JP6555150B2 - Powder identification method - Google Patents

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. Since coke is used for iron making, 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 environmentally preferable 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 order to prevent scattering as much as possible, it is necessary to clarify in which area the measures should be taken. For this reason, it was important to identify what powder was scattered from which area in the factory site.

  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 it is possible to quickly and accurately identify powders such as coal and coke scattered from establishments that manufacture carbon-based materials such as coke. The purpose is to provide an analysis method.
Another object of the present invention is to provide an analysis method that can quickly and accurately identify the shape and chemical structure of a carbon-based powder that is difficult to identify visually.

  In order to solve the above-mentioned problems, the present inventors diligently studied to automate the preparation of a sample that has been performed by a skilled worker and to automate the identification judgment that has been performed by a skilled worker. As a result, the inventors have found that the above problem can be solved by appropriately combining a specific sampling method, image analysis method, reflected light measurement method, and spectrum spectroscopy method, and have reached the present invention.

That is, the gist of the present invention is the following [1] to [12].
[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, and at least the following step (1) and step The powder identification method which performs (2) in this order, and then performs the following process (4) and process (5).
[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 The step of measuring and analyzing the reflected light intensity of the body [Step (5)] The step of Raman spectroscopic analysis of the powder having the specified position [2] The analysis of the step (5) is 1250 to 1450 cm ⁻¹ . The powder identification method according to [1], which is performed by analyzing at least one of a waveform having a peak top in a range and a waveform having a peak top in a range of 1500 to 1700 cm ⁻¹ .
[3] The analysis of the step (5) is performed by accumulating Raman spectroscopic data of the powder in advance and collating and analyzing the data and the analysis data. Powder identification method.
[4] The powder identification method according to [1] to [3], wherein the measurement in the step (4) is measurement by reflected illumination using monochromatic light or white light as a light source.
[5] The powder according to [1] to [4], wherein the analysis in the step (4) is performed by accumulating the reflected light intensity data of the powder in advance and collating this data with the measurement data. Body identification method.
[6] The powder identification method according to [1] to [5], in which the following step (3) to step (5) are performed after performing the step (2).
[Step (3)] A step of analyzing the shape of the powder whose position is defined [Step (4)] A step of measuring and analyzing the reflected light intensity of the powder whose position is defined [Step (5) [Step 7] Raman spectroscopic analysis of the powder with the specified position [7] In the analysis in the step (3), the shape data of the powder is accumulated in advance, and this data is compared with the analysis data for analysis. [6] The powder identification method according to [6].
[8] The powder identification method according to [1] to [7], in which a sample including powder having a major axis diameter of 1 to 1500 μm is identified.
[9] The powder identification method according to [1] to [8], wherein the step (1) is a step of dispersing the powder by an air flow.
[10] The step of dispersing the powder by the air flow causes a pressure difference between the sample chamber in which the powder is placed and the outside, and the air flow generated by opening at least a part of the pressure difference. The powder identification method according to [9], which is a step of dispersing.
[11] 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. 10].
[12] The powder identification method according to [1] to [11], wherein all 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 powders such as coal and coke scattered from a business office that manufactures coke.
According to the present invention, it is possible to provide an analysis method capable of quickly and accurately identifying the shape and chemical structure of a carbon-based powder that is 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. Stereomicroscopic images of powders of coal, coke, needle coke and needle coke raw materials. An image obtained by converting the stereoscopic microscope images of coke powder and needle coke powder into two gradations. The figure which shows the reflected light intensity | strength of each powder of coal, coke, needle coke, and a needle coke raw material. The correlation diagram which contrasted the Raman spectrum intensity | strength and reflected light intensity | strength about each powder of coal, coke, needle coke, and a needle coke raw material.

  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 interpreted 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 powder other than elemental carbon (for example, organic matter or sand particles) is mixed in the measurement sample, it is easily discriminated in step (3), step (4) or step (5) described later. , Can be excluded from the powder to be identified.
In addition, the powder identification method of the present invention may be a method of identifying a plurality of types of powders as one group from other powders. Specifically, for example, a method may be used in which needle coke powder and pitch coke powder are combined into one group and distinguished from coal powder or coke powder.

<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 the raw material for coke, weakly caking coal or strongly caking coal is preferably 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 (hereinafter sometimes referred to simply as “needle coke”) is produced using coal tar generated in the process of producing coke as a raw material, and used as a graphite electrode raw material for steel making, etc. It is done.
<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 this invention, Usually, it is preferable to identify the sample containing a 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 be irradiated when performing Raman spectroscopic analysis in the following step (5), and the accuracy of fractional analysis is reduced. Tend to.
As for the preferable particle diameter of the target powder to be identified, the major axis diameter is preferably 2 to 1000 μm, more preferably 5 to 500 μm, and still more preferably 10 to 300 μm for the same reason as described above.

In the present invention, it is not necessary that the major axis diameters of all powders to be identified are within the above range, and powders having major axis diameters outside the above range may be included. The number ratio of the powder having the major axis diameter 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; buildings, outdoor nets, various equipment and devices, vehicles and other deposits on the interior; clothing, Examples include deposits on helmets and masks. 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 includes at least the following steps (in the following description, each step is referred to as “step (1)”, “step (2)”, “step (4)”), “step (5 ) "In some cases.
In the present invention, “sample” does not mean the powder itself, but means a preparation for analysis in each step, but a filter, plate, sheet or film in which particles are captured or dispersed, The “sample” also includes those obtained by embedding and polishing a powder in a curable epoxy resin or acrylic resin.
[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 measuring and analyzing reflected light intensity of body [Step (5)] Step of performing Raman spectroscopic analysis of powder with specified position As the order of the above steps, usually, step (1), step (2) ) Are performed in this order, and then step (4) and step (5) are performed. Either step (4) or step (5) may be performed first. Step (4) may be substantially the same as step (3) described later.

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, step (3), step (4), and step (5) may be performed in any order. However, from the viewpoint of the reason described later, it is preferable to perform the step (5) after the step (3) and the step (4). In addition, since the step (2), the step (3), and the step (4) can be performed at the same time, the step (5) is preferably performed after the step (3) and the step (4). In addition, when not performing a process (3) and a process (4) simultaneously, any may be performed first.

In this invention, each process of process (1)-process (5) 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, the following methods are mentioned.
-Process (2) and process (3) are automated-Process (2) and process (4) are automated-Process (2) and process (5) are automated-Process (2) -The process (4) is automated-All of the process (2)-the process (5) are automated Furthermore, in addition to the above, the method by which the process (1) is also automated is mentioned. Among these, it is particularly preferable that all of the steps (1) to (5) 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. If a plurality of processes are incorporated in one apparatus, it is easy to correlate the analysis results of both processes for one powder and reflect them in the identification results, and it is also desirable because the analysis time is shortened. .

  Since the powder identification method of the present invention has a plurality of analysis steps, after collecting the measurement results obtained in each step, an algorithm can be formed and analyzed using these data. That is, the analysis step is constructed and identified by combining the analysis result of the reflected light intensity in the step (4), the result of the Raman spectroscopic analysis in the step (5), and the analysis result of the powder shape in the step (3). Is possible. Furthermore, the analysis results obtained in the steps (3) to (5) can be parameterized, and the powder can be identified by the correlation (ratio, etc.) of these numerical values. By adopting these methods, it is preferable that powders of various types of elemental carbon (elemental carbon) can be mixed with each other with high accuracy.

According to the present invention, since it is possible to analyze quickly, a large amount of powder can be analyzed. There is no limitation on the number of powders to be analyzed, but it is also effective when identifying 100 or more, more than 1000, and especially 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 in order to perform analysis in steps (3) to (5) described later.
The sample is not limited as long as it can be analyzed in step (3), step (4), and step (5). 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 step (5), a substrate that is strong against lasers 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, there is a risk that the analysis accuracy may be lowered not only for the definition of the powder position in the step (2) but also for any analysis in the steps (3) to (5). .
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.
Amount of powder subjected to the measurement (bulk volume) is not limited, in order to perform highly accurate analysis is usually 100 mm ³ or less, preferably 0.1 to 50 mm ^3, more preferably 0.5 to 20 mm ^3, further It is preferable to disperse an amount of about 1 to 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. In this case, even if no unit operation is performed, it corresponds to step (1) in the present invention.

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 illuminating illumination or transmissive illumination, but is preferably reflective (imaging). 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, step (2) and at least one of step (3), step (4), and step (5) to be described later can be performed with one device, and these steps are performed simultaneously. You can also
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. If the target powder is fibrous, the major axis diameter (fiber length), minor axis diameter (fiber width) In addition, parameters such as the aspect ratio indicated by these ratios, the fiber elongation rate, and the fiber straightness can also be used.

Among these, parameters such as circularity, area circularity, and aspect ratio 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.
In addition to the above, the parameters that define the powder shape include <luminance average value>, <luminance dispersion value>, etc., which are <parameters related to particle transmittance>, and these are the step (4) described later. Independent measurement object.

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 may be analyzed according to the total number or purpose of the powders. Good.
Even when the step (3) is performed after the step (5) described later, it is not always necessary to analyze the shape of all the powders subjected to the Raman spectroscopic analysis in the step (5). Similarly, 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 whose reflected light intensity is measured in the step (4).

[Step (4)]
In step (4), the reflected light intensity is measured and analyzed for the powder whose position is defined in step (2). A method for measuring the reflected light intensity of the powder is not limited, but it is preferable to perform measurement by reflection (epi-illumination) illumination using monochromatic light or white light as a light source. Specifically, there is a method of using a stereomicroscope to measure the intensity of reflected light when irradiated with monochromatic light or white light from the upper part of the powder sample, and the light source is preferably white light.
As described above, the step (3) and the step (4) can be performed at the same time. In this case, a device having a function of measuring the powder shape and a function of measuring the intensity of reflected light in one device. Is preferably used.

The value of the reflected light intensity may be handled independently or statistically. Specifically, “brightness average value” which means an average value of reflected light intensity for each particle, “brightness dispersion value” which means dispersion (deviation) of reflected light intensity for each particle, and the like.
The measurement result of step (4) may be used independently for identification determination, but may be used for identification determination by correlation with the parameters defining the powder shape in step (3). .

  When identifying powder by reflected light intensity, it may be judged from the result of measuring the powder itself, but library data using known powder is held in advance, and this data and measurement data It is preferable to analyze by collating. Furthermore, it is also preferable to reinforce the library data by reflecting individual measurement results in the library data. By using the library data for the powder identification determination, the accuracy of the identification can be improved.

Elemental carbon (elemental carbon) powder is known to have different crystallinity depending on its origin. However, in general, an X-ray diffractometer or the like is necessary to measure the crystallinity of the powder, and it is not practical to use it as an identification means by measuring each grain.
On the other hand, in the step (4), substantially the same analysis is simply performed by analyzing the characteristics of the powder surface called reflected light intensity rather than analyzing the structure inside the powder called crystallinity. Is possible. That is, attention was paid to the fact that crystallinity contributes to the orientation of the powder, and that the difference in orientation is manifested as a difference in surface glossiness.

Specifically, needle coke powder and pitch coke powder have the highest crystallinity, and in the following, coke powder, needle coke, pitch coke raw material powder, and coal powder in descending order of crystallinity. I found out that it was in order.
In addition, although it is the same in the point which pays attention to the crystallinity of powder also in process (5) mentioned below, process (4) reduces the analysis load of process (5), and improves identification efficiency. It also has implications for screening.

In the present invention, it is not always necessary to measure the reflected light intensity for all of the powders whose positions are defined in step (2), and only a part of the powders are analyzed according to the total number of powders and the purpose. May be.
In addition, since step (5) takes more time than step (4), it is preferable to perform step (5) after step (4). By adopting this order, it is possible to perform the Raman spectroscopic analysis by excluding the powder identified in the step (4), so that it is possible to identify efficiently.

Also, in the case where the step (3) and the step (4) that are arbitrarily performed are not performed at the same time, and the step (4) is performed after the step (3), the shape of the powder subjected to the shape analysis in the step (3) is not necessarily included. It is not necessary to measure the reflected light intensity for all, and only a part of the powder may be analyzed according to the total number of powders and the purpose. Furthermore, the powder that can be identified by the powder shape analysis in the step (3) can be analyzed by excluding this.
In such a case, the number of powders to be analyzed in the step (4) is preferably 5000 or less, more preferably 3000 or less, and still more preferably 1000 or less. The lower limit of the number ratio is not limited, but is usually 100 or more, preferably 200 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 are cases. 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 the reflected light intensity of the carbon-based powder is measured, identification based on the difference in the primary structure or secondary structure of the carbon-based powder is possible.

[Step (5)]
In step (5), 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 (5) 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 peak 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 (5) 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 (5) takes more time than step (3), it is preferable to perform step (5) 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 (5) 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 (5), 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, identification based on the difference in its molecular structure is possible.

Further, even when the step (5) is performed after the step (4), it is not always necessary to perform the Raman spectroscopic analysis on all the powders subjected to the reflected light intensity in the step (4). Depending on the above, only a part of the powder may be analyzed. Furthermore, powder that can be identified by measuring the reflected light intensity in step (4) and powder that is not suitable for Raman spectroscopic analysis can be excluded and analyzed.
Since the process (5) takes more time than the process (4), it is preferable to perform the process (5) after the process (4). By adopting this order, it is possible to perform the Raman spectroscopic analysis by excluding the powder identified in the step (4), so that it is possible to identify efficiently.
The number ratio of the number of powders to be analyzed in step (5) with respect to the number of powders to be analyzed in step (4) is the same as the case of the number of powders to be analyzed in step (3) described above. It is the same.

The number of powders to be analyzed in the step (5) is not limited, but is preferably 1000 or less, more preferably 500 or less, still more preferably 300 or less, and particularly preferably 200 or less. The lower limit of the number ratio is not limited, but is usually 20 or more, preferably 50 or more.
Even if the reflected light intensity is measured in step (4), the powder can be identified if the primary structure and the secondary structure are greatly different. However, in order to quantitatively identify more accurately, the process ( 5) must be performed. This is because, as described above, when carbon-based powder is measured by Raman spectroscopy, it is possible to identify with high accuracy based on the difference in molecular structure inside the powder.

[Other processes]
The powder identification method of the present invention may further include steps other than steps (1) to (5) and identification means. Specifically, spectroscopic analysis such as infrared spectroscopy (IR) and ultraviolet-visible spectroscopy (UV) can be used in combination. Further, the color tone of the powder may be added as an identification factor. 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]
From the bag filters (2μm cut) attached to the exhaust ports of the coal crushing equipment, coke production equipment, needle coke production equipment, needle coke raw material production equipment of Mitsubishi Chemical Corporation / Sakaide Office, respectively, black Of powder was collected. These powders themselves were measured, and a mixture of these four types of black powders at a constant weight was used as a model powder.

[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, and the reflected light intensity can be measured by the microscope unit.
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.

[Reference Example 1]
A stereomicroscope image (5 times the objective lens) is shown in Fig. 5 for four types of powders of coal powder, coke powder, needle coke powder and needle coke raw material powder.
From Fig.5, needle coke powder, which is a powder with high crystallinity, is observed brighter (whiter) and reflected light than coal powder, coke powder, and needle coke raw material powder with low crystallinity. It was confirmed that the strength was high.
Further, among the above powders, for the coke powder and needle coke powder, an image in which the reflected light intensity obtained from the stereoscopic microscope image is two-graded is shown in FIG. The result of FIG. 6 shows that the discrimination ability can be further improved by binarizing or gradationing the reflected light intensity.
As described above, it was confirmed that a powder with high crystallinity and a powder with low crystallinity can be distinguished by measuring the intensity of reflected light for each powder.

[Reference Example 2]
200 pieces of each of four kinds of powders of coal powder, coke powder, needle coke powder, and needle coke raw material powder were sampled, and the reflected light intensity was measured using the above-described measuring device (Morophoro G3-ID). The measurement result of reflected light intensity is shown in Fig.7.
From FIG. 7, it was confirmed that the reflected light intensity of the needle coke powder is high. The other three powders were needle coke raw material powder, coke powder, and coal powder in descending order of reflected light intensity. The result of FIG. 7 was consistent with the results of FIGS. 5 and 6 in Reference Example 1.

[Reference Example 3]
200 particles were collected from each of four types of powders of coal powder, coke powder, needle coke powder, and needle coke raw material powder, and the reflected light intensity and Raman spectral intensity ( The intensity at a wavelength of 300 cm ⁻¹ was measured. Figure 8 shows the correlation between the reflected light intensity and the Raman spectrum intensity of each powder.
From Fig. 8, it was confirmed that the four types of powders showed distributions in different ranges, and it was confirmed that the powders can be applied to discriminating and judging carbon-based powders.

[Example 1]
Using the above measuring device (Morophorg G3-ID), in advance, powder shape, reflected light intensity, Raman spectroscopic analysis is performed for each known powder of coal powder, coke powder, needle coke powder, needle coke raw material powder, It was kept as library data.
Subsequently, each of coal powder, coke powder, needle coke powder, and needle coke raw material powder was first sieved to particles of 50 μm to 125 μm using a sieve. The four kinds of particles separated by sieving were mixed in a vial with the mixing ratio as shown in Table 1 to obtain a mixed powder 1.
Using the measurement device (Morophog G3-ID), the mixed powder 1 is dispersed to prepare a sample, the position of the powder dispersed in the sample is defined, the powder shape is analyzed, and the reflected light intensity And Raman spectroscopic analysis were performed.
The obtained result was discriminated and judged in comparison with the library data. In each step, the following data was identified as a judgment target. The results are shown in Table-2.
-Process (3): Area circularity, aspect ratio-Process (4): Reflected light intensity-Process (5): Fluorescence intensity, D-band spectral shape, G-band spectral shape Weight%) ”to“ mixing ratio (volume%) ”shown in Table-2, it is assumed that the particle size of each powder is uniform by sieving as described above, and each powder The weight ratio was taken as the volume ratio value. Further, the “blending ratio (number%)” obtained by the discrimination judgment was converted into “blending ratio (volume%)” using the sphere equivalent volume obtained in the step (3).

[Examples 2 to 4]
As shown in Table 1, mixed powders 2 to 4 were obtained in the same manner as in Example 1 except that the blending ratio was different from that of the mixed powder 1.
Except that the obtained mixed powders 2 to 4 were used, analysis of powder shape, measurement of reflected light intensity, and Raman spectroscopic analysis were performed in the same manner as in Example 1, and identification judgment was performed in the same manner as in Example 1. The results are shown in Table-2.

[Comparative Examples 1-4]
Table 1 shows the results of identification and determination in the same manner as in Example 1 except that the mixed powders 1 to 4 were used and the analysis step (step of measuring and analyzing reflected light intensity) of the step (4) was not performed. -2.

  From the results in Table 2, it was confirmed that the powder could be identified quickly and accurately by combining the steps (3) to (5). Especially Examples 1-4 which performed the powder identification method including the process of measuring and analyzing reflected light intensity are compared with Comparative Examples 1-4 which performed the powder identification method which does not include the process of measuring reflected light intensity. In comparison, it was confirmed that the identification accuracy was remarkably increased.

Claims (12)

A powder identification method for identifying at least one powder among coal, coke, needle coke, pitch coke, carbon fiber, and intermediate products thereof, and at least the following steps (1) and (2) Are performed in this order, and then the following step (4) and step (5) are performed.
[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 A step of measuring and analyzing the reflected light intensity of the body [Step (5)] A step of performing Raman spectroscopic analysis of the powder whose position is specified Claims analyzing of step (5) 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 (5) is performed by accumulating Raman spectroscopic data of the powder in advance and collating and analyzing the data and the analysis data. .   The powder identification method according to any one of claims 1 to 3, wherein the measurement in the step (4) is measurement by reflected illumination using monochromatic light or white light as a light source.   The powder according to any one of claims 1 to 4, wherein the analysis of the step (4) is performed by accumulating the reflected light intensity data of the powder in advance and collating this data with the measurement data. Body identification method. The powder identification method according to any one of claims 1 to 5, wherein after the step (2) is performed, the following steps (3) to (5) are performed.
[Step (3)] A step of analyzing the shape of the powder whose position is defined [Step (4)] A step of measuring and analyzing the reflected light intensity of the powder whose position is defined [Step (5) The step of Raman spectroscopic analysis of the powder whose position is specified   The powder identification method according to claim 6, wherein the analysis in the step (3) is performed by accumulating powder shape data in advance and comparing the data with the analysis data for analysis.   The powder identification method according to any one of claims 1 to 7, 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 8, 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 9.   11. The method according to claim 10, 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 of the steps are automated.