JP2012219363A - Method for production of sintered ore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the yield and productivity of a sintered ore by keeping the quality of the sintered ore constant with elapsed time by inhibiting the change of the quality of the sintered ore with elapsed time.SOLUTION: In a sintered ore production method for producing the sintered ore with a continuous sintering machine, (a) the image of the fracture surface of a sintered cake with an exposed red-hot zone at the time of ore discharge is periodically taken with an imaging device set at the ore discharge part of the continuous sintering machine, (b) at every image taken, (b1) the areal ratio Z (%) of the red-hot zone image to the entire image taken is calculated, (b2) the image taken is divided into n portions in the width direction of the sintered cake, and the areal ratio Zm (m=1 to n) (%) of the red-hot zone image to the corresponding divided image for every image is calculated, and (b3), the standard deviation σw of the areal ratio Zm (m=1 to n) (%) is calculated on the basis of the areal ratio Z (%), and (c) the change of the standard deviation σw with elapsed time is monitored.

Description

  The present invention maintains the quality of sintered ore (strength, reduction powder resistance, reducibility, etc.) over time when producing the sintered ore charged into the blast furnace with a continuous sintering machine. The present invention relates to a method for stably producing sintered ore.

  In blast furnace operation, sintered ore obtained by sintering sintered raw materials such as powdered ores as well as massive ores is used as an iron-making raw material. Usually, the sintered ore is a continuous sintering machine, for example, a plurality of sintered pallets are arranged in an endless track from the feeding section to the feeding section, the ignition furnace on the feeding section side, and the lower part of the sintering pallet It is manufactured by a DL-type sintering machine provided with a wind box for sucking air.

  Sintering raw materials, in addition to iron-containing raw materials such as powdered ore and iron-containing dust, auxiliary materials such as limestone and silica, and fuel such as powdered coke, etc. are mixed at a predetermined ratio, mixed while adjusting the amount of water, It is granulated and turned into pseudo particles, and is charged into the sintering pallet from the supply section to form a raw material packed layer on the sintering pallet.

  After igniting the surface layer of the raw material packed bed in the ignition furnace, the air is sucked in the windbox, the sintering pallet is moved horizontally to the discharge section, the raw material packed bed is fired from the upper layer, and the sintered ore ( Sinter cake). The sintered ore is discharged from the waste ore portion of the sintering machine and crushed into a sintered ore having a required particle size.

  Sintered ores are required to have the qualities required for blast furnace raw materials (strength, reduction powder resistance, reducibility, etc.). In the manufacture of sintered ore, it is required to manufacture with high productivity while maintaining the required quality. Therefore, various manufacturing methods have been proposed so far (see Patent Documents 1 to 8).

  According to the production methods described in Patent Documents 1 to 3, (a) the difference in suction air volume in the width direction of the sintered pallet, (b) the temperature in the width direction of the sintered pallet due to the difference in the shrinkage amount of the sintered layer And (c) deterioration in quality and yield in the width direction of the sintered pallet due to this “variation” can be suppressed.

  However, in the methods described in Patent Documents 1 to 3, the temperature of the exhausted portion that determines the quality of the sintered ore is not managed, and the quality improvement effect in the height direction of the sintered layer is small. Therefore, sufficient improvement in the quality of the sintered ore has not been achieved.

  In patent documents 4 and 5, the temperature of the sintered ore (exhaust part) is measured for each section partitioned in the width direction of the sintering pallet with a radiation thermometer arranged in the exhaust part of the sintering machine, Based on the measured temperature, the granulation conditions (moisture content, quick lime content) of the sintering raw material are set so that the area ratio of the region of 1100 ° C. or lower where the sintering is completed is 90% or more in each section. A method for adjusting the charging conditions is described.

  However, in the methods described in Patent Documents 4 and 5, it is difficult to accurately grasp the progress of the sintering, and the height direction of the sintered layer is the same as the methods described in Patent Documents 1 to 3. Since the quality improvement effect in is small, the quality of the sintered ore cannot be sufficiently improved.

  In Patent Document 6, the temperature is measured for each sintered layer height (upper layer, middle layer, lower layer) with an infrared camera arranged in the exhausting section, and based on the area ratio of the red hot section of 150 ° C. or higher, the feeding section Describes a method of injecting carbonaceous material according to the height of the raw material packed bed from the carbonaceous material blowing device arranged in the above.

  However, Patent Document 6 does not disclose a standard related to the area ratio of the red hot part at 150 ° C. or higher for maintaining the quality of the sintered ore. Since the red hot part having a temperature of 150 ° C. or higher includes a red hot part having a temperature of 1100 ° C. or higher where the sintering has not been completed, the method described in Patent Document 6 cannot be expected to significantly improve the quality of the sintered ore.

  In Patent Document 7, the temperature distribution in the height direction of the sintered ore (exhaust part) is measured with a thermal image camera arranged in the exhaust part, and the red hot layer (1100 ° C. or higher in the thermal image) of the exhaust ore part. A method for controlling the conveying speed of the sintering pallet and the suction speed of the wind box so that the temperature of the pallet is located at the bottom of the sintering pallet is disclosed.

  However, in the method described in Patent Document 7, since the red hot layer of 1100 ° C. or higher includes a sintered part insufficiently fired in the sintered layer above the bottom of the sintered pallet, the quality of the sintered ore is reduced. It is difficult to make it high enough.

  In Patent Document 8, the fracture surface of the sintered ore at the time of the ore is imaged with a camera arranged in the ore part, and based on the captured image over time, the entire captured image is 360 ° C. or more and 1000 ° C. or less. The area ratio Sh (t) (%) of the region and the sum Σσxy (t) of the standard deviation values of the temperature in the width direction and the height direction of the sintered pallet are calculated, and the area ratio Sh (t) (%) is A method is disclosed in which the operating conditions are controlled such that the reference value A is greater than or equal to the sum Σσxy (t) is less than or equal to the reference value B.

  However, since the method described in Patent Document 8 determines whether the operating state is good or bad based on the measurement result only at the time t, it is difficult to identify the cause. In particular, it is difficult to maintain the required level.

Japanese Patent Laid-Open No. 06-136456 Japanese Patent Laid-Open No. 06-330194 Japanese Patent Application Laid-Open No. 07-180972 Japanese Patent Laid-Open No. 08-127822 JP 08-143981 A Japanese Patent Laid-Open No. 10-310828 Japanese Patent Application Laid-Open No. 07-126763 JP 2009-280837 A

  In the production of sintered ore, (a) appropriately controlling the temperature in the sintering pallet width direction and / or the sintered layer height direction in the discharge section of the sintering machine can improve the quality of the sintered ore. In addition, it is important in terms of (b) suppressing the non-uniformity of firing in the sinter over time and maintaining the quality of the sinter constant over time. This is important in terms of productivity.

  However, a method for improving the yield and productivity of the sintered ore by suppressing the fluctuation and paying attention to the temporal change in the quality of the sintered ore has not been proposed so far.

  Accordingly, an object of the present invention is to suppress the temporal fluctuation of the quality of the sintered ore, maintain the quality of the sintered ore constant over time, and improve the yield and productivity of the sintered ore. An object of the present invention is to provide a method for producing a sintered ore that solves the problem.

  The present inventors diligently studied a method for solving the above problems. As a result, the fracture surface of the sintered ore where the red tropics are exposed is periodically imaged at the discharge section of the continuous sintering machine, and based on the captured image, the width direction of the sintered ore (sintered pallet) It was found that the above problem can be solved by obtaining the standard deviation of the red-tropical distribution in the width direction and monitoring the temporal variation of the standard deviation.

  This invention was made | formed based on the said knowledge, and the summary is as follows.

(1) In the manufacturing method of the sintered ore which manufactures the sintered ore with a continuous sintering machine,
(A) With an imaging device installed in the discharge section of the continuous sintering machine, periodically image the vertical fracture surface of the sinter cake during the discharge, where the red tropics are exposed,
(B) For each imaging,
(B1) While calculating the red-tropical area ratio Z (%) to the entire captured image,
(B2) The captured image is divided into n pieces in the width direction of the sintering machine pallet, and for each of the divided images, the red-tropical area ratio Zm (m = 1 to n) (%) with respect to the divided image is calculated.
(B3) A standard deviation σw of the area ratio Zm (m = 1 to n) (%) is calculated based on the area ratio Z (%),
(C) A method for producing a sintered ore characterized by monitoring the time course of the standard deviation σw.

  (2) The sintering according to (1), wherein the monitoring is performed in comparison with a normal operation range in which a predetermined range is changed while the area ratio Z and the standard deviation σw maintain a proportional relationship. Manufacturing method of ore.

  (3) During the monitoring, if the fluctuations of Z and σw have a peculiar fluctuation that deviates from the proportional band, the factor of the fluctuation is specified, and the operating condition is changed to remove the factor. The manufacturing method of the sintered ore as described in said (2).

  (4) The method for producing a sintered ore according to any one of (1) to (3), wherein the reddish tropical region is a region of 700 ° C. or higher.

(5) The operation condition to be changed is one or more of Al ₂ O ₃ amount of the sintering raw material, FeO amount of the sintering raw material, and powder coke blending amount. The method for producing a sintered ore according to any one of (1) to (4).

  ADVANTAGE OF THE INVENTION According to this invention, the time-dependent fluctuation | variation of the quality of a sintered ore can be suppressed, and the yield and productivity of a sintered ore can be aimed at.

It is a figure which shows the aspect of manufacture of the sintered ore by DL type sintering machine. It is a figure which shows typically the image and temperature distribution of the fracture surface of the sintered ore imaged with the CCD camera. (A) shows an image of a fracture surface, and (b) shows a temperature distribution of the fracture surface (isothermal lines are 700 ° C. and 850 ° C.). It is a figure which shows the width direction cross section of the pallet with a pallet height of 720 mm and a pallet width of 5500 mm, and an image of the fractured surface of the sintered ore sintered with the pallet (imaged at time t). (A) shows the arrangement mode of the sub-gates (SG1 to SG9) that divide the flow path of the sintered raw material when the sintered raw material is charged, and (b) is an image obtained by imaging the fracture surface of the sintered ore ( (Image is taken at time t1), and (c) shows an image obtained by subjecting the image to image processing for distinguishing a band of 700 to 850 ° C. and a band of 850 ° C. or higher (red tropical high temperature part). It is a figure which shows the distribution of the red-tropical area ratio calculated by classifying the image of the fracture surface of a sintered ore into 12 in the pallet width direction, and the change with time (the time interval is 20 to 40 seconds). It is a figure which shows typically the aspect from which the standard deviation (sigma) w fluctuates and remove | deviates from the proportional relationship with the thickness of a center cake. (A) shows the variation of the standard deviation σw with the increase in the amount of Al ₂ O _{3 in the} sintering material, and (B) shows the variation in the standard deviation σw with the increase in the amount of FeO (heat amount) in the sintering material. (C) shows the fluctuation of the standard deviation σw accompanying the increase in the operation rate (increased red tropical thickness). It is a figure which shows the fluctuation | variation of the standard deviation (sigma) w in Example 1. FIG. It is a figure which shows the fluctuation | variation of the standard deviation (sigma) w in Example 2. FIG.

  The present invention will be described. In FIG. 1, the aspect of manufacture of the sintered ore by a DL type sintering machine is shown. A sintered raw material 1 in which iron ore powder, carbonaceous material (coke powder), limestone powder, etc. are blended at a predetermined ratio, mixed with water, granulated into pseudo particles, was provided in the feed section of the sintering machine. It is stored in the surge hopper 2.

  The sintering raw material 1 is cut out from a drum feeder 3 provided in the lower part of the surge hopper 2 and laid on the floor of a sintering pallet 6 moving in the direction of the arrow in the figure from the chute 5 (floor hopper 7 ' 2 ′ to the floor covering raw material 1 ′ are continuously supplied onto the raw material filling layer 7 by being supplied prior to the supply of the sintering raw material 1).

  In the ignition furnace 13 provided on the side of the feed section, the upper surface of the raw material packed bed 7 is ignited to burn the carbonaceous material. The sprocket 4 is driven to move the sintered pallet 6 at a constant speed in the direction of the arrow, and through the wind box 8, the main duct 9, the exhaust gas dust collector 10, and the suction blower 11 provided below the pallet 6. Intake air is supplied to the combustion zone of the raw material packed bed 7. Note that the sucked gas is discharged from the chimney 12.

  The combustion zone in which the carbonaceous material in the raw material packed bed 7 burns moves from the surface layer of the raw material packed layer 7 to the lower layer, and firing is completed by the time the raw material packed layer 7 reaches the exhausting portion 14 of the sintering machine. The moving speed of the sintering pallet 6 is controlled. The raw material packed layer 7 that has been fired is cracked in the width direction of the sintered pallet 6 in the surface layer portion at the discharge portion 14 of the sintering machine, and falls as a sintered ore 15. It is conveyed to the next process.

  Immediately before the sintered ore 15 falls from the discharge portion 14 of the sintering machine, the fracture surface of the sinter cake that is broken and exposed is imaged by the imaging device 16. The imaging device is not limited to a specific device, but a CCD camera or an ITV camera is preferable. For example, when an image is captured by a CCD camera, the temperature can be obtained from the relationship between the ratio of the R component and the G component of the radiance of the RGB signal and a calibration curve created in advance using a black body furnace.

  Here, FIG. 2 schematically shows an image of the fracture surface of the sinter cake taken by the CCD camera and the temperature distribution. FIG. 2A shows an image of a fracture surface, and FIG. 2B shows the temperature distribution in the captured image shown in FIG. 2A with isothermal lines at 700 ° C. and 850 ° C.

  The present inventors periodically image the fracture surface of the sinter cake where the red tropics are exposed at the discharge section of the continuous sintering machine, and based on the captured image, the temporal change in the quality of the sintered ore is observed. We examined the monitoring method and created the following method.

(A) Regularly image the fracture surface of the sinter cake during the excavation where the red tropics are exposed,
(B) For each imaging,
(B1) While calculating the area ratio Z (%) of the red tropical image with respect to the whole captured image,
(B2) The captured image is divided into n pieces in the transverse direction of the sintered ore, and the area ratio Zm (m = 1 to n) (%) of the red tropical image to the divided image is calculated for each divided image.
(B3) A standard deviation σw of the area ratio Zm (m = 1 to n) (%) is calculated based on the area ratio Z (%),
(C) Monitor the trend of the standard deviation σw over time.

  The above technique forms the basis of the present invention. The above method will be described in detail with reference to FIGS.

  FIG. 3 shows a cross-section in the width direction of a sintered pallet having a pallet height of 720 mm and a pallet width of 5500 mm, and an image of a fractured surface of a sintered cake sintered with the sintered pallet (imaged at time t1). FIG. 3A shows an arrangement mode of sub-gates (SG1 to SG9) that divide the flow path of the sintering raw material when the sintering raw material is charged. Directly below the sintering pallet, thermocouples (TC1 to TC7) are arranged corresponding to the sub-gates (SG2 to SG8).

  FIG. 3B shows an image of the fracture surface of the sinter cake. FIG. 3C shows an image subjected to image processing for distinguishing a band of 700 to 850 ° C. (red tropical low temperature region) and a band of 850 ° C. or higher (red tropical high temperature region).

  As shown in FIG. 3B and FIG. 3C, the image of the fracture surface of the sinter cake is divided into 12 pieces in the width direction of the pallet corresponding to the width of the sub-gates (SG1 to SG9). Yes.

  However, the number of sections of the image of the fracture surface of the sintered ore does not need to correspond to the number of subgates, and may be set as appropriate in consideration of the shape of the red-tropical shape actually captured. Further, the width of the segmented image does not need to correspond to the width of the sub-gate, and may be set as appropriate, for example, by subdividing a portion to be measured in detail.

As described above, for each captured image of the fracture surface of the sinter cake taken periodically,
(B1) While calculating the red-tropical area ratio Z (%) to the entire captured image,
(B2) The captured image is divided into n pieces in the horizontal direction of the sinter cake, and the red-tropical area ratio Zm (m = 1 to n) (%) with respect to the divided image is calculated for each divided image.

  FIG. 4 shows the distribution of red-tropical area ratio (hereinafter referred to as “compartment area ratio”) calculated by dividing the image of the fracture surface of the sinter cake into 12 sections in the width direction of the sintering pallet and the time course. Showing fluctuations. The time interval is 20-40 seconds.

  The red tropical distribution in the width direction of the fracture surface of the sinter cake greatly affects the quality of the sinter. Therefore, as shown in FIG. 4, the present inventors pay attention to the fact that the distribution of the red-tropical section area ratio in the width direction of the fracture surface of the sinter cake fluctuates over time, and the distribution of the section area ratio, I thought that if the fluctuations could be statistically organized, the temporal fluctuations in the quality of the sintered ore could be grasped quantitatively and the fluctuations in the quality of the sintered ore could be suppressed.

  The inventors calculated the standard deviation σw of the divided area ratio Zm (m = 1 to n) (%) calculated based on the area ratio Z (%) of the red tropical image with respect to the entire captured image as a sinter at time t. Adopted as an indicator to display the quality of the fracture surface of the cake, the trend over time of the standard deviation σw was monitored.

  According to the monitoring results of the present inventors, it is found that in the graph (hereinafter referred to as monitoring diagram) in which the horizontal axis represents the thickness of the red tropics Z and the vertical axis represents the standard deviation σw, both fluctuate as follows. did.

  (W) In a normal and favorable operating state, σw and Z vary with time within a certain range while being approximately proportional.

(X) When the amount of Al ₂ O _{3 in the} sintering raw material is increased, the viscosity of the melt produced by the sintering reaction is increased, the air permeability is locally inhibited, and uneven burning is promoted. As a result, the correspondence relationship between σw and Z moves upward from the above-mentioned good position and changes.

  (Y) When the amount of heat input to the sintering raw material increases, the area ratio of the red tropics increases, so fluctuations in σw and Z move to the right and fluctuate. When the heat input decreases, it moves to the left.

  (Z) When the operation rate changes significantly as in the production increase operation, the bed thickness is increased and the input heat amount is increased in the actual operation, so the thickness of the red tropics itself increases and the fluctuation range also increases. It can be said that this change is the same as the cause during the normal operation, and the situation is manifested by increasing the layer thickness. The correspondence between σw and Z moves in the upper right direction while maintaining a proportional relationship.

  As described above, since the proportional relationship between the standard deviation σw and the red tropical zone Z is established with the required width, the fluctuation of the standard deviation σw and the red tropical zone Z is compared with the fluctuation range in a good state. To grasp. Here, it is difficult to determine the fluctuation range in a good state uniquely or in advance.

  Therefore, in implementing the present invention, the past operation status is analyzed from the above viewpoint to obtain a good fluctuation range in advance, and the subsequent operation is monitored based on the range. Specific methods will be described in Examples.

  FIG. 5 schematically shows the fluctuations of (x), (y), and (z). (A) in FIG. 5 shows the fluctuation of the above (x), (B) in FIG. 5 shows the fluctuation of (y), and (C) in FIG. Showing fluctuations.

  In actual operation, the fluctuation of the standard deviation σw is the fluctuation of the above (x), (y), and (z) (refer to (A), (B), and (C) in FIG. 5 respectively). Will be mixed.

  Of these, the fact that the amount of heat input to the sintered raw material has increased due to the increase in the amount of FeO in the sintered raw material (y) can also be understood from the temperature of the hot air sucked by the wind box. Further, the change in granulation property due to the amount of fine powder of the blended raw material of (z) and the amount of added water at the time of granulation can also be detected by JPU (sintering aeration index) which is an aeration property index. Therefore, the remaining fluctuation of the detected standard deviation σw can be determined as the contribution of (x).

  Thus, by monitoring the proportional relationship between the standard deviation σw and the red tropical zone Z, the cause of the operational fluctuation can be immediately grasped. And if the cause of the fluctuation | variation of standard deviation (sigma) w can be specified, the operating condition which removes this cause will be changed, standard deviation (sigma) w will be returned to the original proportional zone, and the fluctuation | variation of the quality of a sintered ore can be suppressed. .

  In practicing the present invention, red tropics are preferably in the region of 700 ° C. or higher, more preferably 850 ° C. or higher, in order to accurately reflect operational fluctuations in the operation. If the temperature is 1000 ° C. or higher, the area ratio itself is lowered, and the detection rate is lowered.

  Next, examples of the present invention will be described. The conditions of the examples are one example of conditions adopted for confirming the feasibility and effects of the present invention, and the present invention is limited to this one example of conditions. Is not to be done. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

Example 1
A description will be given of an example in which the present invention is implemented by installing a CCD camera in the exhaust section of the actual sintering machine. Every 20-40 seconds, the fractured surface of the sintered ore where the red tropics were exposed was imaged. The area ratio Z (%) of the red-tropical image with respect to the entire captured image is calculated from the image for each captured image, and the captured image is divided into n pieces in the width direction of the sintered ore. The area ratio Zm (m = 1 to n) (%) of the red tropical image with respect to is calculated, and the standard deviation of the area ratio Zm (m = 1 to n) (%) based on the area ratio Z (%) σw was calculated.

  The trend of the calculated standard deviation σw was monitored over time in comparison with the proportional region where the proportional relationship between the thickness of the raw material packed bed and the standard deviation σw is established.

First, the relationship between Z and σw was tracked in advance for two months. FIG. 6 shows an example in which the trend of the standard deviation σw is monitored. The black triangles and ◇ in Fig. 6 are the data obtained at that time, and the black triangles are in good operation, while ◇ is judged to be in a deteriorated operating condition. did. Furthermore, the transition from black triangle to ◇ was considered to be affected by an increase in the amount of raw material alumina, so measures were taken to reduce the amount of Al ₂ O _{3 in the} sintering raw material.

  As a result, the standard deviation σw after the above measures changed to ◆. It has been confirmed that the raw material alumina shifts the operating point in the figure of the present invention.

Moreover, ◆ has not returned to the black triangle, but ◆ has a production rate of about 3 t / m ² / d, which is higher than the production rate of the black triangle. In this way, even in the same stable operation, the area indicated by the black triangle is low in operation, and when the operation increases as production increases, as indicated by ◆, the red tropical of the sinter cake at low operation It was verified that the thickness Zw and the standard deviation σw varied along a straight line indicating the proportional relationship.

(Example 2)
FIG. 7 shows an operation example in another period. The plot on a certain day changed to ● in the right direction on the monitoring chart against the good state indicated by the black triangle. As a result, it was judged that the operation was excessively thermal for some reason, and an action to reduce the blended amount of powder coke was taken. In addition, the plot of another day changed to a left circle in the monitoring chart. As a result, it was judged that the operation was thermally insufficient for some reason, and an action to add the amount of powder coke was taken. As a result, it returned to the favorable fluctuation range of the black triangle.

  As described above, daily thermal operation management can be accurately performed by the monitoring method of the present invention.

  As described above, according to the present invention, it is possible to suppress the temporal variation of the quality of the sintered ore and improve the yield and productivity of the sintered ore. Thus, the present invention has high applicability in the sintering technology that supports the steel industry.

DESCRIPTION OF SYMBOLS 1 Sintering raw material 1 'Floor covering raw material 2 Surge hopper 2 Floor covering hopper 3 Drum feeder 4 Sprocket 5 Chute 6 Sintering pallet 7 Raw material filling layer 7' Floor covering 8 Wind box 9 Main duct 10 Exhaust gas dust collector 11 Suction blower 12 Chimney 13 Ignition furnace 14 Exhaust section 15 Sintered ore 16 Imaging equipment

Claims (5)

In the manufacturing method of the sintered ore which manufactures the sintered ore with a continuous sintering machine,
(A) With an imaging device installed in the discharge section of the continuous sintering machine, periodically image the vertical fracture surface of the sinter cake during the discharge, where the red tropics are exposed,
(B) For each imaging,
(B1) While calculating the red-tropical area ratio Z (%) to the entire captured image,
(B2) The captured image is divided into n pieces in the width direction of the sintering machine pallet, and for each of the divided images, the red-tropical area ratio Zm (m = 1 to n) (%) with respect to the divided image is calculated.
(B3) A standard deviation σw of the area ratio Zm (m = 1 to n) (%) is calculated based on the area ratio Z (%),
(C) A method for producing a sintered ore characterized by monitoring the time course of the standard deviation σw.   2. The method for producing a sintered ore according to claim 1, wherein the monitoring is performed in comparison with a normal operation range in which a predetermined range is changed while the area ratio Z and the standard deviation σw maintain a proportional relationship. .   3. If the fluctuation of Z and σw is different from the proportional band during the monitoring, the factor of the fluctuation is specified and the operation condition is changed to remove the factor. The manufacturing method of the sintered ore as described in 1 ..   The method for producing a sintered ore according to any one of claims 1 to 3, wherein the reddish tropical region is a region of 700 ° C or higher. The operation condition to be changed is any one or two or more of Al ₂ O ₃ amount of sintered raw material, FeO amount of sintered raw material, and powder coke blending amount. Item 5. The method for producing a sintered ore according to any one of Items 1 to 4.

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