JP7452267B2 - Abrasive paper for preparing observation samples for mineral analysis and polishing method using the same - Google Patents

Description

The present invention relates to an abrasive paper for preparing an observation sample for mineral analysis and a polishing method using the same, and more specifically to an abrasive paper in which an ore to be analyzed by a mineral analyzer (MLA) is embedded in a resin. The present invention relates to an abrasive paper for polishing a package sample and a method for preparing an observation sample using the abrasive paper.

Ore extracted from mines contains multiple types of minerals containing oxides and sulfides of metals such as copper, lead, zinc, and nickel, and in metal smelting using these ores as raw materials, By subjecting ores to a series of treatments such as crushing, beneficiation, smelting, and electrolysis, the target valuable metals are gradually raised to a predetermined grade. In the processing of the above ores, information such as the type, content, particle size distribution, proportion of unit ores, proportion of unused minerals, etc. of minerals contained in the ore raw materials to be processed and intermediates that have been processed to some extent is collected in advance. It is preferable to know this. This makes it possible to determine more efficient treatment processes and treatment conditions, thereby making it possible to reduce smelting costs.

A method to obtain information on the ore raw materials and intermediates in advance is to image the sampled ore sample using an optical microscope, identify the mineral species based on the difference in optical properties, and perform quantitative analysis based on the area ratio. There are known methods for conducting an analysis using a mineral analysis device MLA (Mineral Liberation Analyzer) using a scanning electron microscope SEM and an energy dispersive X-ray spectrometer EDS. In either method, an observation sample is obtained by embedding the ore sample to be analyzed in resin and solidifying it, and then polishing the resulting embedded sample to a smooth cross section that includes the ore sample. used.

An automatic polishing device that performs wet polishing is generally used to polish the embedded sample. This automatic polishing device, such as the rotary polishing device Tegramin-25 manufactured by Struers, sets water-resistant abrasive paper on a turntable that is rotatable, and has an arm that rotates while facing the turntable. The embedded sample is attached to the surface and polished while supplying water to an abrasive grain size of approximately 5 μm. After that, if necessary, a buffing device or diamond particles with an abrasive grain size of approximately 1 μm are used to achieve a so-called mirror-like state. Polishing is performed until it becomes .

Most ore samples can be polished with the above wet polishing equipment, but some ore samples include minerals that are sensitive to water, and some ore samples are brittle as a whole. It is difficult to polish embedded samples with the above-mentioned wet automatic polishing equipment. Therefore, in the case of ore samples containing water-resistant minerals or brittle ore samples, manual dry polishing is preferably performed. That is, in dry polishing, the embedded sample is held by hand and rubbed against the polishing paper to polish it without supplying water to the polishing paper, so even minerals that are sensitive to water can be polished well. Note that an ore that is weak in water refers to an ore that contains water-soluble components, so that when it comes into contact with water, a part of the ore is eluted, and surrounding minerals are likely to fall off accordingly.

In addition, in manual dry polishing, the force with which the embedded sample is pressed by hand can be freely adjusted, so the frictional force applied to the polished surface can be suppressed to a level that does not damage the ore sample. Therefore, even brittle ores can be polished well. On the other hand, with the above-mentioned wet-type automatic polishing machine, as mentioned above, the observation surface of the embedded sample is pressed against the water-resistant abrasive paper set on the turntable while being polished by the arm, so the slight adjustment of the force is required. Furthermore, although the rotation speed can be adjusted, it is common to polish at a speed of several tens of revolutions per minute or more, so brittle ores can easily break and some or all of the minerals can fall off. Sometimes I put it away.

As a method for preparing an embedded sample suitable for the above-mentioned dry polishing method, Patent Document 1 discloses a technique for preparing a fragile sample thin section. Specifically, the embedded sample obtained by embedding and solidifying a fragile sample in resin is cut into a rectangular parallelepiped shape, and then rocks or minerals are pasted on at least four sides perpendicular to the polished surface and polished. , it is stated that a high degree of smoothness can be obtained even on the surface of a thin piece.

Japanese Patent Application Publication No. 2014-126546

The technique of Patent Document 1 mentioned above is a method that enables polishing of an embedded sample while maintaining the flatness of the observation surface and determining the thickness of the embedded sample. There is no particular limit to the amount of polishing, and it was excessive for producing an observation sample for MLA which does not require mirror polishing. Further, even when using the embedded sample of Patent Document 1, in the case of manual dry polishing, the quality of the observation sample often depended on the skill level of the operator.

Therefore, there has been a need for a method for relatively easily preparing observation samples for mineral analysis such as MLA without being affected by the skill level of the operator. The present invention was made in view of the above situation, and it is possible to relatively easily process ore samples such as MLA, regardless of the skill level of the worker, even if the ore sample is water-resistant or brittle. The purpose of this invention is to provide a polishing method that can produce observation samples for analysis.

In order to achieve the above object, the polishing method for preparing an observation sample for mineral analysis according to the present invention is a method of manually dry polishing an ore sample embedded in a resin, in which the abrasive grains are embedded. After polishing the ore sample using abrasive paper coated with wax on the surface side to the extent that no wax is applied, the ore sample is finally polished using abrasive paper with a finer abrasive grain size that is not coated with wax. It is characterized by

In addition, the abrasive paper of the present invention is a waterproof abrasive paper used for polishing ore samples embedded in resin, and wax is directly applied to the surface of the base to an extent that the abrasive grains are not buried. It is a feature.

According to the present invention, it is possible to perform dry polishing relatively easily, regardless of the skill level of the worker, even if the ore sample is water-resistant or an embedded sample containing a brittle ore sample. Become.

1 is a perspective view of an embedded sample targeted by a polishing method according to an embodiment of the present invention. 1 is a schematic partially enlarged vertical cross-sectional view of the abrasive paper coated with wax and the abrasive paper before the wax is applied according to an embodiment of the present invention; FIG. These are microscopic photographs before and after wax application. 1 is a photograph showing a procedure for applying wax to abrasive paper in order to prepare an abrasive paper according to a specific example of the present invention. It is a micrograph of the observation surface of the observation sample produced in Example 1 of the present invention, and the part surrounded by a white circle is the part that fell off. This is a micrograph of the observation surface of an observation sample prepared in a comparative example of the present invention, and the part surrounded by a white circle is the part that fell off.

Hereinafter, a polishing method according to an embodiment of the present invention for preparing an observation sample for mineral analysis will be described in detail. The polishing method according to this embodiment of the present invention targets an embedded sample obtained by embedding an ore sample in a resin and solidifying it. This embedded sample has a cylindrical shape, for example, as shown in FIG. It is composed of a disk-shaped solidified pellet part 3 and a covering part 4 preferably made of a phenolic resin containing a filler and covering the solidified pellet part 3 except for its observation surface. The size of the cylindrical embedded sample is not particularly limited, but generally the outer diameter is about 25 to 30 mm and the height is about 10 to 20 mm. Further, the above-mentioned embedding sample can be produced, for example, using a Citopress, which is a hot consolidation machine manufactured by Struers.

In the polishing method of the embodiment of the present invention, the embedded sample is manually polished using a dry method that does not use water. Specifically, abrasive paper is placed on the surface of a flat substrate such as a glass plate, the covered part of the embedded sample is grasped, and the surface to be observed where the ore is exposed is faced down, and the sample is placed on the abrasive paper. Let them come into contact with you. In this state, the observation surface is polished by sliding the embedded sample in one direction or rotating it in a circular motion. As mentioned above, the reason why the abrasive paper is placed on top of the glass plate is that the glass plate is almost flat over its entire surface without any local inclinations or irregularities. It is also possible to form an extremely smooth polished surface. On the other hand, if the base on which the abrasive paper is placed is not flat, not only will it not be possible to obtain a smooth polished surface, but there is also a risk that the solidified sample will fall off.

It is preferable to use water-resistant abrasive paper as the above abrasive paper, especially abrasive paper selected from abrasive papers with count numbers #1000, #1200, #1500, #2000, #2500, and #4000 specified in JISR6253. It is preferable to use From among these abrasive papers, rough polishing was performed using #1200, and first, second, and third polishing were performed using #1200, #2000, and #2500 coated with wax, respectively. , #4000 is used for final polishing as an example.

1. Rough polishing process The purpose of the rough polishing process is to remove the minerals that are almost completely buried in the resin before this rough polishing so that as much ore as possible is exposed on the observation surface of the embedded sample. ing. In this way, in rough polishing, it is important to expose as much ore as possible on the viewing surface, so it does not matter if some ore falls off. Therefore, we use #1200 (particle size 15 μm) abrasive paper, which has an abrasive grain size larger than that of the abrasive paper used in the first polishing in the post-process, as it is, and transfer the embedded sample to the first polishing in the post-process. Polish by pressing it against the abrasive paper a little more forcefully than in the second and third polishing steps. Note that if it is acceptable to take time to prepare the observation sample, this rough polishing step may be omitted and the process may be started from the first polishing in the subsequent step.

2. Process of applying wax to the surface of the abrasive paper In the application process, #1200 (particle size of about 15 μm), #2000 (particle size of about 12 μm), and #2500 (particle size of about 12 μm), which are used in the first to third polishing steps in the subsequent process, are used. Apply wax to the surface of abrasive paper with a diameter of approximately 8 μm. At this time, the wax is applied so as to be rubbed against the surface of the abrasive paper, and the wax is applied thinly so that the wax does not completely cover the abrasive grains, that is, so that the abrasive grains are not buried in the wax until they are no longer visible. Specifically, as shown in FIG. 2, it is preferable to apply the wax 12 so as to fill approximately 1/3 to 1/2 of the height of the abrasive grains 11 protruding from the base 10 of the abrasive paper.

As shown in Figure 3 before wax application (on the left of the page) and after application (on the right of the page), the abrasive grains are only visible in an area that is about 1/3 to 1/2 of the total surface area of the abrasive paper. You can also rub the wax in a thick layer. The reason why it is not necessary to apply wax to the entire surface of the abrasive paper is that if you start polishing by rubbing the embedded sample against the abrasive paper that has been partially coated with wax, the wax will easily deform. This is because the gap between the abrasive grains is pushed out, and as a result, almost all of the abrasive grains protrude from the wax layer, as shown in the right diagram of FIG.

Whether or not the amount of wax applied to the abrasive paper is appropriate can be easily determined by actually sliding an embedded sample on the abrasive paper after applying the wax. That is, if the ore continues to fall off from the embedded sample, the amount of coating is small, and if the embedded sample is not polished at all, the amount of coating is excessive. Depending on the size of the abrasive grains of the abrasive paper and the type of wax, the force with which the wax is pressed when applied to the abrasive paper may be adjusted. Note that FIG. 4 shows an example of a procedure for applying wax to abrasive paper, in which a general candle made of paraffin wax is cut into a size that is easy to hold.

3. Polishing process using abrasive paper coated with wax (1) First polishing Place the #1200 abrasive paper coated with wax in the above coating process on the substrate such as the glass plate, preferably with one hand. While holding down the abrasive paper so that it does not move, hold the embedded sample with your other hand and place it against the abrasive paper with the observation side facing down. Polishing is performed by reciprocating a stroke distance of about 15 cm in the direction or rotating in a circle with a diameter of about 15 cm.

During this polishing, it is preferable to use a weaker force to press the embedded sample against the polishing paper than during the rough polishing in the previous step. The abrasive paper used in this first polishing is coated with wax to intentionally fill in the gaps between the abrasive grains and clog them, thereby reducing the height difference between the unevenness on the surface of the abrasive paper. It's lower than it should be. This makes it possible to polish most of the fragile minerals without them falling off. In addition, holes caused by falling off during rough polishing in the previous step can be efficiently erased.

(2) Second polishing In the second polishing, the embedded sample is polished in the same manner as the first polishing described above, except that #2000 abrasive paper coated with wax in the coating process described above is used. The abrasive paper used in this second polishing has finer abrasive grains than the abrasive paper used in the rough polishing and the first polishing, so the polishing scratches that occur on the observation surface of the embedded sample are caused by these coarse polishings. It becomes thinner than in the case of the first polishing, and therefore looks better when viewed under a microscope.

(3) Third polishing In the third polishing, the embedded sample is polished in the same manner as the first polishing and second polishing described above, except that #2500 abrasive paper that has been coated with wax in the coating process described above is used. Do this. The size of the abrasive grains of the abrasive paper used in this third polishing is finer than that of the abrasive paper used in the second polishing, so the polishing scratches that occur on the observation surface of the embedded sample are thinner than in the second polishing. Therefore, the appearance when viewed under a microscope becomes even more beautiful.

In addition, in the polishing process using abrasive paper coated with wax, an example will be described in which polishing was performed in three stages using three types of abrasive paper with abrasive grain sizes of #1200, #2000, and #2500. However, it is not limited to this, as long as abrasive paper with an abrasive grain size coarser than that of the abrasive paper used in the final polishing process in the subsequent process is used, and one or two types of abrasive paper may be used. Polishing may be performed using abrasive paper, or polishing may be performed using four or more types of abrasive paper. When using multiple types of abrasive papers, it is preferable to use them in descending order of number.

3. Final polishing process The final polishing process is performed by using #4000 (particle size approximately 5 μm) abrasive paper, which is smaller than the abrasive grain size of the abrasive paper used in the third polishing, without applying wax. Let's do it. At this time, it is preferable that the force with which the embedded sample is pressed against the abrasive paper be slightly stronger than in the first to third polishing steps in the previous steps. Further, it is preferable to make the stroke distance short (about 5 cm) when making a reciprocating motion, and to make the diameter small (about 5 cm) when making a circular rotational motion.

As a result, polishing scratches generated on the observation surface can be made extremely fine, and the boundary line 5 between the solidified pellet 3 shown in FIG. 1 and the covering portion 4 surrounding it can be clearly seen. By making the polishing scratches that occur on the observation surface finer in this way, not only does the appearance become clearer, but it also prevents the charge-up phenomenon caused by the electron beam hitting the polishing scratches when analyzing with MLA. , an observation sample suitable for MLA can be prepared.

In addition, in dry polishing, buffing is not performed in which polishing is performed while supplying water, so as mentioned above, abrasive paper with an abrasive paper count of about 4000 and an abrasive grain size of about 5 μm is used as the final abrasive paper for final polishing. become. For this reason, it is difficult to finish to a mirror polish, but if it is an observation sample to be analyzed by MLA, practical analysis accuracy can be ensured by polishing with #4000 abrasive paper.

As mentioned above, rough polishing, first to third polishing, and final polishing are all manual dry polishing processes, so it is necessary for the operator to polish each embedded sample one by one. Compared to polishing using a wet-type automatic polishing machine that can be set on the arm and polished all at once, the time required to prepare each observation sample is longer. Furthermore, in the case of brittle ores, it is necessary to adjust the force applied to the observation surface or to increase or decrease the speed at which the embedded sample is rubbed and moved to prevent the mineral from falling off.

Therefore, if the first to third polishing and final polishing are all done using conventional abrasive paper that is not coated with wax, even experienced workers will have to spend a lot of time to prepare the observation sample from the embedded sample. It took about 90 minutes. On the other hand, as mentioned above, by performing rough polishing and then polishing using abrasive paper coated with wax in the first to third polishing, observation samples with less variation can be obtained from embedded samples by approximately It can be manufactured in about 60 minutes.

The reason why we are able to create observation samples with little variation as described above is that by applying wax to the surface of the abrasive paper, the base side of the abrasive grains can be buried in the wax layer. The height of the unevenness can be made lower than that without wax coating, so even if the embedded sample is strongly pressed against the abrasive paper and rubbed, it is less likely to be scraped excessively, thus preventing minerals from falling off easily. This is because it can be done. On the other hand, the reason why the polishing time can be reduced by about 30 minutes per piece is because the gaps between the abrasive grains, which correspond to the joints, are filled with a layer of wax, which reduces frictional resistance and improves sliding. This is because the workability of polishing is improved, and rough polishing is performed using an abrasive paper with the coarsest abrasive grains that is not coated with wax.

Furthermore, since the wax applied to the abrasive paper is hydrophobic and repels moisture in the environment, it is possible to suppress any adverse effects on ore samples containing minerals that are sensitive to water. In addition, by using waterproof abrasive paper, the base that supports the abrasive grains is water resistant, so even if the wax melts due to frictional heat during polishing, it will not penetrate into the base. Therefore, the height difference between the unevenness of the abrasive grains does not become significantly large, so that polishing can be maintained to a certain extent with reduced grinding force.

As explained above, the polishing method for preparing observation samples for mineral analysis according to the present invention is dependent on the skill level of the polishing worker, even for ore samples that are sensitive to water or brittle. Observation samples for mineral analysis, such as MLA, can be produced relatively easily.

[Example 1]
Struers' hot-setting resin "Multifast" is charged into the embedding device, Struers' hot-setting machine "SitoPress", and minerals that are easily soluble in water such as iron hydroxide are added. A cylindrical embedded sample as shown in FIG. 1 was prepared by charging an ore sample whose main component was brittle ore. For this embedded sample, a skilled worker manually performed rough polishing, first to third polishing, and final polishing in this order to prepare an observation sample.

For these polishings, multiple types of water-resistant abrasive paper "SiC-Paper" manufactured by Struers were used. Specifically, JIS standard #1200 was used for rough polishing, and JIS standard #1200, #2000, and #2500 were coated with wax for the first, second, and third polishing, respectively. JIS #4000 was used for final polishing.

The wax applied to the abrasive paper used in the first, second, and third polishing was prepared by cutting a candle (approximately 40 mm in diameter) manufactured by Koyosha Candle Industries into a cylinder shape with a height of approximately 20 mm ( (solid form) was used. In this way, an observation sample as shown in FIG. 5 could be obtained. In addition, the working time required for polishing the embedded samples to prepare this observation sample was about 60 minutes per piece. When the obtained observation sample was analyzed using MLA650FEG, which is an MLA device manufactured by FEI, analysis results could be obtained without any particular problem.

(Example 2)
An observation sample for MLA was prepared in the same manner as in Example 1 above, except that a general worker who was not a skilled worker performed manual dry polishing after receiving guidance from a skilled worker. . As a result, it was possible to produce an observation sample that would not cause any particular problems even when analyzed using an MLA apparatus comparable to that used in Example 1. The working time required for polishing the embedded samples to prepare the observation samples of Example 2 was about 60 minutes per piece.

(Comparative example)
Observation samples for MLA were prepared by skilled workers in the same manner as in Example 1 above, except that no wax was applied to the abrasive paper used in the first to third polishing. As a result, it was possible to produce only observation samples with extremely large amounts of shedding, from which highly reliable information could not be expected to be obtained when used for MLA analysis, as shown in FIG. The working time required for polishing the embedded samples to prepare the observation samples of this comparative example was about 60 minutes per piece.

1 Ore 2 Resin 3 Solidified pellet portion 4 Covering portion 5 Boundary line 10 Base portion 11 Abrasive grains 12 Wax

Claims (6)

This is a manual dry polishing method for ore samples embedded in resin, in which the ore sample is polished using abrasive paper coated with wax on the surface to an extent that the abrasive grains are not buried, and then the wax is removed. A method for polishing an observation sample for mineral analysis, characterized by final polishing the ore sample using an uncoated abrasive paper with finer abrasive grain size. Before polishing using the abrasive paper coated with the wax, use an abrasive paper to which wax is not coated and which has an abrasive grain size larger than the abrasive grain size of the abrasive paper coated with the wax. 2. The method of polishing an observation sample for mineral analysis according to claim 1, comprising rough polishing. 3. The method for polishing an observation sample for mineral analysis according to claim 1, wherein the abrasive paper is a waterproof abrasive paper. The wax-coated abrasive paper is characterized by using at least one type of abrasive paper selected from among abrasive papers having count numbers #1000, #1200, #1500, #2000, and #2500 specified in JISR6253. The method of polishing an observation sample for mineral analysis according to claim 3. 5. The method of polishing an observation sample for mineral analysis according to claim 4, wherein when using a plurality of types of abrasive paper coated with the wax, the abrasive papers are used in order from the one with the smallest number. A water-resistant abrasive paper used for polishing ore samples embedded in resin, characterized in that wax is directly applied to the surface of the base to an extent that abrasive grains are not embedded.

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