Component analysis method for steelmaking dust, and steelmaking dust recycling method

Abstract

Provided is a component analysis method with which the component content of steelmaking dust can be quickly and accurately obtained. This component analysis method for steelmaking dust comprises: a dust preparation step for preparing steelmaking dust having a moisture content of 10 wt% or less; a particle size adjustment step for adjusting the particle size of the steelmaking dust to obtain an analysis sample; and an analysis step for analyzing the component content of the steelmaking dust by using the intensity of fluorescent X-rays from the analysis sample. The analysis sample is a powder that has a maximum particle size of 2 mm or less and that satisfies formula (1) and formula (2). (1): (W1+W2) / W ≤ 0.70 (2): 0.50 ≤ W1 / W2 ≤ 0.75

Description

Component analysis method of steelmaking dust and recycling method of steelmaking dust

[0001] The present invention relates to a component analysis method of steelmaking dust and a recycling method of steelmaking dust.

[0002] Generally, steelmaking dust is generated by cooling vaporized molten steel in the production of steel under high-temperature conditions. In the component composition of steelmaking dust, the main component is generally iron, but elements such as Cr, Zn, and Pb, which are easily vaporized, tend to be concentrated and may be contained in large amounts.

[0003] Steelmaking dust is reused as an inexpensive iron source in the steelmaking process from the viewpoints of waste reduction, resource saving, and energy saving. Since the reuse from the generation of steelmaking dust to the steelmaking process is completed within the steelworks, this method may be referred to as in-plant recycling.

[0004] However, steelmaking dust also contains elements other than Fe derived from raw materials and the like. Therefore, when steelmaking dust is reused as an iron source, some of these elements other than Fe may remain as impurities in the produced steel, which may have an unintended impact on the quality. Therefore, it is required to perform component analysis of the steelmaking dust used as a recycling raw material to grasp the amount of impurities contained therein.

[0005] As a method for analyzing the components of steelmaking dust, X-ray fluorescence analysis is widely used. For the analysis of steelmaking dust by X-ray fluorescence analysis, either the powder briquet method or the fusion bead method can be used. In the powder briquet method, measurement is performed using a briquet (formed body) obtained by compressing and molding pulverized steelmaking dust into fine powder. In the fusion bead method, measurement is performed using a glass bead obtained by melting steelmaking dust at a high temperature together with a melting agent such as borate (Patent Documents 1 and 2).

[0006] In addition, the components of steelmaking dust can also be analyzed by chemical analysis methods. Examples of the chemical analysis methods include, for example, atomic absorption spectrometry and ICP (inductively coupled plasma) emission spectrometry. When using a chemical analysis method, the steelmaking dust may be finely pulverized and decomposed with an acid or an alkali before analysis.

[0007] JP-A No. 11-064186 JP-A No. 53-069096

[0008] However, conventional chemical analysis and X-ray fluorescence analysis required cumbersome sample preparation and took a long time to obtain analytical results. This resulted in delays in determining the amount of steelmaking dust to be recycled, leading to delays in steelmaking dust processing, increased inventory, and a shortage of storage space for steelmaking dust within the plant. Therefore, to ensure the smooth operation of in-house steelmaking dust recycling, a component analysis method capable of quickly and accurately determining the component content of steelmaking dust was needed.

[0009] This invention has been made in view of the above problems, and aims to provide a component analysis method that can quickly and accurately determine the component content of steelmaking dust.

[0010] The gist of the present invention for solving the above problems is as follows.

[0011] 1. A method for analyzing the components of steelmaking dust, comprising: a dust preparation step of preparing steelmaking dust having a moisture content of 10 wt% or less; a particle size adjustment step of adjusting the particle size of the steelmaking dust to obtain an analytical sample; and an analysis step of analyzing the component content of the steelmaking dust using the intensity of fluorescent X-rays from the analytical sample, wherein the analytical sample is a powder with a maximum particle size of 2 mm or less and satisfying the following formulas (1) and (2): (W1 + W2) / W ≤ 0.70 ... (1) 0.50 ≤ W1 / W2 ≤ 0.75 ... (2) where, W1: weight of the analytical sample with a particle size in the range of 125 μm or less W2: weight of the analytical sample with a particle size in the range of more than 500 μm and 2 mm or less W: weight of the analytical sample with a particle size in the range of 2 mm or less.

[0012] 2. The method for analyzing the components of steelmaking dust according to paragraph 1, wherein in the dust preparation step, steelmaking dust having a moisture content of 10 wt% or less is selected from among a plurality of steelmaking dusts.

[0013] 3. The method for analyzing the components of steelmaking dust according to paragraph 1, wherein the water content of the steelmaking dust is reduced to 10 wt% or less by heating the steelmaking dust in the dust preparation step.

[0014] 4. A method for analyzing the components of steelmaking dust according to any one of items 1 to 3, wherein in the particle size adjustment step, the steelmaking dust is sieved using a sieve with a mesh opening of 2 mm and the material below the sieve is collected.

[0015] 5. A method for recycling steelmaking dust, which determines the type and amount of steelmaking dust to be recycled to the steelmaking process based on the component content of the steelmaking dust analyzed using the component analysis method for steelmaking dust described in any one of items 1 to 4 above.

[0016] Furthermore, the gist of another aspect of the present invention is as follows:

[0017] 1. A method for analyzing the components of steelmaking dust, comprising: a selection step of selecting steelmaking dust having a moisture content of 10 wt% or less from among the steelmaking dust; a particle size adjustment step of adjusting the particle size of the steelmaking dust selected in the selection step to prepare an analytical sample; and an analysis step of analyzing the component content of the steelmaking dust using the intensity of fluorescent X-rays from the analytical sample, wherein the analytical sample is a powder with a maximum particle size of 2 mm or less and satisfying the following formulas (1) and (2): (W1 + W2) / W ≤ 0.70 ... (1) 0.50 ≤ W1 / W2 ≤ 0.75 ... (2) where, W1: weight of the analytical sample with a particle size in the range of 125 μm or less W2: weight of the analytical sample with a particle size in the range of more than 500 μm and 2 mm or less W: weight of the analytical sample with a particle size in the range of 2 mm or less.

[0018] 2. The method for analyzing the components of steelmaking dust according to paragraph 1, wherein in the particle size adjustment step, the steelmaking dust is sieved using a sieve with a mesh opening of 2 mm and the material below the sieve is collected.

[0019] 3. A method for recycling steelmaking dust, which determines the type and amount of steelmaking dust to be recycled to the steelmaking process based on the component content of the steelmaking dust analyzed using the steelmaking dust component analysis method described in 1 or 2 above.

[0020] According to the present invention, a component analysis method can be provided that can quickly and accurately determine the component content of steelmaking dust.

[0021] Figure 1 is a graph showing the Cr, Zn, and Pb content, with the X-ray fluorescence analysis values ​​on the vertical axis and the chemical analysis values ​​on the horizontal axis.

[0022] The present invention will be described in detail below. However, the present invention is not limited to the following embodiments.

[0023] (Steelmaking Dust) This invention relates to a method for analyzing the components of steelmaking dust. Here, steelmaking dust is dust generated in the steelmaking process, as already explained, and is typically caused by fine particles resulting from the evaporation and scattering of iron during smelting. Steelmaking dust is mainly separated and recovered from the exhaust gas by wet dust collectors installed in the exhaust gas treatment systems of refining furnaces such as electric furnaces, decarburization furnaces, and molten reduction furnaces.

[0024] In the present invention, any steelmaking dust can be analyzed without particular limitations. The steelmaking dust may be at least one selected from the group consisting of, for example, electric furnace dust, decarburization furnace dust, and molten reduction furnace dust.

[0025] The main component of steelmaking dust is usually iron oxide, and therefore steelmaking dust can be reused as an inexpensive iron source in the steelmaking process. In addition to iron oxide, steelmaking dust also contains various components resulting from the raw materials used. For example, in many cases, steelmaking dust contains silica (SiO₂) derived from Si contained in iron ore. ２ ) contains. Also, when iron scrap such as galvanized steel sheets is used as raw material, the recovered steelmaking dust contains a relatively large amount of zinc oxide (ZnO). When lime is used as a slag-forming agent to remove impurities such as phosphorus and sulfur in a converter, the recovered steelmaking dust contains a relatively large amount of calcium oxide (CaO).

[0026] Since the present invention relates to the component analysis of steelmaking dust, it is not particularly limited, and steelmaking dust having any component composition can be analyzed. The steelmaking dust may typically contain iron oxide. In addition, the steelmaking dust may contain SiO ２It may contain at least one selected from the group consisting of Zn and CaO. The content of these components is not particularly limited, but for example, SiO in steelmaking dust ２ The content of may be 1 to 10% by mass. The Zn content may be 0.5 to 30% by mass. The CaO content may be 1 to 20% by mass. Furthermore, the steelmaking dust may contain either or both of Cr and Pb.

[0027] Furthermore, the steelmaking dust may be stainless steel dust. Stainless steel dust is dust generated during the steelmaking process when manufacturing stainless steel. Generally, stainless steel dust may contain Cr in an amount of 0.5% to 20% by mass and Zn in an amount of, for example, 0.03% to 0.5% by mass. Like other steelmaking dust, stainless steel dust can be recycled as an iron source.

[0028] However, since stainless steel dust contains a relatively large amount of chromium (Cr), the amount of stainless steel dust used as a recycled material must be carefully controlled. In other words, the amount of Cr mixed in from the ironmaking process is reflected in the amount of chromium in the molten iron, so it is not possible to reuse stainless steel dust as an iron source in an amount exceeding the chromium removal capacity in the steelmaking process. For this reason, the present invention is particularly suitable for stainless steel dust.

[0029] [Method for analyzing the components of steelmaking dust] The method for analyzing the components of steelmaking dust according to this embodiment comprises a preparation step, a particle size adjustment step, and an analysis step.

[0030] (Preparation Process) In the preparation process, steelmaking dust with a moisture content of 10 wt% or less is prepared. If the moisture content of the steelmaking dust exceeds 10 wt%, the X-rays are absorbed by the moisture, causing the measured value of the component content to be lower than the actual value. Therefore, from the viewpoint of measurement accuracy, it is necessary to use steelmaking dust with a moisture content of 10 wt% or less. The lower limit of the moisture content is not particularly limited and may be 0%.

[0031] In one embodiment of the present invention, in the preparation step, steelmaking dust having a moisture content of 10 wt% or less may be selected from among a plurality of steelmaking dusts. In this case, the dust preparation step can be called a selection step. In another embodiment of the present invention, in the dust preparation step, the moisture content of the steelmaking dust may be reduced to 10 wt% or less by heating the steelmaking dust. In this case, the dust preparation step can be called a heating step or a drying step.

[0032] In the aforementioned preparation step, the moisture content of the steelmaking dust may or may not be measured.

[0033] In the preparation step, if the moisture content of the steelmaking dust is actually measured, if the moisture content obtained by the measurement is 10 wt% or less, it is considered that steelmaking dust with a moisture content of 10 wt% or less has been prepared. In other words, in one embodiment of the present invention, in the preparation step, the moisture content of the steelmaking dust is measured, and the steelmaking dust with a moisture content of 10 wt% or less is subjected to the next particle size adjustment step.

[0034] For example, in the preparation step, when selecting steelmaking dust with a moisture content of 10 wt% or less from among multiple steelmaking dusts, the moisture content of the multiple steelmaking dusts can be measured, and the steelmaking dust with a moisture content of 10 wt% or less can be selected based on the measurement results.

[0035] Furthermore, in the dust preparation step, if the moisture content of the steelmaking dust is reduced to 10 wt% or less by heating the steelmaking dust, the moisture content of the steelmaking dust should be measured after drying by heating to confirm that it is 10 wt% or less.

[0036] The method for measuring moisture content is not particularly limited and any method can be used. For example, the loss on drying method, time-domain reflectometry, and capacitance method can be used. From the viewpoint of faster measurement, it is preferable to use a moisture meter using the time-domain reflectometry or capacitance method.

[0037] However, it is not always necessary to actually measure the moisture content in the dust preparation process. For example, if heating conditions that can reduce the moisture content to 10 wt% or less are determined in advance and heating is performed under those conditions, it is not necessary to measure the moisture content. In that case, when determining the heating conditions in advance, it is sufficient to measure the moisture content by some method and confirm that the moisture content is 10 wt% or less.

[0038] In cases other than those mentioned above, it is sufficient if the moisture content is 10 wt% or less, even if actual measurements have not been taken. In that case, if the moisture content measured by time-domain reflection is 10 wt% or less, the moisture content of the steelmaking dust is considered to be 10 wt% or less.

[0039] (Particle size adjustment process) In the particle size adjustment process, the particle size of the steelmaking dust is adjusted to prepare an analytical sample. The analytical sample is a powder with a maximum particle size of 2 mm or less and that satisfies formulas (1) and (2) above.

[0040] - Maximum particle size: 2 mm or less. If the maximum particle size of the analytical sample exceeds 2 mm, the measured value will be lower than the actual value, and the repeatability will deteriorate. Therefore, from the viewpoint of measurement accuracy, the maximum particle size should be 2 mm or less. The maximum particle size can be determined by sieve analysis. On the other hand, from the viewpoint of measurement accuracy, a finer particle size is preferable, so the lower limit of the maximum particle size is not particularly limited and may be greater than 0 mm. In other words, in one embodiment of the present invention, particle size adjustment is performed so that the maximum particle size is greater than 0 mm and 2 mm or less.

[0041] • Equation (1) If the total amount of coarse and fine powder in the analytical sample is large, the measurement accuracy will decrease. Furthermore, if (W1 + W2) / W exceeds 0.70, sufficient measurement accuracy cannot be obtained. Therefore, (W1 + W2) / W should be 0.70 or less. On the other hand, there is no particular lower limit for (W1 + W2) / W. However, from the viewpoint of further improving measurement accuracy, it is preferable that it be 0.40 or higher.

[0042] - In Equation (2), if the content of fine powder is too high relative to the content of coarse powder in the analysis sample, the measured value will be lower than the actual value. And when W1 / W2 exceeds 0.75, sufficient measurement accuracy cannot be obtained. Therefore, W1 / W2 should be 0.75 or less. On the other hand, if the content of fine powder is too low relative to the content of coarse powder in the analysis sample, the measurement accuracy will instead decrease. And when W1 / W2 is less than 0.50, sufficient measurement accuracy cannot be obtained. Therefore, W1 / W2 should be 0.50 or more.

[0043] Here, W1 in the above equations (1) and (2) is the weight of the analysis sample in the range where the particle size is 125 μm or less. In other words, W1 is the mass of the particles in the analysis sample with a particle size of 125 μm or less.

[0044] Also, W2 is the weight of the analysis sample in the range where the particle size is more than 500 μm and 2 mm or less. In other words, W2 is the mass of the particles in the analysis sample with a particle size of more than 500 μm and 2 mm or less.

[0045] W is the weight of the analysis sample in the range where the particle size is 2 mm or less. In the present invention, since the maximum particle size of the analysis sample is 2 mm or less, W can be regarded as the weight of the analysis sample.

[0046] The units of W, W1, and W2 are the same (for example, g). Therefore, both (W1 + W2) / W and W1 / W2 are dimensionless.

[0047] Incidentally, W, W1, and W2 can be obtained by measuring the weight after sieving the analysis sample using the corresponding mesh sieves. Specifically, it can be obtained by the method described in the examples.

[0048] The method for adjusting the particle size in the particle size adjustment step is not limited. For example, the particle size of steelmaking dust can be adjusted by sieving.

[0049] The steelmaking dust for sieving may be a part of the steelmaking dust to be analyzed. That is, an operation of sampling the steelmaking dust for sieving from the steelmaking dust to be analyzed may be performed.

[0050] The sieve used for screening is not limited, and any sieve can be used. After screening, the material on the top or bottom of the sieve should be collected. In order to reduce the maximum particle size of the analytical sample to 2 mm or less, it is preferable to screen the steelmaking dust using a sieve with a mesh size of 2 mm and collect the material below the sieve. This allows for even faster particle size adjustment. As a sieve, a test sieve with a mesh size of 2 mm as specified in JIS Z 8801 is preferred.

[0051] Furthermore, the moisture content of the analytical sample is typically equivalent to that of steelmaking dust before particle size adjustment. In other words, the moisture content of the analytical sample is usually 10 wt% or less.

[0052] (Analysis Process) In the analysis process, the component content of steelmaking dust is analyzed using the intensity of fluorescent X-rays from the analysis sample. More specifically, fluorescent X-ray analysis is performed using the analysis sample, and the content of at least one element contained in the analysis sample (i.e., steelmaking dust) is calculated from the measured intensity of fluorescent X-rays.

[0053] As previously explained, conventional methods for analyzing steelmaking dust using X-ray fluorescence analysis have included the powder briquette method and the molten bead method. However, the process of creating briquettes is time-consuming and requires equipment for crushing and compressing the powder. Similarly, the process of creating glass beads is also time-consuming and requires equipment for melting the sample. In contrast, the present invention allows the analytical sample to be subjected to X-ray fluorescence analysis while still in powder form, eliminating the need for compression molding, melting, and other processing. Therefore, according to the present invention, it is possible to perform component analysis of steelmaking dust quickly and without requiring special equipment.

[0054] The fluorescence X-ray intensity from the sample to be analyzed can be determined using an fluorescence X-ray analyzer. From the viewpoint of rapid analysis, it is preferable to use a fluorescence X-ray analyzer capable of on-site analysis. Specifically, this includes battery-powered fluorescence X-ray analyzers, such as handheld models. This makes it possible to perform component analysis at locations where steelmaking dust is generated during the steelmaking process.

[0055] For analysis, the analysis window of the X-ray fluorescence analyzer should be pressed against the sample. If the analysis window and the sample are not in sufficient contact, the accuracy of the analysis may decrease. Therefore, it is preferable to flatten the sample and then ensure that the flattened surface of the sample and the analysis window are in close contact without any gaps. Furthermore, it is preferable to make the flat surface wider than the size of the analysis window so that the sample covers the entire analysis window.

[0056] During analysis, the analyte sample may be filled into a container. When filling into a container, the analyte sample can be leveled by a leveling operation. The shape of the container may be, for example, cylindrical. The diameter of the part in which the analyte sample is filled should be determined according to the size of the analysis window of the X-ray fluorescence analyzer, but it may be, for example, 15 mm in diameter or larger. For example, if the analysis window of the X-ray fluorescence analyzer is 8 mm in diameter, the steelmaking dust can be filled into a cylindrical container of approximately 20 mm in diameter.

[0057] The material of the container is not particularly limited, but it is preferable to use hard rubber such as silicone rubber. Hard rubber has appropriate hardness and elasticity, so by using hard rubber as the material of the container, the filled analytical sample and the analytical window can be brought into close contact. As an example, a container may be used in which a cylindrical hole of about 20 mm in diameter is provided in a hard rubber block with a thickness of about 30 mm.

[0058] The thickness of the sample to be analyzed in the direction from which X-rays are irradiated by the X-ray fluorescence analyzer is not particularly limited. However, if the thickness of the sample to be analyzed is less than 10 mm, the X-ray intensity may change depending on the thickness, and the measurement accuracy may be poor. For this reason, the thickness of the sample to be analyzed is preferably 10 mm or more. When filling the sample to be analyzed into a container, it is preferable that the depth of the portion filled with the sample to be 10 mm or more.

[0059] The elements analyzed in the above analysis step are not particularly limited, and the content of at least one arbitrary element can be determined. When determining the amount of steelmaking dust to be recycled, attention is often focused on Cr, Zn, and Pb. Therefore, it is preferable to analyze the content of at least Cr, Zn, and Pb.

[0060] To analyze the content of a particular element, the intensity of the fluorescent X-rays originating from that element can be measured. For example, when analyzing Cr content using an energy-dispersive fluorescent X-ray analyzer, the content can be calculated based on the intensity of Cr-Kα rays (5.4 keV) or Cr-Kβ rays (5.9 keV). Similarly, when analyzing Zn content, the content can be calculated based on the intensity of Zn-Kα rays (8.6 keV) or Zn-Kβ rays (9.5 keV). When analyzing Pb content, the content can be calculated based on the intensity of Pb-Lα rays (10.5 keV) or Pb-Lβ rays (12.6 keV).

[0061] Any method can be used to determine the content from the measured intensity of fluorescent X-rays, but typically, the calibration curve method or the fundamental parameter method can be used. When using the calibration curve method, a calibration curve (relational equation) that shows the relationship between the fluorescent X-ray intensity and the content of a specific component is prepared in advance. Then, the content of the component can be determined from the measured fluorescent X-ray intensity using the calibration curve. On the other hand, the fundamental parameter method is a method that obtains analytical results theoretically from the measurement results. With the fundamental parameter method, the content can be calculated without using a calibration curve.

[0062] Alternatively, the component content may be determined using a function built into the X-ray fluorescence analyzer. For example, if the X-ray fluorescence analyzer has a built-in function for determining component content using the fundamental parameter method, that function may be used.

[0063] Although specific embodiments have been described above, in other embodiments of the present disclosure, the method for analyzing the components of steelmaking dust may have, for example, the following configuration: A method for analyzing the components of steelmaking dust, comprising: a sample preparation step of preparing an analytical sample from the steelmaking dust; and an analysis step of analyzing the component content of the steelmaking dust using the intensity of fluorescent X-rays from the analytical sample, wherein the analytical sample is a powder having a moisture content of 10 wt% or less, a maximum particle size of 2 mm or less, and satisfying the above formulas (1) and (2).

[0064] Furthermore, in other embodiments of the present disclosure, the method for analyzing the components of steelmaking dust may have, for example, the following configuration: A method for analyzing the components of steelmaking dust, comprising: a selection step of selecting steelmaking dust having a moisture content of 10 wt% or less from among the steelmaking dust; a particle size adjustment step of sieving the steelmaking dust using a sieve with a mesh opening of 2 mm or less and collecting the sieved portion to be used as an analysis sample; and an analysis step of analyzing the component content of the steelmaking dust using the intensity of fluorescent X-rays from the analysis sample, wherein the analysis sample is a powder satisfying the above formulas (1) and (2).

[0065] [Method for Recycling Steelmaking Dust] As described above, steelmaking dust can be recycled as an iron source in the steelmaking process. In the steelmaking dust recycling method according to this embodiment, the type and amount of steelmaking dust to be recycled to the steelmaking process is determined based on the component content of the steelmaking dust analyzed using the component analysis method described above. For example, the type and amount of steelmaking dust to be recycled can be determined so that the total amount of a predetermined component contained in the steelmaking dust to be recycled is within a predetermined range. This range may be determined based on a target value for the component content of the steel obtained in the steelmaking process. According to this method, the type and amount of steelmaking dust allocated for recycling to the steelmaking process can be precisely controlled. Therefore, by managing steelmaking dust inventory based on this method, it is possible to promote the reduction of steelmaking dust inventory. Furthermore, by promoting in-house recycling using this method, it becomes possible to reduce the unit cost of the steelmaking process.

[0066] Typically, the steelmaking process consists of multiple steps. In this invention, steelmaking dust can be used in any of these steps. For example, in one embodiment of the present invention, steelmaking dust analyzed using the above-described component analysis method can be used in the sintering process. That is, steelmaking dust can be recycled as an iron source in the sintering process for producing sintered ore.

[0067] The present invention will be described in more detail below based on the following examples. However, the present invention is not limited to the following examples.

[0068] (Example 1) Two types of steelmaking dust, A and B, were collected from a steelmaking plant for analysis. For comparison, prior to analysis using the method of the present invention, the Cr, Zn, and Pb content in each steelmaking dust was measured using a known chemical analysis method. The obtained chemical analysis values ​​are shown in Table 1.

[0069] Next, several analytical samples with different moisture content and particle size were prepared from the steelmaking dust A and B, and the content of Cr, Zn, and Pb was determined by fluorescent X-ray analysis. The specific procedure was as follows.

[0070] First, each of the collected steelmaking dust samples was dried. Next, approximately 200 g of steelmaking dust was sieved using sieves with mesh sizes of 2 mm, 1 mm, 500 μm, and 125 μm, and the top or bottom of the sieve was collected. The sieves used were all test sieves as specified in JIS Z 8801. The specific conditions for sieving are shown in Table 1.

[0071] In the table, if the sieve mesh size is listed in the "Below Sieve" column and "-" is listed in the "Above Sieve" column, the steelmaking dust was sieved using a sieve with the mesh size listed in the "Below Sieve" column, and the "Below Sieve" portion was collected. In the table, if the sieve mesh size is listed in both the "Above Sieve" and "Below Sieve" columns, the sieve with the mesh size listed in the "Below Sieve" column was placed on top, and the sieve with the mesh size listed in the "Above Sieve" column was placed on the bottom, and the steelmaking dust was sieved, with the steelmaking dust between the two sieves being collected. In the table, if "-" is listed in both the "Above Sieve" and "Below Sieve" columns, no sieving was performed.

[0072] For samples No. 9 and 19, sieving was first performed using sieves of 2 mm, 500 μm, and 125 μm to obtain samples in the following four particle size ranges. These samples were mixed in predetermined ratios to prepare the analytical samples. The particle size of each analytical sample is shown in Table 1. 1: 125 μm or less 2: greater than 125 μm, 500 μm or less 3: greater than 500 μm, 2 mm or less 4: greater than 2 mm

[0073] W1, W2, and W were determined from the weights after sieving. Here, W1 is the weight of the analytical sample with a particle size of 125 μm or less, W2 is the weight of the analytical sample with a particle size of more than 500 μm and 2 mm or less, and W is the weight of the analytical sample with a particle size of 2 mm or less.

[0074] Next, the obtained steelmaking dust was filled into a container, and the top was leveled by scraping. The container used was a silicone rubber block approximately 30 mm thick with a cylindrical hole approximately 20 mm in diameter.

[0075] Next, to evaluate the effect of moisture content, water was added to some of the analytical samples to prepare analytical samples with different moisture content for convenience. The moisture content is shown in Table 1.

[0076] Next, the analysis window of a fluorescent X-ray analyzer (Thermo Scientific Niton XL3t) was pressed against the portion of the container filled with the sample, and the intensity of the fluorescent X-rays from the sample was measured. The analysis conditions were: primary X-ray source: Rh, tube voltage: 50 kV, analysis mode: mineral analysis mode, integration time: 60 seconds. The obtained fluorescent X-ray intensities were substituted into the previously determined calibration curve formula to calculate the content of each component. Five samples were prepared and analyzed for each condition, and the measured values ​​(average) and standard deviation were calculated. The results are shown in Table 1.

[0077]

[0078] When a powder with a moisture content of 10 wt% or less, a maximum particle size of 2 mm or less, and satisfying the above formulas (1) and (2) was used as the analytical sample, it was confirmed that the discrepancy between the X-ray fluorescence analysis value and the chemical analysis value was small, and the standard deviation was also small.

[0079] (Example 2) On-site analysis was performed in the dust yard where steelmaking dust was stored within the steelworks. First, the moisture content of the steelmaking dust was confirmed to be 10 wt% or less using a moisture meter (Fujiwara Seisakusho TDR-341F). Next, steelmaking dust was sampled and sieved using a test sieve with a mesh size of 2 mm as specified in JIS Z 8801, and the sieved portion was collected. It was confirmed that the obtained analytical sample satisfied the above formulas (1) and (2). Then, the content of Cr, Zn, and Pb in the obtained analytical sample was determined using a fluorescent X-ray analyzer (Thermo Scientific Niton XL3t). The above procedure was performed at 15 locations in the dust yard, and then the chemical analysis values ​​of the same sample were determined. The results are shown in Figure 1.

[0080] Figure 1 is a graph showing the Cr, Zn, and Pb content, with the X-ray fluorescence analysis values ​​on the vertical axis and the chemical analysis values ​​on the horizontal axis. In each figure, the relationship between the chemical analysis values ​​and the X-ray fluorescence analysis values ​​approximated by the least squares method is shown as a dashed line. Also, the R shown in the figure... ２ This is the coefficient of determination in the aforementioned approximation, and a value closer to 1 indicates a higher correlation.

[0081] As shown in Figure 1, R is present in all of Cr, Zn, and Pb. ２ The value was sufficiently close to 1, and the discrepancy between the X-ray fluorescence analysis value and the chemical analysis value was small. From these results, it can be seen that the component content of steelmaking dust can be determined quickly and accurately according to the component analysis method of the present invention.

Claims

1. A method for analyzing the components of steelmaking dust, comprising: a dust preparation step of preparing steelmaking dust having a moisture content of 10 wt% or less; a particle size adjustment step of adjusting the particle size of the steelmaking dust to obtain an analytical sample; and an analysis step of analyzing the component content of the steelmaking dust using the intensity of fluorescent X-rays from the analytical sample, wherein the analytical sample is a powder with a maximum particle size of 2 mm or less and satisfying the following formulas (1) and (2): (W1 + W2) / W ≤ 0.70 ... (1) 0.50 ≤ W1 / W2 ≤ 0.75 ... (2) where, W1: weight of the analytical sample with a particle size in the range of 125 μm or less W2: weight of the analytical sample with a particle size in the range of more than 500 μm and 2 mm or less W: weight of the analytical sample with a particle size in the range of 2 mm or less.

2. The method for analyzing the components of steelmaking dust according to claim 1, wherein in the dust preparation step, steelmaking dust having a moisture content of 10 wt% or less is selected from among a plurality of steelmaking dusts.

3. The method for analyzing the components of steelmaking dust according to claim 1, wherein in the dust preparation step, the moisture content of the steelmaking dust is reduced to 10 wt% or less by heating the steelmaking dust.

4. A method for analyzing the components of steelmaking dust according to any one of claims 1 to 3, wherein in the particle size adjustment step, the steelmaking dust is sieved using a sieve with a mesh opening of 2 mm and the material below the sieve is collected.

5. A method for recycling steelmaking dust, comprising determining the type and amount of steelmaking dust to be recycled to the steelmaking process based on the component content of the steelmaking dust analyzed using the steelmaking dust component analysis method described in any one of claims 1 to 4.

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