Powder component quantification method

Abstract

To provide a powder component quantification method which enables quick quantification of powder components.SOLUTION: A powder component quantification method is provided, comprising a binder mixing step of adding water to a powder such that the water content of the powder is in a range of 10-20 mass%, inclusive, a molding step of molding the powder with water added in the binder mixing step, and a measurement step of quantifying components of the molded body molded in the molding step using a fluorescence X-ray analysis device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for rapidly quantifying the components of a powder. [Background technology]

[0002] Methods for analyzing zinc in steel samples include atomic absorption spectrometry as specified in JIS G 1257:2013 and X-ray fluorescence analysis as specified in JIS G 1256:2013. Furthermore, the analysis of zinc oxide is specified in JIS K 1410:2006, and proposals aimed at further improving accuracy and methods for quantifying zinc oxide in a zinc plating bath have been proposed (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 57-80558 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-237742 Summary of the Invention [Problem to be solved by the invention]

[0004] However, these methods are primarily intended for the analysis of bulk or plate steel or high-concentration zinc solutions, and are not applicable to the quantitative determination of zinc contained in powder as is. Generally, the quantitative determination of zinc in powder in the steel industry is carried out by dissolving the powder and then analyzing it using ICP (inductively coupled plasma) atomic absorption spectroscopy or other methods (wet methods).

[0005] Quantifying zinc using such analytical methods requires procedures such as alkali fusion and acid dissolution of the powder followed by ICP or atomic absorption spectroscopy, making the process extremely cumbersome. The analytical equipment also requires delicate operation, making it difficult for non-specialized analysts to maintain and manage the equipment. Consequently, many analyses are outsourced to analytical companies, but it takes about two weeks to obtain analytical results. In research and development where the next step in the project must be determined after obtaining the analytical results, this analysis time often limits the development speed. The present invention was conceived in consideration of the above circumstances, and aims to provide a method for quantifying powder components that can rapidly quantify the components of a powder. [Means for solving the problem]

[0006] The means for solving the above problems are as follows. [1] A method for quantifying the components of a powder, comprising: a binder mixing step of adding water to a powder to adjust the moisture content of the powder to 10% by mass or more and 20% by mass or less; a molding step of molding the powder to which water has been added in the binder mixing step; and a measurement step of quantifying the components of the molded body molded in the molding step using a fluorescent X-ray analyzer. [2] The method for quantifying the components of a powder according to [1], wherein starch is added in the binder mixing step to make the starch content of the powder 10% by mass or more and 20% by mass or less. [3] The molding pressure in the molding step is 600 kgf / cm 2 The method for quantifying powder components according to [1] or [2] above. [4] The method for quantifying the components of a powder according to any one of [1] to [3], wherein the atmosphere during measurement in the measurement step is air. [5] The method for quantifying the components of a powder according to any one of [1] to [4], wherein the powder is blast furnace dust. [Effects of the Invention]

[0007] By implementing the powder component quantitative determination method according to the present invention, powder components can be determined more quickly than by conventional powder component quantitative determination methods. [Brief explanation of the drawings]

[0008] [Figure 1] Figure 1 is a graph showing the particle size distribution of five of the 17 powders. [Figure 2] FIG. 2 is a graph showing the relationship between the fluorescent X-ray intensity and the zinc concentration in the dust in measurement No. 4. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below through embodiments of the invention. The powder component quantification method according to this embodiment includes a binder mixing step of adding water to a powder, a molding step of molding the powder, and a measurement step of quantifying the components of the molded body molded in the molding step using an X-ray fluorescence analyzer. The powder whose components are quantified by the powder component quantification method according to this embodiment is, for example, blast furnace dust.

[0010] <Binder mixing step> First, the binder mixing step will be described. To obtain a molded body suitable for measurement with an X-ray fluorescence analyzer, a binder mixing step in which water is added to the powder must be performed to reduce the powder's moisture content to between 10% and 20% by mass. If the powder's moisture content is less than 10% by mass, the molded body will be brittle and easily chipped or cracked, making it unsuitable for measurement. In order for the molded body to have strength suitable for measurement, the powder's moisture content must be 10% by mass or more. On the other hand, if the powder's moisture content is more than 20% by mass, residue from the molded body will easily adhere to the analyzer, increasing the variability in the analysis results and reducing the accuracy of quantitative component determination. Therefore, the powder's moisture content is set to 20% by mass or less. It is more preferable that the powder's moisture content be between 12% and 18% by mass.

[0011] In the binder mixing step, it is preferable to further add starch to the powder to adjust the starch content of the powder to 10% by mass or more and 20% by mass or less. Adding an appropriate amount of starch to the powder reduces the voids between particles in the molded body and reduces the diffuse reflection of irradiated fluorescent X-rays between particles. This improves the accuracy of quantifying the powder's components. On the other hand, if the starch content of the powder is less than 10% by mass, the powder and starch will not be mixed uniformly, and conversely, the accuracy of quantifying the powder's components will decrease. Furthermore, if the starch content of the powder exceeds 20% by mass, the amount of impurities derived from the starch will increase, reducing the accuracy of quantifying the powder's components.

[0012] <Molding step> Next, the molding step will be described. Generally, powders have a wide particle size distribution, and even similar powders often have particle sizes that vary by more than one order of magnitude. Therefore, if the powder is subjected to an X-ray fluorescence analyzer as is, the measurement surface of the powder will not be smooth, resulting in large variations in the analysis results and reduced accuracy in quantifying the powder components. For this reason, in the powder component quantification method according to this embodiment, a molding step is performed in which the powder is molded using a press or the like, so that even powders with different particle sizes can be molded into molded bodies with smooth surfaces. As a result, even when powders with different particle sizes are used, the variations in the analysis results obtained by measurement with the X-ray fluorescence analyzer are reduced, and the accuracy in quantifying the powder components is improved. Furthermore, the molding pressure in the molding step is 600 kgf / cm 2 It is preferable that the pressure is 800 kgf / cm or more. 2 On the other hand, it is more preferable that the molding pressure is 1000 kgf / cm or more. 2 If the molding pressure is higher than 1000 kgf / cm, the compressed air between the particles will expand when the pressure is released, making the molded body more susceptible to chipping and cracking. 2 It is preferable that:

[0013] <Measurement steps> Next, the measurement step will be described. In the measurement step, the components of the molded body molded by the above procedure are quantified using an X-ray fluorescence analyzer. When the component contained in the powder is zinc, it is expected that zinc will be unevenly distributed in the powder, so it is preferable to make the collimator (a collimator; in this case, the diameter of the irradiation surface that irradiates the X-rays) as large as possible. A typical X-ray fluorescence analyzer can have an irradiation surface with a diameter of about 10 mm. It is possible to increase the measurement sensitivity by using helium as the atmosphere during measurement. However, in the case of a component such as zinc, sufficient sensitivity is achieved even when the atmosphere during measurement is air, so considering the effort required for gas replacement in the measurement chamber, it is preferable to use air as the atmosphere during measurement.

[0014] In this way, the powder component quantification method according to this embodiment involves performing a binder mixing step and a molding step to mold the powder, and then quantifying the components of the molded body using an X-ray fluorescence analyzer, thereby enabling rapid quantification of the powder components. The entire powder component quantification process, from the binder mixing step to the measurement step, took approximately one hour. [Example]

[0015] Examples are described below. Seventeen types of powders prepared by drying wet blast furnace dust slurry were used. Figure 1 is a graph showing the particle size distribution of five of the 17 types of powder. Six grams of each of these 17 types of powders with different particle size distributions was subjected to a binder mixing step, in which distilled water was added to and mixed with the powder to adjust the moisture content of the powder. In this binder mixing step, starch water containing starch in the distilled water was used under some conditions.

[0016] Following this binder mixing step, a molding step was carried out, and molded bodies were produced by press molding at various molding pressures. A measurement step was carried out using these molded bodies, and the zinc content of the molded bodies was quantitatively measured using an X-ray fluorescence analyzer. The collimator was set to 10 mm, and measurements were taken at 10 points by slightly changing the X-ray irradiation position on the molded body, and the standard deviation of the measured values at these 10 points was calculated. The standard deviation was normalized by setting the average X-ray fluorescence intensity at 10 points.

[0017] In addition, the zinc concentration of 17 types of powder was measured using a conventional component measurement method, and the coefficient of determination between the zinc concentration and the fluorescent X-ray intensity of the molded bodies produced under each condition was calculated. Figure 2 is a graph showing the relationship between the fluorescent X-ray intensity and the zinc concentration in the dust for Measurement No. 4. As shown in Figure 2, the coefficient of determination was calculated by plotting the correlation between the fluorescent X-ray intensity and the zinc concentration. In this case, too, the zinc concentration was normalized by setting the zinc concentration of the powder with the lowest concentration among the 17 types of powder as 1. The binder composition, molding pressure in the molding step, standard deviation, and coefficient of determination for the examples are shown in Table 1 below.

[0018] In Table 1, the measurement results were evaluated as 0 to 3. A higher evaluation result indicates a more accurate analysis. When the standard deviation was 0.03 or more and the coefficient of determination was less than 0.9, the measurement method was evaluated as not having the precision to quantify the powder components and was given a value of 0. When the standard deviation was 0.024 or more but less than 0.03 and the coefficient of determination was 0.9 or more but less than 0.92, the measurement method was evaluated as having the precision to quantify the powder components and was given a value of 1. When the standard deviation was 0.016 or more but less than 0.024 and the coefficient of determination was 0.92 or more but less than 0.94, the measurement method was evaluated as having high precision to quantify the powder components and was given a value of 2. When the standard deviation was less than 0.016 and the coefficient of determination was 0.94 or more, the measurement method was evaluated as having even higher precision to quantify the powder components and was given a value of 3.

[0019] [Table 1]

[0020] As shown in Table 1, all of the invention examples, which are the powder component quantification method according to this embodiment, achieved evaluation results of 1 or more, confirming that the method is a measurement technique with the measurement accuracy to quantify powder components. Among the invention examples, Nos. 18 to 20 and 23 to 25, in which the starch content of the powder was 10% by mass or more and 20% by mass or less, achieved evaluation results of 2 or more, confirming that the method is a measurement technique that can quantify powder components with high accuracy. Furthermore, among the invention examples, Nos. 18 to 20 and 23 to 25, in which the starch content of the powder was 10% by mass or more and 20% by mass or less, achieved evaluation results of 2 or more, confirming that the method is a measurement technique that can quantify powder components with high accuracy. 2 The above Nos. 23 to 25 received an evaluation result of 3, confirming that this is a measurement method that can quantify powder components with even higher accuracy.

[0021] Furthermore, it has been confirmed that the powder component quantification method according to this embodiment can quantify the components of a powder sample in about one hour, making it a rapid measurement method that can significantly shorten the measurement time compared to conventional methods that require outsourcing to an analysis company and take about two weeks to obtain results. Note that although the examples have been described using an example of zinc as a component contained in powder, the component is not limited to zinc, and the powder component quantification method according to this embodiment can be applied to any component that can be quantified using an X-ray fluorescence analyzer.

Claims

1. A powder is mixed with water to adjust the moisture content of the powder to 10% by mass or more and 20% by mass or less. an binder mixing step; a molding step of molding the powder to which water has been added in the binder mixing step; A measuring step in which the components of the molded body molded in the molding step are quantified using an X-ray fluorescence analyzer. and A method for quantifying the components of a powder, wherein starch is added in the binder mixing step to make the starch content of the powder 15% by mass.

2. The molding pressure in the molding step is 600 kgf / cm ２ The method for quantifying components of powder according to claim 1 .

3. 3. The method according to claim 1, wherein the atmosphere during the measurement in the measuring step is air. Method for quantifying the components of powder.

4. 3. The method for quantifying components of powder according to claim 1, wherein the powder is blast furnace dust.

5. The method for quantitatively determining the components of powder according to claim 3, wherein the powder is blast furnace dust.

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