JP2004306210A - Processing method and processing equipment for reusing cerium oxide-based polishing agent and water, in drainage in glass polishing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for reusing a cerium oxide-based polishing agent and water from a discharged water discharged at the time of water polishing and rinsing in glass polishing, that is, re-circulating water itself to reduce the polishing cost and also regenerating not only the discharged water but also slurry itself to be circulated for use. <P>SOLUTION: The discharged water discharged from a polishing device 1 is passed through a discharged water tank 4 and water is separated from that by a centrifugal separator 5 to obtain enriched cerium oxide solution. The enriched cerium oxide solution is subjected to dispersion processing by a dispersant in a dispersion tank 6, coarse particles are removed from the obtained solution in a centrifugal separator 7, and the components thereof are adjusted in a preparation tank 8 and fed to a slurry tank 2. The water from the centrifugal separator 5 is used as utility water for water polishing and rinsing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a processing method and a processing apparatus for reusing a cerium oxide-based abrasive and water used when polishing glass.
[0002]
[Prior art]
The spread of computers, flat panel display devices, mobile phones, and the like is remarkable. Many glass components are used as components of these devices. In many cases, very high surface roughness is required on the surface of the glass component. In order to obtain this surface roughness, mirror polishing is performed using an abrasive mainly composed of cerium oxide (cerium oxide-based abrasive).
[0003]
The cerium oxide-based abrasive is usually used repeatedly. However, deterioration occurs during repeated use, and a desired polishing rate cannot be maintained. At present, most of such deteriorated cerium oxide-based abrasives are treated as industrial waste. Since such a situation is not preferable from the viewpoints of resource depletion, environmental conservation, reduction of polishing cost, etc., it has been desired to recycle these abrasives.
[0004]
Cerium oxide has very low hardness compared to abrasive grains used for polishing metals and the like (for example, alumina abrasive grains), and has much lower hardness than glass to be polished. . Nevertheless, it is believed that the reason why the glass can be polished is that cerium oxide and silicon oxide, which is a component of the glass, undergo a chemical reaction, and the silicon oxide adheres to the cerium oxide and is carried away. Cerium oxide used for ordinary-level glass polishing is said to be formed into agglomerated particles (average particle size of about 1 to 2 μm) to some extent.
[0005]
FIG. 1 is an enlarged plan view (bottom) and an enlarged sectional view (top) schematically showing a state observed on a glass surface immediately after polishing using a cerium oxide-based abrasive. As shown in an exaggerated manner in this figure, a large number of concave portions a are present on the glass surface so as to overlap with each other, and the attached matter b is seen at the top of a contour (convex portion) surrounding the concave portion a. The recess a is a depression caused by the glass material adhering to the lump cerium oxide and being partially removed, and the deposit b is partially dropped on the lump cerium oxide side due to the adhesion. Is considered to be left behind on the glass surface side.
[0006]
It is thought that the reason why the polishing ability is reduced while using this abrasive is that the attached glass covers much of the surface of the cerium oxide lump and the area to which the glass material can adhere is reduced. Have been. Japanese Patent Application No. 2002-005567 filed by the present inventors discloses a technique for regenerating an abrasive by removing glass attached to a cerium oxide lump.
[0007]
When the polishing of the glass with the cerium oxide-based abrasive is completed, a so-called water polishing operation is performed to remove the cerium oxide attached to the glass surface. Water polishing is a polishing operation performed using only a polishing pad while supplying a large amount of water instead of a cerium oxide-based abrasive. By the water polishing, the deposit b attached to the top is removed. At the same time, the cerium oxide-based abrasive present over the entire polishing section is washed away. Thereafter, dirty water generated by water polishing is washed away from the glass surface using a large amount of water (rinse).
[0008]
The following is a list of known documents related to abrasive regeneration.
[0009]
[Patent Document 1]
JP-A-04-315576 (JP-B-07-041535)
[Patent Document 2]
Japanese Patent Application Laid-Open No. 06-254768 [Patent Document 3]
JP-A-07-186041 (Japanese Patent No. 2737108)
[Patent Document 4]
JP 08-173849 A [Patent Document 5]
JP 09-285967 A (Patent No. 2816133)
[Patent Document 6]
JP-A-11-090825 (Japanese Patent No. 3134189)
[Patent Document 7]
JP 2000-170793 A [Patent Document 8]
JP 2002-239906 A
[Problems to be solved by the invention]
As described above, in the glass polishing, not only a large amount of water is consumed and discharged in each of the water polishing and rinsing steps, but the discharged water is simply disposed of as industrial waste. In view of the above situation, the present invention recycles a cerium oxide-based abrasive and water, that is, recirculates water itself, and collects cerium oxide from discharged water discharged during water polishing and rinsing. Provide technology to reuse, reduce polishing cost and reduce environmental impact, and also provide technology to recycle not only waste water but also slurry used in circulation The task is to Note that glass polishing in this specification means polishing of a material containing silicon oxide as a main component such as so-called blue plate glass, white plate glass, quartz glass, and quartz, and may be crystalline or amorphous. I don't care.
[0011]
[Means for Solving the Problems]
The above problem is solved by the following means. That is, the first solution of the present invention is to concentrate the discharged water recovered during water polishing and rinsing in a glass polishing apparatus using a cerium oxide-based abrasive, and to separate the water and a cerium oxide concentrated solution. In the first step, the second step for adding a dispersant and water as needed to the cerium oxide concentrated solution separated in the first step to redisperse, and the second step, This is a treatment method for reusing the cerium oxide-based abrasive and water in the effluent in the glass polishing consisting of the third step for removing coarse particles from the concentrated cerium oxide concentrate.
[0012]
According to a second aspect of the present invention, in the processing method of the first aspect, the water separated in the first step is used as water for water polishing or rinsing in a glass polishing apparatus. This is a treatment method for reusing cerium oxide-based abrasives and water in wastewater in glass polishing.
[0013]
According to a third aspect of the present invention, in the processing method according to the first or second aspect, the dispersant is oxycarboxylic acid, polyacrylic acid, or a salt thereof. Is a treatment method for reusing the cerium oxide-based abrasive and water in the effluent in the above. The salt of oxycarboxylic acid or polyacrylic acid is not particularly limited, but a sodium salt and a potassium salt are preferred.
[0014]
According to a fourth aspect of the present invention, in the processing method according to any one of the first to third aspects, the glass component adhering to the polishing agent surface is provided between the second step and the third step. This is a treatment method for reusing a cerium oxide-based abrasive and water in discharged water in glass polishing, which is provided with a glass component removing step for removing water.
[0015]
According to a fifth aspect of the present invention, in the processing method according to any one of the first to fourth aspects, when the cerium oxide-based abrasive repeatedly used in the glass polishing apparatus is deteriorated, the deteriorated oxidation is performed. A method for reusing a cerium oxide-based abrasive and water in discharge water in glass polishing, wherein the cerium-based abrasive is subjected to a glass component removing treatment after the second step.
[0016]
According to a sixth aspect of the present invention, in the treatment method according to any one of the first to fifth aspects, the separation of the water and the cerium oxide concentrate in the first step is performed by a centrifugal separation method. This is a treatment method for reusing cerium oxide-based abrasives and water in discharged water during glass polishing.
[0017]
According to a seventh aspect of the present invention, in the processing method according to any one of the first to sixth aspects, the removal of coarse particles from the cerium oxide concentrated solution in the third step is performed by centrifugation. This is a treatment method for reusing cerium oxide-based abrasives and water in discharged water during glass polishing.
[0018]
An eighth aspect of the present invention provides a discharge water tank for storing discharge water from a polishing apparatus, a method for concentrating the discharge water stored in the discharge water tank, and water and cerium oxide for use in water polishing and rinsing. A concentrating device for separating into a concentrated solution, a cerium oxide concentrated solution concentrated in the concentrating device, a dispersion tank for dispersing with a dispersant, and a cerium oxide liquid dispersed in the dispersing tank And a separation device for removing coarse particles contained in the cerium oxide-based abrasive and wastewater in the glass polishing.
[0019]
A ninth aspect of the present invention is the processing apparatus according to the eighth aspect, wherein the dispersion tank stores slurry fed from a slurry tank provided in the polishing apparatus. Is a processing device for reusing the cerium oxide-based abrasive and water in the effluent in the above.
[0020]
A tenth aspect of the present invention is the processing apparatus according to the eighth or ninth aspect, further comprising a preparation tank, wherein the cerium oxide liquid from which the coarse particles have been separated by the separation device is once used. This is a processing apparatus for reusing a cerium oxide-based abrasive and water in discharge water in glass polishing, which is fed into the preparation tank and where component adjustment is performed.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2 is a schematic diagram of a processing apparatus for describing the method (first embodiment) of the present invention. FIG. 3 is a schematic diagram of a processing apparatus for explaining (second embodiment) of the present invention. FIG. 4 is a processing flow diagram summarizing the first embodiment and the second embodiment of the present invention. A fine dotted line indicates the second embodiment, and a large dotted line indicates optional items.
[0022]
First Embodiment Hereinafter, a first embodiment will be described based on FIG. 2 with reference to FIG. The processing apparatus 100 includes a drainage tank 4, a centrifugal separator 5, a dispersion tank 6, a centrifuge 7, and a preparation tank (optional) 8, and separates and treats discharged water from the polishing apparatus 1. Then, the regenerated slurry and water (service water) from which the cerium oxide-based abrasive has been removed are returned to the slurry tank 2 and the service tank 3 provided in the polishing apparatus, respectively.
[0023]
The polishing apparatus 1 has a polishing platen 11 to which a polishing cloth 12 made of a nonwoven fabric, a synthetic resin foam, synthetic leather, or the like is adhered, and the polishing platen 11 is rotatable. During the polishing operation, the polishing platen 11 is rotated while pressing the workpiece (glass) W against the polishing platen 11 with a predetermined pressing force. At the same time, a liquid (slurry) of a cerium oxide-based abrasive is supplied from the slurry nozzle 13. The cerium oxide-based abrasive is stored in the slurry tank 2 and repeatedly circulates between the polishing apparatus 1 and the slurry tank 2.
[0024]
Water (service water) to be used for water polishing or rinsing described above is stored in the water tank 3, and in the case of water polishing or rinsing, a large amount of water is supplied to the polishing platen 11 through the water nozzle 14 from here. Be poured. This water is not used during normal polishing (polishing while supplying slurry). The above is no different from the case of the conventional glass polishing.
[0025]
The discharge water tank 4 is a tank for storing water used after water polishing or rinsing, and is constantly stirred by stirring blades 41 to prevent sedimentation and coagulation. The discharged water from the discharge water tank 4 is periodically or continuously fed to an appropriate concentration device, in this case, a centrifugal separator 5, where it is separated into water and a cerium oxide concentrate (first step). , Concentration step). The separated water is returned to the water tank 3, while the concentrated cerium oxide liquid is fed to the dispersion tank 6. In the dispersion tank 6, a redispersion treatment is performed by adding a dispersant and water regularly or continuously (second step, dispersion step). In addition, in order to prevent sedimentation and aggregation in the dispersion tank 6, stirring is always performed by the stirring blade 61. As the dispersant, oxycarboxylic acid, polyacrylic acid or a salt thereof can be used. The salt of oxycarboxylic acid or polyacrylic acid is not particularly limited, but a sodium salt and a potassium salt are preferred.
[0026]
The redispersed cerium oxide liquid is fed to an appropriate separator, in this case, a centrifugal separator 7, to remove coarse particles that could not be dispersed even by the redispersion process in the second step (No. 3), and fed to the preparation tank 8. The coarse particles separated here are discarded (third step, separation step). Here, the coarse particles mean particles having a particle size of 7 μm, preferably larger than 5 μm.
[0027]
In the preparation tank 8, while stirring with the stirring blade 81, concentration adjustment of the cerium oxide liquid and pH adjustment with sodium hydroxide, sodium carbonate and the like are performed (preparation step). The liquid (slurry) whose polishing ability has been recovered by component adjustment is returned to the slurry tank 2 and is used again for polishing. Note that this component adjustment is an arbitrary matter, and it can be determined whether or not to perform the adjustment in consideration of economic efficiency and the like. Further, a filter may be provided at an arbitrary place in the apparatus as needed.
[0028]
Second Embodiment Hereinafter, a second embodiment will be described based on FIG. 3 with reference to FIG. This processing apparatus 100 is different from the processing apparatus of the first embodiment in that it has a path for feeding the slurry from the slurry tank 2 to the dispersion tank 6 and that the processing here is added to the reaction tank 9. I do. Since the same reference numerals are the same as those in the first embodiment, these descriptions are based on the first embodiment, and only different points will be described below.
[0029]
As described above, a glass component adheres to the surface of the cerium oxide-based abrasive during repeated glass polishing, and the polishing performance deteriorates. For this reason, the inventor has developed a technique for removing and attaching the glass component from the surface of the cerium oxide-based abrasive as described in Japanese Patent Application No. 2002-005567. According to the second embodiment, not only the cerium oxide-based abrasive and the water in the waste water in the glass polishing can be reused, but also the slurry and the abrasive in the waste water can be regenerated and reused. .
[0030]
A part of the slurry is fed from the slurry tank 2 to the dispersion tank 6 by switching the pipeline when the slurry is deteriorated, or not only when the slurry is deteriorated as described above. The fed slurry is mixed with a cerium oxide concentrate that has undergone the same process as in the first embodiment, or one of them is used alone in the second step, that is, in the dispersing tank 6, such as oxycarboxylic acid or polyacrylic acid. Is performed by adding a dispersant and water. Thereafter, the dispersion liquid is sent to the reaction tank 9. In the reaction tank 9, the glass component is removed, that is, an alkali component (or an aqueous solution thereof) such as sodium hydroxide, potassium hydroxide, or sodium carbonate is added so as to have a pH of 10.5 or more. By heating, the glass component attached to the surface of the cerium oxide-based abrasive is removed from the surface (reaction step).
[0031]
Thereafter, the cerium oxide-based abrasive liquid from which the glass component has been removed is supplied to the preparation tank 8, and the same processing as in the first embodiment is performed. The stirring blades 91 provided in the reaction tank 9 not only prevent precipitation and aggregation, but also promote the reaction by stirring. In the preparation tank 8, an alkali component is also added. This is a component adjustment for maximizing polishing performance, and is different from that for removing the glass component. In addition, this component adjustment can be arbitrarily performed as needed as in the first embodiment.
[0032]
As shown in the two embodiments, the effluent discharged from the polishing apparatus is separated into water and a cerium oxide concentrate, and the water is reused in each of the steps of water polishing and rinsing, and cerium oxide contains coarse particles. Is removed and used again for polishing, so that cerium oxide contained in the discharged water can be prevented from diffusing into the environment, and the polishing cost can be reduced. Further, according to the second embodiment, not only the discharged water but also the slurry used for circulation is regenerated, so that the polishing cost can be further reduced.
[0033]
【The invention's effect】
According to the present invention, the discharged water discharged from the polishing apparatus is separated into water and a cerium oxide concentrated solution, the water is reused in each step of water polishing and rinsing, and cerium oxide removes coarse particles. And is used for polishing again, so that there is an effect that the polishing cost can be reduced. Further, since not only the discharged water but also the slurry itself used for circulation is regenerated, there is an effect that the polishing cost can be further reduced.
[Brief description of the drawings]
FIG. 1 is an enlarged plan view (bottom) and an enlarged cross-sectional view (top) schematically showing a state observed on a glass surface immediately after polishing using a cerium oxide-based abrasive.
FIG. 2 is a schematic diagram of a processing apparatus for explaining the first embodiment.
FIG. 3 is a schematic diagram of a processing apparatus for explaining a second embodiment.
FIG. 4 is a processing flowchart summarizing the first embodiment and the second embodiment, wherein a fine dotted line indicates the second embodiment, and a large dotted line indicates an optional item.
[Explanation of symbols]
REFERENCE SIGNS LIST 100 Processing apparatus 1 Polishing apparatus 11 Polishing table 12 Polishing cloth 13 Slurry nozzle 14 Water nozzle 2 Slurry tank 3 Water tank 4 Discharge water tank 41 Stirrer blade 5 Centrifugal separator 6 Dispersion tank 61 Stirrer blade 7 Centrifuge 8 Preparation tank 81 Stirring Blade 9 Reaction tank 91 Stirring blade a Recess b Deposits

Claims (10)

A first step for concentrating the discharged water collected during water polishing and rinsing in a glass polishing apparatus using a cerium oxide-based abrasive, and separating the water and a cerium oxide concentrated solution;
A second step of adding a dispersant to the cerium oxide concentrated solution separated in the first step and redispersing the same, and
In the second step, a treatment method for reusing a cerium oxide-based abrasive and water in discharge water in glass polishing in the third step for removing coarse particles from the redispersed cerium oxide concentrate. A processing method for reusing a cerium oxide-based abrasive and water in discharge water in the glass polishing according to claim 1,
A process for reusing a cerium oxide-based abrasive and water in discharged water in glass polishing, wherein the water separated in the first step is used as water for water polishing or rinsing in a glass polishing apparatus. Method. A processing method for reusing a cerium oxide-based abrasive and water in discharge water in the glass polishing according to claim 1,
A method for reusing a cerium oxide-based abrasive and water in discharge water in glass polishing, wherein the dispersant is oxycarboxylic acid, polyacrylic acid, or a salt thereof. A processing method for reusing a cerium oxide-based abrasive and water in effluent water in glass polishing according to any one of claims 1 to 3,
A cerium oxide-based effluent in the glass polishing, wherein a glass component removing step for removing glass components attached to the abrasive surface is provided between the second step and the third step. A treatment method for reusing abrasives and water. A processing method for reusing a cerium oxide-based abrasive and water in effluent water in glass polishing according to any one of claims 1 to 4,
When the cerium oxide-based abrasive repeatedly used in the glass polishing apparatus is deteriorated, the deteriorated cerium oxide-based abrasive is subjected to a glass component removing treatment after the second step, and the discharged water in the glass polishing is characterized in that A treatment method for reusing cerium oxide-based abrasives and water. A processing method for reusing a cerium oxide-based abrasive and water in discharge water in glass polishing according to any one of claims 1 to 5,
A method for reusing a cerium oxide-based abrasive and water in discharged water in glass polishing, wherein the separation of water and a cerium oxide concentrate in the first step is performed by a centrifugal separation method. A processing method for reusing a cerium oxide-based abrasive and water in discharge water in glass polishing according to any one of claims 1 to 6,
A method for reusing a cerium oxide-based abrasive and water in discharged water in glass polishing, wherein the removal of coarse particles from the cerium oxide concentrate in the third step is performed by a centrifugal separation method. A drain tank for storing drain water from the polishing device,
A concentrating device for concentrating the discharged water stored in the discharge water tank and separating it into water and a cerium oxide concentrated solution for use in water polishing and rinsing,
The cerium oxide concentrated liquid concentrated in the concentration device is stored, and a dispersion tank for performing a dispersion treatment with a dispersant, and
The cerium oxide liquid dispersed in the dispersion tank is composed of a separating device for removing coarse particles contained in the cerium oxide liquid. For processing equipment. A processing apparatus for reusing cerium oxide-based abrasives and water in discharge water in the glass polishing according to claim 8,
A processing apparatus for reusing a cerium oxide-based abrasive and water in discharge water in glass polishing, wherein the dispersion tank also stores slurry fed from a slurry tank provided in a polishing apparatus. A processing apparatus for reusing a cerium oxide-based abrasive and water in discharge water in the glass polishing according to claim 8,
Further, a preparation tank is provided, and the cerium oxide liquid from which coarse particles have been separated by the separation device is once fed to the preparation tank, where components are adjusted, and discharge in glass polishing is performed. Processing equipment for reusing cerium oxide abrasive and water in water.

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