JP7614564B2 - Sinter manufacturing method - Google Patents

Description

This invention relates to a method for producing higher quality sintered ore by accurately and quickly grasping the strength, reducibility, etc. of sintered ore and reflecting this in the operation of a sintering machine.

Sintered ore is produced by adding moisture to a sintering raw material mixture, which is a mixture of various brands of fine iron ore, auxiliary raw material powders such as limestone, silica, and serpentine, miscellaneous raw materials such as dust, scale, and return ore, and solid fuels such as powdered coke, in appropriate amounts, and then mixing and granulating the mixture. The resulting granulated raw material is then loaded into a DL sintering machine or the like and fired. The sintering raw material mixture absorbs moisture during granulation, causing it to aggregate together and become pseudo-particles. By loading the pseudo-particled granulated raw material for sintering onto the pallet of the sintering machine, good ventilation is ensured during firing, allowing smooth sintering to proceed.

In recent years, the quality of fine iron ore, which is a raw material for sintering, has been depleted of high-quality iron ore, and this tendency has become evident, i.e., the content of slag has increased and the material has become finer, which has led to a decrease in the productivity of sintered ore. In particular, the increase in alumina content associated with the decrease in quality increases the blast furnace slag ratio, which leads to an increase in the amount of reducing material. In addition, sintered ore used in blast furnaces is required to have a low slag ratio, high reducibility, and high strength in order to reduce the cost of producing molten pig iron and the amount of _CO2 generated. Therefore, some kind of measures are required to deal with the adverse effects of the decrease in quality of iron ore.

In general, in order to improve productivity in the production of sintered ore, it is necessary to (1) improve the yield of sintered ore and (2) improve the permeability of the sintered layer. In particular, if the product yield of sintered ore is high, there is no need to add extra raw materials to the blast furnace, and operation becomes stable. In addition, when producing sintered ore, the permeability of the raw material layer on the pallet has a strong effect on the firing speed, and when the permeability is particularly high, the firing speed also increases, making it possible to produce more sintered ore in the same amount of time.

Normally, fine sintered ore with a particle size of less than 5 mm cannot be charged into a blast furnace. Therefore, when producing sintered ore, the ratio of fine sintered ore is measured at the outlet of the sintering machine and used as an indicator of yield management. In addition, when producing sintered ore, the amount of coke powder, anthracite, and other agglomerating agents is adjusted so as to satisfy pulverization resistance indicators in the blast furnace, such as tumbler strength and shutter strength.

The strength of sintered ore is usually confirmed by sampling a portion of the sintered ore on the belt conveyor for sending to the blast furnace at the final point of the sintering plant and conducting a prescribed drop test. As the drop test, the tumbler strength test specified in JIS M-8712 or the shutter strength test specified in JIS M-8711 is adopted. In addition, the produced sintered ore is usually sampled by an extracting device at regular intervals during daily operation and sent to an offline analyzer, and the operator usually takes necessary actions such as changing and adjusting the operating conditions to satisfy the quality while looking at the results. The measured value of sintered ore strength is sometimes compared with the FeO analysis value in the sintered ore (the content of Fe ₃ O ₄ in the sintered ore converted into FeO). The magnetite structure of sintered ore is a structure that is generated in a reducing atmosphere in the combustion melting zone and remains without being reoxidized under the rapid cooling conditions on the sintering machine, and is used as an index of the heat input because the FeO concentration in the sintered ore tends to be high when the heat input is high.

In addition, in the production of sintered ore using a DL-type sintering machine, it is known that the state of pseudo-particle formation of the sintered raw material affects the permeability of the packed bed during firing, and greatly affects the productivity of sintered ore. Therefore, regarding the permeability of the produced sintered ore, an index called the air permeability (JPU) is used to monitor the permeability during operation, and it is known that the higher the exhaust gas volume, the higher the exhaust gas suction pressure, or the thinner the raw material layer, the higher the JPU value. In addition, when granulating the sintered raw material, moisture is important as a binder that adheres the fine powder in the sintered raw material to the coarse particles, so in order to properly perform pseudo-particle formation, it is also important to properly control the amount of moisture.

Regarding the above-mentioned breathability, in addition to monitoring the JPU value, it is also effective to monitor the temperature under the wind box to monitor the fire-break condition of the pallet that reaches the vicinity of the ore discharge section, and to adjust the pallet speed using an index called BTP (Burn Through Point).

The yield of sintered ore mentioned above is also related to the strength of the sintered ore itself. Therefore, in order to maximize the productivity of sintered ore, it is important to manage the strength of the sintered ore.

Regarding the strength of sintered ore, an estimation formula for sintered ore yield is known, as disclosed in the following prior literature (non-patent literature) (1). According to the description in this literature, it is possible to estimate the yield using the matrix strength and porosity of sintered ore obtained by tablet testing. Furthermore, prior literature (non-patent literature) (2) reports examples of measurements of reducibility and strength for each matrix. These clearly show that hematite and calcium ferrite, which are the main mineral structures of sintered ore, have higher strength and reducibility than slag structures.

Generally, quantitative analysis using powder X-ray diffraction and quantification using optical microscope observation are known for quantifying mineral structure, while well-known methods for evaluating porosity include evaluation using optical microscope observation and microfeature X-ray CT images.

Japanese Patent No. 5020446 (JP 2003-49227 A) JP 2014-173957 A

Oyama et al.: Tetsu-to-Haganen, 82(1996), p719. D.A.Kissin: STAL', 5(1960), p318. Ramanaidou, E.R., Wells, M.A., 2011a. Hyperspectral imaging of iron ores. In: Broekmans, M. (Ed.), 10th International Congress for Applied Mineralogy (ICAM), Trondheim.

However, the above-mentioned conventional techniques used in the manufacture of sintered ore have the following problems. For example, to predict the strength of sintered ore, a sample of the actual fired sintered ore is required, which must be embedded in resin or the like, polished, or otherwise treated before being observed under an optical microscope. Furthermore, with conventional optical microscope observation, the image quality varies depending on the conditions of the sample being measured, so corrections such as contrast and brightness are required each time a measurement is made. Also, mineralogy knowledge and observational skills are required to distinguish the typical mineral structures in sintered ore, and a certain level of skill is also required.

For example, in Patent Document 1, in the production of sintered ore, the kaolin (clay mineral) content of each iron ore raw material is measured using infrared absorption spectroscopy, and the iron ore is blended based on the content. According to this method, the granulation property and productivity improve as the kaolin content increases, and it is said that the productivity of sintered ore can be improved by controlling the blending amount of kaolin. However, in actual operation, there is variation in the blending ratio and components of iron ore, so in order to stabilize the properties of sintered ore, it is essential to control the granulation property (moisture adjustment) and heat input control (coke fine adjustment) to compensate for the variation in the raw material properties. Therefore, there is a problem that simply evaluating the raw materials used, as described in this document, does not lead to a reliable improvement in sintering productivity.

Patent Document 2 also shows a method for evaluating the degree of sintering of a sintered body by acquiring intensity spectrum and wavenumber data based on a micrograph of the sintered body and performing a Fourier transform. In this method, the unevenness of the surface of the sintered body changes depending on the degree of sintering, so the degree of sintering can be controlled by indexing the degree of unevenness. However, since the sintering process uses a blend of multiple iron ores as a raw material and the degree of sintering is affected by each raw ore, there is a problem in that effective action cannot be taken unless it is possible to determine which raw ore is causing the poor sintering of the sintered ore product.

Furthermore, Non-Patent Document 3 discloses a method for evaluating the mineral abundance state of an ore deposit surface based on hyperspectral images of each mineral texture. In order to obtain such a hyperspectral image, the reflected light must be wavelength-resolved using a spectroscopic element, and the light intensity of each wavelength must be calculated. With this method, even if colors are difficult to distinguish with the naked eye, different minerals can be identified if their wavelength spectra are different, making it possible to efficiently find ore deposits that contain a lot of impurities such as gangue and stripping soil, and efficiently mine iron ore with a high iron content. However, this method does not propose a method for observing the strength or reducibility of sintered ore.

The object of the present invention is to propose a method for easily evaluating the strength and reducibility of the produced sintered ore, and for efficiently producing sintered ore by quickly and appropriately reflecting the evaluation results in the operating conditions of the sintering machine.

In this invention, therefore, the inventors came to the conclusion that in order to solve the above-mentioned problems of the conventional technology and achieve the above-mentioned objectives, it would be effective to determine the mineral structure using a quicker and more objective indicator and sinter while feeding this back to the operation of the sintering machine, and thus developed the present invention. In other words, the inventors focused on the fact that each type of mineral structure, sintered ore, has a different spectroscopic spectrum and decided to utilize this as a means of increasing the objectivity of the mineral structure, i.e., sintered ore quality judgment.

The present invention, developed based on the above findings, is a method for producing sintered ore by adding moisture to a sintering raw material mixture, which is a mixture of powdered materials containing iron ore, auxiliary materials, miscellaneous materials, and solid fuel, mixing and granulating the mixture, and sintering the resulting granulated pseudo-particles. The method is characterized in that the sintered ore produced is observed using a hyperspectral camera, and the observation results are reflected in the operation of the sintering machine to adjust the operating conditions.

In addition to the above configuration, the present invention also has the following configuration:
(1) Observation of sintered ore using a hyperspectral camera has revealed either or both of the strength and reducibility of the produced sintered ore;
(2) In observing sintered ore using a hyperspectral camera, predicting either or both of the strength and reducibility of the produced sintered ore based on the spectroscopic information, strength, and reducibility that are prepared in advance for each mineral structure, and adjusting the operating conditions of the sintering machine based on the prediction results;
(3) The observation of the sintered ore involves collecting the produced sintered ore, preparing a polished sample, and observing the sample using a hyperspectral camera;
(4) The observation of the sintered ore using the hyperspectral camera is a measurement of the area ratio of one or more of hematite, magnetite, calcium ferrite, slag, and voids;
(5) The adjustment of the operating conditions is a change in one or more of the coke fine blending ratio, the lime source blending ratio, the particle size of the coke fine, the coke fine addition position in the granulated raw material, the amount of city gas blowing, and the amount of oxygen blowing.
It is a more preferred embodiment to adopt one or more of the above.

The method of the present invention, configured as described above, can take the necessary action to quickly and appropriately produce sintered ore, compared to the problems faced by the prior art, in which the causes of variations and declines in the strength and reducibility of sintered ore could not be quickly and thoroughly identified, forcing the user to take symptomatic action to improve strength and reducibility (quality), resulting in increased costs for agglomeration materials and increased strength fluctuations due to over-specifying the strength of the sintered ore.

In other words, by adopting the method of the present invention, the structure of sintered ore can be evaluated quickly and accurately, making it easy to quickly identify the cause of changes in the strength and reducibility of the sintered ore, and making it possible to take appropriate action at the right time. As a result, the variation in the strength and reducibility of the sintered ore product is reduced, improving the quality of the sintered ore, which in turn makes it possible to reduce the manufacturing cost of sintered ore and improve productivity.

FIG. 2 is a schematic diagram of a method for observing the structure of sintered ore. FIG. 1 is a diagram showing wavelength spectrum data for each mineral texture suitable for the method of the present invention. FIG. 2 is a diagram showing physical property data for each mineral texture measured according to the method of the present invention. FIG. 1 is an explanatory diagram showing an evaluation flow of sintered ore according to a conventional method. FIG. 2 is an explanatory diagram showing an evaluation flow of sintered ore according to a comparative method. FIG. 2 is an explanatory diagram showing an evaluation flow of sintered ore according to the invention method. 1 is a graph comparing the variation in strength between the conventional method and the method of the present invention. 1 is a graph comparing the variation in reducibility between the conventional method and the method of the present invention. 1 is a graph comparing the conventional method and the method of the present invention with respect to the variation in strength in Example 2.

In developing this invention, the inventors first focused on a hyperspectral camera and used it to observe the structure of sintered ore. As a result, they found that the main structures in sintered ore, namely hematite, magnetite, various forms of calcium ferrite structures, silicate slag structures, and voids, each have their own unique spectral spectrum, and that they can be easily classified.

Figure 1 shows a schematic diagram of a general observation method for mineral (sintered ore) texture. As shown in this figure, when observing the cross-sectional texture of sintered ore, first, a portion of sintered ore is taken with an actual machine, set in a plastic container, and embedded in resin to prepare a sample. Next, the sample is polished until a desired cross-section is revealed to prepare a polished sample, and then the sintered ore texture is observed under an optical microscope to identify various mineral textures. For example, it is possible to observe multiple types of mineral textures (e.g., A1 to A5) based on color tone, pores (P in the figure), and resin.
Here, for raw materials with small particle sizes, such as return fines generated in the sintering process, if they are laid out flat on a belt conveyor or the like, they can be measured as is without being filled with resin or polished.

As shown in Figure 1, mineral textures A1 to A5 do not only exist as single textures, but also exist mixed with other textures, and the colors are complex. When the color tone is gradated, the difficulty of identifying the texture becomes significantly more pronounced. That is, it is known that hematite shows a clear white color under optical microscope observation, magnetite shows a white to pink color, calcium ferrite shows a white to gray color, and slag shows a dark gray or transparent color, but the color changes greatly depending on the light amount and contrast of the optical microscope. Therefore, when comparing samples made on different days or by different observers, the distinction between hematite and magnetite, calcium ferrite and slag, and the resin of slag may become unclear, and the results may not be consistent. In addition, in optical microscope observation, in order to distinguish textures that are difficult to see, it is possible to increase the magnification and make a judgment based on the shape of the microstructure, or to make a comprehensive judgment by changing the polarization, but it is not an objective method as it depends largely on the observer's experience.

In contrast, the method according to the present invention connects a hyperspectral camera to an optical microscope, selects, for example, four mineral structures in the field of view, and measures the spectroscopic spectrum. Figure 2 shows the spectroscopic spectra of hematite, magnetite, calcium ferrite, and slag, which are examples of mineral structures. As shown in this figure, hematite has a higher visible light reflection spectrum intensity in the 400-800 nm range than other minerals, with a peak near 680 nm. In addition, the intensity of magnetite decreases as the wavelength increases in the 400-800 nm range. Furthermore, calcium ferrite has a significantly lower reflection spectrum intensity in the 550-650 nm range compared to hematite. Slag has the darkest color and a low intensity spectrum at all wavelengths. Thus, in the observation of mineral structures according to the method of the present invention, it was found that each structure has its own unique reflection spectrum, and that accurate classification of sintered ore structures is possible by comparing the overall shape of the wavelengths and the intensity of specific wavelengths.

FIG. 3 shows an image of the physical property data for each mineral structure. As shown in this figure, it can be seen that each mineral structure is given a different simple strength (matrix strength MPa) and reducibility (%). The strength and reducibility of the sintered ore as a mineral structure as a whole structure differ depending on the abundance ratio of the simple minerals, the porosity, and the pore structure. For example, when the abundance ratio of the _A1 structure and the _A2 structure greatly affects the strength σ, the overall strength σ can be expressed as a function of the abundance ratio of _A1 and _A2 . In the following formula (1), _X1 and _X2 are the abundance ratios of _A1 and _A2 .

In addition, when the abundance ratio of the _A3 to _An structures greatly affects the reducibility r, the reducibility r can be expressed as a function of the abundance ratio of _A3 and _An as shown in the following formula (2), where _X3 and _Xn are the abundance ratios of _A3 and _An .

In this way, by creating a list in advance of the relationship between the physical property data of each individual mineral structure and the strength and reducibility of the sintered ore, it becomes possible to quantitatively and quickly predict the strength and reducibility according to the proportion of sintered ore structures present.

The above-mentioned formulation method may be any method, for example, the effects of all the ore textures (A ₁ to A ₅ ) may be included by multiple regression analysis, or a formula may be formed by selecting variables with a high correlation. Furthermore, in addition to the mineral texture, information such as porosity and pore size distribution index may be used as variables, or the formula may be formed taking into account operational influences other than the mineral texture.

Furthermore, the formation of mineral structures is related to various raw material and operating conditions. For example, it is known that the proportion of hematite structures decreases under high temperature conditions. This is because part of the hematite changes to magnetite during the high-temperature firing process, or reacts with the CaO source to change to calcium ferrite.

As for magnetite, its proportion increases as the firing temperature rises. As for calcium ferrite, the optimum temperature range for its formation is said to be between 1200 and 1350°C, and at temperatures higher than this, it decomposes into secondary hematite and silicate slag. Therefore, the proportion of calcium ferrite present varies depending on the temperature conditions.

Furthermore, the amount of calcium ferrite generated varies depending on the basicity (CaO/SiO ₂ ). The main CaO source is limestone, and the SiO ₂ source is iron ore. If the mixing state is poor, that is, if the powders are not in micro-contact with each other, the area around the iron ore will have a low basicity locally, and the amount of calcium ferrite generated will decrease. Conversely, the area around the limestone will have a high basicity, which makes it easier for the molten liquid to be generated. For these reasons, if the calcium ferrite in the sintered ore structure is significantly reduced, segregation of the CaO source is suspected, and operational actions such as strengthening monitoring of the mixing state in the drum mixer and strengthening moisture management of the limestone (changing the amount of lime blended) will be taken. In order to carry out such actions based on the chemical analysis value of the sintered ore, a large number of N-number analyses are required, which is difficult in reality. However, if the mineral structure can be directly observed using a hyperspectral camera as in the present invention, it will be possible to easily detect the variation in the microscopic components.

By using the method according to the present invention as described above, the relationship between the mineral structure, temperature conditions, and raw material conditions can be organized in advance. For example, when the structure that causes the strength of sintered ore to decrease increases, it is effective to take operational action such as reducing the amount of coke powder blended in order to reduce the heat content. Conversely, it is also possible to take action aimed at selectively increasing the mineral structure that improves quality.

Therefore, preferred embodiments of the present invention will be described below.
FIG. 4 is a diagram of the evaluation flow of sintered ore based on the conventional method. The sintered ore discharged from the sintering machine is coarsely crushed by a crusher, introduced into the sintering machine cooler and cooled. After that, it is sized by various sieve screens and sent to the blast furnace. Here, a sampler is generally installed at the belt transfer section so that a part of the sintered ore after sizing can be collected, and the sintered ore collected by the sampler is sized and sent to a drop and rotation strength test, a reducibility test, and a reduction disintegration test. In normal operation, the strength of the sintered ore is measured once every 1 to 2 hours, and if the strength standard is not met, an action to increase the amount of heat is taken. However, such a conventional method has a limit to identifying the cause of the change in sintered ore strength at an early stage. That is, under the conventional method, in order to determine whether the input heat amount is appropriate, it was necessary to comprehensively judge various operation parameters such as the FeO ratio in the sintered ore, the red heat state of the sintered ore at the discharge section, and the main exhaust gas temperature.

In contrast, Figure 6 shows the flow for evaluating the quality of sintered ore according to the method of the present invention. The sintered ore discharged from the sintering machine is coarsely crushed in a crusher and then introduced into a cooler to be cooled. The basic processing method is the same as that of the conventional method described above, but the major difference is that a portion of the sintered ore (sample) collected by a sampler is polished to create a horizontal surface as shown in Figure 1, and then the cross section is observed with a hyperspectral camera.

Prior to carrying out the necessary operational actions according to the method of the present invention as described above, samples (sintered ore) can be collected from the actual equipment not only by using a dedicated box-type sampler, but also by manually collecting the sintered ore from the belt conveyor using a ladle or other method. For example, a robot arm can be used to continuously collect a portion of the sintered ore flowing on the belt, or an arm can be used to continuously select and collect the sintered ore from a sample container that has been sorted by particle size for strength measurement. Furthermore, the sample can be collected from the sample container by hand by an operator, and this can be done periodically and continuously.

The effects of adopting the conventional method, the comparative method, and the inventive method (the method of the present invention) in an actual sintering machine are compared and examined.
(1) In the conventional method, as shown in Fig. 4, the operator judged the heat level based on the tumbler strength value of the sintered ore sampled every hour by the sampler, and took the action of adding coke fine blending ratio. That is, when the tumbler strength value of the sampled sintered ore (hereinafter referred to as "measured value") was lower than the target shutter strength (hereinafter referred to as "target value"), the coke fine blending ratio was increased as heat input control, and when the strength of the sampled sintered ore was higher than the target, the coke fine blending ratio was decreased. The action width of the coke fine blending ratio was 0.5 kg/t-s. In addition, since RI measurement takes time, the sampled sintered ore was stored and measured offline.

(2) As for the comparative method, as shown in Figure 5, sintered ore from the same lot as that used to measure the tumbler strength of the sintered ore sampled with a sampler was individually sampled, a horizontal cross-sectional sample was prepared, and the cross-sectional surface was observed using a CCD camera.

(3) Next, for the inventive method, following the sintered ore evaluation flow shown in Figure 6, sintered ore from the same lot as that for which the tumbler strength of the sintered ore collected with a sampler was measured was individually collected, horizontal cross-sectional samples were prepared, and the cross-sectional observations were performed using a hyperspectral camera. Based on the observation results, the following actions were taken.

In other words, if the measured value was greater than the target value, and the cross-sectional observation determined that the amount of secondary hematite had increased and the porosity had decreased, it was determined that there was an excess of heat, and the coke powder blending ratio was reduced. On the other hand, if only one of the two factors had affected the amount of secondary hematite, such as an increase in the amount of secondary hematite or a decrease in the porosity, action was temporarily withheld. And, if there was no change in either the amount of secondary hematite or the porosity, one operational action was postponed. In this example, the amount of secondary hematite was observed, but the amount of magnetite may also be used as an indicator of heat.

On the other hand, if the measured value was smaller than the target value, the calcium ferrite ratio was low as a result of the above-mentioned cross-sectional observation, and there were many fine pores, it was determined that there was insufficient heat, and the coke powder mixing ratio was increased. Furthermore, the crystal water contained in the ore was dehydrated at around 250 to 300°C and became porous, and in a high-temperature environment, the dense pores were integrated into coarse pores due to a melting and assimilation reaction with the calcium ferrite molten liquid that was generated. From this, it was found that the amount of fine pores or coarse pores is related to the progress of the sintering reaction.

In addition, if there was an impact of either a decrease in calcium ferrite or an increase in the amount of micropores, action was temporarily suspended. If there was no change in either the amount of calcium ferrite or the amount of micropores, one operational action was postponed.

Next, Fig. 7 shows the variation in the measured values of sinter strength for the conventional method, the comparative method, and the inventive method. With the conventional method, the variation in shutter strength was about 1.4%, while with the comparative method it was 0.96%, and with the inventive method it was about 0.45%.
In addition, the comparative method makes it possible to suppress excessive action and stabilize the strength value by simultaneously evaluating not only the shutter strength but also the sintered ore structure. However, this method lacks quantitativeness when it comes to distinguishing calcium ferrite and secondary hematite due to differences in the surface condition of the embedded samples, and the action of the coke fine blending ratio may be excessive or insufficient.
In contrast, the method of the present invention using a hyperspectral camera was able to distinguish the structure well and accurately determine the variation in calcium ferrite and secondary hematite content for each sintered ore, which resulted in a significant reduction in the variation in strength.

Next, Figure 8 shows the variation in reducibility for the conventional method, the comparative method, and the inventive method. In the conventional method, the variation in reducibility was about 3.0%, while in the comparative method it was 2.4% and in the inventive method it was about 1.5%. In the conventional method, the RI analysis value could not be obtained on-site, and the morphology of the sintered ore structure was also unknown, so the operation was carried out without any prior information on RI. As a result, the variation was relatively large. In addition, in the comparative method, although the RI analysis could not be obtained on-site, the coke powder blending ratio was adjusted according to the amount of secondary hematite, porosity, and calcium ferrite based on optical microscope observation. Such actions also suppress extreme increases or decreases in reducibility.

In this embodiment, changes in raw material conditions will be described.
The experiment was carried out by blending iron ore powder with 2 mass% of steelmaking slag as the sintering raw material in the yard. Since the slag contains CaO compounds (a mixture of lime aluminate and undissolved CaO), the limestone blending ratio was adjusted based on the results of component analysis of sintered ore sampled every two hours to keep the basicity constant, as in the conventional method.
In contrast, in the method according to the present invention shown in FIG. 6, the calcium ferrite ratio in the sintered ore was measured every hour, and when the calcium ferrite ratio was low, the limestone blending ratio was increased within a range not exceeding the basicity setting, and when the calcium ferrite ratio was high and the basicity was also high, the limestone blending ratio was decreased within a range not falling below the basicity setting.

Figure 9 shows the results of a comparison of strength variation between the conventional method and the inventive method. The conventional method had a variation of about 1.5%, while the inventive method had a variation of about 0.6%. In particular, the conventional method took action to keep the CaO concentration constant based on chemical analysis values every two hours, which caused the amount of calcium ferrite to fluctuate. When the amount of calcium ferrite was low, the strength of the resulting sintered ore decreased, and when the amount of calcium ferrite was high, the strength improved, but the strength variation increased. On the other hand, with the inventive method, instead of the usual action every two hours, a judgment based on the results of mineral structure observation was made every hour, which made it possible to speed up the evaluation of component variation and reduced the strength variation.

In addition, the amount of slag or magnetite structure may be used as an indicator of strength variation other than the above-mentioned hematite, calcium ferrite, and voids. This is because, in the sintering process, when the amount of fine coke is increased, the hematite structure decreases and the magnetite increases. Therefore, the amount of heat can be determined by quantifying the amount of magnetite. Conventionally, the FeO concentration is used as an indicator of magnetite, but the method using a hyperspectral camera can quantify the magnetite structure more quickly. In addition, calcium ferrite structure decomposes into slag in a high-temperature environment. Therefore, the amount of heat can be determined by quantifying the amount of slag. Furthermore, since the generation of slag is affected by the state of gangue in the ore, the quality of the gangue addition state in the raw material can be determined.

Another operational action that can be taken using the method of the present invention is to change the particle size of the coke fines. When there is little calcium ferrite in the sintered ore structure and a large amount of slag, it is possible that there is excessive heat. In such cases, coarse coke fines may segregate to the lower layer of the sintered bed, resulting in the production of coarse, dense sintered ore. In such cases, it is effective to reduce the particle size of the coke fines to promote segregation to the upper layer of the sintered bed.

Another method of operation action using the method of the present invention is to change the position of coke powder addition (internal granulation, external granulation). In some cases, the coke powder is cut from the storage tank into a drum mixer like the raw ore and uniformly granulated (internal granulation), and in other cases, it is projected from the rear end of the drum mixer into a location where the particles have grown (external granulation). In the former process, the coke becomes the nucleus of pseudoparticles and becomes pseudoparticles with an attached powder layer, or is embedded in the pseudoparticles. In the latter process, the coke exists alone or as an attached powder layer of pseudoparticles. When the amount of calcium ferrite in the sintered ore decreases, there may be excess heat. In such cases, external granulation of the coke increases the contact efficiency with oxygen, improves combustion efficiency, and enables sintering with a low heat amount.

Other operational actions using the method of the present invention include changing the amount of city gas and oxygen blown in. In order to retain the primary hematite in the sintered ore and maximize the amount of calcium ferrite, it is important to control the heat pattern (temperature history). In order to promote the formation of calcium ferrite, it is best to hold the temperature at about 1200°C to 1350°C for an appropriate time, and low-temperature sintering is possible by reducing the amount of powdered coke mixed and controlling the amount of city gas and oxygen blown in from above the sintering machine. Since the heat pattern varies depending on the raw material conditions such as particle size, moisture, and composition, and the operational conditions, it is effective to observe the sintered ore structure produced with a hyperspectral camera and quantify the structure, which can contribute to more appropriate operational actions.

The technology of the present invention utilizing the above-described hyperspectral camera is not limited to the observation of mineral structures, particularly sintered ore structures, and the production of sintered ore while reflecting information based on the observation results in the operation of a sintering machine, but can also be applied to the observation of other mineral structures and the production methods of products based on the results of the observation.

Claims (5)

A method for producing sintered ore by adding moisture to a sintering mixture obtained by mixing and granulating a powdery material containing iron ore, auxiliary materials, miscellaneous materials, and solid fuel, and sintering the resulting granulated pseudo-particles, comprising the steps of:
The sintered ore produced was observed using a hyperspectral camera.
The observation of the sintered ore using the hyperspectral camera includes measuring the area ratio of one or more of hematite, magnetite, calcium ferrite, slag, and voids;
When adjusting the operating conditions by reflecting the observation results in the operation of the sintering machine,
The method for producing sintered ore is characterized in that the adjustment of the operating conditions is carried out by changing one or more of the following: the blending ratio of fine coke, the blending ratio of lime source, the particle size of fine coke, the position where fine coke is added in the granulated raw material, the amount of city gas injected, and the amount of oxygen injected . The method for producing sintered ore described in claim 1, characterized in that the observation of the sintered ore using the hyperspectral camera is either or both of the strength and reducibility of the produced sintered ore. The method for producing sintered ore described in claim 1 or 2, characterized in that, in observing the sintered ore using the hyperspectral camera, one or both of the strength and reducibility of the produced sintered ore are predicted based on the spectral information, strength, and reducibility that are prepared in advance for each mineral structure, and the operating conditions of the sintering machine are adjusted based on the prediction results. 3. The method for producing sintered ore according to claim 1 or 2 , characterized in that the observation of the sintered ore is carried out by taking a sample of the produced sintered ore, preparing a polished sample, and observing the sample using a hyperspectral camera. 4. The method for producing sintered ore according to claim 3, characterized in that the observation of the sintered ore comprises taking a sample of the produced sintered ore, preparing a polished sample, and observing the sample using a hyperspectral camera.

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