Classification methods of iron ore

Abstract

Iron ore is classified based on its silicon content. [Solution] A method for classifying iron ore, wherein elemental mapping is performed on a sample in which the iron ore to be classified is embedded in a base material using SEM / EDS. Next, the mapping region is classified into multiple types of Si-containing regions based on the Si content of each measurement point measured by elemental mapping. Then, the iron ore is classified based on the area ratio of the area of ​​a specific Si-containing region to the total area of ​​the mapping region.

Description

Technical Field

[0001] The present invention relates to a method for classifying iron ores based on the existing form of Si in iron ores.

Background Art

[0002] In the production process of sintered ore, iron ores from multiple production areas and brands are blended, and auxiliary raw materials are further added for component adjustment. Then, after firing in a sintering machine, sintered ore with ensured size, strength, reactivity, etc. as raw materials for blast furnaces is produced. Here, a method for discriminating the minerals constituting the sintered ore is disclosed in Patent Document 1.

[0003] Patent Document 1 discloses a method for discriminating the mineral species of the minerals constituting the sintered ore. Specifically, based on elemental analysis using characteristic X-rays obtained by irradiating with primary rays, the mass ratio of each element in the primary ray irradiation spot of the analysis element group (consisting of Fe, Ca, Si, Al, and O) is obtained. Next, for the results obtained by elemental analysis, based on a predetermined conversion formula, the mass ratio of a predetermined metal oxide corresponding to the metal element in the analysis element group is obtained. Next, based on the result of the mass ratio of the metal oxide, the mineral species of the mineral corresponding to the primary ray irradiation spot is discriminated. For example, the mineral species is discriminated as follows.

[0004] When the total mass ratio of metal oxides (Fe2O3, CaO, SiO2, and Al2O3) is 20% or less, the location corresponding to the primary ray irradiation spot is discriminated as a pore. When the mass ratio of the metal oxide (SiO2) is 50% or more, the mineral corresponding to the primary ray irradiation spot is discriminated as quartz. When the mass ratio of the metal oxide (SiO2) is 20% or more and less than 50%, the mineral corresponding to the primary ray irradiation spot is discriminated as larnite or silicate slag.

[0005] In the pseudo-ternary phase diagram of xyz, where x=SiO2, y=CaO, and z=Fe2O3+Al2O3, if the mass ratio (x,y,z) falls within the range enclosed by the five points (20,30,50), (0,20,80), (0,10,90), (10,0,90), and (35,15,50), the mineral corresponding to the primary irradiation spot is determined to be SFCA. In the pseudo-ternary phase diagram of xyz, where x=SiO2, y=CaO, and z=Fe2O3+Al2O3, if the mass ratio (x,y,z) falls within the range enclosed by the four points (0,30,70), (10,35,55), (15,29,56), and (0,20,80), the mineral corresponding to the primary irradiation spot is determined to be SFCA-I. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-091276 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The inventors of this invention have discovered that iron ore can be classified by focusing on the Si content at each measurement point in elemental mapping using SEM / EDS, and have completed the present invention. The minerals constituting sintered ore are thought to be influenced by the raw material, iron ore, but no method for classifying iron ore based on the Si content at each measurement point in elemental mapping is disclosed in Patent Document 1. [Means for solving the problem]

[0008] This invention relates to a method for classifying iron ore. First, elemental mapping is performed on a sample in which the iron ore to be classified is embedded in a base material using SEM / EDS. Next, the mapping region is classified into several types of Si-containing regions based on the Si content of each measurement point measured by the elemental mapping. Then, the iron ore is classified based on the area ratio of a specific Si-containing region to the total area of ​​the mapping region.

[0009] A boundary value for Si content used to classify Si-containing regions can be set to 7.0% by mass or more and 10.0% by mass or less. Here, a specific Si-containing region can be defined as the region where the measured Si content is equal to or greater than the boundary value.

[0010] For classifying iron ore, two boundary area ratios can be set: a first boundary area ratio and a second boundary area ratio higher than the first. When the area ratio is less than the first boundary area ratio, the iron ore can be classified as a type in which Fe and Si coexist. When the area ratio is equal to or greater than the second boundary area ratio, the iron ore can be classified as a type in which Si exists alone. For example, the first boundary area ratio can be set to 40%, and the second boundary area ratio can be set to 60%.

[0011] For the iron ore to be classified, a coarse-grained portion consisting of iron ore with a particle size larger than the standard particle size can be used, and a fine-powdered portion consisting of iron ore with a particle size smaller than or equal to the standard particle size can also be used. [Effects of the Invention]

[0012] According to the present invention, a novel method for classifying iron ore is provided that focuses on the Si content at each measurement point of elemental mapping by SEM / EDS in the iron ore. [Brief explanation of the drawing]

[0013] [Figure 1] This is a flowchart explaining how to classify iron ore. [Figure 2]This figure shows the ternary system state of Fe2O3-SiO2-CaO. [Figure 3] This figure shows the results of elemental mapping of iron ore A (coarse-grained portion). [Figure 4] This figure shows the results of elemental mapping of iron ore C (coarse grain). [Modes for carrying out the invention]

[0014] The iron ore classification method of this embodiment will be explained using the flowchart shown in Figure 1.

[0015] In step S101, a sample is prepared by embedding the iron ore to be classified in a resin base material. Specifically, a sample is prepared by embedding the iron ore to be classified in a resin base material and polishing the surface. A cylindrical body with polished end faces can be used as the sample.

[0016] The iron ore to be embedded in the base material can be divided into coarse-grained and fine-powdered sections according to its particle size. By embedding each of these sections into the base material, two types of samples can be prepared. In the sintering process, the iron ore contains particles that act as nuclei for pseudo-particles and particles that adhere to the surface of these nuclei. Therefore, it can be divided into a coarse-grained section, which consists of the nuclei, and a fine-powdered section, which consists of the adhering particles.

[0017] A reference particle size (boundary value) for distinguishing between coarse-grained and fine-powdered portions can be predetermined. Iron ore with a particle size larger than the reference particle size can be designated as the coarse-grained portion, and iron ore with a particle size smaller than or equal to the reference particle size can be designated as the fine-powdered portion. For example, the reference particle size can be set to 0.25 to 1.0 mm. Alternatively, iron ore containing a mixture of coarse-grained and fine-powdered portions can be embedded in the base material without distinguishing between the two.

[0018] The total number of iron ore particles embedded in the base material can be, for example, 100 to 1000. If the total number of particles is too small, the accuracy of iron ore classification may decrease due to variations caused by individual differences in the particles. Also, if the total number of particles is too large, it will take too much time to classify the iron ore. Considering this point, the total number of particles can be determined. When classifying iron ore into a coarse particle part and a fine powder part as described above, for each of the coarse particle part and the fine powder part, the above-described total number of particles may be prepared.

[0019] In step S102, elemental mapping (elemental analysis) by SEM / EDS is performed on the sample produced in the process of step S101. In the present embodiment, in the process of step S103 described later, classification is performed based on the Si content rate in the iron ore, and thus the element to be analyzed is Si. Here, in addition to Si, Fe and O can be the elements to be analyzed. By performing elemental mapping on these elements, the content rate of each element can be measured.

[0020] The region for performing elemental mapping can be a region including the above-described total number of particles (for example, 100 to 1000). The higher the resolution of the elemental mapping, the more the accuracy of the elemental analysis can be improved, but the time for the elemental analysis becomes longer. Considering the accuracy and time of the elemental analysis, the resolution of the elemental mapping can be appropriately determined. As the apparatus for performing elemental mapping, a commercially available apparatus (for example, the FE-SEM Sigma series of ZEISS) can be used.

[0021] In step S103, the entire mapping region in the process of step S102 is classified into a plurality of types of Si-containing regions according to the Si content rate [mass%]. Here, by determining a boundary content rate regarding the Si content rate in advance, a plurality of types of Si-containing regions can be classified. The boundary content rate may be one or plural.

[0022] When one boundary content ratio is set, two types of Si-containing regions can be set. That is, for regions where the Si content ratio is lower than the boundary content ratio, they can be classified as low-Si-containing regions, and for regions where the Si content ratio is not less than the boundary content ratio, they can be classified as high-Si-containing regions. Here, the high-Si-containing region can be regarded as the region where Si mainly exists, and the low-Si-containing region can be regarded as the region where iron oxide mainly exists instead of Si.

[0023] The above-mentioned boundary content ratio can be appropriately determined in consideration of the proportion of Si existing in the iron ore. For example, for iron ore with Fe and O as the main components and containing SiO2 (mass%) as an impurity, the boundary content ratio can be set to not less than 7.0% by mass and not more than 10.0% by mass, for example.

[0024] When two different boundary content ratios are set, three types of Si-containing regions can be set. Here, the two boundary content ratios are the first boundary content ratio Si_th1 and the second boundary content ratio Si_th2, and the second boundary content ratio Si_th2 is higher than the first boundary content ratio Si_th1 (Si_th1 < Si_th2). In this case, the following three types of Si-containing regions (low-Si-containing region, medium-Si-containing region, high-Si-containing region) can be set.

[0025] Low-Si-containing region: Si content ratio < Si_th1 Medium-Si-containing region: Si_th1 ≤ Si content ratio < Si_th2 High-Si-containing region: Si_th2 ≤ Si content ratio

[0026] Here, the high-Si-containing region can be regarded as the region where Si mainly exists, the low-Si-containing region can be regarded as the region where iron oxide mainly exists instead of Si, and the medium-Si-containing region can be regarded as the region where Si and iron oxide coexist.

[0027] The first boundary content Si_th1 and the second boundary content Si_th2 can be appropriately determined considering the proportion of Si present in the iron ore. For example, the first boundary content Si_th1 can be set to 40 mass%, and the second boundary content Si_th2 can be set to 60 mass%.

[0028] If three or more boundary content ratios that are different from each other are set, four or more types of Si-containing regions can be set based on the same approach as the one or two boundary content ratios described above.

[0029] When performing elemental mapping as described in step S102, the Si content is obtained for each measurement point of the elemental mapping. Therefore, by comparing the Si content of each measurement point with the boundary content described above, it is possible to determine which of the multiple types of Si-containing regions each measurement point belongs to.

[0030] When a boundary content is set, measurement points where the Si content is lower than the boundary content can be identified as belonging to the low Si content region described above. Conversely, measurement points where the Si content is equal to or greater than the boundary content can be identified as belonging to the high Si content region described above.

[0031] When two different boundary content rates are set, measurement points with a Si content lower than the first boundary content rate Si_th1 can be identified as belonging to the low Si content region described above. Furthermore, measurement points with a Si content equal to or greater than the first boundary content rate Si_th1 and lower than the second boundary content rate can be identified as belonging to the medium Si content region described above. In addition, measurement points with a Si content equal to or greater than the second boundary content rate Si_th2 can be identified as belonging to the high Si content region described above.

[0032] In step S104, the iron ore is classified based on the classification results from the process in step S103. Specifically, the process in step S103 allows us to determine the area ratio of each Si-containing region to the total area including all types of Si-containing regions. By pre-determining boundary area ratios for classifying the iron ore and comparing the area ratio of a specific Si-containing region with the boundary area ratio, the iron ore can be classified. There may be one boundary area ratio or multiple boundary area ratios.

[0033] For example, when determining the area ratio of the high-Si content region mentioned above, the boundary area ratio for classifying iron ore can be predetermined, and the iron ore can be classified by comparing the area ratio of the high-Si content region with the boundary area ratio.

[0034] When a single boundary area ratio is set, iron ore can be classified into two types. For example, samples (iron ore) where the area ratio of the high Si-containing region is greater than or equal to the boundary area ratio can be classified as a type in which Si exists alone in the iron ore (hereinafter referred to as the "Si-only type"). On the other hand, samples (iron ore) where the area ratio of the high Si-containing region is lower than the boundary area ratio can be classified as a type in which Si and Fe coexist in the iron ore (hereinafter referred to as the "Fe-Si coexistence type").

[0035] Here, the Si-only type is a type in which Si exists alone in the iron ore, and Si exists independently of Fe in the iron ore as individual SiO2 particles. The Fe-Si coexistence type is a type in which Fe and Si coexist in the iron ore, and Si is dispersed within the iron ore (particles) and positioned in close proximity to Fe.

[0036] The boundary area ratio mentioned above can be appropriately determined considering the proportion of Si in the iron ore. For example, the boundary area ratio can be set to 50%.

[0037] When two different interfacial area ratios are set, iron ore can be classified into three types. Here, the two interfacial area ratios are the first interfacial area ratio AR_th1 and the second interfacial area ratio AR_th2, and it is assumed that the second interfacial area ratio AR_th2 is higher than the first interfacial area ratio AR_th1 (AR_th1 < AR_th2). In this case, the following three types (Si single type, intermediate type, Fe-Si coexistence type) can be set.

[0038] Fe-Si coexistence type: area ratio < AR_th1 Intermediate type: AR_th1 ≤ area ratio < AR_th2 Si single type: AR_th2 ≤ area ratio

[0039] Here, the Si single type and the Fe-Si coexistence type are as described above. The intermediate type is a type that does not belong to either the Si single type or the Fe-Si coexistence type. Considering the above three types, the first interfacial area ratio AR_th1 and the second interfacial area ratio AR_th2 can be determined in advance.

[0040] The first interfacial area ratio AR_th1 and the second interfacial area ratio AR_th2 can be appropriately determined considering the proportion of Si present in the iron ore. For example, the first interfacial area ratio AR_th1 can be set to 40% and the second boundary content ratio AR_th2 can be set to 60%.

[0041] When three or more different interfacial area ratios are set, based on the same concept as one or two interfacial area ratios described above, iron ore can be classified into four or more types.

[0042] As described above, by classifying iron ore focusing on Si contained in the iron ore, it can be used as a criterion for judgment when using iron ore in the production of sintered ore and blast furnace operation. In other words, considering the classification result of iron ore, it is possible to select iron ore when producing sintered ore or select iron ore to be charged into the blast furnace.

[0043] In this embodiment, iron ore is classified based on the form of Si present in the iron ore. The form of Si present in the iron ore greatly affects the melt assimilation reaction and melt formation reaction during calcination. This point will be explained using the ternary phase diagram of Fe2O3-SiO2-CaO shown in Figure 2. Here, Figure 2 is based on the diagram described in J. Am. Ceram. Soc., 42(1959), No.9, p413-.

[0044] In Figure 2, there are two regions, R1 and R2, where a melt (liquid phase) occurs above 1300°C. Region R1 is the region where a melt of calcium ferrite (hereinafter referred to as "CF system") is formed, and region R2 is the region where a melt of calcium silicate (hereinafter referred to as "CS system") is formed.

[0045] Considering the production of sintered ore and the use of iron ore in blast furnace operation, CF-type melts are considered superior to CS-type melts in terms of quality, such as strength and reactivity (resistance to reduction and pulverization in the blast furnace). Sintered ore is produced by adding limestone (Ca source) to iron ore (Fe source) and firing it. When sufficient amounts of Fe and Ca are present at the location where the melt is generated, whether a CF-type melt or a CS-type melt is produced depends on the local amount of Si present.

[0046] In Figure 2, the boundary value that determines the formation of CF-based melt and CS-based melt corresponds to the dotted line L1 in Figure 2. Here, the dotted line L1 is a line that passes through the center of the line (indicated by a double arrow) connecting the region R1 where CF-based melt is formed and the region R2 where CS-based melt is formed, starting from the CaO vertex (lower left vertex) in Figure 2. In Figure 2, at the intersection PI of the line connecting the SiO2 vertex and the Fe2O3 vertex and the dotted line L1, the Fe2O3 content is approximately 82 mass%, and the SiO2 content is approximately 18 mass%. It is estimated that CF-based melt is formed when the SiO2 content is less than the boundary value indicated by the dotted line L1, and CS-based melt is formed when the SiO2 content is equal to or greater than the boundary value indicated by the dotted line L1.

[0047] In elemental mapping by SEM / EDS (step S102 shown in Figure 1), the content of elements such as Fe, Si, and O is measured, rather than the relative abundance of each mineral shown in Figure 2. Therefore, when converted to the content of each element at intersection PI, the content of Fe is approximately 57.4 mass%, the content of Si is approximately 8.4 mass%, and the content of O is approximately 34.2 mass%. For this reason, the boundary content (Si content) used in the processing of step S103 shown in Figure 1 can be set to 8.4 mass%.

[0048] Considering that the iron component in iron ore exists not only as iron oxide (Fe2O3) but also as iron hydroxide (FeOOH), at intersection PI shown in Figure 2, the Fe content is approximately 58.4 mass%, the Si content is approximately 7.7 mass%, and the O content is approximately 33.9 mass%. Therefore, the boundary content (Si content) used in the treatment of step S103 shown in Figure 1 can be set to 7.7 mass%. The Si content may also differ depending on the mineralogical properties of the source and mine, but since iron oxide and iron hydroxide are mixed in iron ore, considering the ternary phase diagram of Fe2O3(FeOOH)-SiO2-CaO, the Si content at intersection PI is considered to be within the range of 7.7 mass% to 8.4 mass%.

[0049] On the other hand, iron ore may contain Al2O3 as an impurity in addition to SiO2, and MgO may be added to adjust the composition of sintered ore. Therefore, the Si content at intersection PI may deviate from the theoretical value (7.7-8.4 mass%) in the ternary phase diagram of Fe2O3(FeOOH)-SiO2-CaO mentioned above.

[0050] The presence of Al2O3 and MgO generates a silico-ferrite of calcium and aluminum (SFCA), which alters the equilibrium composition, melting point, and ultimately Si content of the CF-based melt. Here, since MgO is hardly present in iron ore itself, it does not affect the classification method of iron ore in this invention. On the other hand, Al2O3 contains Fe within the silico-ferrite.3+ Ions and Al 3+ Because ions mutually substitute and solid-solve, the presence of Al2O3 makes it easier for CF-based melts to form, and it is thought that the Si content required to distinguish between CF-based melts and CS-based melts increases.

[0051] As mentioned above, in the ternary phase diagram shown in Figure 2, the SiO2 content is approximately 18 mass%. However, if, for example, the Al2O3 content in iron ore is 3.0 mass%, then in the ternary state of (Fe2O3+Al2O3)-SiO2-CaO, the amount of Al that makes it easier for CF-based melt to be formed increases. As a result, the SiO2 content becomes approximately 21 mass% (=18+3), and the converted Si content becomes 9.8 mass%.

[0052] Considering the points mentioned above, the boundary content (Si content) used in the process of step S103 shown in Figure 1 can be a value within the range of 7.0 mass% to 10.0 mass%.

[0053] In the Fe-Si coexistence type described above, there is mainly a region where the Si content is below the boundary content, and it is assumed that Si is dispersed in the iron ore. When it assimilates with CaO particles, which are the melt source, there is a high possibility that a CF-type melt will be formed. On the other hand, in the Si-only type, there is mainly a region where the Si content is above the boundary content, and since there is little Fe and Si is unevenly distributed at high concentrations, there is a high possibility that a CS-type melt will be formed.

[0054] Therefore, according to the iron ore classification method of this embodiment, for example, iron ore can be classified according to the type of molten material produced by the sintering reaction (assimilation reaction). [Examples]

[0055] The following describes embodiments of the present invention. However, the present invention is not limited to the embodiments described below.

[0056] (sample) Four types of iron ore, A to D, were prepared, and each type of iron ore A to D was separated into a coarse-grained portion and a fine-powdered portion. For the coarse-grained portion, sieved samples of each iron ore A to D with a particle size of 2.0 to 2.8 mm were used, while for the fine-powdered portion, sieved samples of each iron ore A to D with a particle size of 0.25 mm or less were used. Approximately 200 particles were prepared from both the coarse-grained and fine-powdered portions.

[0057] For each iron ore A to D, a total of eight types of samples were prepared by embedding the coarse-grained and fine-powdered portions into a resin base material. For these samples, cylindrical bodies with a diameter of 32 mm were used, and their ends were polished.

[0058] (Classification of samples) Using silicon as the analytical element, elemental mapping was performed on each sample using SEM / EDS. Specifically, after depositing gold onto the polished surface of each sample, the sample was placed in an SEM (scanning electron microscope) and elemental mapping was performed using energy-dispersive X-ray spectroscopy (EDS). For samples with embedded coarse grains, the resolution was set to 18 μm / pixel for the entire sample (a circular region with a diameter of 32 mm). For samples with embedded fine powders, the resolution was set to 1.8 μm / pixel for a portion of the entire sample (a circular region with a diameter of 32 mm).

[0059] In this example, one boundary content was set to 10 mass%. Since the Si content was obtained for each measurement point by elemental mapping, the Si content of each measurement point was compared with the boundary content. Measurement points where the Si content was equal to or greater than the boundary content were identified as belonging to the high Si content region.

[0060] Next, for each sample, the area percentage occupied by the high-Si content region was determined, and by comparing this area percentage with the boundary area percentage, iron ore samples A to D were classified into three types. Here, two boundary area percentages were set: the first boundary area percentage AR_th1 was set to 40%, and the second boundary area percentage AR_th2 was set to 60%. For sample classification, MLA (Mineral liberation analysis) software (for example, Mineralogy from ZEISS or AMICS from Hitachi High-Tech) can be used.

[0061] Table 1 below shows the classification results for each sample.

[0062] [Table 1]

[0063] For the coarse-grained portion of iron ore A, the area ratio of the high-Si content region was 39%, which was lower than the first boundary area ratio AR_th1 (40%), so it was classified as an Fe-Si coexistence type. For the fine powder portion of iron ore A, the area ratio of the high-Si content region was 15%, which was lower than the first boundary area ratio AR_th1 (40%), so it was also classified as an Fe-Si coexistence type. For iron ore A, both the coarse-grained and fine powder portions were of the same type (Fe-Si coexistence type).

[0064] For the coarse-grained portion of iron ore B, the area ratio of the high-Si content region was 50%, which was between the first boundary area ratio AR_th1 (40%) and the second boundary area ratio AR_th2 (60%), so it was classified as an intermediate type. For the fine powder portion of iron ore B, the area ratio of the high-Si content region was 37%, which was lower than the first boundary area ratio AR_th1 (40%), so it was classified as an Fe-Si coexistence type. In the case of iron ore B, the coarse-grained portion and the fine powder portion each exhibited different types.

[0065] For the coarse-grained portion of iron ore C, the area ratio of the high-Si content region was 81%, and the second boundary area ratio AR_th2 (60%) was 60% or higher, so it was classified as a Si-only type. For the fine powder portion of iron ore C, the area ratio of the high-Si content region was 89%, and the second boundary area ratio AR_th2 (60%) was 60% or higher, so it was classified as a Si-only type. For iron ore C, both the coarse-grained and fine powder portions were of the same type (Si-only type).

[0066] For the coarse-grained portion of iron ore D, the area ratio of the high-Si content region was 61%, which was higher than the second boundary area ratio AR_th2 (60%), so it was classified as a Si-only type. For the fine powder portion of iron ore D, the area ratio of the high-Si content region was 23%, which was lower than the first boundary area ratio AR_th1 (40%), so it was classified as an Fe-Si coexistence type. The types of iron ore D differed between the coarse-grained and fine powder portions.

[0067] Figure 3 shows the elemental mapping results for the coarse-grained portion of iron ore A, and Figure 4 shows the elemental mapping results for the coarse-grained portion of iron ore C. In Figures 3 and 4, the Si content is divided into three categories, and each category is color-coded. Here, in addition to the boundary content (10 mass%), the Si content is divided into 0.1 increments for reference, and it was found that iron ore C has a larger number of regions with a Si content of less than 0.1 compared to iron ore A.

Claims

1. A method for classifying iron ore, For samples in which the iron ore to be classified is embedded in the base material, elemental mapping is performed using SEM / EDS. Based on the Si content at each measurement point measured by the aforementioned elemental mapping, the mapping region is classified into multiple types of Si-containing regions. A method for classifying iron ore, characterized by classifying the iron ore based on the area ratio of a specific Si-containing region to the total area of ​​the mapping region.

2. The boundary value for Si content to classify the Si-containing region is set to be 7.0% by mass or more and 10.0% by mass or less. The method for classifying iron ore according to claim 1, characterized in that the specific Si-containing region is a region in which the measured Si content is equal to or greater than the boundary value.

3. The boundary of the area ratio for classifying iron ore has a first boundary area ratio and a second boundary area ratio that is higher than the first boundary area ratio. When the area ratio is less than the first boundary area ratio, it is classified as a type in which Fe and Si coexist in the iron ore. The method for classifying iron ore according to claim 1, characterized in that when the area ratio is equal to or greater than the second boundary area ratio, it is classified as a type in which Si exists alone in the iron ore.

4. The method for classifying iron ore according to claim 3, characterized in that the first boundary area ratio is 40% and the second boundary area ratio is 60%.

5. The method for classifying iron ore according to claim 1, characterized in that the iron ore to be classified consists of a coarse-grained portion, which is made up of iron ore with a particle size larger than a standard particle size, and a fine-powdered portion, which is made up of iron ore with a particle size less than or equal to the standard particle size.

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