bunker, and the raw materials charged into the top bunker are caused to collide with the movable plate. When the tip of the rotating chute is tilted from the periphery of the blast furnace toward the center, the movable plate is operated so that the direction of the falling raw materials is the direction of the discharge port of the top bunker, and the falling position of the raw materials charged into the top bunker is set directly above the discharge port of the raw materials, so that within the top bunker, due to the accumulation characteristics of the raw materials, fine particles gather near the discharge port and coarse particles gather at a position away from that. When tilting the tip of the rotating chute from the center of the blast furnace toward the periphery, the movable plate is operated so that the falling direction of the raw materials is opposite to the discharge port of the furnace top bunker, and the falling position of the raw materials charged into the furnace top bunker is set to the side wall away from the discharge port, so that the coarse raw materials gather near the discharge port and the fine raw materials gather far from the discharge port. A method for charging raw materials into a blast furnace using a furnace top bunker and a bell-less type charging device, characterized by depositing coarse particles in the center of the blast furnace. has been proposed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4591520 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the technology of Patent Document 1, there are cases where the intended particle size distribution of the raw materials is not necessarily obtained in the furnace top bunker, and improvements in this respect have been desired.

[0007] The present invention was developed in consideration of the above-mentioned current situation, and aims to provide a method for charging raw materials into a blast furnace that can achieve an intended particle size distribution of raw materials in a furnace top bunker and thereby obtain a desired particle size distribution of raw materials in the blast furnace. [Means for solving the problem]

[0008] The inventors have conducted extensive research to achieve the above object and have come to the following findings. (1) The particle size distribution of the raw materials in the top bunker is determined by the pile shape formed during the process of storing the raw materials in the top bunker. In other words, any disturbance in the pile shape of the raw materials can cause the particle size distribution of the raw materials in the top bunker to become unintended. (2) Normally, in a parallel bunker type blast furnace, when raw materials are charged into one top bunker selected by the raw material charging top bunker switching device, the switching chute of the raw material charging top bunker switching device is rotated so that the raw material discharge outlet of the raw material charging top bunker switching device is directly facing the one selected top bunker (in other words, in the horizontal plane, the center of rotation of the switching chute of the raw material charging top bunker switching device (hereinafter also referred to as the center of rotation), the center of the raw material discharge outlet of the raw material charging top bunker switching device, and the center of the top bunker are positioned on the same straight line. Hereinafter, this position will also be referred to as the directly facing position). (3) The raw materials transported from the charging BC to the top bunker switch retain the horizontal kinetic energy resulting from the transport of the charging BC when they are charged into the top bunker switch, and thus have a velocity in the direction of the charging BC's transport. Furthermore, in a parallel bunker-type blast furnace, as shown in Figure 2, two or more top bunkers are arranged in parallel. Therefore, the relative angle between the charging direction of the raw materials at the opposite position and the raw material transport direction of the charging BC varies for each top bunker, resulting in a different raw material charging trajectory (flow pattern) for each top bunker. This difference in the raw material charging trajectory for each top bunker affects the raw material pile shape and can lead to unintended grain size distribution within the top bunker. Furthermore, the discharge velocity from the discharge port of the top bunker switch changes depending on the raw material charging mass velocity, affecting the charging trajectory. As a result, in the worst case scenario, the raw material flow may change to the point where it does not collide with the structure and is directly charged into the top bunker, adversely affecting the raw material pile shape.

[0009] In light of the above, the inventors have conducted further intensive research. (4) As a result, the inventors discovered that by controlling the direction of raw material charging from the raw material charging top bunker switching device to the top bunker for each selected top bunker, for example, by shifting it from the directly opposite position depending on the relative angle between the raw material transport direction of the charging BC and the direction of the top bunker placement and the raw material charging mass speed, the differences in the raw material charging trajectory for each top bunker can be canceled out and the intended raw material particle size distribution can be achieved within the top bunker.

[0010] (5) In addition, the inventors have discovered that controlling the raw material charging position into the top bunker for each top bunker using a movable control plate arranged in the raw material flow path from the raw material charging top bunker switching device to each top bunker is also advantageous in offsetting differences in the raw material charging trajectory for each top bunker. The present invention was completed based on the above findings and further investigations.

[0011] That is, the gist and configuration of the present invention are as follows. 1. A method for charging raw materials into a blast furnace, comprising: The blast furnace is 2 or more furnace bunkers; a raw material charging top bunker switching device that is arranged above the top bunkers and charges raw materials transported by the charging belt conveyor into one selected top bunker from the top bunkers; and The raw material charging method for a blast furnace comprises: a process of charging the raw materials transported by the charging belt conveyor into the selected top bunker via the raw material charging top bunker switching device, causing the raw materials to collide with a structure arranged inside the top bunker, and then storing the raw materials in the top bunker; With A raw material charging method for a blast furnace, wherein the charging direction of the raw materials from the raw material charging furnace top bunker switching device to the furnace top bunker is controlled for each selected furnace top bunker.

[0012] 2. A method for charging raw materials into a blast furnace as described in 1 above, in which the direction in which the raw materials are charged is controlled according to the relative angle between the raw material transport direction of the charging belt conveyor and the arrangement direction of the furnace top bunker.

[0013] 3. A method for charging raw materials into a blast furnace according to 1 or 2 above, wherein the charging direction of the raw materials is controlled according to the mass velocity of the raw materials transported by the charging belt conveyor.

[0014] 4. A method for charging raw materials into a blast furnace described in any one of 1 to 3, in which the trajectory of raw materials being charged into the top bunker is controlled for each selected top bunker by a movable control plate arranged in the raw material flow path from the raw material charging top bunker switching device to the top bunker.

[0015] 5. A method for charging raw materials into a blast furnace as described in any one of 1 to 4 above, wherein the raw material collision surface of the structure is inclined downward from the top of the structure toward the end of the raw material collision surface at least in the eccentric direction of the furnace top bunker on which the structure is placed, the direction opposite to the eccentricity, and first and second directions perpendicular to the eccentric direction and the vertical direction. [Effects of the Invention]

[0016] According to the present invention, in a parallel bunker-type blast furnace, it is possible to realize an intended particle size distribution of raw materials in the top bunker regardless of the arrangement of the top bunker, and it is possible to obtain a desired particle size distribution of raw materials in the blast furnace. This improves the flow of reducing gas in the blast furnace during operation, making it possible to further improve gas permeability and reduction efficiency. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing how raw materials are stored in a furnace top bunker. [Figure 2] FIG. 1 is a schematic diagram showing an example of the arrangement of a furnace top bunker, a raw material charging furnace top bunker switching device, and a charging BC when viewed from above in the vertical direction. [Figure 3] FIG. 2 is a schematic diagram showing an example of the arrangement of each part of a top bunker when viewed from the horizontal direction. [Figure 4] FIG. 2 is a schematic diagram showing an example of the arrangement of each part of a top bunker when viewed from above in the vertical direction. [Figure 5] FIG. 2 is a schematic diagram showing an example of the shape (peripheral shape) from the top of the structure to the end of the raw material collision surface. [Figure 6] FIG. 2 is a schematic diagram showing an example of a structure installed inside a furnace top bunker. [Figure 7] FIG. 2 is a schematic diagram showing a preferred region where the top of the structure is located. [Figure 8] FIG. 1 is a schematic diagram of an apparatus used in the examples. [Figure 9] FIG. 1 is a schematic diagram showing the particle size distribution of the raw material of Test No. 1. [Figure 10] FIG. 1 is a schematic diagram showing the particle size distribution of the raw material of Test No. 2. [Figure 11] FIG. 1 is a schematic diagram showing the particle size distribution of the raw material of Test No. 3. [Figure 12] FIG. 1 is a schematic diagram showing the particle size distribution of the raw material of Test No. 4. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described based on the following embodiments.

[0019] A method for charging raw materials into a blast furnace according to one embodiment of the present invention includes: The blast furnace 2 or more furnace bunkers; a raw material charging top bunker switching device that is arranged above the top bunkers and charges raw materials transported by the charging belt conveyor into one selected top bunker from the top bunkers; and The raw material charging method for a blast furnace comprises: a process of charging the raw materials transported by the charging belt conveyor into the selected top bunker via the raw material charging top bunker switching device, causing the raw materials to collide with a structure arranged inside the top bunker, and then storing the raw materials in the top bunker; With The direction of the raw material being charged from the raw material charging top bunker switching device to the top bunker is controlled for each selected top bunker. The terms "upper," "lower," "top," and "lower" refer to the vertical direction unless otherwise specified. The direction referred to here is the direction with the center of rotation of the switching chute of the material charging furnace top bunker switching device in the horizontal plane as the reference point (center), and hereafter, the direction of material transport on the belt conveyor is represented as 0°, and the clockwise direction as viewed from above in the vertical direction is represented as +.

[0020] The blast furnace here is a parallel bunker-type blast furnace in which two or more top bunkers are arranged in parallel. The number of top bunkers is not particularly limited and can be set appropriately depending on the number of raw material types and the required volume of the bunkers, but is typically two to four. In such a parallel bunker-type blast furnace, as shown in FIG. 1, a top bunker switching device is installed above the top bunker. The raw materials transported by the charging BC are continuously charged into one top bunker selected by the top bunker switching device via the top bunker switching device, where they collide with a structure installed inside the top bunker and are stored in that top bunker. The raw materials stored in the top bunker are charged into the blast furnace as appropriate in accordance with the operation of the blast furnace. For example, by opening a flow rate control gate, the raw materials are gradually discharged under their own weight from the raw material discharge port at the bottom of the top bunker, and then charged into the blast furnace via a collecting hopper and a rotating chute.

[0021] In the method for charging raw materials into a blast furnace according to one embodiment of the present invention, it is extremely important to control the direction of raw material charging from the raw material charging top bunker switching device to the top bunker (hereinafter simply referred to as the raw material charging direction) for each selected top bunker. Here, the raw material charging direction is the direction in the horizontal plane from the center of rotation (center of rotation) of the switching chute of the raw material charging top bunker switching device to the center of the raw material discharge port of the raw material charging top bunker switching device.

[0022] As described above, the materials transported from the charging BC to the top bunker switching device retain the horizontal kinetic energy resulting from the transport of the charging BC, and move at a speed that is oriented in the direction of the charging BC. In a parallel bunker-type blast furnace, two or more top bunkers are arranged in parallel, as shown in Figure 2. Therefore, the relative angle between the charging direction of the materials at the opposite positions and the direction of the charging BC's material transport varies for each top bunker. Consequently, the charging trajectory (flow pattern) of the materials also varies for each top bunker. This difference in the charging trajectory of the materials for each top bunker affects the pile shape of the materials and can lead to unintended particle size distribution within the top bunker. To compensate for the difference in the charging trajectory of the materials for each top bunker, it is important to control the charging direction of the materials for each selected top bunker.

[0023] For example, it is preferable to control the raw material charging direction for each selected top bunker according to the relative angle between the raw material transport direction of the charging BC and the arrangement direction of the top bunker, and the raw material charging mass speed.

[0024] Here, the raw material transport direction of the charging BC is the running direction of the belt. The running direction of the belt is not particularly limited and can be set appropriately depending on the size of each device and the surrounding space, but from the perspective of ease of control, it is preferable to have the belt run toward the center of rotation (center of rotation) of the switching chute of the raw material charging top bunker switching device. Furthermore, the arrangement direction of the top bunker is the direction from the center of rotation (center of rotation) of the switching chute of the raw material charging top bunker switching device toward the center position of the top bunker in a horizontal plane. Note that the arrangement direction of the top bunker and the directly opposite position are usually the same direction. The mass velocity of the raw materials transported by the charging BC (raw material charging mass velocity) is the mass of raw materials supplied from the charging BC to the raw material charging top bunker switching device per unit time.

[0025] Furthermore, it is preferable to appropriately adjust the direction of raw material charging for each top bunker so that one end of the width of the raw material flow at the discharge port of the raw material charging top bunker switching device does not exceed the width of a movable control plate arranged in the raw material flow passage, and although it depends on the size of the control plate, it is preferable to control it within a range of ±5° from the position directly facing each top bunker. Note that the specific raw material charging direction for each top bunker can be determined, for example, by conducting tests using an actual machine, model experiments, numerical simulations, etc., and investigating the particle size distribution of the raw materials in the top bunker at that time.

[0026] Furthermore, it is preferable to control the trajectory of the raw materials, for example, the raw material charging position into the top bunker (the distance from the center of rotation (center of rotation) of the switching chute of the raw material charging top bunker switching device at the height level where the top of the structure installed inside the top bunker is located), for each selected top bunker using a movable control plate arranged in the raw material flow path from the raw material charging top bunker switching device to the top bunker, as shown in Figure 1. For example, it is preferable to adjust the raw material charging position into the top bunker according to the raw material charging mass velocity. Specifically, it is preferable to adjust the charging position so that the majority of the charged raw materials (80% or more of the total raw material flow) collide with the raw material collision surface of the structure installed inside the top bunker. The structure of the movable control plate is not particularly limited, and an example shape is shown in Figure 1. The operating mechanism is also not particularly limited, and examples include an electric-operated type and an air-operated type.

[0027] Next, an example of a raw material charging furnace top bunker switching device and a furnace top bunker used in a raw material charging method for a blast furnace according to one embodiment of the present invention will be described.

[0028] [Materials charging furnace top bunker switching device] The structure of the raw material charging top bunker switching device used in the raw material charging method for a blast furnace according to one embodiment of the present invention is not particularly limited as long as it can control the raw material charging direction for each top bunker, and an example of such a device is a switching chute type device as shown in Figure 1. In a switching chute type device, a switching chute having a raw material discharge port is rotated by a driving device such as an electric or pneumatic type to adjust the raw material charging direction.

[0029] [Furnace Bunker] The structure of the furnace top bunker used in the method for charging raw materials into a blast furnace according to one embodiment of the present invention is not particularly limited. For example, as shown in FIGS. 3 and 4, A raw material storage section; a raw material inlet for introducing raw material into the raw material storage section from above the raw material storage section; a structure disposed inside the top bunker and having a raw material collision surface on which the raw material charged from the raw material charging port collides; a raw material discharge port that discharges the raw material in the raw material storage section below the raw material storage section; An example of such a furnace top bunker is one that has the following features: In the figure, 6-1 is a raw material storage section, 6-2 is a raw material outlet, 6-3 is a raw material inlet, 6-4 is a structure, and 6-5 is a raw material collision surface.

[0030] The raw material inlet is located above the raw material storage section. The position of the raw material inlet in the horizontal plane is not particularly limited, but it is usually located on the axial side of the blast furnace from the center of the raw material storage section (in the same direction as the raw material discharge port).

[0031] The raw materials introduced through the raw material inlet collide with the raw material collision surface of the structure arranged inside the top bunker, then drop into the raw material storage section and are temporarily stored therein. The amount of raw materials temporarily stored in the raw material storage section is usually one batch's worth. The raw material storage section has a body section that is cylindrical, truncated cone-shaped, or a combination of these, and a tapered section whose diameter decreases downward. The maximum diameter (outer diameter) of the top bunker is usually about 4000 to 5000 mm, and the height of the top bunker is about 9000 to 13000 mm.

[0032] Furthermore, the shape of the structure placed inside the furnace top bunker is not particularly limited. However, as shown in FIG. 3, for example, it is preferable that the shape of the raw material collision surface be inclined downward from the top of the structure (raw material collision surface) toward the end of the raw material collision surface at least in the eccentric direction, the direction opposite to the eccentricity, and in a first direction and a second direction perpendicular to the eccentric direction and the vertical direction. Here, the eccentricity direction is defined as the direction from the center of the raw material storage area toward the center of the raw material discharge port in a horizontal plane, and when viewed from above in the vertical direction, a direction rotated 90° clockwise from the eccentricity direction is called the first direction, a direction rotated 180° clockwise is called the anti-eccentric direction, and a direction rotated 270° is called the second direction. Note that the raw material discharge port of the top bunker is positioned eccentrically toward the axis of the blast furnace from the center of the raw material storage area in a horizontal plane (a plane projected in the vertical direction), so when the top bunker is installed at the top of the blast furnace, the eccentricity direction is usually the direction from the center of the raw material storage area toward the axis of the blast furnace, that is, the same direction as the arrangement direction of the top bunker.

[0033] Here, "sloping downward from the top of the structure toward the end of the raw material collision surface" in the eccentric direction and the anti-eccentric direction means that, when a vertical cross section of the structure passing through the top of the structure is viewed from the first direction, as shown in Figure 3, the structure slopes downward from the top of the structure toward the end of the raw material collision surface. Similarly, "sloping downward from the top of the structure toward the end of the raw material collision surface" in the first and second directions means that, when a vertical cross section of the structure passing through the top of the structure is viewed from the eccentric direction, as shown in Figure 3, the structure slopes downward from the top of the structure toward the end of the raw material collision surface in the first and second directions. Alternatively, "sloping downward from the highest point of the raw material collision surface toward the end" in the cross sections of the structure along the first and second directions.

[0034] The raw material collision surface is the upper surface of the structure (the area of ​​the structure when viewed from above). Therefore, the top of the structure is the highest point in the vertical direction of the raw material collision surface. If there are multiple highest points on the raw material collision surface, the point among the highest points that is farthest from the raw material discharge port in the eccentric direction is considered to be the top. Also, members for fixing the structure are excluded from the raw material collision surface. The raw material collision surface may be composed of one continuous surface or multiple surfaces.

[0035] The inclination angles α and α' of the line segment connecting the top of the structure and the end of the raw material collision surface from the horizontal in the eccentric direction and the opposite direction to the eccentric direction are preferably 25 to 45°, and more preferably 40 to 43°.

[0036] Furthermore, the inclination angles β and γ of the line segment connecting the top of the structure and the end of the raw material collision surface from the horizontal in the first and second directions are preferably 25 to 45°, and more preferably 40 to 43°.

[0037] Similarly, the shape from the top of the structure to the end of the raw material collision surface in the direction from the first direction, passing through the direction opposite to the eccentricity, to the second direction (a direction between 90° and 270° clockwise from the eccentricity direction) is also preferably inclined downward from the top of the structure to the end of the raw material collision surface. The suitable inclination angles from the horizontal of the line connecting the top of the structure and the end of the raw material collision surface in these directions are also the same as the inclination angles α, α', β, and γ described above.

[0038] The shape (peripheral shape) from the top of the structure to the end of the raw material collision surface in each vertical cross section of the structure does not need to have a constant inclination regardless of the direction, and may have a shape in which the inclination changes in various ways, for example, an arc shape or a shape in which the inclination changes stepwise as shown in Figure 5.

[0039] In addition, the shape from the top of the structure to the end of the raw material collision surface in the direction from the first direction, through the eccentric direction, to the second direction (directions between 0 and 90°, and 270 and 360° clockwise from the eccentric direction, excluding the first and second directions) is not particularly limited. For example, similar to the direction opposite to the eccentricity, the first direction, and the second direction, the structure may be inclined downward from the top of the structure toward the end of the raw material collision surface. In this case, the shape of the structure may be, for example, a cone, an oblique cone, an elliptical cone, a shape in which a cone is glued to the top of a truncated cone (Shape 1), a shape in which a half of a circular cone and a half of an elliptical cone are glued together with their cut surfaces facing each other (Shape 2), a dome shape in which the raw material collision surface is spherical, a polyhedron such as a square pyramid, a hexagonal pyramid, or an octagonal pyramid, or a shape obtained by cutting any of these shapes vertically at any position, as shown in FIG. 6 . The interior of the structure may be hollow, and no components may be provided on surfaces other than the raw material collision surface, such as the bottom and side surfaces. The above-mentioned shapes also include shapes that are modified by adding components to the bottom or other surface, as long as the area of ​​the raw material collision surface remains the same.

[0040] Additionally, the length a of the structure (the distance between the ends of the raw material collision surface in the horizontal direction when the structure is viewed from the first direction) is preferably 0.4 to 0.8 times the inner radius R of the raw material reservoir (see Figures 3 and 4; the same applies to the width and height of the structure described below). The width b of the structure (the distance between the ends of the raw material collision surface in the horizontal direction when the structure is viewed from the eccentric direction) is preferably 0.4 to 0.8 times the inner radius R of the raw material reservoir. The height h of the structure (the distance from the bottom to the top of the raw material collision surface) is preferably 0.47 to 1.0 times the length a of the structure.

[0041] The shape of the structure may be asymmetric in the first direction and the second direction, but is preferably symmetric.

[0042] The position where the structure is installed is not particularly limited, and it may be installed at a position where the raw material collides with the raw material collision surface. For example, regarding the horizontal installation position, it is preferable that the top of the structure be located at a dimensionless distance (r / R) from the center of the raw material storage section in the range of 0 to 0.6, as shown in Fig. 7. Here, the dimensionless distance (r / R) is the value obtained by dividing the distance (r) from the center of the raw material storage section in the horizontal plane (vertical projection plane) by the inner radius (R) of the raw material storage section. Regarding the installation position in the vertical direction, it is preferable that the dimensionless height (h' / H) at the top of the structure is set within the range of 0.75 to 0.85. Here, the dimensionless height (h' / H) is the value obtained by dividing the distance (height): h' from the bottom end of the furnace top bunker (height position of the raw material discharge port) to the top of the structure in the vertical direction by the height: H of the furnace top bunker.

[0043] Furthermore, as long as the above-mentioned structure is inclined downward from the top of the structure toward the ends in the first and second directions, it does not have to be symmetrical with respect to a vertical line passing through the center of the raw material storage section when viewed from the eccentric direction, but it is preferable to arrange it so that it is symmetrical.

[0044] In addition, the material of the structure is not particularly limited, but it is preferable to use a material that is wear-resistant. Furthermore, the method of installing the structure is also not particularly limited. For example, a beam member may be fixed to the inner wall of the top bunker by metal fittings or welding, and the structure may be fixed to the beam member by metal fittings or welding. Furthermore, the structure may have a position adjustment mechanism for changing its position and an installation angle adjustment mechanism for changing the installation angle.

[0045] As shown in Figure 4, the raw material discharge port is eccentric toward the axis of the blast furnace from the center of the raw material storage section in the horizontal plane. Typically, the horizontal distance between the centers of the raw material storage section and the raw material discharge port (eccentricity amount): A is 0.60 to 0.70 times the inner radius: R of the raw material storage section. Also, the inner radius: B of the raw material discharge port is typically 0.10 to 0.30 times the inner radius: R of the raw material storage section. The center position and inner diameter of the raw material storage section are based on the height position of the top of the structure. The center position and inner diameter of the raw material discharge port are based on the lower end position of the raw material storage section. This also applies to the following. Note that Figure 4 illustrates an example in which the horizontal cross section of the raw material storage section is circular, but for other shapes, the center of the raw material storage section is the center of gravity of the horizontal cross section with the largest area. In this case, the eccentricity direction is the direction from the center of the raw material storage section connecting the center of the raw material discharge port and the center of the raw material storage section in the horizontal cross section (the horizontal cross section with the largest area) toward the center of the raw material discharge port, and R is set to 1 / 2 the length of the raw material storage section in the eccentricity direction of the horizontal cross section. Then, for example, by opening a flow rate adjustment gate installed at the raw material discharge port, the raw materials are gradually discharged from the raw material discharge port under their own weight, and are charged into the blast furnace via the collecting hopper and rotating chute.

[0046] The conditions for charging the raw materials other than those described above are not particularly limited and may be in accordance with conventional methods. In addition, the configuration of the blast furnace and the blast furnace auxiliary equipment such as the charging belt conveyor are also not particularly limited, and conventionally known equipment can be used. [Example]

[0047] The top section of a parallel bunker-type blast furnace, in which four top bunkers are arranged in parallel, was simulated as shown in Fig. 2. Here, the relative angles between the direction of material transport of the charging BC and the direction of arrangement of each top bunker were set as follows: No.1-BK (furnace top bunker) +67° No.2-BK (furnace top bunker) +157° No.3-BK (top bunker) +247°(-113°) No.4-BK (top bunker) +337°(-23°)

[0048] Under the conditions shown in Table 1, raw materials (ore) transported by the charging BC were sequentially charged into the top bunkers No. 1 to 4-BK via the top bunker switching device, with each batch of raw materials being loaded. The materials were then collided with an oblique cone-shaped structure located inside the model top bunker, and stored in the respective top bunkers. The target particle size distribution of the raw materials in the top bunkers was such that a large amount of large-sized raw materials was discharged in the initial stage of discharge from the top bunker. Specifically, the target particle size distribution of the raw materials in all top bunkers was such that the maximum non-dimensional particle size at 0 to 25% of the non-dimensional discharge time was 1.2 or greater (the initial target particle size range of Figures 9 to 12), and the minimum non-dimensional particle size at 75 to 100% of the non-dimensional discharge time was 0.8 or less (the final target particle size range of Figures 9 to 12). The non-dimensional particle size and non-dimensional discharge time are as described below. In addition, the specific direction of raw material charging for each furnace top bunker was determined in advance by performing numerical simulations.

[0049] After storing the raw materials in the top bunker, the gates of the discharge ports connected to the bottom of each top bunker were opened, and the raw materials were discharged from the ports. As shown in Figure 8, the raw materials discharged from each top bunker were collected in multiple sampling boxes at regular intervals. The sampling boxes were gradually moved horizontally by a belt conveyor for the sampling boxes, and the discharged raw materials were separated in a time series at regular intervals from the start to the end of discharge. The raw material particle size is expressed as a dimensionless particle size, where the average particle size of the raw materials (ore) before being charged into the top bunker is 1.0. The discharge time for each top bunker is expressed as a dimensionless discharge time, where the time when all the raw materials are discharged from that top bunker is 100%. In the figure, reference numeral 6 denotes the top bunker, 12 denotes the collecting hopper, 13 denotes the sampling boxes, 14 denotes the roller conveyor, and 15 denotes the belt conveyor for the sampling boxes. Next, the raw materials collected in each sampling box were sieved, and the average particle size of the raw materials collected in each sampling box was calculated. For each top bunker, this was divided by the average particle size of all the raw materials before being charged into the top bunker to calculate the dimensionless particle size of the raw materials for each dimensionless discharge time. The results are shown in Figures 9 to 12.

[0050] [Table 1]

[0051] As shown in Figures 9 to 11, in all of the invention examples of Tests No. 1 to 3, in which the raw material charging direction was controlled for each top bunker, the target raw material particle size distribution was achieved in all of the top bunkers No. 1 to 4-BK. On the other hand, as shown in Figure 12, in the comparative example of Test No. 4, in which the raw material charging direction was not controlled for each top bunker (aligned to a directly facing position), the target raw material particle size distribution could not be achieved in some of the top bunkers Nos. 1 to 4-BK. [Explanation of symbols]

[0052] 1: Charging belt conveyor 2: Raw material charging furnace top bunker switching device 3: Casing 4: Raw material distribution path 5: Movable control panel 6: Furnace Bunker 6-1: Raw material storage section 6-2: Raw material discharge port 6-3: Raw material input port 6-4: Structure 6-5: Raw material collision surface 12: Collection hopper 13: Sampling Box 14: Roller conveyor 15: Belt conveyor for sampling boxes

Claims

1. A method for charging raw materials into a blast furnace, comprising: The blast furnace is Two or more furnace bunkers; a raw material charging top bunker switching device that is arranged above the top bunkers and charges raw materials transported by a charging belt conveyor into one of the top bunkers selected; and The raw material charging method for a blast furnace comprises: a process of charging the raw materials transported by the charging belt conveyor into the selected top bunker via the raw material charging top bunker switching device, causing the raw materials to collide with a structure arranged inside the top bunker, and then storing the raw materials in the top bunker; With A raw material charging method for a blast furnace, wherein the charging direction of the raw materials from the raw material charging furnace top bunker switching device to the furnace top bunker is controlled for each selected furnace top bunker.

2. 2. The method for charging raw materials into a blast furnace according to claim 1, wherein the charging direction of the raw materials is controlled according to a relative angle between a raw material transport direction of the charging belt conveyor and an arrangement direction of the furnace top bunker.

3. 3. The method for charging raw materials into a blast furnace according to claim 1, wherein the charging direction of the raw materials is controlled according to a mass velocity of the raw materials transported by the charging belt conveyor.

4. 3. The raw material charging method for a blast furnace according to claim 1, wherein the trajectory of the raw material being charged into the top bunker is controlled for each selected top bunker by a movable control plate arranged in the raw material flow passage from the raw material charging top bunker switching device to the top bunker.

5. A method for charging raw materials into a blast furnace as described in claim 3, in which the trajectory of raw materials being fed into the top bunker is controlled for each selected top bunker by a movable control plate arranged in the raw material flow passage from the raw material feeding top bunker switching device to the top bunker.

6. 3. The method for charging raw materials into a blast furnace according to claim 1, wherein the raw material collision surface of the structure is inclined downward from the top of the structure toward the end of the raw material collision surface at least in the eccentric direction of the top bunker on which the structure is placed, the direction opposite to the eccentricity, and first and second directions perpendicular to the eccentric direction and the vertical direction.

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