JP2507569B2 - Method for producing high-purity abrasive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a high-purity abrasive, and in particular, using natural buoy sand or pumice stone as a raw ore, a high hardness crystalline mineral is converted into a heavy mineral by table beneficiation. A method for producing a high-abrasive material which is an abrasive material in which the purity of natural glassy particles has been increased, and which is suitable for a cathode ray tube abrasive material, particularly as a precision abrasive material for a high-definition television or display cathode ray tube. It is about.

(Background Art) Naturally produced floating stones and pumice stones are distributed all over the country,
It is called with various names in each land, but it is called Silas, especially in the southern Kyushu region, and exists in large numbers. Further, the particle size distribution of the floating sand or pumice differs greatly depending on the place of production, and for example, those containing almost no coarse particles of 1000 μm or more to those containing 50% or more of coarse particles of 1000 μm or more are produced. For example, even among the shirasu widely distributed in southern Kyushu, there are coarse-grained ones and fine-grained ones due to the difference between the fallen pumice layer called the primary shirasu and the secondary sedimented pumice layer called the secondary shirasu. , It is known that the primary shirasu from Kanoya in Kagoshima Prefecture contains more than 40% of coarse grains of 10 mm or more.

By the way, such floating stones and pumice stones have long been sized and sieved by sieving and used as polishing sands.In addition to natural glassy volcanic glass, they are also used as crystalline minerals such as feldspar, quartz, and pyroxene. , Mica, zircon, magnetite, etc. Therefore, of these crystalline minerals, except for mica, they have a high hardness, so when polishing glass with abrasive sand, deep scratches are left on the polished surface, which becomes a fatal defect, and the cathode ray tube. It was not suitable for use as an abrasive.

Therefore, the applicant of the present application has clarified a high-grade abrasive material manufactured from pumice and the like and a manufacturing method thereof in Japanese Patent Publication No. 6395/1975 as a solution to such a problem. The previously proposed high-grade abrasive is made from pumice, etc., as a raw material, and is processed by a table beneficiation machine to separate and remove impurities with high hardness. It has a particle size of 100 μm or less, and today, it has come to be used in large quantities mainly as an abrasive material for television cathode ray tubes.

However, due to the high quality of television and the development of computer displays in recent years, the polished surface of the cathode ray tube is required to have higher precision, and therefore, the demand for the quality of the abrasive is higher. It is becoming.

(Problem to be Solved) Here, the present invention has been made in view of such circumstances, and it is advantageous to provide a high-purity abrasive that provides a polishing surface having much more smoothness than conventional abrasives. It is the one to be manufactured.

(Solution Means) The present invention provides (a)
A step of preparing a raw material which does not contain coarse particles of 10 mm or more using natural buoy sand or pumice as a raw ore; and (b) classifying the raw material to remove the clay content, and the content of particles of 5 μm or less is And (c) crushing and classifying the raw material from which the clay content has been removed, or sieving.
By a pulverizing / classifying operation, a step of adjusting the particle size so that the maximum particles are 800 μm or less and the content of particles of 45 μm or less is 20% by weight or less, and (d) applying the particle size adjusted raw material to a table beneficiation machine After beneficiation, the heavy minerals mixed in the raw material are separated and removed, and after the table beneficiation, the particle size is adjusted by further sieving or sieving / pulverizing, if necessary, and the pulverized product is again subjected to the table beneficiation. A process for producing a high-purity abrasive characterized by comprising a process for obtaining a natural glassy product in which the content of a heavy mineral having a specific gravity of 2.52 or more and 0.15 wt% or less is applied to an operation. It is a thing.

In short, according to the present invention as described above, floating sand or pumice stone is used as a raw ore, and a high hardness crystalline mineral which is a heavy mineral is removed from the raw ore to produce a precision abrasive particularly useful for cathode ray tubes. Regarding the method, the results of many experimental studies were carried out after various studies were made on the relationship between the content of crystalline minerals and the scratch generation on the polished surface of the cathode ray tube, the method of adjusting the raw ore for table beneficiation, the method of table beneficiation, etc. , It has been completed.

The specific gravity of natural glass is around 2.1, depending on the number of bubbles, but the specific gravity of crystalline minerals is 2.52 or more, so the content of crystalline minerals is 2.52 or more. The relationship between the precision of the polished surface and the content of heavy minerals can be measured by performing various experiments.As a result of various experiments, in order to precisely finish the polished surface of a cathode ray tube, the content of heavy minerals should be 0.15 wt. They found that it needed to be less than or equal to%. And, as a result of repeating various experiments in order to produce a refined product in which the content of heavy minerals is 0.15% by weight or less by subjecting floating sand or pumice to table beneficiation,
By combining various methods of adjusting the raw ore for table beneficiation, the method of table beneficiation, etc., it has become possible to advantageously manufacture the desired high-purity abrasive.

(Specific Configuration) By the way, in the case of producing a high-purity abrasive by using naturally occurring floating sand or pumice as a raw ore according to the present invention, it is necessary to first remove coarse particles. When an abrasive is produced by table dressing without removing these coarse particles, it is difficult to reduce the amount of heavy minerals having a specific gravity of 2.52 or more to 0.15% by weight or less. In order to know what grain size or more of coarse grains needs to be removed, the present inventors use only the coarse grain parts of various ores to perform table beneficiation by the method according to the present invention to remove heavy minerals. As a result of examining the content, it was found that at least 10 mm or more of coarse particles had to be removed, depending on the origin of the ore and the degree of weathering. 10 mm
Even if the above coarse particles are crushed to be subjected to table beneficiation, the removal of heavy minerals is insufficient.The reason is that the coarse-grained ore has a strong bond between volcanic glass and heavy minerals, It is considered that there are particles that are not sufficiently separated. In addition, this
Various machines can be used for the sieving operation for removing coarse particles of 10 mm or more, but a rotary sieve is simple and suitable.
In this way, the abrasive grain manufacturing raw material is prepared by removing coarse particles of 10 mm or more from the fluff sand or pumice ore, but if it is a raw ore that does not contain such coarse particles, it is ground as it is. It goes without saying that it can be used as a raw material.

In addition, the floating sand and pumice of the ore contain fine particles. In particular, the raw ore called secondary shirasu produced in southern Kyushu contains many fine particles of 5 μm or less,
When the fine particles were examined by X-ray diffraction, it was found that clay minerals such as halloysite and montmorillonite were contained. For this reason, the abrasive material raw material not containing coarse particles of 10 mm or more prepared above, prior to the table beneficiation,
It is necessary to remove fines containing those clay minerals. If the table is subjected to beneficiation without removing this fine powder, the beneficiation will be insufficient. The reason for this is presumed to be that the viscosity of the slurry becomes high due to the inclusion of clay and that the clay adheres to the table surface and the friction coefficient decreases. The clay content can be removed by fine powder cutting by classification, but it is necessary to classify so that the content of particles of 5 μm or less is 3% by weight or less. Even if the abrasive is manufactured according to the method of the present invention while the content of the fine particles containing the clay mineral of 5 μm or less exceeds 3% by weight, the specific gravity is
It is difficult to reduce the content of heavy minerals of 2.52 or more to 0.15% by weight or less. Further, as a method for such classification, there is a method in which water is added to the raw material from which coarse particles have been removed, the mixture is sufficiently stirred, and then a known drum classification or cyclone is used.

Then, the raw material from which the clay content has been removed is pulverized / classified or sieved / pulverized / classified so that the maximum particles are 800 μm or less and the content of particles of 45 μm or less is 20% by weight or less. The particle size is adjusted. More specifically, the raw material after the clay removal is crushed by using a crusher such as a vibration mill so as not to be over-crushed, passed through a sieve of 250 to 800 μm, and the top of the sieve is returned to the crusher. When using this vibration mill, the lining of the mill is rubber lining,
A steel ball is suitable as the grinding medium, and the grinding time is preferably 5 minutes or less. When the raw material is fine and has many particles of 250 to 800 μm or less, it is preferable that the material is first sieved and crushed only on the sieve. If the raw material whose particle size is adjusted contains fine particles of 45 μm or less in a proportion of more than 20% by weight, the fine particles of 45
The content of particles less than μm needs to be 20% by weight or less. If the content of particles less than 45 μm exceeds 20% by weight, the accuracy of table beneficiation decreases and the specific gravity is 2.52 or more. It is difficult to keep the content of 0.15% by weight or less. Various methods can be adopted for the classification operation, but a cyclone or the like is generally simple and effective.

By the way, as the particle size of the high-purity abrasive in the present invention, various kinds of particles having a maximum particle size of about 400 μm to about 150 μm are required according to the purpose of use, but a product of about 250 μm or less is required. If you want to manufacture 45
In order to reduce the generation amount of particles of μm or less, it is desirable to adjust the coarser particles than the target particle size of the product and perform table beneficiation. In addition, 800μ in the raw material for this table
Even when large particles exceeding m are contained, the purification purity is lowered. It is thought that this is because there are many particles of 800 μm or more that are not sufficiently separated from volcanic glass and heavy minerals, and the size distribution range of the raw material is large, resulting in insufficient separation in table processing. To be Therefore,
The maximum particle size is the particle size of the raw material for table beneficiation.
It is necessary that the content of particles of 800 μm or less and 45 μm or less is 20% by weight or less.

Then, the raw material whose particle size has been adjusted is subjected to table beneficiation using an ordinary table beneficiation machine, and the heavy minerals mixed in the raw material, in other words, high hardness crystalline minerals are separated and removed, so that the specific gravity is 2.52. The content of the above heavy minerals is 0.15
Natural glass-based abrasive products with a weight percentage of less than are collected. The conditions for this table beneficiation are:
The slurry concentration of the raw material supplied to the table beneficiation machine is 4 to
It is desirable to set it as low as about 10%, and it is desirable that the amount of ore supply be 10 kg / hour or less per 1 m ² of the table surface.

In addition, if the grain size is adjusted to a coarser grain than the target grain size of the product and the table is subjected to beneficiation, it is necessary to adjust the grain size by sieving and crushing after the beneficiation. Therefore, in such a case, it is necessary to perform beneficiation by table beneficiation again. The amount of heavy minerals newly separated by beneficiation depends on the type of raw ore, but it can be refined to 0.15 wt% or less by re-beneficiation.

And after being refined by such table beneficiation,
The product is dehydrated and, if necessary, dried to obtain the target natural glass product, but prior to such dehydration, the so-called magnetic separation is performed to remove iron powder and the like mixed by the magnet. It is desirable to perform processing.

The following heavy-liquid separation method is used to measure the content of heavy minerals in the abrasive material product. That is, ethyl alcohol was added to tetrabromoethane, 200 cc of heavy liquid adjusted to have a specific gravity of 2.52 was placed in a separatory funnel, 100 g of sample was added, the stopper was added, and the mixture was inverted upside down and shaken 30 times. After that, put the funnel on the table and let it stand for 5 to 16 hours,
Place a filter paper 5C on the V funnel, remove the heavy minerals from the funnel on the separatory funnel, dry, transfer to a medicine packing paper, and weigh accurately. In the present invention, the content of heavy minerals by this measuring method is set to 0.15% by weight or less. On the other hand, when the content of the crystalline mineral was measured by the X-ray diffraction method instead of the heavy liquid separation method, no peak of the crystalline mineral was observed even when the content of the heavy mineral exceeded 0.15% by weight. It was not there.

By the way, when the content of the heavy mineral exceeds 0.15% by weight, scratches are generated on the polished surface when the polishing test is performed by the following method.

That is, in the polishing test, using a rotary lens polishing machine, a face portion of a 4-inch cathode ray tube was set on a rubber plate in which a groove having a width of 2 mm and a depth of 2 mm was dug at intervals of 2 mm,
Then, apply a load of 5.4 kg with a weight and rotate the rubber plate at 300 rpm.
While rotating at rpm, the face part of the cathode ray tube is reciprocated at a speed of 120 times per minute, while supplying a slurry in which an abrasive is suspended at a concentration of 10% and polishing for 10 minutes to observe the finish of the processed surface. By doing.

(Examples) Hereinafter, some examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is not limited by the description of the examples. It goes without saying that it is not interpreted.

Further, in addition to the above specific description and the following examples, the present invention can be carried out in various modes without departing from the spirit of the present invention, and the present invention is as such. It should be understood that it also includes various embodiments.

Example 1 Shirasu produced in Kakuto, Ebino City, Miyazaki Prefecture was used as a raw ore, and the particle size distribution was as shown in the table below.

Further, the sample was sieved to collect a portion of 45 μm to 250 μm, and the heavy liquid residue amount (heavy mineral amount) was determined, and it was 0.735% by weight.

Then, add 100 l of water to 10 kg of such ore,
After uniformly mixing and stirring, the coarse particles were removed with a 1 mm sieve.
The coarse particles removed were 240 g. Then, fine grains were removed from the raw ore from which the coarse grains were removed by an elutriation method. The amount of fine particles removed was 840 g. The content of particles of 5 μm or less in the raw material after removing the fine particles is 1.2% by weight.
Met. Furthermore, as a result of examining the removed fine particles by an X-ray diffraction method, it was found that clay minerals such as halloysite and montmorillonite were contained.

Then, the raw material from which the fine particles had been removed was sieved at 400 μm, the bottom of the sieve was sampled, and a sample for table mineral processing was sampled. The raw material on the 400μm sieve was 430g, but this was pulverized with a rubber lining vibration mill and a steel ball for 2 minutes, the pulverized product was sieved with 400μm, and the bottom of the sieve was collected and used as a sample for table mineral processing. added. This sieving upper part pulverization-sieving operation was repeated three more times. The sample thus obtained was classified by a cyclone to remove the fine powder portion. The amount of the obtained sample was 7250 g, and the particle size distribution was as shown in the table below. The content of particles of 45 μm or less was 9.0% by weight.

After that, such a particle size-adjusted sample was beneficiated using a Wilfrey table tester (750 mm × 1500 mm). Table conditions are the maximum riffle height: 3 mm, width: 7
mm, interval: 35 mm, range: 10 mm, table angle: 5.0 degrees, frequency: 240 rpm, water removal amount: 6 l / min, slurry concentration: 5.2 wt%,
Feeding speed: 98 g / min. The concentrate obtained by this table processing was 5200 g.

Further, the concentrate thus obtained was sieved at 250 μm, and the bottom of the sieve was collected to obtain a purified particle size-adjusted product.
The upper part of the sieve was pulverized with a rubber-lined vibration mill and a steel ball for 2 minutes, sieved at 250 μm, and the lower portion of the sieve was collected. This crushing-sieving operation is repeated three more times, the collected under-sieve is mixed, and the table is subjected to beneficiation under the same conditions as described above, the concentrate is added to the refined particle size adjusted product, and the iron powder is magnetized with a magnet. After removing the product, the product was dehydrated and dried to obtain 4680 g of a product. The content of heavy minerals in the obtained product was 0.05% by weight.

A Braun tube polishing test was performed on the thus obtained product, and as a result, a Braun tube having a polished surface with extremely excellent smoothness without any scratch was obtained.

Example 2 Floating sand from Naegi, Nakatsugawa City, Gifu Prefecture was used as a raw ore. The particle size distribution is shown in the table below.

The raw ore was sieved, a portion of 45 μm to 250 μm was collected, and the content of heavy minerals was measured. As a result, it was 1.62% by weight.

First, 100 l of water was added to 10 kg of the raw ore, and the mixture was uniformly mixed and stirred, and then the coarse particles were removed with a 5 mm sieve. The removed coarse particles weighed 440 g. The fine particles were removed by the elutriation method. The amount of fine particles removed was 320 g. The content of particles of 5 μm or less in the raw ore after removing the fine particles was 0.7% by weight. As a result of examining the removed fine particles by an X-ray diffraction method, it was found that halloysite was contained as a clay mineral.

Then, the sample after removing the fine particles is crushed for 2 minutes with a rubber-lined vibration mill and a steel ball to obtain 400 μm.
Sieving was carried out with a sieve, and the bottom of the sieve was used as a sample for table mineral processing. The upper part of the sieve was crushed for 2 minutes with a rubber-lined vibration mill and a steel ball, and the lower part of the sieve of 400 μm was sampled and added to a sample for table mineral processing. Further, the operation of crushing and sieving the upper part of the sieve is performed in 2
Repeated times. The obtained sample was classified by a cyclone and the fine powder portion was removed. The obtained sample weighed 8310 g, and the particle size distribution was as shown in the table below, and the particles having a size of 45 μm or less was 10.5% by weight.

Then, the sample was subjected to table beneficiation using a Wilfrey table tester (750 mm × 1500 mm). Table conditions are maximum riff height: 3mm, width: 7mm, spacing: 35m
m, range: 10 mm, table angle: 4.5 degrees, frequency, 240 rpm,
The slurry concentration was 4.5% by weight, the ore feeding speed was 80 g / min, and the sprinkling amount was 6 l / min. And the concentrate obtained by this table beneficiation was 5060 g.

Then, the obtained concentrate was sieved at 250 μm, and the bottom of the sieve was collected to obtain a purified particle size-adjusted product. The upper part of the sieve is a rubber lining vibration mill and steel balls.
It was ground for 1 minute, sieved at 250 μm, and the bottom of the sieve was collected.
Then, this crushing-sieving operation is repeated three more times,
The collected sieves were mixed and subjected to table beneficiation under the same conditions as described above. The concentrate was added to the refined particle size control product, dehydrated and dried to obtain 4550 g of a product. The content of heavy minerals in the obtained product was 0.09% by weight.

A Braun tube polishing test was carried out using the product thus obtained, and it was possible to obtain a Braun tube having no scratches and excellent in smoothness.

Example 3 Using the raw ore used in Example 1, a refined product obtained by the same step as in Example 1 was sieved to 250 μm and the sieve was subjected to 2 with a rubber-lined vibration mill and a steel ball.
After pulverizing for 1 minute, the pulverized product was sieved at 250 μm, and the bottom of the sieve was collected. This crushing-sieving operation was repeated three more times, and the samples obtained were mixed and the heavy minerals were measured. As a result, the content was 0.59% by weight. Then, the obtained sample was subjected to table beneficiation under the same beneficiation conditions as in Example 1, and as a result, the heavy mineral content of the concentrate was 0.06% by weight.

Comparative Example 1 Using the raw ore used in Example 2, an abrasive was manufactured by the same method except that the step of removing coarse particles of 5 mm or more was removed. The content of heavy minerals in the obtained product is 0.
It was 19% by weight, and as a result of a cathode ray tube polishing test using this product, scratches were recognized, although it was very slight.

Comparative Example 2 The raw ore used in Example 1 was uniformly dispersed and mixed in water in the same manner as in Example 1, and the coarse particles were removed with a 1 mm sieve, and the clay content was not removed. As a result of measuring the particle size, the content of particles of -5 μm was 4.5% by weight.
Then, using this sample, sieving and pulverization were performed in the same manner as in Example 1 to prepare a sample for beneficiation, and an abrasive was manufactured by the same method as in Example 1 below. The content of heavy minerals in the obtained product was 0.22% by weight, and as a result of a cathode ray tube polishing test using this product, very slight scratches were recognized.

Comparative Example 3 Using the raw ore used in Example 1, uniform mixing and stirring with water, removal of coarse particles and removal of fine particles were carried out in exactly the same manner as in Example 1, and then a 400 μm sieve was used instead. A 250 .mu.m sieve was used, the vibration time of the vibration mill was set to 10 minutes, and the fine powder was not removed by cyclone classification. The obtained sample for table mineral processing was 6950 g, and the particle size distribution was as shown in the table below, and the particles having a particle size of 45 μm or less was 25.3% by weight.

Next, using the obtained sample for table beneficiation, table beneficiation was performed in the same manner as in Example 1, and the obtained concentrate was dehydrated and dried to obtain an abrasive. The content of heavy minerals in the obtained product was 0.17% by weight, and as a result of a cathode ray tube polishing test using this product, it was very small,
Scratch was observed.

(Effects of the Invention) As is apparent from the above description, according to the present invention, floating sand or pumice stone is used as a raw ore, and heavy minerals, which are high hardness crystalline minerals, are effectively removed by table beneficiation, The glassy high-purity abrasive of the present invention is advantageously obtained, and by using such a high-purity abrasive, it has become possible to obtain an extremely smooth polished surface. The present invention has a great industrial significance in that it can be advantageously used as an abrasive for use as a precision abrasive for cathode ray tubes of televisions and displays.

Claims (1)

(57) [Claims] 1. A natural ore-bearing sand or pumice stone as a raw ore,
A step of preparing a raw material containing no coarse particles of 10 mm or more; a step of classifying the raw material to remove a clay content so that the content of particles of 5 μm or less becomes 3% by weight or less; The maximum particle is 800 μm by crushing and classifying or sieving, crushing and classifying the removed raw material.
The step of adjusting the particle size so that the content of particles having a particle size of 45 μm or less is 20% by weight or less, and the raw material having the adjusted particle size is subjected to beneficiation by a table beneficiation machine to remove heavy minerals mixed in the raw material. After separation and removal of the table, and if necessary, further sieving or sieving / grinding to adjust the particle size, and the crushed material is subjected to the table beneficiation operation again, and the specific gravity is 2.52 or more. And a step of obtaining a natural glassy product containing 0.15% by weight or less of the above.