JP6507992B2 - Sample frame and sample analysis method - Google Patents

Description

  The present invention is an analysis method for fixing a measurement piece of an analysis sample to a sample frame, irradiating the sample with a primary beam such as an electron beam, and acquiring information of metal elements contained in the analysis sample, and the analysis method It relates to the sample frame used.

  Energy Dispersive X-ray Spectrometry (EDS) is widely used as an analysis and evaluation tool for various materials. In energy dispersive X-ray analysis, a measurement piece of an analysis sample is irradiated with a primary beam such as an electron beam or X-ray, and characteristic X-rays or fluorescent X-rays generated from the analysis sample are dispersed in an energy dispersive type such as a semiconductor detector. It detects using a detector and analyzes the elements, concentration, etc. that make up the analysis sample from its energy and intensity. By using an SEM-EDS system in which an energy dispersive detector is incorporated into a scanning electron microscope (SEM: Scanning Electron Microscope), information of elements present in the field of view of the observation image of the scanning electron microscope and the concentration thereof It becomes possible to obtain.

  Such a method is a particularly effective means to analyze the types and proportions of minerals contained in natural ores and industrial raw materials, which are raw materials of base metals and rare metals which are essential as materials for electronic devices. is there. Specifically, automatic analysis using a mineral particle analyzer (MLA: Mineral Liberation Analyzer) based on the SEM-EDS system as shown in FIG. 1 is performed.

  As disclosed in JP-A-2015-040724, mineral analysis using the mineral particle analyzer 1 is performed as follows. First, an ore sample is embedded in a resin, and the measurement surface is polished to form a measurement piece. Next, the measurement piece is fixed to the sample frame 30, introduced into the scanning electron microscope 10, and a backscattered electron image of the measurement surface is obtained. The controller 20 identifies the mineral region of each mineral particle by using the difference in the reflected electron brightness in the reflected electron image. In addition, EDS spectra are obtained from representative points in the mineral region of each mineral particle. From acquisition of the reflection electron image to acquisition of the EDS spectrum is automatically repeated while changing the visual field until a predetermined condition (predetermined visual field, predetermined number of particles, predetermined measurement time, etc.) is reached. After completion of the measurement, the control device 20 identifies the mineral species of each mineral particle based on the EDS spectrum, calculates the area of each mineral region, and calculates the proportion of each ore species in the ore. Do. Furthermore, the composition of the ore is calculated from the proportion of each ore species and its composition.

  In order to introduce the measurement piece of the mineral sample into the scanning electron microscope 10, the sample frame 30 shown in FIG. 2 is used. The sample frame 30 is made of a metal frame body 31 such as aluminum, a sample hole 32 formed in the frame body 31, and a metal such as aluminum, and is internally fitted in the sample hole 32, and the inside And a sample holder 33 for holding the measurement piece. As described above, the sample frame 30 is made of metal in order to ensure the conductivity of the measurement piece and to avoid charging the analysis sample at the time of irradiation of the primary line. Thereby, the measuring piece is electrically connected to the sample stage 12 of the electron microscope 10 through the sample frame 30.

  By using such a mineral particle analyzer 1, it becomes possible to automatically analyze the specification of the minerals contained in the mineral sample and the proportion thereof, but at that time, the mineral sample which is the analysis sample It is necessary to measure the measurement surface of the.

JP, 2015-40724, A

  By the way, when the sample is analyzed using a metal sample frame, when the end of the measurement piece of the analysis sample is measured, the metal sample frame is in the observation field of the backscattered electron image by the scanning electron microscope. Because it is contained, the information of the metal element derived from the mineral and the information of the metal element derived from the sample frame may be mixed, which may affect the result of measurement and analysis.

  Therefore, when analyzing the measurement result of the measurement piece of the analysis sample, it is necessary to perform an operation such as removing the image of the sample frame included in the observation field of view from the observation field of view.

  The present invention has been made to solve such a problem, and a measurement piece of an analysis sample such as energy dispersive X-ray analysis is fixed to a sample frame, and a primary line such as an electron beam is irradiated on the sample surface. A sample frame which is not affected by the reflection of the sample frame when analyzing the measurement result of the analysis sample in the analysis method for obtaining information of the metal element contained in the analysis sample; The purpose is to provide an analysis method using a frame.

  The inventors of the present invention, as a result of intensive studies, have found that, of a metal sample frame such as aluminum used to introduce a measurement piece of an analysis sample into a measurement apparatus, a sample holder for holding the measurement piece internally is a carbon material Analysis of the analysis sample because the sample holder is not detected as metal even if it performs EDS measurement while securing the conductivity between the measurement piece, the sample frame, and the sample stage of the measurement instrument by configuring Furthermore, the carbon material has a significantly lower reflected electron emission efficiency (reflected electron luminance) compared to metal without affecting the result, so that a large luminance difference from the metal-containing portion can be provided in the reflected electron image. After paying attention, the present invention was completed.

  That is, one aspect of the present invention is to introduce the measurement piece to a measurement instrument that irradiates a primary line to a measurement piece of an analysis sample and acquires information of metal elements contained in the analysis sample. It relates to the sample frame. The sample frame includes a metal frame body, a sample hole formed in the frame body, and a sample holder fitted in the sample hole and holding the measurement piece inside. In particular, in the sample frame of the present invention, the sample holder is made of a conductive material, a material having lower reflection electron emission efficiency (reflection electron brightness) than metal and durability, that is, a carbon material. It is characterized by

  According to another aspect of the present invention, a measuring instrument for irradiating a primary line to a measurement piece of an analysis sample to acquire information of metal elements contained in the analysis sample, a metal frame body, and the frame body are formed. A sample frame provided with a sample holder, a sample holder internally fitted into the sample hole and holding the measurement piece inside, and an analyzer for analyzing information on the metal element The measurement piece is introduced into the measurement device while holding the measurement piece inside the sample holder, and the measurement piece is irradiated with a primary line by the measurement device, and the analysis sample is Method of acquiring information of metal elements contained in the group automatically while changing the field of view until a predetermined condition is reached, and analyzing the information of the acquired metal elements by the analyzer. Pertain to.

  In particular, the analysis method of the present invention is characterized in that the sample holder made of a carbon material is used as the sample holder, and the influence of the sample holder is excluded when acquiring the information of the metal element by the measuring device. Do.

  In a preferred aspect of the analysis method of the present invention, the measurement device is a scanning electron microscope, and acquires information of the metal element by energy dispersive X-ray analysis or Raman spectroscopy.

  The analysis sample is an analysis sample in which a particulate solid containing a metal element is embedded in and solidified in a resin, and a reflected electron image of a measurement surface of the measurement piece is obtained as information of the analysis sample, and the reflection electron The reflection electron luminance in the image is expressed using a relative value of 256 gradations in which the resin part is "0" and the gold single substance is "255", and the portion in which the reflection electron luminance is 20 or more is the particulate solid It is preferable to extract as

  In the analysis method of the present invention, the particulate solid is an ore, and a mineral region of each of the mineral particles constituting the ore is identified by using a difference in reflection electron luminance, and a mineral of each mineral particle is determined. The present invention is suitably applied to mineral particle analysis to obtain EDS spectra from representative points in the region.

  According to the present invention, for example, when analyzing metal components in ore using an ore particle analyzer or the like, that is, when observing a reflection electron image and simultaneously measuring an EDS spectrum, it becomes an analysis target Even in the field of view including the sample holder of the sample frame, which is the end of the measurement piece of the ore sample, no measurement results will be affected even if it is measured as it is without masking in image processing. In addition, when observing and measuring the entire measurement piece of the analysis sample evenly, observation and measurement are performed while moving the field of view and changing it, but there is no need to perform masking as described above. It becomes possible to operate. Therefore, it is possible to significantly reduce the time required for analysis of the backscattered electron image.

FIG. 1 is a block diagram of a mineral particle analyzer to which the present invention is applied. FIG. 2 is a block diagram of a conventional sample holder. FIG. 3 is a block diagram of a sample holder according to the present invention.

  A sample frame according to the present invention will be described. As shown in FIG. 3, the sample frame 40 of the present invention also has the same structure as the conventional sample frame 30 shown in FIG. Specifically, the sample frame 40 is inserted into the frame body 41, the sample hole 42 formed in the frame body 41, and the sample hole 42, and the sample holding the measurement piece of the analysis sample inside And a holder 43.

  The sample stage 12 of the scanning electron microscope 10 is provided with a screw hole (not shown) for fixing the sample frame 40, and a screw (not shown) is built in the center of the sample frame 40. It is done. The sample frame 40 can be fixed to the sample stage 12 by screwing the screw of the sample holder 40 into the screw hole of the sample stage 12 using a dedicated driver.

  Hereinafter, the sample frame 40 will be described by exemplifying a rectangular shape having a length of 150 mm × width 150 mm × height 40 mm, but the size and shape are arbitrary, and the scanning electron microscope 10 is used. Thus, any of the known sample frames used for energy dispersive X-ray analysis or Auger spectroscopy are widely applicable to the present invention.

In the central portion of the frame main body 41 of the sample frame 40, a bottomed (24 mm deep) sample hole 42 having a cylindrical shape with an inner diameter of 30 mm is provided. It is also possible to directly fit and hold a cylindrical measurement piece with an outer diameter of 30 mm in this sample hole 42, but usually, the inner diameter is 30 mm, the radial width is 2.5 mm, and the inner diameter is 30 mm. There using a sample holder 43 which is cylindrical fitting hole of 25mm provided, the sample holder 43 as a spacer, the internal diameter is internally fitted retain a cylindrical measuring piece of 25mm in the sample frame 43.

  In the present invention, the frame main body 41 constituting the sample frame 40 is made of metal such as aluminum as in the conventional sample frame 30. On the other hand, in the present invention, the sample holder 43 is made of a carbon material, unlike the conventional sample holder 33 made of metal such as aluminum. As the carbon material, a composite of graphite, carbon black and carbon fiber reinforced plastic (CFRP) composited with carbon fiber or carbon fiber as a filler can be suitably applied, but is not limited thereto. Absent. That is, it is also possible to form the conductive resin to which conductivity is imparted by mixing carbon powder or the like.

  In the present invention, since the sample holder 43 is made of a conductive carbon material, the measurement piece internally fitted and in contact with the sample holder 43 is electrically connected to the sample holder 43. Similarly, the sample holder 43 abuts on the frame main body 41 and is electrically connected to the frame main body 41. Therefore, the measurement piece and the sample stage 12 of the scanning electron microscope 10 can be electrically connected via the sample frame 40. As described above, since the measurement piece and the sample stage 12 of the scanning electron microscope 10 are electrically connected, also in the present invention, at the time of backscattered electron image acquisition and EDS spectrum acquisition using the scanning electron microscope 10. , There is no chance that the measuring piece will charge up.

  The present invention is characterized in that, of the sample frame 40, only the sample holder 43 is made of a carbon material having conductivity and having lower reflection electron emission efficiency (reflection electron luminance) than metal. Although it is possible to form the entire sample frame 40 of a carbon material, in general a carbon material is mechanically brittle compared to a metal material, so care must be taken in handling it other than when inserting and removing sample pieces, In addition, it is not economical to construct the entire sample frame 40 of a carbon material because it is expensive.

  Alternatively, the entire sample frame 40 including the sample holder 43 may be formed of a conductive resin to which conductivity is imparted by mixing carbon powder or the like, but the sample frame 40 is a scanning electron microscope 10. During the measurement according to the above, since the irradiation with the primary line continues, the frame main body 41 and the sample holder may be deteriorated or deformed. Therefore, it is not desirable in terms of performance to form the sample frame 40 of a conductive resin. Therefore, also in the present invention, the frame main body 41 is made of a metal material such as aluminum.

  Hereinafter, measurement analysis of a mineral sample using a mineral particle analyzer by energy dispersive X-ray analysis, which is an example of the analysis method of the present invention, will be described. In the present invention, the primary line refers to an electron beam or an X-ray that the analyzer irradiates the measurement piece. In addition, this analysis method can be applied to Auger spectroscopy and the like.

  The configuration of an example of a mineral particle analysis apparatus used for measurement analysis of a mineral sample according to the present invention is shown in FIG. As shown in FIG. 1, the mineral particle analyzer 1 is a measuring device in the present invention, a scanning electron microscope (SEM) 10 in which an energy dispersive X-ray analyzer (EDS) 11 is incorporated, and in the present invention And a control device (computer) 20 which is an analysis device. The scanning electron microscope 10 is connected to a controller 20, and the control of the scanning electron microscope 10 and the energy dispersive X-ray analyzer 11 is performed by the controller 20. Further, data (information on metal elements) obtained by the scanning electron microscope 10 and the energy dispersive X-ray analyzer 11 is input to the control device 20, and analysis processing described later is executed. Here, although the control device 20 is widely applied to an arithmetic processing device such as a general computer, it is not particularly limited thereto.

  Mineral analysis by the mineral particle analyzer 1 is roughly divided into two steps of measurement processing and analysis processing. The following will be described in order.

(Measurement process)
First, a measurement piece of an ore sample is prepared. As the ore sample, powdered ore may be used, or massive ore may be used. For example, as the ore subjected to the flotation treatment in the smelting process, a powdered ore having a particle diameter similar to that of the particle diameter in the flotation treatment (particle diameter distribution (D80) is 5 μm to 200 μm) is used. The ore sample is mixed with a resin such as Bakelite or phenolic resin and embedded in a resin, and then embedded and solidified into a resin, and then the surface to be measured is rough-polished and intermediate-polished with water-resistant abrasive paper etc. Mirror finish (mirror polishing) using such a cloth on which abrasive grains are contained together with a lubricant, and applying carbon deposition to impart conductivity to the polished surface subjected to mirror polishing Thus, a measurement piece is obtained.

  The obtained measurement piece is internally fitted and held in the sample holder 43, and the sample holder 43 holding the measurement piece is fitted and fitted in the sample hole 42 of the frame main body 41. The sample frame 40 on which the measurement piece is mounted is introduced into the sample chamber in the scanning electron microscope 10 and fixed on the sample stage 12. After setting conditions such as the optical axis adjustment of the scanning electron microscope 10, the focus adjustment, and the filament application voltage, the measurement is started.

(1) Acquisition of Reflection Electron Image In measurement, first, a backscattered electron (BSE) image of a part (field portion) of the measurement surface of the measurement piece is acquired using the scanning electron microscope 10. Reflected electron luminance in a reflected electron image is usually expressed by 256 gray levels. In the present invention, the reflection electron luminance is expressed by setting the reflection electron luminance of the resin portion to "0", the reflection electron luminance of gold alone to "255", and the reflection electron luminance to a relative value of 256 gradations. . Hereinafter, this relative value will be described as the reflection electron luminance.

(2) Image Processing of Edge Portion of Sample In the reflection electron image of the obtained measurement piece, the region (hereinafter referred to as “mineral region”) of each mineral particle is specified by the scanning electron microscope 10. This mineral area reveals the shape and size of each mineral particle.

  Specifically, only the mineral part is extracted by specifying the mineral area. The reflected electron emission intensity (reflected electron luminance) depends on the average atomic weight, and the larger the average atomic weight, the larger the value of the reflected electron luminance. That is, the reflection electron luminance of the resin portion is relatively small, and the reflection electron luminance of the mineral portion is relatively high. Specifically, the reflection electron luminance of the resin portion is set to "0". In the present invention, a portion having a reflection electron luminance of “20” or more is extracted as a mineral. The reflection electron luminance of the carbon material is in the range of "5 to 15".

  The reflected electron brightness of the mineral part is relatively high compared to the reflected electron brightness of the resin part. The resin part and the mineral part are separated by utilizing the difference in the reflection electron luminance, and only the mineral part is extracted. For example, it is assumed that the reflection electron luminance ranges from “0 to 19” as the resin part and the part of “20” or more is extracted as the mineral part.

  Next, mineral particles of adjacent different mineral species are separated. If the mineral type is different, that is, if the constituent elements are different, the reflection electron luminance is different, so that the position change rate of the reflection electron luminance is high at the boundary. For this reason, the boundary can be found from the position change rate of the reflection electron luminance, and mineral particles of different mineral types can be separated.

  Next, the EDS spectrum of the representative point in the mineral area of each mineral particle is acquired by the energy dispersive X-ray analyzer 11 about the mineral particle distinguished by the reflection electron image. Here, an EDS spectrum refers to a spectrum obtained by energy-splitting characteristic X-rays, fluorescent X-rays, Auger electrons and the like generated from a sample by irradiating a primary line.

  The mineral analyzer 1 performs the predetermined number of times (predetermined number of fields of view, predetermined number of particle detections, predetermined measurement time, and the like from the reflection electron image acquisition to the EDS spectrum acquisition described above by the analysis routine previously given from the control device 20. Repeat automatically while changing the field of view until it reaches).

  Thus, although the mineral particles can be separated from the embedded resin portion etc. by the brightness of the reflection electron image, when using a conventional metal sample holder such as aluminum, the reflection electron at the end of the measurement piece In the image, both the reflection electron brightness of the metal element constituting the metal sample holder and the reflection electron brightness of the metal element constituting the mineral particles of the sample piece become high. Since the EDS spectrum measurement program is designed to acquire the EDS spectrum of the high-brightness part, when the EDS spectrum is measured without performing any processing on the obtained reflected electron image, the edge of the measurement piece is obtained. At the same time, the metal element that constitutes the sample frame is also detected at the same time, and an error occurs in the information from only the mineral part to be measured. Therefore, in the conventional sample analysis method, it is necessary to remove the sample holder from the reflection electron image by image processing at the image analysis stage in order to obtain correct information only from the minerals in the measurement piece.

  On the other hand, when this measurement processing is performed by the sample analysis method of the present invention, the sample holder made of carbon material will be in circumferential contact with the periphery of the measurement piece, and the frame body itself of the sample frame enters the field of view. There is no. For this reason, even if the sample holder is included in the field of view of the reflection electron image, the reflection electron luminance from this sample holder is less than "20", so the sample holder is recognized as a metal element at the reflection electron image stage. Not excluded from being measured. That is, it is possible to acquire an EDS spectrum from only the mineral part without performing any image processing.

  As described above, in the conventional measurement processing, an operation of manually and selectively deleting an image of a portion unnecessary for measurement such as a sample holder is required between operations of acquisition of a backscattered electron image and acquisition of an EDS spectrum. However, according to the analysis method of the present invention, it is possible to automatically advance the analysis routine as it is and continuously obtain correct results without performing processing such as deletion for these sites. . Moreover, since such an artificial process is not required, the analysis method of the present invention can prevent the occurrence of a loss of measurement time.

(Analysis process)
The analysis process is the same as the conventional and generally used method. For example, after the measurement process is completed, in the analysis process, the mineral species of each mineral particle is identified using the elemental fraction obtained from the EDS spectrum, and the area of the mineral region is determined from the reflection electron image. The percentage of mineral species in the ore is determined by Also, the detailed elemental fraction of the ore is calculated from the abundance ratio of the mineral species and the chemical composition.

  Hereinafter, examples of the present invention will be shown. The present invention is not limited to these examples.

(Common condition)
Mineral analysis was performed under the following conditions for both the example and the comparative example. As a mineral analyzer, MLA650 FEG manufactured by FEI was used. In addition, molybdenum concentrate from Chile was used as an ore sample. In addition, the chemical analysis was beforehand performed by ICP emission analysis about this molybdenum concentrate. The composition of the molybdenum concentrate obtained by ICP emission analysis is shown in Table 1.

  Molybdenum concentrate is embedded in a phenol resin (Struas, Multifast) to obtain consolidated pieces, and rough measurement, intermediate polishing, and mirror polishing are sequentially applied to the measurement surface of the consolidated pieces, and carbon is further added. Measurement pieces were obtained by vapor deposition. The obtained measurement piece was introduced into a scanning electron microscope and the measurement was performed. The measurement conditions were a magnification of 400 times, a resolution of 1 μm / pixel, and a measurement range of 6.75 mm × 6.75 mm.

Example 1
For fixing the measurement piece, a sample frame 40 made of an aluminum frame main body 41 and a carbon sample holder 43 was used.

  At the stage of measurement processing, the resin part and the mineral part were separated from the reflection electron image by utilizing the difference in reflection electron luminance. At this time, it was separated as a resin part at this stage, assuming that the reflection electron luminance of the sample holder 43 was comparable to that of the resin part.

  Therefore, even if the sample holder 43 is present in the field of view, it is recognized as a resin part, so it is not a measurement target of the EDS spectrum and also excluded from the analysis target because the EDS spectrum is not obtained at the analysis processing.

  As a result, the operation of selecting and deleting the region of the carbon sample holder on the screen was not performed at all. A total of 2.25 hours were required, including measurement and analysis for one measurement piece.

  Table 1 shows the results of calculating the composition of the molybdenum concentrate from the mineral species obtained by the analysis process and the proportion thereof.

(Comparative example 1)
Measurement of minerals was performed in the same manner as in Example 1 except that the sample frame 30 provided with the aluminum sample holder 33 was used to fix the sample. In the measurement process, when the holder 33 is in the range of the measurement field of view, the reflected electron luminance becomes a portion of “20” or more, and is extracted as a mineral portion on the measurement program. The image of the holder 33 was selected and deleted on the monitor screen. At this time, it took 2.5 hours to combine the measurement processing and the analysis processing and the deletion operation performed between them for one measurement piece. Table 1 shows the results of calculating the composition of the molybdenum concentrate from the mineral species obtained by the analysis process and the proportion thereof.

(Comparative example 2)
Measurement of minerals was performed in the same manner as in Example 1 except that a sample holder 33 made of aluminum was used to fix the sample. In the measurement processing, when the sample holder 33 is in the measurement visual field range, the reflection electron luminance is a portion of “20” or more, and it is extracted as a mineral part on the measurement program, but the analysis processing was performed as it is. At this time, it took 2.25 hours for the measurement process and the analysis process, and the deletion operation to be performed between them, for one measurement piece. Table 1 shows the results of calculating the composition of the molybdenum concentrate from the mineral species obtained by the analysis process and the proportion thereof.

  From the above results, when the carbon sample holder 43 of Example 1 is used, the image of the sample holder 43 is not selected and removed from the reflection electron image before acquiring the EDS spectrum at all. As compared with Comparative Example 1, the total processing time was reduced by 0.25 hours. In addition, although the total working time in Example 1 was the same as in Comparative Example 2, the measurement analysis could be performed more accurately than in Comparative Example 1 in chemical analysis.

Reference Signs List 1 mineral particle analyzer 10 scanning electron microscope 11 energy dispersive X-ray analyzer 12 sample stage 20 controller 30, 40 sample frame 31, 41 frame main body 32, 42 sample hole 33, 43 sample holder

Claims (5)

For introducing the measurement piece to a scanning electron microscope which irradiates a primary line to a measurement piece of an analysis sample embedded in a resin and is solidified , and acquires information of metal elements contained in the analysis sample A sample frame,
A metal frame body, a bottomed sample hole formed in the frame body, and a sample holder internally fitted in the sample hole and holding the measurement piece inside;
A sample frame characterized in that the sample holder is made of a carbon material. A scanning electron microscope which irradiates a primary line to a measurement piece of an analysis sample embedded in a resin and solidified it , and acquires information of metal elements contained in the analysis sample, a metal frame body, and the frame body A sample frame provided with a sample holder with a bottomed sample hole formed and a sample holder internally fitted into the sample hole and holding the measurement piece inside, and an analysis process for information on the metal element Using an analyzer to
In a state where said measurement strip is held inside of the sample holder, introducing the measurement piece to the scanning electron microscope, by the scanning electron microscope, irradiating the primary beam with respect to the measurement piece, the analytical Acquisition of information on the metal element contained in the sample is automatically repeated while changing the field of view until a predetermined condition is reached, and analysis is performed by the analysis apparatus, which performs analysis processing on information on the acquired metal element In the method
A sample holder made of a carbon material is used as the sample holder, and the influence of the sample holder is excluded when acquiring the information of the metal element by the scanning electron microscope . The d Nerugi dispersive X-ray analysis or Auger spectroscopy to acquire the information of the metal element analysis method according to claim 2.   The analysis sample is an analysis sample in which a particulate solid containing a metal element is embedded in and solidified in a resin, and a reflected electron image of a measurement surface of the measurement piece is obtained as information of the analysis sample, and the reflection electron Expressing the reflection electron luminance in the image using a relative value of 256 gradations where the resin part is 0 and the gold alone is 255, and the portion having the reflection electron luminance of 20 or more is extracted as the particulate solid. The analysis method according to claim 2, characterized by   The particulate solid is an ore, and the difference in reflection electronic brightness is used to identify the mineral region of each mineral particle constituting the ore, and from the representative point in the mineral region of each mineral particle, EDS The analysis method according to claim 4, characterized in that a spectrum is obtained.

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