Raw material charging method for blast furnace

Abstract

To provide a raw material charging method for a blast furnace capable of continuing smooth operation by suppressing influence on the operation when one furnace top bunker cannot discharge raw materials during mixed charging by two furnace top bunkers out of four furnace top bunkers.SOLUTION: In a method for charging raw materials into a blast furnace according to the present invention, mixed charging can be performed from two of four furnace top bunkers in the blast furnace. When one furnace top bunker of the two furnace top bunkers performing the mixed charging becomes unable to discharge raw materials, the one furnace top bunker is stopped, and the raw material charging is continued by the three furnace top bunkers excluding the stopped one furnace top bunker. When the stopped furnace top bunker is restored from the state incapable of discharging raw materials to the state capable of discharging raw materials, the raw materials remaining in the stopped furnace top bunker are preferentially discharged at a dischargeable timing, and after the discharge of the remaining raw materials from the stopped furnace top bunker is completed, the mixed charging using the four furnace top bunkers is restored.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] In a blast furnace, raw materials such as ore and coke are charged into the furnace from the top. High-temperature air heated by a hot stove is blown into the furnace through tuyere tubes located at the bottom. Coke and auxiliary fuel are burned before the tuyere tubes to maintain the temperature of the molten material in the furnace at 1500°C or higher. High-temperature reducing gases (over 2000°C) generated before the tuyere tubes ascend through the furnace, exchanging heat with the raw materials and reducing and melting the iron ore. Thus, the raw materials and gases flow countercurrently within the blast furnace, and reactions such as preheating, reduction, and melting occur. Efficient control of the progress of these reactions throughout the blast furnace ensures stable blast furnace operation. Maintaining smooth gas ventilation and smooth lowering of the raw materials is essential for this. If ventilation is not controlled and local gas blow-by or local pressure fluctuations occur, the heat exchange between the raw materials and the gas and the progress of reduction will be insufficient, causing fluctuations in furnace heat and making it impossible to maintain stable blast furnace operation. Therefore, for stable blast furnace operation, it is important to maintain proper raw material distribution and ensure good ventilation.

[0003] When charging, raw materials such as ore and coke are stored in separate top bunkers according to type, and the raw materials are discharged in a specified order, allowing the raw materials and coke to be piled up inside the furnace. Conventional raw material charging methods have involved storing different raw materials in three top bunkers and discharging the different raw materials from the three top bunkers in order to form raw material layers inside the furnace. In recent years, four-bunker operation using four top bunkers has been studied (see, for example, Patent Documents 1 and 2).

[0004] The four-top bunker system enables mixed charging, in which ore raw materials and coke are simultaneously discharged from two top bunkers and mixed in the furnace. However, if there are three top bunkers, mixed charging is difficult because the top bunkers cannot be filled with raw materials in time for the next charging. By performing mixed charging, a mixed layer of ore raw materials and coke can be formed. Next, only the ore raw materials are discharged from the top bunker and charged into the furnace, forming a single layer of ore raw materials above the mixed layer. This allows CO gas generated by the solution loss reaction of the coke in the mixed layer to be used to reduce the single layer of ore raw materials in the upper layer of the mixed layer, improving the reduction efficiency of the ore raw materials.

[0005] In the case of three-bunker operation using three top bunkers, if one bunker becomes unusable due to an abnormality, operation will be carried out using the remaining two top bunkers, but the charging schedule will be tight in relation to the unloading of raw materials. This will require a reduction in the blast furnace airflow, which will affect blast furnace operation. In the case of normal charging using four top bunkers, if one top bunker becomes unusable, conventional three-bunker operation can be continued. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-169345 [Patent Document 2] Japanese Patent Publication No. 2022-083500 Summary of the Invention [Problem to be solved by the invention]

[0007] During mixed charging using four top bunkers, different raw materials are charged simultaneously from two of the top bunkers. Because mixed charging is not performed in conventional three-bunker operation, no smooth response method that minimizes operational disruption when a problem occurs during mixed charging using four top bunkers has been known. For example, Patent Documents 1 and 2 do not disclose a charging method when a problem occurs that prevents one of the top bunkers from discharging raw materials during mixed charging using two of the four top bunkers.

[0008] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a raw material charging method for a blast furnace that can minimize the impact on operations and continue smooth operations when one of the four top bunkers becomes unable to discharge raw materials during mixed charging using two of the four top bunkers. [Means for solving the problem]

[0009] In order to solve the above problems and achieve the objectives, (1) The raw material charging method for a blast furnace according to the present invention is a raw material charging method for a blast furnace capable of performing mixed charging in which ore raw materials and coke are simultaneously discharged as raw materials from two of the four top bunkers in the blast furnace, and when one of the two top bunkers performing the mixed charging becomes unable to discharge raw materials, the one top bunker is stopped, and raw material charging is continued using the three top bunkers of the four top bunkers excluding the one stopped top bunker, and when the one stopped top bunker returns from being unable to discharge raw materials to being able to discharge raw materials, the raw materials remaining in the one top bunker are discharged at a timing when they can be discharged, preferentially over the three top bunkers, and after the discharge of the remaining raw materials from the one top bunker is completed, the mixed charging using the four top bunkers is resumed.

[0010] (2) In the method for charging raw materials into a blast furnace according to the present invention, in the invention (1) above, the timing at which the remaining raw materials can be discharged from one furnace top bunker is determined based on the remaining raw materials.

[0011] (3) In the method for charging raw materials into a blast furnace according to the present invention, in the invention (1) above, the timing at which the remaining raw materials can be discharged from the one top bunker is the timing at which the remaining raw materials and the raw materials to be charged from any one of the three top bunkers immediately after the remaining raw materials are discharged from the one top bunker are the same type of raw materials.

[0012] (4) In the method for charging raw materials into a blast furnace according to the present invention, in the invention (3) above, the remaining raw materials are the ore raw materials, and the remaining ore raw materials are discharged from one of the top bunkers at the same time as the next raw material charging by the three top bunkers.

[0013] (5) In the method for charging raw materials into a blast furnace according to the present invention, in the invention (3) above, the remaining raw materials are the coke, and the remaining coke is discharged from one of the top bunkers at the same time as the next charging of raw materials by the three top bunkers.

[0014] (6) The raw material charging method for a blast furnace according to the present invention is any one of the above (1) to (5), wherein the mixed charging of the ore raw material and the coke by the two furnace top bunkers is performed in one of two ways: a forward mixing method in which the charging of the coke is started before the ore raw material and the charging of the coke is completed during the charging of the ore raw material; and a forward simultaneous mixing method in which the charging of the coke and the charging of the ore raw material are started simultaneously and the charging of the coke is completed during the charging of the ore raw material. and mid-mixing, in which the charging of the coke is started during the charging of the ore raw material and the charging of the coke is completed during the charging of the ore raw material; rear simultaneous mixing, in which the charging of the coke is started during the charging of the ore raw material and the charging of the coke and the charging of the ore raw material are completed simultaneously; and rear mixing, in which the charging of the coke is started during the charging of the ore raw material and the charging of the coke is completed after the charging of the ore raw material. [Effects of the Invention]

[0015] The raw material charging method for a blast furnace according to the present invention has the effect of minimizing the impact on operations and allowing smooth operation to continue when one of the four top bunkers becomes unable to discharge raw materials during mixed charging using two of the four top bunkers. [Brief explanation of the drawings]

[0016] [Figure 1] Figure 1 shows an example of four top bunkers installed at the top of a blast furnace. [Figure 2] FIG. 2 is a diagram showing the state of the pile at the top of the raw material charging layer in the furnace formed by mixed charging. [Figure 3] FIG. 3 is a diagram showing forward simultaneous mixing, which is an example of the timing and charging period of raw material charging from each furnace top bunker when forming an ore raw material layer during mixed charging. [Figure 4] FIG. 4 is a diagram showing an example of a raw material charging method when a bunker trouble occurs during mixed charging. [Figure 5] FIG. 5 is a diagram showing an example of the order of raw material charging when a problem occurs in which the first top bunker filled with raw ore materials during mixed charging becomes unable to discharge. [Figure 6] FIG. 6 is a diagram showing an example of the raw material charging sequence when the shut down first top bunker recovers from a problem and returns to four-bunker operation. [Figure 7] FIG. 7 is a diagram showing an example of the order of raw material charging when a problem occurs in which the second furnace top bunker filled with coke during mixed charging becomes unable to discharge. [Figure 8] FIG. 8 is a diagram showing an example of the raw material charging sequence when the shut-down second top bunker recovers from a problem and returns to four-bunker operation. [Figure 9] Figure 9 shows an image of five patterns of mixed charging. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the method for charging raw materials into a blast furnace according to the present invention will be described. However, the present invention is not limited to the embodiment.

[0018] 1 is a diagram showing an example in which four top bunkers 2A, 2B, 2C, and 2D are installed at the top of a blast furnace 1. As shown in FIG. 1, a first top bunker 2A, a second top bunker 2B, a third top bunker 2C, and a fourth top bunker 2D are installed in parallel at the top of the blast furnace 1. In the following description, when there is no particular distinction between the first top bunker 2A, the second top bunker 2B, the third top bunker 2C, and the fourth top bunker 2D, they will also be referred to simply as the top bunker 2.

[0019] The first top bunker 2A, the second top bunker 2B, the third top bunker 2C, and the fourth top bunker 2D are filled with either raw ore material (a) such as iron ore or coke (b) as raw materials to be charged into the blast furnace 1 using a charging belt conveyor or the like. For example, the first top bunker 2A and the third top bunker 2C are filled with raw ore material (a), and the second top bunker 2B and the fourth top bunker 2D are filled with coke (b).

[0020] A hopper 3 is provided below the first furnace top bunker 2A, the second furnace top bunker 2B, the third furnace top bunker 2C, and the fourth furnace top bunker 2D. The hopper 3 supplies the raw materials discharged from the furnace top bunkers 2 to a distribution chute 4 provided inside the furnace below the hopper 3. The distribution chute 4 is provided so that it can rotate within the furnace by adjusting its tilt angle, and charges the raw materials into the furnace while controlling the charging position.

[0021] In the blast furnace 1 according to the embodiment, mixed charging can be performed by simultaneously charging different raw materials into the furnace using two of the four top bunkers 2. For example, mixed charging can be performed by simultaneously charging the ore raw material (a) and the coke (b) into the furnace using the first top bunker 2A filled with the ore raw material (a) and the second top bunker 2B filled with the coke (b). Furthermore, mixed charging can be performed by simultaneously charging the ore raw material (a) and the coke (b) into the furnace using the third top bunker 2C filled with the ore raw material (a) and the fourth top bunker 2D filled with the coke (b).

[0022] First, we will explain an example of mixed charging using four furnace top bunkers 2. In mixed charging, raw materials are charged into a blast furnace 1 equipped with four furnace top bunkers 2 and a distribution chute 4 (bell-less type charging device) so that a coke layer made of coke (b) and an ore raw material layer made up of a mixed layer of part or all of the ore raw material (a) and coke (b) are formed.

[0023] FIG. 2 is a diagram showing the state of deposition at the top of the in-furnace raw material charging layer formed by mixed charging. Reference numeral 10 in FIG. 2 denotes the furnace wall of the blast furnace 1. FIG. 3 is a diagram showing forward simultaneous mixing, which is an example of the timing and charging period of raw material charging from each furnace top bunker 2 when forming an ore raw material layer during mixed charging. (a-1) and (a-2) in FIG. 3 indicate raw ore, and (b-1) and (b-2) in FIG. 3 indicate coke.

[0024] First, coke (b) is filled into the first top bunker 2A, the second top bunker 2B, the third top bunker 2C, and the fourth top bunker 2D, and the coke (b) is charged into the furnace from each top bunker 2 to form a coke layer Z as shown in Figure 2. Next, half of the total amount of ore material (a) charged into the furnace in one charge, ore material (a-1), is filled into the first top bunker 2A. Also, half of the total amount of coke (b) charged into the furnace in one charge, coke (b-1), is filled into the second top bunker 2B. Then, as shown in FIG. 3, as the first batch, the ore material (a-1) and coke (b-1) are simultaneously discharged and mixed from the first furnace top bunker 2A and the second furnace top bunker 2B, and the charging of the coke (b-1) is completed when 50 mass% of the ore material (a-1) has been charged. As a result, the first mixed layer X1 as shown in FIG. 2 is formed. Subsequently, the remaining 50 mass% of the ore material (a-1) from the first furnace top bunker 2A is charged while adjusting the tilting angle of the distribution chute 4 so that it becomes the upper layer of the first mixed layer X1. As a result, the second single ore material layer Y1 as shown in FIG. 2 is formed.

[0025] Furthermore, by the time the charging of the ore material (a-1) from the first furnace top bunker 2A is completed, the remaining half of the total amount of ore material (a) charged into the furnace in one charge, i.e., the remaining half of the total amount of coke (b) charged into the furnace in one charge, i.e., the remaining half of the total amount of coke (b-2), is charged into the fourth furnace top bunker 2D by the time the charging of the ore material (a-1) from the first furnace top bunker 2A is completed.

[0026] Next, as shown in Fig. 3, as the second batch, the ore material (a-2) and coke (b-2) are simultaneously discharged from the third furnace top bunker 2C and the fourth furnace top bunker 2D and mixed and charged, and the charging of the coke (b-2) is completed when 50 mass% of the ore material (a-2) has been charged. As a result, a third mixed layer X2 is formed as shown in Fig. 2. Note that Fig. 2 shows the first three layers of the in-furnace material charging layers formed by mixed charging.

[0027] Subsequently, the remaining 50% by mass of the ore material (a-2) is charged from the third top bunker 2C while adjusting the tilting angle of the distribution chute 4 so that it becomes the upper layer of the third mixed layer X2. As a result, a fourth single ore material layer Y2 (not shown) is formed. That is, one charge of the ore material (a) is charged in two batches, and from the bottom up, a first mixed layer X1, a second single ore material layer Y1, a third mixed layer X3, and a fourth single ore material layer Y2 are formed to form the ore material layers. The total amount of the ore material (a-1) in the second single ore material layer Y1 and the ore material (a-2) in the fourth single ore material layer Y2 is 50% by mass of the total amount of the ore material (a) charged in one charge.

[0028] In this way, with the mixed charging of four bunkers using the raw material charging method described above, it is possible to achieve the piled state at the top of the raw material charging layer as shown in Figure 2.

[0029] Figure 4 shows an example of a raw material charging method when a bunker trouble occurs during mixed charging. In Figure 4, 1BK is the first furnace top bunker 2A, 2BK is the second furnace top bunker 2B, 3BK is the third furnace top bunker 2C, and 4BK is the fourth furnace top bunker 2D.

[0030] First, as explained using Figures 2 and 3, mixed charging is performed using the first top bunker 2A and the second top bunker 2B. In this case, for example, if a problem occurs in the first top bunker 2A, the first top bunker 2A will immediately stop operation at the time of the problem without discharging all of the raw materials. On the other hand, the second top bunker 2B will continue operation until all of the raw materials have been discharged.

[0031] Next, while the first top bunker 2A is being restored, operations continue using three bunkers: the second top bunker 2B, the third top bunker 2C, and the fourth top bunker 2D. The raw material charging method in this case is not mixed charging using two top bunkers 2, but rather the normal charging schedule for each top bunker 2 individually. For example, once the second top bunker 2B has finished discharging raw materials, the third top bunker 2C discharges raw materials, while the second top bunker 2B is charged with raw materials. Once the third top bunker 2C has finished discharging raw materials, the fourth top bunker 2D discharges raw materials, while the third top bunker 2C is charged with raw materials. Once the fourth top bunker 2D has finished discharging raw materials, the second top bunker 2B, which has already been charged, discharges raw materials, while the fourth top bunker 2D is charged with raw materials. This sequence is repeated to continue operations.

[0032] After that, when the first top bunker 2A is restored, the operation of the second top bunker 2B, the third top bunker 2C, and the fourth top bunker 2D is temporarily stopped at an appropriate timing that minimizes the impact on operations. Then, all of the materials remaining in the first top bunker 2A at the time of the trouble are preferentially discharged. The timing of this discharge is determined by the amount of materials remaining in the first top bunker 2A.

[0033] When charging raw materials into the blast furnace 1, it is desirable to maintain a constant ore-to-coke layer thickness ratio in order to maintain constant ventilation and the raw material reduction rate within the furnace. Furthermore, the formation of a thin coke layer increases ventilation resistance and impedes ventilation within the furnace. Therefore, if the raw material remaining in the troubled first bunker 2A is ore raw material (a), the first bunker 2A should be preferentially discharged with ore raw material (a) before the next raw material is charged from another bunker 2, which is the same type of ore raw material (a). Similarly, if the raw material remaining in the troubled first bunker 2A is coke (b), the first bunker 2A should be preferentially discharged with coke (b) before the next raw material is charged from another bunker 2, which is the same type of coke (b). This prevents significant changes in the ore-to-coke layer thickness ratio of the charging raw materials, allowing the raw materials to be charged without forming a thin coke layer.

[0034] After the remaining raw materials in the first furnace top bunker 2A have been discharged, mixed charging operations are resumed using four bunkers: the first furnace top bunker 2A, the second furnace top bunker 2B, the third furnace top bunker 2C, and the fourth furnace top bunker 2D.

[0035] Next, the differences in the sequence depending on the type of raw material remaining in the top bunker 2 where the trouble occurred will be explained.

[0036] FIG. 5 is a diagram showing an example of the order of raw material charging when a problem occurs in which the first furnace top bunker 2A filled with raw ore (a-1) during mixed charging becomes unable to discharge.

[0037] When the first top bunker 2A filled with ore material (a) becomes unable to discharge, the coke (b-1) is first discharged from the second top bunker 2B. After the coke (b-1) has been discharged from the second top bunker 2B, the second top bunker 2B is filled with the same weight of ore material (a-1) as the ore material (a-1) that became unable to discharge from the first top bunker 2A. While the second top bunker 2B is being filled with ore material (a-1), the coke (b-2) from the fourth top bunker 2D and the ore material (a-2) from the third top bunker 2C are charged into the furnace in this order. Then, the ore material (a-1) that has been completely filled into the second top bunker 2B is charged. This minimizes charging downtime and enables a transition to normal charging using three bunkers: the second top bunker 2B, the third top bunker 2C, and the fourth top bunker 2D. In addition, because the weight of the raw materials originally planned to be charged remains unchanged, it is possible to transition to normal charging using three bunkers without significantly changing the reduction rate.

[0038] FIG. 6 is a diagram showing an example of the raw material charging sequence when the shut down first top bunker 2A recovers from a trouble and returns to four-bunker operation.

[0039] When the suspended first top bunker 2A recovers from the trouble and returns to four-bunker operation, the next raw material charge in normal operation with three bunkers is the timing for charging ore raw material (a), and the remaining ore raw material (a-1) in the first top bunker 2A is discharged. For example, as shown in Figure 6, in normal operation with three bunkers, the next raw material charge is the timing for charging ore raw material (a-2) from the third top bunker 2C, and the remaining ore raw material (a-1) is discharged from the first top bunker 2A. This allows switching from three-bunker operation to four-bunker operation to minimize charging downtime and without changing the raw material ratio.

[0040] FIG. 7 is a diagram showing an example of the order of raw material charging when a problem occurs in which the second furnace top bunker 2B filled with coke (b-1) during mixed charging becomes unable to discharge.

[0041] If the second top bunker 2B, which is filled with coke (b), becomes unable to discharge, the ore material (a-1) is first discharged from the first top bunker 2A. After the ore material (a-1) has been discharged from the first top bunker 2A, the first top bunker 2A is filled with coke (b-1) of the same weight as the coke (b-1) that became unable to discharge from the second top bunker 2B. While the first top bunker 2A is being filled with coke (b-1), the ore material (a-2) from the third top bunker 2C and the coke (b-2) from the fourth top bunker 2D are charged into the furnace in this order. Then, the coke (b-1) that has been completely filled into the first top bunker 2A is charged. This minimizes charging downtime and enables a transition to normal charging using the three bunkers. In addition, since the weight of the raw materials initially planned to be charged remains unchanged, it is possible to transition to normal charging operations with three bunkers without significantly changing the reduction rate.

[0042] FIG. 8 is a diagram showing an example of the raw material charging sequence when the shut down second top bunker 2B recovers from a trouble and returns to four-bunker operation.

[0043] When the suspended second top bunker 2B recovers from the trouble and returns to four-bunker operation, the next raw material charging in normal operation using the third bunker is the timing for charging coke (b), and the remaining coke (b-1) in the second top bunker 2B is discharged. For example, as shown in Figure 8, in normal operation using the third bunker, the next raw material charging is the timing for charging coke (b-2) from the third top bunker 2C, and the remaining coke (b-1) is discharged from the second top bunker 2B. This allows switching from three-bunker operation to four-bunker operation to minimize charging downtime and without changing the raw material ratio.

[0044] Figure 9 shows five different mixed charging patterns. There are five different mixed charging patterns depending on how the ore raw material (a) and coke (b) are scattered: forward mixing, simultaneous forward mixing, mid-stream mixing, simultaneous backward mixing, and backward mixing.

[0045] As shown in Figure 9(1), in forward mixing, the charging batch of coke (b) is started before the charging batch of ore material (a), and the charging batch of coke (b) is finished in the middle of the charging batch of ore material (a).

[0046] As shown in Figure 9(2), in the forward simultaneous mixing, the charging batch of coke (b) and the charging batch of ore material (a) are started simultaneously, and the charging batch of coke (b) is terminated in the middle of the charging batch of ore material (a).

[0047] As shown in Figure 9(3), in the mid-stream mixing, a charging batch of coke (b) is started in the middle of a charging batch of ore material (a), and the charging batch of coke (b) is finished in the middle of a charging batch of ore material (a).

[0048] As shown in Figure 9(4), in the case of rear simultaneous mixing, a charging batch of coke (b) is started in the middle of a charging batch of ore material (a), and the charging batch of coke (b) and the charging batch of ore material (a) are completed simultaneously.

[0049] As shown in Figure 9(5), in the backward mixing, the charging batch of coke (b) is started in the middle of the charging batch of ore material (a), and the charging batch of coke (b) is finished after the charging batch of ore material (a).

[0050] By selectively using the five patterns shown in Figures 9(1) to 9(5) as a method for mixed charging of ore raw material (a) and coke (b), the position where a mixed layer of ore raw material (a) and coke (b) is formed in the radial direction of the furnace can be changed. Furthermore, coke (b) has the role of ensuring ventilation within the blast furnace 1. Therefore, the gas flow within the furnace changes depending on the radial arrangement of coke (b) within the furnace. Therefore, by selectively using the above five patterns as a method for mixed charging of ore raw material (a) and coke (b), the gas flow within the furnace can be changed. In this way, each pattern is used depending on the radial position within the blast furnace 1 where the reduction reaction is desired to be further promoted and the portion of the blast furnace 1 where the gas flow is desired to be ensured (the center, intermediate portion, or peripheral portion near the furnace wall 10).

[0051] Because the charging timing of the ore raw material (a) and the coke raw material (b) differs, the setting of the distribution chute 4's rotation offset and the tilting angle of the distribution chute 4 at the timing when the two raw materials are simultaneously discharged must be consistent when setting the raw material charging method. Thus, when performing mixed charging, the ore raw material (a) and the coke raw material (b) are closely related. This does not occur, for example, with a standard raw material charging method using three top bunkers 2. Therefore, for example, if a problem occurs during the charging batch of ore raw material (a) and it becomes impossible to discharge it, the coke (b) charging batch cannot be started, which has an impact that does not occur with a standard raw material charging method using three top bunkers 2. Therefore, when performing mixed charging using four top bunkers 2, the sequence of events when a problem occurs, as described above, is important.

[0052] In the raw material charging method for a blast furnace 1 according to the embodiment, when one of the four top bunkers 2 becomes unable to discharge raw materials during mixed charging using two of the four top bunkers 2, that one top bunker 2 is shut down, and operation continues with the three top bunkers 2 until it is restored. Then, when the one top bunker 2 recovers from being unable to discharge raw materials to being able to discharge raw materials, the raw materials remaining in that one top bunker 2 are discharged preferentially over the other three top bunkers 2. This minimizes the waiting time for charging, allowing recovery from trouble with minimal impact on operations, and enabling more stable operation of the blast furnace 1. Furthermore, the raw material charging method for a blast furnace 1 according to the embodiment enables the improvement of the reduction efficiency of the ore raw material (a), which is an advantage of four-bunker operation, to be implemented with low risk, thereby improving yield. [Explanation of symbols]

[0053] 1 blast furnace 2 Furnace Top Bunker 2A No. 1 Furnace Top Bunker 2B No. 2 Furnace Top Bunker 2C No. 3 Furnace Top Bunker 2D No. 4 Furnace Top Bunker 3 Hopper 4. Distribution shot 10 Furnace wall

Claims

1. A raw material charging method for a blast furnace capable of performing mixed charging in which ore raw materials and coke are simultaneously discharged as raw materials from two of four furnace top bunkers in the blast furnace, When one of the two top bunkers performing the mixed charging becomes unable to discharge raw materials, the one top bunker is stopped, and raw material charging is continued using the three top bunkers excluding the one stopped top bunker among the four top bunkers, When the one furnace top bunker that has been stopped returns from being unable to discharge raw materials to being able to discharge raw materials, the raw materials remaining in the one furnace top bunker are discharged preferentially over the three furnace top bunkers at a timing when they can be discharged, and after the discharge of the remaining raw materials from the one furnace top bunker is completed, the mixed charging using the four furnace top bunkers is resumed. Method of charging raw materials into a blast furnace.

2. The timing at which the remaining raw materials can be discharged from the one furnace top bunker is determined based on the remaining raw materials. The method for charging raw materials into a blast furnace according to claim 1.

3. The timing at which the remaining raw materials can be discharged from the one top bunker is the timing at which the remaining raw materials and the raw materials to be charged from any one of the three top bunkers immediately after the remaining raw materials are discharged from the one top bunker become the same type of raw materials. The method for charging raw materials into a blast furnace according to claim 1.

4. the remaining raw material is the ore raw material, The next time the three top bunkers are used for charging raw materials, the remaining raw materials are discharged from the one top bunker at the same time as the next charging of raw materials. The method for charging raw materials into a blast furnace according to claim 3.

5. the remaining raw material is the coke, The next charging of raw materials by the three furnace top bunkers is at the same timing as the charging of the coke, and the remaining coke is discharged from the one furnace top bunker. The method for charging raw materials into a blast furnace according to claim 3.

6. The mixed charging of the ore raw material and the coke by the two furnace top bunkers is forward mixing in which charging of the coke is started before charging of the ore raw material and charging of the coke is completed during charging of the ore raw material; a forward simultaneous mixing method in which the charging of the coke and the charging of the ore raw material are started simultaneously and the charging of the coke is completed during the charging of the ore raw material; mid-mixing in which charging of the coke is started during the charging of the ore raw material and charging of the coke is completed during the charging of the ore raw material; a rear simultaneous mixing method in which charging of the coke is started during charging of the ore raw material and charging of the coke and charging of the ore raw material are completed simultaneously; a rear mixing method in which charging of the coke is started during charging of the ore raw material and charging of the coke is completed after charging of the ore raw material; Use them appropriately to execute The method for charging raw materials into a blast furnace according to any one of claims 1 to 5.

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