JP2016045167A - Powder identification method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an analytical method capable of quickly and accurately identifying the powder of coal or coke, etc., dispersed from a factory manufacturing coke.SOLUTION: The powder identification method for identifying at least one or more kinds of powder of coal, coke, needle coke, pitch coke, carbon fiber and an intermediate product thereof comprises at least the following steps (1), (2) and (4) in this order: the step (1) of dispersing the powder to prepare a sample; the step (2) of defining the position of the powder dispersed in the sample; and the step (4) of performing Raman spectroscopic analysis of the powder having the defined position.SELECTED DRAWING: None

Description

  The present invention relates to a powder identification method for identifying at least one powder among coal, coke, needle coke, pitch coke, carbon fiber, and intermediate products thereof.

Coke is obtained by carbonizing coal and is mainly used as a fuel for iron making. For this reason, the amount of coke produced is large, and it is produced on a scale of 1 million to 5 million tons per year at one factory.
For this reason, a large amount of coal is always carried in at the coke production plant and a large amount of coke is carried out, so it is usually difficult to store them indoors, and they are piled up on the site of the production plant. .
In addition, because the coal used as the raw material for coke is properly used by blending multiple coals according to the characteristics of the target coke, etc., different areas are usually stored in the site, and different coal is stored. The same applies to product coke.

Normally, coal used as a raw material for coke is called pulverized coal with a diameter of 3 mm or less, and contains a large amount of powder (dust and soot). Moreover, although the coke which is a product has a shape of about 40-50 mm, a large amount of powder exists also in this. For this reason, when these are piled up, powder will be scattered by wind etc.
It is not preferable in terms of environment that fine powder of coal or coke is scattered inside or outside the site of the factory. For this reason, usually the storage area is sprinkled with a sprinkler or covered with a protective net to prevent fine powder from being scattered, but these methods are also limited in terms of capital investment, and the powder is completely scattered. It is difficult to prevent.
Therefore, even if the above measures are taken in an attempt to prevent scattering as much as possible, it is important to identify from which area in the premises the scattered powder is what powder. It was.

  In addition, the establishments that produce coke also produce various carbon-based materials such as graphite, petroleum pitch, carbon black, needle coke, pitch coke, and carbon fiber that are made from coke and its co-products. However, there are similar problems with powders produced in these productions. In other words, powder is discharged and scattered from the pulverizer, conveyor, hopper, storage location, dust collector exhaust port, chimney, etc., and these are mixed with the scattered powder of coal and coke, making identification more difficult. It was.

On the other hand, the method for collecting and measuring dust and soot in the room and the environment is described in JIS Z8813, etc. Usually, after collecting them with a dust jar or deposit gauge, the weight is measured. Yes. Furthermore, for analyzing the contents of dust and soot, a plasma emission analyzer (hereinafter referred to as ICP-AES) is used to analyze the amount of metal elements, and a total carbon analyzer or CHN element analyzer is used to analyze the carbon concentration. Has been.
However, in establishments that produce coke, the powders of coal, coke, and other carbon-based materials are black powders mainly composed of carbon, and therefore cannot be identified by the above method. There's a problem.

Usually, in the field of atmospheric chemistry and environmental science, carbon-based powders in atmospheric dust are classified into organic carbon (hydrocarbon) and elemental carbon (elemental carbon) composed almost of carbon. It is considered that the black powder mainly composed of carbon generated from the establishment that manufactures coke mainly has a high ratio of elemental carbon. However, although various analyzes have been performed on organic carbon, a highly accurate analysis method has not yet been established for elemental carbon (Non-Patent Documents 1 and 2).

Yoichi Sakai, Kaoru Tsunowaki, Journal of the Japan Society for Air Pollution, 21 (1986) 396 Masamasa Ito, SCAS NEWS, II (2002) 18

Due to the situation described above, conventionally, in order to identify and separate black powder (carbon dust, soot, etc.) scattered inside or outside the coke plant site, this was collected and examined with a microscope. A method of confirming has been taken. Specifically, the collected powder is used as it is or dispersed in an epoxy resin, embedded (fixed), polished, and used as a sample, and then the powder shape is observed with an optical microscope or an electron microscope, or with a polarizing microscope. A method for confirming the presence or absence of a liquid crystal phase in a powder cross section has been adopted.
However, since these analysis methods require complicated steps, identification takes time and the number of samples that can be measured is limited. Moreover, in the observation of the liquid crystal phase with a polarizing microscope, it cannot be confirmed unless the particle diameter is about 20 μm or more from the viewpoint of the resolution of the polarizing microscope, and there is a limit to the measurement accuracy and target sample. Furthermore, analysis based on the results of microscopic observation often depends on the experience of the analyst, requiring skillful experience, and also has the problem that the analysis results are not constant.
For this reason, conventionally, it was difficult to collect scattered carbon powder and quickly identify it.

When micro-infrared spectroscopy, which is generally used for identification of organic powders, is applied to the analysis of carbon-based powders, the spectrum cannot be obtained because the irradiated infrared rays are almost absorbed by the sample. For this reason, Raman spectroscopy is used for analysis of powders mainly composed of carbon (for example, Y. Wang, DCAlsmeyer and RLMaCreery, Chem. Mater., 2 (1990) 557-563).
However, since the conventional Raman spectroscopic analysis is performed independently of other analyses, when applying this analysis to a powder, it is necessary to aim and analyze in units of one grain. For this reason, identifying powder using Raman spectroscopic analysis requires an excessive work load, and there is a limit to the number of measurements. As a result, it is difficult to identify with high accuracy.

The present invention has been made in view of the above situation, and provides an analysis method capable of quickly and accurately identifying powders of coal, coke, and the like scattered from an office that manufactures coke. With the goal.
Another object of the present invention is to provide an analysis method that can quickly and accurately identify the shape and chemical structure of carbon-based powders that are difficult to identify visually.

  In order to solve the above-mentioned problems, the present inventors automated the preparation of a sample that has been performed by an expert in the past, and, as a result of earnestly examining automating the identification judgment that has been performed by an expert in the past, The present inventors have found that the above problem can be solved by appropriately combining a specific sampling method, image analysis method, and spectral spectroscopy method, and have reached the present invention.

That is, the gist of the present invention is the following [1] to [10].
[1] A powder identification method for identifying at least one kind of powder among coal, coke, needle coke, pitch coke, carbon fiber, and intermediate products thereof, wherein at least the following steps (1), ( The powder identification method which has 2) and (4) in this order.
[Step (1)] A step of preparing a sample by dispersing powder [Step (2)] A step of defining the position of the powder dispersed in the sample [Step (4)] Powder having the specified position analysis of the body of the Raman spectroscopic analysis step [2] the step (4) is a waveform having a peak top in the range of 1250～1450Cm ^-1, any at least of the waveform having a peak top in the range of 1500～1700Cm ^-1 The powder identification method according to [1], which is performed by analyzing the above.
[3] The analysis of the step (4) is performed by accumulating the Raman spectroscopic data of the powder in advance and comparing the data with the analysis data for analysis. [1] or [2] Powder identification method.
[4] The powder identification method according to [1] to [3], further including the following step (3) after step (2).
[Step (3)] Step [5] of analyzing the shape of the powder whose position is defined [5] In the analysis of the step (3), the shape data of the powder is accumulated in advance, and this data and the analysis data [4] The powder identification method according to [4], which is performed by comparing and analyzing.
[6] The powder identification method according to [1] to [5], in which a sample including powder having a major axis diameter of 1 to 1500 μm is identified.
[7] The powder identification method according to [1] to [6], wherein the step (1) is a step of dispersing the powder by an air flow.
[8] The step of dispersing the powder by the airflow causes a pressure difference between the sample chamber in which the powder is placed and the outside, and the airflow generated by opening at least a part of the pressure difference. The powder identification method according to [7], which is a step of dispersing.
[9] Release of the pressure difference is either a method of opening a shutter provided in the sample chamber, or a method of forming at least a part of the sample chamber with a thin film and releasing it by breaking the thin film. 8].
[10] The powder identification method according to [1] to [9], wherein all of the steps are automated.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an analysis method capable of quickly and accurately identifying powder such as coal and coke scattered from a business office that produces coke.
In addition, according to the present invention, it is possible to provide an analysis method that can quickly and accurately identify the shape and chemical structure of carbon-based powders that are difficult to identify visually.

The correlation diagram which compared the equivalent circle diameter and circularity about each powder shape of coal, coke, and needle coke. The correlation diagram which compared the equivalent circle diameter and the area circularity about each powder shape of coal, coke, and needle coke. The correlation diagram which compared the equivalent circle diameter and the aspect ratio about each powder shape of coal, coke, and needle coke. The correlation figure which compared the equivalent circle diameter and the brightness | luminance average value about each powder shape of coal, coke, and needle coke. The figure which shows the Raman spectroscopic analysis result of each powder of coal, coke, and needle coke.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In the following, “mass%” and “wt%” and “part by mass” and “part by weight” have the same meaning.

[Powder to be identified]
The powder identification method of the present invention is intended for substantially elemental carbon powder, and more specifically, coal, coke, needle coke, pitch coke, carbon fiber, and these. At least one kind of powder among the intermediate products is targeted. Each powder will be described below, but the definition of each powder targeted by the present invention is not construed in a narrow sense by these descriptions.
In the present invention, “powder” includes the concept of “dust”. In addition, in the powder identification method of the present invention, as long as the above-described target powder is contained, other powders and those containing substances other than the powder may be identified. Even if powders other than elemental carbon (for example, organic matter, sand particles, etc.) are mixed in the measurement sample, it is easily discriminated in the step (3) or step (4) described later, and the powder to be identified. Can be excluded from the body.

<Coal>
The coal targeted by the present invention is not limited, and specific examples include peat, lignite, lignite, bituminous coal, weakly caking coal, strongly caking coal, anthracite. Among these, as a raw material for coke, weakly caking coal or strongly caking coal is used.
<Coke>
Coke is produced by dry distillation of coal in a coke oven, and includes those used as ironmaking raw materials by the blast furnace method, as well as for castings and general uses.
<Coal needle coke>
Coal-based needle coke is produced using coal tar generated in the process of producing coke as a raw material, and is used as a graphite electrode raw material for steel making.
<Pitch coke>
Pitch coke is produced using coal tar generated in the process of producing coke as a raw material, and is used as a raw material for a special carbon material or as a raw material for an anode when refining aluminum.

Although there is no restriction | limiting in the particle size of the object powder identified in the powder identification method of this invention, Usually, it is preferable to identify the sample containing the powder whose major axis diameter (maximum diameter) is 1-1500 micrometers. Here, the major axis diameter is synonymous with the parameter in step (3) described later.
When the powder has a major axis diameter of more than 1500 μm, it may be difficult to disperse the sample in the step (1) described later, or the shape may be difficult to grasp in the step (3) described later. In addition, the powder whose major axis diameter is less than 1 μm is easy to pick up the surrounding information from the spread of the laser beam to irradiate when performing Raman spectroscopic analysis in the following step (4), and the accuracy of fractional analysis decreases. Tend to.
A preferable particle diameter of the target powder to be identified is preferably a long axis diameter of 2 to 1000 μm for the same reason as described above.

In the present invention, the maximum length of all target powders need not be within the above range, and may include powders having a maximum length outside the above range. The ratio of the number of powders having a maximum length within the above range is not limited, but it is desirable to target a powder containing usually 50% or more, preferably 80% or more, more preferably 90% or more.
Moreover, if the range of the particle diameter of the target powder to be identified is wide, it may be difficult to set the magnification in the microscope observation in the step (2) described later. In such a case, the target powder may be subjected to sieving to narrow the particle size range for measurement.
The shape of the target powder to be identified in the powder identification method of the present invention is not limited, and may be any of a spherical shape, a flat shape, a rod shape, a fiber shape, an indefinite shape, etc., and these various shapes are mixed. It may be a thing.

The collection location of the target powder identified in the present invention is not limited and may be determined according to the purpose. Specifically, ground such as paved road surfaces and soil surfaces, water surfaces such as ponds and water tanks, underwater or bottom parts; buildings, outdoor nets, various equipment and devices, vehicles and other deposits on the interior; clothing, etc. And the like, and the like. Further, it is also preferable to collect by a device installed for the purpose of collecting and capturing dust, such as a falling dust collecting device, a suction filter, and a cyclone dust collecting device.
Depending on the sampling method and location, the collected powder may be agglomerated, wet with water or the like, or something other than black powder may be mixed. In such a case, it is preferable to break up the aggregate, wash and dry, or select and use it for measurement.
When collecting powder to perform the powder identification method of the present invention, not only the location and date of collection, but also the total amount of collected powder, the amount of collected powder per unit area, When wet, it is preferable to record these dry weights. These values may be measured by a dust amount measuring device using an absorbance method or a light scattering method.

[Powder identification method]
The powder identification method of the present invention has at least the following steps (in the following description, each step may be abbreviated as “step (1)”, “step (2)”, “step (4)”, respectively). is there.)
[Step (1)] A step of preparing a sample by dispersing powder [Step (2)] A step of defining the position of the powder dispersed in the sample [Step (4)] Powder having the specified position Step of Raman spectroscopic analysis of body As the order of the above steps, step (1) is usually performed first, then step (2) is performed, and then step (4) is performed.

The powder identification method of the present invention preferably further includes the following steps (in the following description, it may be abbreviated as “step (3)”).
[Step (3)] The step of analyzing the shape of the powder whose position is defined As the order in the case of having the step (3), the step (1) is usually performed first, and then the step (2) is performed. As the next step, either step (3) or step (4) may be performed first. However, from the viewpoint of the reason described later, it is preferable to perform the step (4) after the step (3). Moreover, since it is also possible to perform a process (2) and a process (3) simultaneously, it is preferable also to perform a process (4) after a process (3) also in this point.

  In this invention, each process of process (1)-process (4) may be comprised by the respectively independent apparatus, and an operator does not use an apparatus about process (1) and process (2). However, it is preferable that each process is automated. Specifically, it is preferable that the process (1), the process (2), and the process (4) are automated, or that all of the processes (1) to (4) are automated. Moreover, although what automated each process independently may be what was systematized continuously, it is more preferable that each process is integrated in one apparatus. In the present invention, the shape of the powder is observed in the step (3) and the analysis is performed by the Raman spectroscopic device in the step (4). However, if the powder is incorporated in one device as described above, one powder This is desirable because it is easy to correlate the analysis results of both processes and reflect them in the identification results, and also shorten the analysis time.

  In the present invention, when the step (3) and the step (4) are used in combination, after the measurement results of both are once accumulated, an algorithm can be formed and analyzed using these data. That is, it is possible to construct and identify an analysis step by combining the analysis result of the powder shape and the result of the Raman spectroscopic analysis. By adopting this method, even if powders of various elemental carbons (elemental carbon) are mixed, it is preferable because the powders can be accurately identified.

Since the powder identification method of the present invention can be analyzed quickly, a large amount of powder can be analyzed. The number of powders to be analyzed is not limited, but 100 or more, and 1
It is also effective in identifying 000 or more, particularly 10,000 or more powders.
Conventionally, in order to identify a carbon-based powder, it is necessary to perform microscopic observation by a skilled worker after preparing the powder as a sample for microscopic observation. Took a lot of effort and time. According to the powder identification method of the present invention, even the number of powders as described above can be accurately identified in a short time.
Hereinafter, each process is explained in full detail.

[Step (1)]
In step (1), a sample (preparation) in which powder is dispersed is prepared for analysis in step (3) and step (4) described later.
The sample is not limited as long as it can be analyzed in the step (3) or the step (4). Usually, a sample in which powder to be identified is dispersed on a substrate is used. Since the substrate is subjected to Raman spectroscopic analysis in the step (4), a substrate that is strong against a laser and does not emit fluorescence that interferes with measurement is preferable. Specifically, the substrate is preferably made of glass, more preferably made of quartz, and still more preferably made of synthetic quartz. If the substrate is made of synthetic quartz, the amount of impurity elements that can be a fluorescent source that interferes with Raman spectroscopic analysis is extremely small, so that analysis with higher accuracy can be performed.

Although the dispersion state of the powder in a sample is not limited, it is preferable that each powder is independent without contacting. If the powders are in contact with each other, the accuracy of the powder position in the step (2), the analysis of the powder shape in the step (3), and the Raman spectroscopic analysis in the step (4) are reduced. May occur.
The dispersion state of the powder can be optimized by appropriately selecting the amount of the powder to be measured and a dispersion method as described later.
The amount of powder to be used for the measurement is not limited, but is usually 100 mm ³ or less, preferably 0.1 to 50 mm ³ , more preferably 0.5 to 20 mm ³ , and further preferably 1 to 1 in order to perform highly accurate analysis. It is preferable to disperse an amount of about 10 mm ³ , particularly preferably about ³ to 5 mm ³ .

There is no limitation on the method of dispersing the powder in the sample, and the powder may be manually dropped from above the substrate using a spatula or sieve, or may be dispersed using an apparatus. When performing manually, it is preferable to use an apparatus because reproducibility may be inferior.
When the powder is collected with a filter cloth or a membrane filter, if the powder to be analyzed exists in the vicinity of these surfaces and the dispersibility of the powder is good, the powder may be used as it is.

A means for dispersing the powder using the apparatus is not limited, but it is preferable to disperse the powder by an air flow. When the powder is dispersed by an air current, the powder is preferably placed on the substrate in advance and an air current is applied thereto.
As a method of applying and dispersing an air flow to the powder, a method of applying and dispersing an air flow directly to the powder with an injection nozzle or the like, or a pressure difference between the sample chamber and the outside, For example, a method of dispersing the powder by an air flow generated by opening at least a part thereof may be used. In such a case, before the air flow is generated, the powder may be placed inside the sample chamber, or the powder may be placed outside the sample chamber and the sample may be generated by the air flow. It may be introduced inside the chamber.

In the case where the powder is dispersed by the air flow generated by opening the pressure difference, for example, a method of opening a shutter provided in the sample chamber or a part of the side or inside of the sample chamber is made of a thin film. And a method of opening when the thin film is broken. Examples of the thin film include aluminum foil. When a pressure difference is generated between the sample chamber and the outside, the pressure in the sample chamber may be higher than the outside, or vice versa.
As an apparatus capable of performing such a method, for example, an automatic sample dispersion unit attached to a product name: Morphologi G3-ID manufactured by Spectris Co., Ltd. may be mentioned. In this apparatus, the powder is placed on a shutter or sandwiched between aluminum foils, and then the sample chamber is pulse-pressed with air and the shutter of the sample chamber is opened in the pressurized state, or aluminum The powder can be dispersed by utilizing the rupture of the foil.

[Step (2)]
In step (2), the position of the powder dispersed in the sample in step (1) is defined. Although the method for defining the position of the powder is not limited, it is usually done by an observation image using a microscope such as an optical microscope. Below, the specific example at the time of prescribing | regulating the position of powder using a microscope is demonstrated.
The illumination of the microscope may be either epi-illumination or transmission illumination, but is preferably epi-illumination. The objective lens may be selected according to the particle size of the powder to be identified, and may be selected from 5 times, 10 times, 20 times, and the like.
When the position of the powder is defined from an image obtained by microscopic observation, a method in which an observer records the result of visual confirmation may be used, but it is preferable to store the image data using an apparatus. By using the apparatus, the step (2) and the step (3) described later can be performed by one apparatus, and further, both the processes can be performed simultaneously.
When storing as image data using an apparatus, it is preferable that the number of powders dispersed in a sample is approximately 5000 to 20000 because accurate and efficient analysis can be performed.

[Step (3)]
In step (3), the shape of the powder whose position is defined in step (2) is analyzed. The method for analyzing the shape of the powder in the step (3) is not limited, but is usually performed by an observation image using a microscope such as an optical microscope. When analyzing the shape of the powder from an image obtained by microscopic observation, a method in which the observer determines the visually confirmed shape may be used, but it is preferable to analyze from the image analysis result using the apparatus.
When the powder shape is analyzed using an apparatus, the shape can be determined by the shape itself, but it is preferable that the shape is a value of various parameters and is determined by the value of the parameter. It is also preferable to analyze the shape based on the correlation between parameters.

The parameters used for analyzing and identifying the powder shape are not limited, but specific examples include the following parameters.
<Parameters related to particle diameter> Circle equivalent diameter (CE), major axis diameter, minor axis diameter, perimeter length, area (projected area), maximum diameter, sphere equivalent volume, etc. <Particle shape parameters> Circularity, envelope (perimeter) Length), elongation rate, area circularity, envelope degree (area), etc. <Parameters relating to particle transmittance> Luminance average value, luminance dispersion value, etc. If the target powder is fibrous, the above length In addition to the shaft diameter (fiber length) and the short shaft diameter (fiber width), parameters such as the aspect ratio indicated by these ratios, fiber elongation, and fiber straightness can also be used.

Of these, parameters such as circularity, area circularity, aspect ratio, and luminance average value are preferably used from the viewpoint of analysis accuracy, analysis speed, and the like. Further, when analyzing by correlation between a plurality of parameters, the correlation between the equivalent circle diameter (CE) and the circularity, the correlation between the equivalent circle diameter (CE) and the aspect ratio, and the like are preferably used.
In calculating the above parameters, commercially available image analysis software can be appropriately selected and used. Further, analysis software provided in the microscope system may be used as it is.

When identifying by the shape of the powder, it may be judged directly from the result of analyzing the powder shape, but it is usually not easy to identify without accumulated data. For this reason, it is preferable to hold library data using known powders in advance, and to identify and judge by comparing the known shape data and analysis data. Furthermore, it is also preferable to reinforce the library data by reflecting individual analysis results in the library data. Thus, the accuracy of identification can be improved by using library data for identification judgment of powder shape.
The library data may be the shape image of the powder itself, but it is usually preferable to create a library of the above-mentioned various shape parameter values or data such as the correlation between parameters.
1-4 show examples of library data when shape analysis is performed using coal powder, coke powder, and needle coke powder as powders.

In the present invention, it is not always necessary to analyze the shape of all the powders whose positions are defined in the step (2), and only a part of the powders are subjected to the shape analysis according to the total number of powders and the purpose. May be.
Even when the step (3) is performed after the step (4) described later, it is not always necessary to analyze the shape of all the powders subjected to the Raman spectroscopic analysis in the step (4).

[Step (4)]
In step (4), Raman spectroscopic analysis is performed on the powder whose position is defined in step (2). Specifically, a sample is irradiated with a laser using a Raman spectrometer to observe Raman spectroscopy. The laser wavelength is not limited, and for example, it is appropriately selected from wavelengths such as 532 nm, 785 nm, and 1064 nm.
The Raman spectroscopic device used in the step (4) is not limited, and examples thereof include G3-ID (Laser wavelength: 785 nm) manufactured by Spectris.
In addition, the measurement procedure, measurement method, measurement conditions, and the like of Raman spectroscopic analysis may be performed according to ordinary methods.

The method for identifying powders by Raman spectroscopic analysis is not limited. Specifically, the spectrum pattern obtained by scanning the detection wavelength of Raman spectroscopy, the peak shape, the peak intensity, the half width of the peak, and the peak between different detection wavelengths. An intensity ratio, a peak area ratio, etc. are mentioned, and a plurality of these may be combined.
Among these, it is particularly preferable to identify the spectrum pattern or peak intensity or area ratio.

It is not particularly limited spectral position of interest in identifying the powder in Raman spectroscopic analysis, a waveform having a peak top in the range of 1250～1450Cm ^-1, the waveform having a peak top in the range of 1500～1700Cm ^-1 It is preferable to carry out at least one of them (the “waveform” here means the peak itself, not only the shape of the peak).
In these wavelength ranges, the former is a D band of graphite, that is, a region having a peak top in the vicinity of 1350 cm ^−1, which correlates with the amorphous nature of the graphite structure, and the latter is the G band of graphite, that is, the crystallinity of the graphite structure. Corresponds to a region having a peak top in the vicinity of 1585 cm ⁻¹ .

  In the present invention, it is preferable to identify by the presence or absence of the above-described D band or G band, or their peak height (peak intensity) or peak area. In addition, when the identification is performed based on the peak height ratio of the D band and the G band or the area ratio of the peak area, the value reflects the quantitative ratio between the amorphous part and the crystalline part of the graphite. There is.

  When identifying powder by Raman spectroscopic analysis, it may be judged directly from the result of analyzing the powder itself, but library data using known powder is held in advance, and this data and analysis are performed. It is preferable to identify and judge by collating with data. Furthermore, it is also preferable to reinforce the library data by reflecting individual analysis results in the library data. By using the library data for the powder identification determination, the accuracy of the identification can be improved.

In addition, as library data in the Raman spectroscopic analysis, it is preferable to measure the powders as shown in the following (A) to (C) in advance as standard powders to obtain library data.
(A) Powder collected from a location that is a source in an area to be identified (such as a manufacturing plant). (B) Powders and pulverized products that are sieved from raw materials and products such as coal, coke, needle coke, pitch coke, and carbon fiber.
(C) Powder and dust standard samples distributed or sold by the National Institute of Standards and Technology (NIST), public organizations, and academic societies.

In the present invention, it is not always necessary to perform the Raman spectroscopic analysis on all the powders whose positions are defined in the step (2), and only a part of the powders are analyzed according to the total number of powders and the purpose. May be.
Further, even when the step (4) is performed after the step (3), it is not always necessary to perform the Raman spectroscopic analysis on all the powders subjected to the shape analysis in the step (3). Depending on the condition, only a part of the powder may be analyzed. Furthermore, powders that can be identified by powder shape analysis in step (3) and powders that are not suitable for Raman spectroscopic analysis can be excluded and analyzed.
Since step (4) requires more time than step (3), it is preferable to perform step (4) after step (3). By adopting this order, it is possible to perform the Raman spectroscopic analysis by excluding the powder that can be identified in the step (3).

The number of powders to be analyzed in step (4) is the number ratio with respect to the number of powders to be analyzed in step (3), preferably 50% or less, more preferably 30% or less, and even more preferably 20% or less. Especially preferably, it is 10% or less. Although the lower limit of the number ratio is not limited, it is usually 1% or more.
The powder shape analysis in the step (3) can also identify powders having greatly different shapes, but it is difficult to quantitatively identify powders having similar particle sizes, circularity, etc. There is a case. On the other hand, by performing the step (4), it is possible to quantitatively identify powders that are similar in shape. This is because, as described above, if a carbon-based powder is measured by Raman spectroscopy, it can be identified based on the difference in its molecular structure.

[Other processes]
The powder identification method of the present invention may further include steps other than steps (1) to (4) and identification means. Specifically, spectroscopic analysis such as infrared spectroscopy (IR) and ultraviolet-visible spectroscopy (UV) can be used in combination. By using these means in combination, the accuracy of identifying the powder may be further improved.

The powder identification method of the present invention can also be employed as a method for identifying powders other than coal, coke, needle coke, pitch coke, carbon fiber, and intermediate materials thereof. Specifically, for example, carbon black, graphite, a negative electrode material for a lithium ion battery, a raw material thereof, and the like can be given. Examples of the negative electrode material and the raw material thereof include a carbon-based material, an alloy-based material in which Si, Sn, or the like is directly mixed with a carbon-based material.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited by a following example, unless the summary is exceeded.

[Adjustment of powder sample]
Black powders were collected from bag filters (2 μm cut) attached to the exhaust ports of the coal crushing equipment, coke production equipment, and carbon material (needle coke) production equipment of Mitsubishi Chemical Corporation / Sakaide Office. These powders themselves were used as measurement objects, and those obtained by mixing these three kinds of black powders at an equal weight were used as model powders.

[measuring device]
As a measuring device, Spectris Co., Ltd., product name: Morphologi G3-ID was used. This equipment consists of a unit that disperses powder (automatic / dry particle dispersion unit of pulse pressurization type), a stage unit that automatically moves a glass plate on which powder is dispersed as a sample (preparation), and a microscope that performs image analysis And a Raman spectroscopic device.
In this embodiment, a method of dispersing powder by opening the shutter is adopted. The magnification of the objective lens of the microscope was 20 times.

[Example 1]
Each of the coal, coke, and needle coke powders collected from the coal pulverization facility, the coke production facility, and the needle coke production facility was analyzed with the above measuring device.
1 to 4 show the results of analyzing the powder shape after defining the position of each powder in the sample in which each powder is dispersed. In each figure, the horizontal axis represents the equivalent-circle diameter of the powder, and the vertical axis represents the circularity (FIG. 1), the area circularity (FIG. 2), the aspect ratio (FIG. 3), and the luminance average value (FIG. 4). From these results, although the three types of powders have a difference in shape distribution, when the three types of powders are mixed, it is difficult to identify them quantitatively only by shape analysis. Note that if the target powder is carbon fiber or the like, even if the particle size is the same, the difference in shape factor is large, and therefore, it is possible to identify quantitatively even in the analysis of the powder shape.
FIG. 5 shows the result of Raman spectroscopic analysis after defining the position of each powder in the sample in which each powder is dispersed. It was confirmed that the three kinds of powders were significantly different in the presence or absence of peaks and the peak shapes in the range of 1250 to 1450 cm ^{−1 and in} the range of 1500 to 1700 cm ⁻¹ .

[Example 2]
The analysis was performed in the same manner as in Example 1 except that a model powder in which three kinds of black powders were mixed at an equal weight was used.
The position of each powder was defined, and 10,000 powder images (10000 particles) were taken to analyze the powder shape. However, quantitative identification was difficult only from the shape analysis.
Of the 10,000 powders described above, every 100 powders were subjected to Raman spectroscopic analysis for a total of 100 powders.
Advance, from the measurement results shown in FIG. 5, coal, coke, the powder each needle coke, peak behavior (peak height D band (1250～1450Cm around ^-1) and G band (1500～1700Cm around ^-1) , Peak area, peak height ratio between D band and G band, peak area ratio between D band and G band).
The composition (number ratio) of each powder was quantified by analyzing the results of Raman spectroscopic analysis of the model powder and accumulated data. Specifically, the peaks of the D band and the G band were separated from the baseline, and each peak height (peak intensity) was analyzed by collating with accumulated data. The results are shown in Table-1.

Example 3
The Raman spectroscopic analysis was carried out in the same manner as in Example 2 except that every 50 powders were measured, and a total of 200 powders were measured. The results of quantifying the composition (number ratio) of each powder from the analysis result chart in the same manner as in Example 2 are shown in Table 1.

  From the results shown in Table 1, even when coal, coke, and needle coke powders were mixed, they could be identified, and fractional analysis could be performed with good reproducibility.

Claims (10)

A powder identification method for identifying at least one powder among coal, coke, needle coke, pitch coke, carbon fiber, and intermediate products thereof, comprising at least the following steps (1), (2) and The powder identification method which has (4) in this order.
[Step (1)] A step of preparing a sample by dispersing powder [Step (2)] A step of defining the position of the powder dispersed in the sample [Step (4)] Powder having the specified position Process of Raman spectroscopic analysis of body Claims analyzing of step (4) is a waveform having a peak top in the range of 1250～1450Cm ^-1, it is performed by analyzing at least one of a waveform having a peak top in the range of 1500～1700Cm ^-1 2. The powder identification method according to 1.   The powder identification method according to claim 1 or 2, wherein the analysis of the step (4) is performed by accumulating Raman spectroscopic data of the powder in advance and collating and analyzing the data and the analysis data. . Furthermore, the powder identification method of any one of Claims 1-3 which has the following process (3) after a process (2).
[Step (3)] A step of analyzing the shape of the powder whose position is defined   The powder identification method according to claim 4, wherein the analysis of the step (3) is performed by accumulating powder shape data in advance and comparing the data with the analysis data.   The powder identification method according to any one of claims 1 to 5, wherein a sample containing powder having a major axis diameter of 1 to 1500 µm is identified.   The powder identification method according to any one of claims 1 to 6, wherein the step (1) is a step of dispersing the powder by an air flow.   The step of dispersing the powder by the air flow is a step of causing a pressure difference between the sample chamber on which the powder is placed and the outside, and dispersing by the air flow generated by opening at least a part of the pressure difference. The powder identification method according to claim 7.   9. The method according to claim 8, wherein the release of the pressure difference is one of a method of opening a shutter provided in the sample chamber and a method of releasing at least a part of the sample chamber by forming a thin film and breaking the thin film. The powder identification method as described.   The powder identification method according to claim 1, wherein all the steps are automated.