JP2015196888A - Estimation method of powder rate of blast furnace raw material, and operation method of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method of the powder rate of a blast furnace raw material, through more accurate perceiving of the powder rate of the raw material to be fed into a blast furnace.SOLUTION: The estimation method of the powder rate of a raw material 3 to be fed into a blast furnace 10 from a furnace top bunker 5 includes: obtaining at least any one of a first tilt angle, i.e. the slope angle of the piled raw material 3 fed in the furnace top bunker 5, and a second tilt angle, i.e. the slope angle of the raw material tilted upward to the sidewall of the furnace top bunker 5 from the position above an outlet 6, which is formed during discharge of the fed raw material 3 from the outlet 6 of the furnace top bunker 5; and estimating the powder rate of the raw material with the tilt angle obtained, based on the predetermined relationship between the tilt angle of a raw material and the powder rate, i.e. the relationship between the obtained tilt angle selected from the first tilt angle and the second tilt angle and the powder rate, and the obtained tilt angle.

Description

  The present invention relates to a method of estimating a powder rate of a charged raw material from a deposition state of a raw material in a furnace top bunker and a method of operating a blast furnace performing an operation action based on the estimated powder rate in a bell-less blast furnace.

  In blast furnace operation, sintered ore that is an iron source, coke that is a reducing agent, and the like are charged from the top of the blast furnace and deposited in layers in the furnace. Sinter or coke is charged into the blast furnace from the top bunker located at the top of the blast furnace.

  In the blast furnace, the powder having a small particle size contained in the charging raw material has a great influence on the air permeability in the furnace. Therefore, it is very important to manage the ratio of the powder in the charged raw material. For example, in the sintering factory, in order to manage the powder rate of the sintered ore when being carried out from the factory, the powder rate is controlled by adjusting the mesh of the final sieve. In addition, the powder rate is controlled by adjusting the mesh of the sieve just before charging into the blast furnace. Further, Patent Document 1 discloses that a probe is inserted into the furnace when the blast furnace is resting, the deposits in the furnace are sampled, and the powder ratio is measured.

JP 7-278623 A

  However, just adjusting the sieve mesh at the sintering plant as described above does not reflect pulverization during the subsequent transportation to the blast furnace, so the powder rate at the time of charging into the blast furnace is sufficiently accurate. I couldn't manage well. Moreover, since the powder rate can be measured only when the blast furnace is closed with the method of Patent Document 1, the frequency of the powder rate measurement cannot be increased. Therefore, the accuracy was not sufficient for the management of the powder rate.

  Therefore, the present invention is based on the powder rate management method of the blast furnace raw material and the powder rate estimated by the powder rate management method for more accurately grasping the powder rate of the raw material at the time of charging into the blast furnace and managing the powder rate. The purpose is to provide a stable blast furnace operation method.

  The present invention has been made to solve the above problems, and the gist of the invention is as follows.

(1) Predetermining the correlation between the powder rate of raw materials charged into the blast furnace from the top bunker and the inclination angle,
Obtain the angle of inclination of the raw material in the furnace top bunker,
A method for estimating a powder rate of a blast furnace raw material that estimates a powder rate of a raw material charged into a blast furnace from the correlation and the obtained inclination angle,
The inclination angle is the angle of the slope of the raw material (first inclination angle) when the charging of the raw material is completed, and / or the discharge of the charged raw material from the outlet of the furnace top bunker is started. The angle of the slope of the raw material (second inclination angle), which is stably formed after a certain transition period, and is inclined upward from the position above the discharge port toward the side wall of the furnace top bunker A method for estimating the powder rate of a blast furnace raw material. According to (1), the above object can be achieved.

  (2) In the method for estimating the powder rate of the blast furnace raw material of (1) above, the furnace top bunker is mounted at a plurality of positions in the range from the position above the discharge port to the side wall in the cross section of the furnace top bunker. A method for estimating a powder rate of a blast furnace raw material, comprising measuring a surface level, which is a height of a surface of the raw material, and obtaining an inclination angle of the raw material based on a difference in the measured surface level of the raw material. According to (2), it is possible to continuously determine the inclination angle of the raw material and specify the powder rate with higher accuracy.

  (3) In the method for estimating the powder rate of the blast furnace raw material of (2) above, the surface level is measured at three or more positions on the slope of the raw material, and the measurement target is measured based on the difference in surface level at two or more positions. A method for estimating a powder rate of a blast furnace raw material, wherein the inclination angle of the slope is determined, and the inclination angle of the raw material is determined based on the determined multiple inclination angles. According to (3), the powder rate of the raw material can be specified more accurately.

(4) Estimating the powder rate of the raw material charged into the blast furnace by the powder rate estimation method of any of the above (1) to (3),
When the estimated powder ratio exceeds a reference value, an operation action that compensates for the deterioration in air permeability of the blast furnace caused by an increase in the powder ratio and an operation action that decreases the powder ratio of the raw material charged in the furnace top bunker A method for operating a blast furnace, characterized by performing at least one of the above. According to (4), the powder rate can be estimated every time the raw material is charged, and an operation action based on the powder rate can be performed, so that a more stable operation of the blast furnace becomes possible.

  (5) In the method for operating a blast furnace according to (4) above, the operation action for compensating for the deterioration in air permeability is at least one of an operation for increasing the coke ratio and an operation for changing the distribution of charges in the blast furnace. A method of operating a blast furnace characterized by being. According to (5), even when the powder rate of the charged raw material is increased, it is possible to appropriately compensate for the deterioration in air permeability.

  (6) In the method for operating a blast furnace according to (4) above, the operation action for reducing the powder rate of the raw material is arranged in a process upstream of the furnace top bunker in the supply path of the raw material to the furnace top bunker. At least one of an operation for increasing the frequency of the above, an operation for changing the sieve to a sieve having a different opening size, and an operation for changing the production conditions of the raw material in order to increase the strength of the raw material. A featured blast furnace operation method. According to (6), when the powder rate increases, the powder rate of the raw material can be reduced, and the decrease in productivity of the blast furnace can be effectively suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the powder rate management method of the blast furnace raw material which grasps | ascertains the powder rate of the raw material charged into a blast furnace more accurately and manages a powder rate, and more stable based on the powder rate estimated by the said powder rate management method It is possible to provide a method for operating a blast furnace.

It is a schematic diagram which shows the structure of a parallel bunker type bell-less charging device. It is a schematic diagram which shows the shape of the raw material surface after raw material charging in a furnace top bunker and during discharge of raw materials. It is a schematic diagram which shows the example of a measurement of the deposition angle of a raw material, and the inclination angle of a fixed area | region. It is a graph which shows the relationship between the inclination-angle of a raw material, and a powder rate. It is a figure which shows the example of arrangement | positioning of the level meter for the level measurement of the raw material in the furnace top bunker in embodiment. It is a schematic diagram which shows the change of the level of the raw material surface after raw material introduction in a furnace top bunker and during raw material discharge | emission.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  With reference to FIG. 1, a configuration and a charging method of a blast furnace raw material charging apparatus according to this embodiment will be described. The raw material charging apparatus shown in FIG. 1 is configured such that iron ore such as sintered ore, pellets and lump ore and coke as a reducing agent are alternately charged into the blast furnace from the top of the blast furnace 10 and accumulated in layers in the furnace. It is a charging device. The raw material charging apparatus in FIG. 1 is a parallel bunker type bellless charging apparatus in which the top bunker 5 is arranged in parallel.

  The raw material charging apparatus shown in FIG. 1 includes a raw material tank 1, a charging belt conveyor 2, a switching chute 4, a furnace top bunker 5, a discharge port 6, a flow rate adjusting valve 7, a collecting hopper 8, and a turning chute. 9, a level meter 12, a level measurement control unit 20, and the like.

  The raw material tank 1 stores the raw material charged into the blast furnace according to the type and particle size of the raw material. When the raw material 3 is charged into the blast furnace 10 using the raw material charging device, each raw material 3 is cut out on the charging belt conveyor 2 by a predetermined weight and supplied to the furnace top bunker 5 through the switching chute 4. To do. The supplied raw material 3 is temporarily stored in the furnace top bunker 5. The stored raw material 3 is discharged from the discharge port 6 of the furnace top bunker 5 through the flow rate adjusting valve 7 to the collecting hopper 8 and charged into the furnace by the turning chute 9. By adjusting the opening degree of the flow rate adjusting valve 7, the discharge flow rate of the raw material from the discharge port 6 of the furnace top bunker 5 is adjusted. The turning chute 9 charges the supplied raw material 3 into a desired position in the furnace of the blast furnace 10. In the case of a parallel bunker type bellless charging device, ore such as sintered ore and coke are alternately charged into the furnace using a plurality of parallel bunker.

  The raw material charging apparatus according to the present embodiment includes a level meter 12 and a level measurement control unit 20 as an inclination angle measuring unit of a slope formed by the raw material charged into the furnace top bunker 5. The level meter 12 measures the level (height) of the surface of the raw material charged in the furnace top bunker 5 in the furnace top bunker. The level measurement control unit 20 controls the level meter 12 to execute the surface level measurement process of the raw material. It should be noted that the powder rate estimation process described later may be performed by the level measurement control unit 20, or another processing unit provided separately may perform the calculation process as the powder rate estimation unit. Further, in FIG. 1, the level meter 12 is shown only in the right furnace top bunker 5, but the level meter 12 is similarly arranged in the other furnace top bunker 5 to measure the surface level of the raw material to be charged. May be done.

  Here, the “powder ratio” is the ratio of the weight of the powder to the total weight of the raw material charged in the blast furnace. In this embodiment, it is the ratio of the powder in the raw material supplied to the furnace top hopper 5 by one charge. The powder is a raw material having a particle size smaller than a predetermined reference particle size. The reference particle size varies depending on the type and composition of the raw material, and also varies depending on other operating conditions, so that it is set appropriately. For example, in the case of iron ore such as sintered ore, particles having a particle size of less than 5 mm or less than 3 mm may be used as powder. For coke, powder having a particle size of less than 35 mm may be used.

  The level meter 12 is not particularly limited as long as the surface level of the raw material can be continuously measured. For example, a non-contact laser distance meter, a microwave distance meter, or the like can be used as the level meter 12. The level meter 12 of this embodiment is used for measuring the surface level of the raw material at a plurality of locations and detecting a change in the surface shape of the raw material in the furnace top bunker 5 with time. More specifically, it is a means for measuring the surface level and grasping the inclination angle of the slope of the raw material in the furnace top bunker 5.

  The level meter 12 only needs to be able to measure at least the surface level of the raw material in the furnace top bunker 5 at a plurality of locations, but when the raw material cut out from the raw material tank 1 in one cut is charged into the furnace top bunker 5 It is preferable to measure the surface level at the position of the top and the surface level at one or more positions other than the top.

  When the raw material is charged from the switching chute 4 with respect to the eccentric type furnace top bunker 5 as shown in FIG. 1, for example, the position of the top after the raw material charging is inside the center of the cross section of the furnace top bunker 5. It becomes the position near the side wall. When the surface shape after charging the raw material is such a shape, at a position near the top of the raw material and at one or a plurality of positions outside the radial direction of the cross section of the furnace top bunker 5 from the position near the top. It is preferable to measure the surface level of the raw material. For example, a total of a first position near the top of the raw material, a second position radially outside the furnace top bunker 5 with respect to the first position, and a third position further radially outward with respect to the second position. The surface level at three positions is measured by the level meter 12. The first to third positions can be, for example, positions that equally divide from the first position to the position of the bunker inner wall (the inner surface of the side wall of the bunker).

  And the level meter 12 of this embodiment is (1) Measurement of the surface level of each point in the state which the raw material after material introduction (before discharge start) has accumulated stably without collapsing, and (2) At least one of the continuous measurement of the surface level at each point while discharging the raw material from the furnace top bunker 5 to the blast furnace 10 is performed. Then, as shown in FIG. 2, the inclination angle (deposition angle) θ1 of the deposited material can be obtained from the surface levels at a plurality of points grasped by the measurement of (1) (FIG. 2 (a)). The inclination angle in the state where it is stably deposited is equivalent to the repose angle of the raw material. Further, according to the measurement of (2), the inclination angle θ2 of the slope of the raw material at a plurality of timings when the raw material is discharged from the discharge port 6 can be obtained (FIG. 2B).

  There is a correlation between the inclination angle of the raw material in the furnace top bunker 5 and the powder ratio of the raw material. The raw material charging apparatus of the present embodiment can obtain (estimate) the raw material powder rate measured from the surface level measurement value based on the correlation obtained in advance. As will be described in detail later, in this embodiment, after a certain transition period has elapsed after starting material discharge, the time during which the overall surface level decreases while maintaining the surface shape in which the inclination angle of the material is maintained substantially constant (Period). Therefore, the inclination angle θ2 of the raw material at the constant surface shape is used for the calculation (estimation) of the powder rate as the inclination angle during discharge of the raw material.

  First, the relationship between the inclination angle of the raw material and the powder rate will be described. FIG. 3 is a schematic diagram showing an example of a measuring apparatus for obtaining the relationship between the inclination angle of the raw material and the powder rate. The measuring device in FIG. 3 is a rectangular parallelepiped slice model that has the function of discharging the charged raw material from below in the same manner as the furnace top bunker. is there. As shown in FIG. 3, in the slice model, the raw material is charged from the upper right, and the raw material is discharged from the lower left outlet.

  The inclination angle of the raw material (that is, the angle of repose of the raw material) α at the time before discharging after the raw material charging is measured with the raw material being loaded into the slice model and deposited without breaking down. Is the angle. In addition, the raw material is discharged from the discharge port at the lower part of the slice model at a constant flow rate, and the same amount of the raw material is supplied from the upper part of the slice model, thereby creating a state in which the inclination angle of the raw material is constant. Then, the constant inclination angle is defined as an inclination angle β during the material discharge.

  Each inclination angle was measured by directly observing the slope formed by the surface of the deposited raw material through the cross section (side surface) of the slice model, and obtaining the inclination angles α and β. Moreover, as a sample used for the measurement, coke samples having various powder ratios were prepared and used for measurement by changing the weight ratio of the powder coke of 1 mm or less in a sample containing coke of 1 mm or more and 5 mm or less.

  FIG. 4 is a graph showing the relationship between the powder ratio and the inclination angles α and β obtained by the measuring apparatus of FIG. 3 for various coke samples having different powder ratios. FIG. 4A shows the relationship between the inclination angle α and the powder rate of each sample. FIG. 4B shows the relationship between the inclination angle β and the powder rate of each sample.

  As shown in FIG. 4A, the inclination angle α tends to decrease as the powder rate of the sample increases. Further, as shown in FIG. 4B, the inclination angle β tends to increase as the powder rate of the sample increases. Thus, between the powder rate and the inclination angle of the raw material, both the inclination angle (rest angle) after charging the raw material and the inclination angle in a state where the surface shape of the raw material is constant during discharge It can be seen that there is a predetermined correlation. Therefore, if the relationship between the powder rate and the inclination angle is obtained in advance in the furnace bunker 5 used for actual operation, the raw material powder rate is determined from the inclination angle of the raw material in the furnace bunker 5 during actual operation. Can be specified (estimated).

  Although the correlation between the inclination angle and the powder ratio can be determined using a reduced model bunker, it is preferable to obtain the correlation with a furnace top bunker that is actually planned in terms of obtaining a highly accurate correlation.

Next, the results of actually charging the raw material into the furnace top bunker 5 of the raw material charging apparatus of the system shown in FIG. 1 and measuring the surface level of the raw material with the level meter 12 will be described. The surface level was measured using a top bunker 5 having a 1 / 5.6 scale of a top bunker used for a blast furnace having a capacity of 5370 m ³ . As an example, the level meter 12 is a level meter that measures the surface level at the top position when the raw material 3 is charged into the furnace top bunker 5 as shown in FIG. A, a level meter B for measuring the surface level at the radially outer position of the cross section of the furnace top bunker 5 relative to the level meter A, and a level for measuring the surface level at a position further outward than the level meter B A total of C was used. The measurement position is a position obtained by equally dividing the measurement position of the level meter A and the inner wall of the furnace top bunker 5 as described above. However, the measurement position does not necessarily have to be equally divided, and the surface level is at a plurality of points. It only needs to be able to measure.

  Sinter was used as the raw material to be charged. As shown in Table 1 below, for the same sintered ore raw material, the change in level was measured by changing the opening degree of the flow control valve 7. That is, in Samples 1-1 and 1-2, a change in level was measured by changing a valve opening degree during discharge for a common raw material. The raw materials are all mixed with sintered ore having a particle size of 2 mm or more and 10 mm or less, and the ratio (powder ratio) of powders less than 5 mm is different between samples 1 and 2.

  FIG. 6 shows a graph of measurement results. The graph of FIG. 6 shows the relationship between the radial level measurement position in the furnace top bunker 5 and the surface level of the raw material. In FIG. 6, the measured value by the level meter A is indicated by a white circle (◯), the measured value by the level meter B is indicated by a black circle (●), and the measured value by the level meter C is indicated by a square (□).

  As shown in FIG. 6, it is understood that the surface shape such as the slope angle of the slope can be grasped by measuring the surface level of the raw material at each position with the level meters 12 of AC. In FIG. 6, samples 1-1 and 1-2 have substantially the same inclination angle θ1 at the time of 0 seconds before the discharge after the raw material charging as shown in the graph. In addition, after starting the material discharge, the area measured by the level meter A above the discharge port 6 becomes a rathole region that becomes a mass flow, so the level is lowered before the region measured by the level meters B and C. I can see that When a certain amount of time has elapsed from the start of discharge (that is, after the transition period has elapsed), an inclined surface inclined upward from the position above the discharge port 6 toward the inner wall of the bunker as shown in FIG. It can be seen that the entire surface level is lowered while maintaining the angle θ2.

  In addition, the inclination angle θ2 that is constant for a certain period during discharge was substantially the same. Specifically, the inclination angle from the time when 30 seconds passed in Sample 1-1 to the time around 50 seconds passed and the inclination angle around 30 seconds in 1-2 became substantially the same. If the same raw material is used, even if the opening degree of the flow rate adjusting valve 7 is changed, the difference in the surface shape change is small and almost the same inclination angle is taken. However, in order to calculate (estimate) the powder rate more accurately, the relationship between the powder rate and the inclination angle is obtained in advance for each valve opening, and the valve opening is also supported when estimating the powder rate. It is preferable to estimate the powder rate based on the data.

  As described above, by measuring the surface level at a plurality of locations using the level meter 12, the inclination angle θ1 and the inclination angle θ2 of the raw material charged in the furnace top bunker can be obtained. And, based on the correlation between the powder ratio and the inclination angle θ1 calculated in advance and the correlation between the powder ratio and the inclination angle θ2, the powder ratio of the raw material charged in the furnace top bunker 5 can be specified (estimated). Is possible. According to the powder rate estimation method of the present embodiment, the powder rate can be grasped every time the raw material is charged into the furnace top bunker 5, and the raw material powder rate can be managed more accurately and reliably. In the present embodiment, the measurement was performed using a 1 / 5.6 scale model of the furnace top bunker 5, but the correlation between the inclination angles θ1 and θ2 and the powder rate is the same as that of the reduced model. You may obtain | require using, and you may obtain | require using the furnace top bunker 5 used for an actual operation. It is more preferable to obtain the correlation with an actual furnace top bunker 5 for estimating the powder ratio because a more accurate correlation is obtained.

  In this embodiment, the measurement example is shown in the case where the raw material is sintered ore, but the inclination angle is calculated in the same manner for other raw materials such as other types of iron ore and coke as a reducing agent. And the powder rate of the raw material can be estimated from the calculated inclination angle.

  In addition, the inclination angle of the raw material is, for example, in the case of measuring the level at three positions as shown in FIG. It is possible to calculate with three patterns: (2) an angle obtained from the measured values of the level meters A and C, and (3) an angle obtained from the measured values of the level meters B and C. As the number of measurement points further increases, the number of calculation patterns capable of calculating the inclination angle for one raw material surface also increases. As described above, when the inclination angles θ1 and θ2 are calculated using a plurality of patterns, the relationship between the inclination angle and the powder ratio may be obtained in advance for each calculation pattern. Similarly, when calculating (estimating) the powder rate, an inclination angle is calculated with each calculation pattern at the time of discharging the raw material once, and a plurality of powders are calculated based on data obtained in advance for the inclination angle with each calculation pattern. The rate can be calculated. And what is necessary is just to finally determine a powder rate based on the value of the some powder rate. If the powder rate is calculated (estimated) from the inclination angles based on a plurality of calculation patterns, the powder rate can be specified more accurately.

  Moreover, the data of the correlation between the powder rate and the tilt angle obtained in advance are, for example, data indicating the relationship between the powder rate and the tilt angle as shown in FIG. 4 (data in which the tilt angle and the powder rate are associated with each other). It is sufficient to store a database constituted by a storage means (not shown) or the like. Then, the level measurement control unit 20 or other processing unit may use the database to calculate the powder rate from the measured inclination angle value.

  Further, the relationship between the powder rate used for calculation (estimation) of the powder rate and the inclination angles θ1 and θ2 can be obtained by obtaining a plurality of data of the inclination angles θ1 and θ2 for each powder rate and using the average value of the data. Good. Moreover, an approximate expression may be calculated | required from the value measured as shown with a broken line in FIG. 4, and the approximate expression may be used for calculation of a powder rate as the said correlation.

  An action to be performed based on the powder rate calculated (estimated) by the method described above will be described. When the powder ratio calculated (estimated) for the raw material charged in the furnace top bunker 5 exceeds the standard powder ratio, the air permeability in the blast furnace deteriorates. In that case, the operation action which compensates the ventilation deterioration in a blast furnace and the operation action which reduces the powder rate in the raw material to charge can be taken. In addition, the powder ratio used as the said reference | standard is suitably set from the relationship between the powder ratio of a raw material, and the air permeability in a blast furnace.

  Examples of the operation action that compensates for deterioration in ventilation include an operation of increasing the coke ratio and adjusting the distribution of charges in the blast furnace. The coke ratio is the amount of coke necessary to produce 1 ton of hot metal. The charge distribution is a distribution of the layer thickness ratio at each position of a predetermined furnace radius between an ore layer such as iron ore and a coke layer that are alternately stacked at the top of the blast furnace.

  In addition, as an operation action for reducing the powder rate of the raw material, the frequency of the sieve provided in the upstream process in the raw material supply path, such as the sieve provided in the raw material tank 1, is increased by increasing the frequency of the powder. For example, operations such as shaking off, changing the size of the sieve, and increasing the strength of the sintered ore and coke to make it difficult to generate powder in the sintering factory and the coke production process.

  As described above, by calculating (estimating) the powder rate of the raw material charged into the blast furnace and taking appropriate operation actions, the productivity of the blast furnace is reduced due to the deterioration of the air permeability in the furnace, The occurrence of serious troubles such as chilling can be prevented in advance. In particular, according to the present embodiment, when the raw material is charged from the furnace top bunker 5, it is possible to grasp the powder rate of the raw material for each charging, so that it is appropriate before the situation of the blast furnace changes. Can take various operational actions.

DESCRIPTION OF SYMBOLS 1 Raw material tank 2 Loading belt conveyor 3 Raw material 4 Switching chute 5 Furnace top bunker 6 Outlet 7 Flow control valve 8 Collecting hopper 9 Turning chute 10 Blast furnace 12 Level meter 20 Level measurement control part

Claims (6)

Predetermining the correlation between the powder rate of raw materials charged from the furnace top bunker and the inclination angle,
Obtain the angle of inclination of the raw material in the furnace top bunker,
A method for estimating a powder rate of a blast furnace raw material that estimates a powder rate of a raw material charged into a blast furnace from the correlation and the obtained inclination angle,
The inclination angle is the angle of the slope of the raw material (first inclination angle) when the charging of the raw material is completed, and / or the discharge of the charged raw material from the outlet of the furnace top bunker is started. The angle of the slope of the raw material (second inclination angle), which is stably formed after a certain transition period, and is inclined upward from the position above the discharge port toward the side wall of the furnace top bunker A method for estimating the powder rate of a blast furnace raw material. In a plurality of positions in the range from the position above the outlet to the side wall in the cross section of the furnace top bunker, measure the surface level that is the height of the surface of the raw material charged in the furnace top bunker,
The method for estimating the powder rate of a blast furnace raw material according to claim 1, wherein the inclination angle of the raw material is obtained based on a difference in the surface level of the raw material to be measured. Measure the surface level at three or more positions on the slope of the raw material,
Obtain the inclination angle of the slope of the measurement object based on the difference in surface level between two or more positions,
The method for estimating the powder rate of a blast furnace raw material according to claim 2, wherein the inclination angle of the raw material is determined based on the obtained plurality of inclination angles. Estimating the powder rate of the raw material charged into the blast furnace by the method for estimating the powder rate of the blast furnace raw material according to any one of claims 1 to 3,
When the estimated powder ratio exceeds a reference value, an operation action that compensates for the deterioration in air permeability of the blast furnace caused by an increase in the powder ratio and an operation action that decreases the powder ratio of the raw material charged in the furnace top bunker A method for operating a blast furnace, characterized by performing at least one of the above.   5. The blast furnace according to claim 4, wherein the operation action that compensates for the deterioration in air permeability is at least one of an operation of increasing a coke ratio and an operation of changing a charge distribution in the blast furnace. Operation method.   The operation action for reducing the raw material powder rate is different from the operation for increasing the frequency of the sieve arranged in the upstream process with respect to the furnace top bunker in the supply path of the raw material to the furnace top bunker. The method of operating a blast furnace according to claim 4, wherein the operation method is at least one of an operation of changing to a size sieve and an operation of changing production conditions of the raw material in order to increase the strength of the raw material.

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