KR20090009266A - Method of recovering abrasive from abrasive slurry waste liquid and apparatus therefor - Google Patents

Abstract

Not only small-diameter foreign matter but also large-diameter foreign matter mixed in polishing is effectively removed from an abrasive slurry waste liquid to thereby attain recovery of abrasive. Recovery of abrasive from an abrasive slurry waste liquid is accomplished by the use of a recovery apparatus comprising a high pressure jet disperser machine capable of mutual collision of abrasive slurry waste liquids as high pressure jet streams in a dispersion vessel; an ultrasonic strainer capable of, while applying ultrasonic waves to the dispersion liquid obtained by dispersion by means of the high pressure jet disperser machine and/or a barrier filter, straining the dispersion liquid through the barrier filter; and a cyclone capable of classifying of the filtrate liquid obtained by straining by means of the ultrasonic strainer.

Description

Abrasive recovery method and apparatus from abrasive slurry waste liquid TECHNICAL FIELD

The present invention relates to a method and an apparatus for recovering an abrasive from an abrasive slurry waste liquid, and in particular, a recovery method for recovering cerium oxide from an abrasive slurry waste liquid when polishing a glass substrate using an abrasive slurry containing cerium oxide as an abrasive. Relates to a device.

Flat panel displays such as liquid crystal displays (LCDs), plasma displays (PDs), inorganic and organic electroluminescent displays, field emission displays (FEDs), and the like have glass substrates of various compositions as glass substrates. Is required. For this reason, mirror polishing using an abrasive slurry is performed on the glass substrate, and cerium oxide capable of mirror polishing is often used as an abrasive even though the hardness is lower than that of the glass substrate.

The abrasive slurry deteriorates and cannot be used during repeated use, and may also damage the glass substrate due to polishing debris or the like mixed by polishing. For this reason, the abrasive slurry used several times was normally discarded as industrial waste.

However, it is not preferable to dispose of the abrasive slurry waste liquid from the viewpoint of recycling of resources. Particularly, it is desirable to recycle the slurry slurry, since cerium oxide is relatively low in resources, which makes it difficult to provide stable supply in the future, and is very expensive compared to alumina abrasive. It is becoming.

As a technique regarding recovery and reuse of abrasives such as cerium oxide, there are patent documents 1 to 3, for example.

Patent Literature 1 separates water by treating the discharged water discharged from glass polishing with a centrifugal separator at the first stage, forms a cerium oxide concentrate, and treats the cerium oxide concentrate with a centrifugal separator at the second stage. To recover. Patent document 2 collect | recovers an abrasive from the waste liquid obtained by adding and heating hydrochloric acid and hydrogen peroxide to a used abrasive. Patent document 3 puts an abrasive slurry waste liquid into a filter, removes coarse impurities, and collect | recovers abrasive | polishing agent by filtering by the ultrafilter which has UF (ultrafiltration membrane) with a hole diameter of 2-100 nm.

Patent Document 1: Japanese Unexamined Patent Publication No. 2004-306210

Patent Document 2: Japanese Unexamined Patent Publication No. 2003-211356

Patent Document 3: Japanese Patent Application Laid-Open No. 10-118899

However, the abrasives in the abrasive slurry waste liquid are present as viscous aggregates by being mixed with silica and abrasive debris (such as curls and iron debris in the supply pipe) generated when the abrasive is agglomerated with each other. Therefore, as in Patent Literature 1, only the centrifugal separation treatment can separate the silica and the abrasive debris with good accuracy even if the water can be separated. There is a drawback that a large amount of the silica and the abrasive debris remain in the recovered abrasive. In addition, in the case of a chemical recovery method using hydrochloric acid and hydrogen peroxide, as in Patent Document 2, there is a high risk of contamination (remaining) of hydrochloric acid and hydrogen peroxide in the recovered abrasive, and washing with water must be repeated to recover the contamination. There is a drawback. In addition, as described in Patent Document 3, even if the filtration treatment is performed in multiple stages, as described above, the abrasive in the abrasive slurry waste liquid is present as a viscous aggregate, so that the filter is clogged for a short time and cannot be used as a real device. . For example, although the particle diameter of cerium oxide is about 0.5-5 micrometers, even if it filters by the filter whose pore diameter is 50 micrometers, it will be clogged in a short time. Therefore, a great deal of time and effort is required for maintenance to eliminate clogging of the filter.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to efficiently remove a small diameter foreign substance or a large diameter foreign substance mixed by polishing from an abrasive slurry waste liquid at a high removal rate to recover an abrasive, and to maintain the recovery apparatus. It is an object of the present invention to provide a method and apparatus for recovering abrasive from waste slurry slurry which is easy.

In order to achieve the above object, the present invention relates to recovering an abrasive from an abrasive slurry waste liquid in which an abrasive, a small diameter foreign matter smaller than the particle diameter of the abrasive, and a large diameter foreign material larger than the particle diameter of the abrasive are present as an aggregate. A recovery method comprising: a dispersion step of carrying out a mechanical dispersion treatment of the abrasive slurry waste liquid, a filtration step of removing the large diameter foreign matter from the dispersion by filtration treatment of the dispersed dispersion liquid, and the filtrate treated with the filtration. Provided is a method for recovering the abrasive from the abrasive slurry waste liquid, comprising a classification step of classifying the abrasive and the small-diameter foreign matter in the filtrate by a cyclone.

According to the present invention, in the dispersion step, mechanical dispersion treatment is performed to disperse the abrasives, small-diameter foreign matters, and large-diameter foreign matters constituting the aggregate in the abrasive slurry waste liquid. Here, "dispersing the abrasive, small-diameter foreign matter and large-diameter foreign matter constituting the aggregate" means dispersing the aggregate to disperse it into abrasives, small-diameter foreign matter and large-diameter foreign matter. This does not mean that it can be dispersed into abrasives, small-diameter foreign matters, and large-diameter foreign matters. By filtering this dispersion liquid with a filtration filter, a large diameter foreign material can be effectively removed from an abrasive slurry waste liquid, and clogging of a filtration filter can be prevented for a long time. Here, "removing a large diameter foreign material by filtration process" means the filtration process for the purpose of removing a large diameter foreign material, and does not mean that a large diameter foreign material can be removed completely. Finally, the filtrate is classified to classify the abrasive and the small diameter foreign matter. In this case, the abrasive can be effectively classified from the small-diameter foreign matter by passing through the dispersion step and the filtration step. Here, "classifying an abrasive | polishing agent and a small diameter foreign material by a classification process" means cyclone processing for the purpose of classifying an abrasive | polishing agent and a small diameter foreign material, and does not mean that a small diameter foreign material can be classified completely.

This removes these foreign substances and the like from the abrasive slurry waste liquid which is present as agglomerates in which the abrasive, the small-diameter foreign matter smaller than the particle diameter of the abrasive, and the large-diameter foreign matter larger than the particle diameter of the abrasive are present. In addition, since clogging of the filtration filter in the filtration treatment can be suppressed, the number of device maintenance is reduced and maintenance is facilitated. In addition, since no chemical treatment is used at all, there is no risk that chemical substances remain as contamination in the recovered abrasive.

In a preferred embodiment of the present invention, the abrasive is a cerium oxide having a particle diameter of 0.5 to 5 µm.

In the case where expensive cerium oxide is used as an abrasive, recovery and reuse are greatly contributing to cost reduction, and since cerium oxide is resource-low and future stable supply is unstable, the present invention is particularly effective.

In a preferred embodiment of the present invention, the dispersion step is a high pressure collision treatment in which the abrasive slurry waste liquid is two or more high pressure jets, and the high pressure jets collide with each other.

As a mechanical dispersion treatment method, there are various dispersion methods such as the bead mill method, but for dispersing agglomerates in which abrasives, small-diameter foreign matters, and large-diameter foreign matters are aggregated, the abrasive slurry waste liquid is used as two or more high-pressure jets, and the high-pressure jets High pressure collision treatments which collide with each other are particularly effective.

Moreover, in preferable embodiment of this invention, the said filtration process is characterized by performing the ultrasonic treatment which gives an ultrasonic wave to the said dispersion liquid and / or a filtration filter, when the said dispersion liquid is filtered with a filtration filter.

Filtration efficiency can be improved by filtering, giving an ultrasonic wave with respect to the dispersion liquid and / or a filtration filter filtered in this way. That is, by applying an ultrasonic wave to a dispersion liquid, it can prevent that the abrasive | polishing agent, the small diameter foreign material, and the large diameter foreign material which were disperse | distributed by the dispersion process again aggregate. In addition, by applying ultrasonic waves to the filtration filter, the filtration filter can be prevented from clogging. Therefore, it is particularly preferable to give ultrasonic waves to both the dispersion liquid and the filtration filter.

In a preferred embodiment of the present invention, the filtration step is characterized by performing a backwashing process for backwashing the filtration filter intermittently with backwash water.

By performing a backwashing process in which the filtration filter is backwashed with the backwash water intermittently in this way, the filtration filter is not clogged more easily.

Moreover, in order to achieve the said objective, this invention is a collection | recovery apparatus which collect | recovers an abrasive from an abrasive slurry waste liquid, Comprising: The high pressure jet which makes said abrasive slurry waste liquid two or more high pressure jets, and makes the said high pressure jets collide with each other in a dispersion container. Classifying and treating the particles in the filtrate filtered by the ultrasonic filter with an ultrasonic filter for filtering the dispersion by the filtration filter while applying ultrasonic waves to the disperser, the dispersion liquid dispersed by the high pressure jet disperser and / or the filtration filter. An abrasive recovery apparatus from an abrasive slurry waste liquid, comprising a cyclone.

According to the above abrasive recovery device, the abrasive slurry waste liquid is sequentially processed by a high pressure jet disperser, an ultrasonic filter, and a cyclone, so that these foreign substances and the like can be removed from the abrasive slurry waste liquid efficiently and at a high removal rate to recover the abrasive.

According to the present invention, by carrying out dispersion treatment, filtration treatment, and classification treatment of abrasive slurry waste liquids in which foreign substances and the like are mixed by polishing, foreign substances and the like can be efficiently and efficiently removed from the abrasive slurry waste liquid and the abrasives can be recovered.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an overall configuration diagram of an abrasive recovery device from an abrasive slurry waste liquid of the present invention.

It is explanatory drawing of the particle size distribution of the abrasive | polishing agent, the small diameter foreign material, and the large diameter foreign material contained in an abrasive slurry waste liquid.

3 is an explanatory diagram illustrating a high pressure jet disperser.

It is explanatory drawing explaining the effect by each process in a high pressure jet disperser, an ultrasonic filtration apparatus, and a cyclone.

It is explanatory drawing explaining the dispersion effect by a high pressure jet disperser.

It is explanatory drawing explaining the effect which combined the high pressure jet disperser and the ultrasonic filtration apparatus.

It is explanatory drawing explaining the effect which combined the high pressure jet disperser, the ultrasonic filtration apparatus, and a cyclone.

* Description of the symbols for the main parts of the drawings *

10... Apparatus for recovering abrasive from abrasive slurry waste liquid

12... . Glass substrate

16... Turn table 18... Nozzle

20... Polishing tool 22.. Polishing pad

24... Abrasive slurry waste liquid 26. Waste Fluid Hopper

28... Waste liquid piping 30.. High pressure jet spreader

32... Ultrasonic filtration device 34. Cyclone

36... Waste tank 38... Supply piping

40... Dispersion vessel 42... Jet nozzle

44... Discharge pipe 46... High pressure pump

48... Dispersion 50... Filtration tank

52... Three-way valve 54.. valve

56... Supply piping 58... Filtration pump

60... Filter vessel 62... Filtration filter

64... Ultrasonic oscillator 66... valve

68... Return tubing 70... Filtrate

72... Tank for cyclone 74... Filtrate Tubing

76... First valve 78.. Second valve

80... Backwash pump 82... Washing water tank

84... Supply piping 86... Cyclone Pumps

88... Cyclone top 90... Circulation piping

92... Abrasive slurry recovery tank 94. Small Diameter Foreign Material Recovery Tank

A… Abrasive B…. Small diameter foreign objects

C… Large diameter foreign matter D... Aggregate

EMBODIMENT OF THE INVENTION Hereinafter, preferable embodiment of the abrasive | polishing agent collection method and apparatus from the abrasive slurry waste liquid concerning this invention is described according to an accompanying drawing.

1 is an overall configuration diagram of an abrasive recovery device 10 from an abrasive slurry waste liquid according to the present invention, and an abrasive slurry when the glass substrate 14 is polished by a polishing machine 12 using cerium oxide as an abrasive. It is an example of recovering the abrasive (A) from the waste liquid 24.

As shown in FIG. 1, the grinder 12 mounts and fixes the glass substrate 14 to the rotation table 16, and rotates it. And the glass substrate 14 is polished by the polishing pad 22 by pressing the polishing tool 20 which rotates from the upper side of the rotating table 16, supplying an abrasive slurry from the nozzle 18. As shown in FIG. In addition, the structure of the grinding | polishing machine 12 is not specifically limited to the said structure, Various grinding machines can be used.

And the used abrasive slurry waste liquid 24 used for grinding | polishing is sent to the collection | recovery apparatus 10 by the waste liquid piping 28 via the waste liquid hopper 26. The abrasive slurry waste liquid 24 includes an abrasive (A), silica particles having a smaller particle size than the abrasive (A) generated by polishing (hereinafter referred to as "small diameter foreign substance (B)"), and an abrasive produced by polishing ( A) A larger grain size, iron rust and the like (hereinafter referred to as "large diameter foreign substance (C)") of an abrasive supply pipe are agglomerated and exist as a viscous aggregate (D).

As shown in FIG. 2, the particle size distribution of the abrasive (A), the small-diameter foreign matter (B), and the large-diameter foreign matter (C) is generally in the range of 0.5 to 5 µm and the small diameter of the abrasive (A; cerium oxide). The foreign matter (B) is generally smaller than 0.5 µm, and the large diameter foreign matter (C) is generally larger than 5 µm. Here, the particle diameter is the maximum particle diameter of each particle. If the abrasive slurry is reused with the silica particles as the small-diameter foreign matter (B) remaining, "precipitation" occurs and the polishing performance is lowered.

In addition, if the abrasive slurry is reused with the large-diameter foreign matter (C), such as a collet, iron rust and the like remaining, the glass substrate 14 is damaged during polishing.

As shown in FIG. 1, the recovery device 10 is mainly composed of a high pressure jet disperser 30, an ultrasonic filter 32, and a cyclone 34, and these devices 30, 32, and 34 are piped. And continuously connected via a tank. Hereinafter, the structure of the collection | recovery apparatus 10 and the collection method (flow of a process) until the abrasive (A) is collect | recovered from the abrasive slurry waste liquid 24 are demonstrated.

The abrasive slurry waste liquid 24 stored in the waste liquid tank 36 of the recovery apparatus 10 through the waste liquid hopper 26 is fed to the high pressure jet disperser 30 through the supply piping 38. It is sent. As shown in FIG. 3, a pair of jet nozzles 42 and 42 oppose the high-pressure jet disperser 30 in the longitudinal direction both sides of the dispersion container 40 which is a sealed container formed in the cylinder shape of internal pressure. Moreover, the discharge pipe 44 which discharges the dispersion liquid 48 processed by dispersion is connected to the center part side surface of the dispersion container 40. On the other hand, as shown in FIG. 1, while the high pressure pump 46 is formed in the supply pipe 38, the supply pipe 38 branches off the discharge side of the high pressure pump 46, and the pair of jet nozzles 42, 42). Thereby, in the dispersing container 40, the abrasive slurry waste liquids 24 collide with each other as a high pressure jet flow, and by this collided energy, the aggregate in the abrasive slurry waste liquid 24 is shown by FIG. 4 (A). (D) is dispersed. 50-100 MPa is preferable and, as for the ejection pressure of the abrasive slurry waste liquid 24 sprayed from the jet nozzle 42, More preferably, it is the range of 50-70 MPa. 5 is a result of the sedimentation test of the abrasive slurry waste liquid 24 and the dispersion liquid 48 in which the abrasive slurry waste liquid 24 is dispersed by the high pressure jet disperser 30. FIG. 5 (A) shows a case where the slurry slurry waste liquid 24 is stirred with a stirring blade at 360 rpm and then placed in a test tube for 15 minutes. FIG. 5 (B) is a case where the dispersion liquid 48 is stirred in the same manner and then placed in a test tube for 15 minutes. 5C is a case where the unused abrasive slurry is stirred in the same manner and then placed in a test tube for 15 minutes. As can be seen from FIG. 5 (A), the abrasive slurry waste liquid 24 in which the abrasive (A), the small diameter foreign substance (B), the large diameter foreign substance (C) is present as a viscous aggregate (D) is stirred. The solid-liquid separation was not carried out as it was after a cloudy solution. On the other hand, in the case of the dispersion liquid 48 which disperse | distributed the abrasive slurry waste liquid 24 with the high pressure jet disperser 30 like FIG. 5 (B), it solid-liquidly isolate | separates in the position of about the middle of a test tube, and FIG. It approximates the solid-liquid separation state of the unused abrasive slurry shown to the following). In this way, the abrasive (A), the small-diameter foreign matter (B), and the large-diameter foreign matter (C) are liable to be solid-liquid separated by the aggregates (D) in the abrasive slurry waste liquid 24 by the dispersion treatment of the high pressure jet disperser 30. ) Is effectively dispersed.

As the disperser, in addition to the high pressure jet disperser described above, an ultrasonic disperser, a bead mill disperser, and the like can be used, but a high pressure jet disperser 30 having the best dispersing performance with respect to the aggregate (D) is particularly preferable.

The dispersion liquid 48 processed by the high pressure jet dispersion machine 30 is fed to the filtration tank 50 through the discharge pipe 44. In this case, the three-way valve 52 formed in the discharge pipe 44 is switched, and the dispersion liquid 48 is returned to the waste liquid tank 36 again (indicated by the broken line) so that the abrasive slurry waste liquid 24 is subjected to a high pressure jet. It can pass through the disperser 30 multiple times. Therefore, it is preferable to set the number of dispersion treatment times (Pass times) according to the difficulty of dispersing the aggregate (D). Moreover, when performing several times of dispersion processing, it is preferable to implement in the state which closed the valve 54 formed in the waste liquid piping 28 once.

Next, the dispersion liquid 48 sent to the filtration tank 50 is supplied to the ultrasonic filtration device 32 by the filtration pump 58 via the supply pipe 56, as shown in FIG. 1. In the ultrasonic filtration device 32, the filtration vessel 60 has the filtration filter 62 as a boundary, and the filtration chamber 60A (FIG. 1 upper chamber) and the filtrate chamber 60B (FIG. 1 bottom) In addition, the ultrasonic wave oscillator 64 which oscillates an ultrasonic wave toward the filtration filter 62 is formed above 60 A of filtration chambers. As conditions of an ultrasonic wave, 500-1000W is preferable, More preferably, it is the range of 500-800W, 15-25 kHz is preferable, More preferably, it is the range of 17-22 kHz. The return pipe 68 provided with the valve 66 is connected to the side wall of the filtration chamber 60A, and the dispersion liquid 48 supplied to the filtration chamber 60A is connected to the filtration tank 50 via the return piping 68. Is cycled to The filtrate pipe 74 for feeding the filtrate 70 filtered by the filtration filter 62 to the cyclone tank 72 is connected to the lower end of the filtrate chamber 60B, and One valve 76 is formed. The filtrate pipe 74 is branched upstream of the first valve and connected to the washing water tank 82 via the second valve 78 and the backwash pump 80. The washing water for washing the filtration filter 62 is stored in the washing water tank 82.

In order to filter the dispersion liquid 48 by the ultrasonic filtration device 32 configured as described above, the filtration pump 58 is driven while the first valve 76 is opened and the second valve 78 is closed. Thereby, the dispersion liquid 48 stored in the filtration tank 50 is circulated through the filtration chamber 60A and the return pipe 68, while receiving the ultrasonic wave oscillated by the ultrasonic oscillator 64, and then the filtration filter ( 62) filter the dispersion (48). As the pore diameter of the filtration filter 62, the abrasive (A) and the small-diameter foreign matter (B) in the dispersion liquid 48 pass, and the large-diameter foreign matter (C) does not pass. You can use Thereby, as shown to FIG. 4 (B), the filtrate chamber 60B remove | eliminates the large diameter foreign material C and the filtrate 70 which mixed the abrasive | polishing agent A and the small diameter foreign material B was gathered. The liquid is fed to the cyclone tank 72 through the filtrate pipe 74. In this filtration process, ultrasonic waves are oscillated with respect to the dispersion liquid 48 and the filtration filter 62 in the filtration container 60, and the abrasive | polishing agent (A) and the small diameter foreign material (B) which were disperse | distributed by the high pressure jet disperser 30 , And large-diameter foreign matter (C) can be prevented from aggregation again. Moreover, the filtration filter 62 vibrates by an ultrasonic wave, and the clogging of the filtration filter 62 can be suppressed.

Since the filtration pressure rises if the filtration treatment is continued for a long time, it is preferable to backwash the filtration filter 62. Backwashing stops the filtration pump 58, closes the 1st valve 76, and drives the backwashing pump 80 in the state which opened the 2nd valve 78. FIG. Thereby, since the washing water stored in the washing water tank 82 passes back through the filtration filter 62 in the reverse direction to the filtration treatment, and backwashes the filtration filter 62, the filtration pressure can be lowered.

Fig. 6 shows the present invention in which the abrasive slurry waste liquid 24 is dispersed by the high pressure jet disperser 30 and then filtered by the ultrasonic filtration device 32, and the abrasive slurry waste liquid 24 is subjected to the ultrasonic filtration device. This is in contrast to the filtration performance of the comparative example subjected to direct filtration treatment. The hole diameter of the used filtration filter 62 was set to 10 micrometers which is slightly larger than 5 micrometers which is an upper limit of the particle diameter of cerium oxide.

As can be seen from FIG. 6, the filtration flow rate in the present invention decreases from about 1500 (mL / min) immediately after the start of filtration to about 800 (mL / min) after 60 minutes, but after that It was stable at 800 (mL / min). On the other hand, the filtration flow volume in the comparative example was a storage amount at about 100 (mL / min) immediately after the start of filtration, and also changed to about 100 (mL / min) after that. As can be seen from this result, the filtration flow rate of the present invention, in which the abrasive slurry waste liquid 24 is dispersed in advance by the high pressure jet disperser 30 and then filtered by the ultrasonic filtration device 32, is not subjected to the dispersion treatment. It was about 8 times the filtered comparative example.

As shown in FIG. 1, the filtrate 70 filtered and delivered to the cyclone tank 72 is transferred to the cyclone 34 of the three-liquid separation type by the cyclone pump 86 through the supply pipe 84. Supplied. And the filtrate 70 supplied to the upper part of the cyclone tower 88 flows in the cyclone tower 88 by turning flow by the discharge pressure (0.6 MPa) of the cyclone pump 86. As shown in FIG. By this swirling flow, the filtrate 70 receives centrifugal force, and the abrasive A having a high specific gravity drops while gathering on the inner circumferential wall side of the cyclone tower 88, while the small diameter foreign matter B having a light specific gravity is cyclone. Ascending while gathering in the center of the tower (88). Therefore, as shown in Fig. 4C, the high specific gravity liquid containing the abrasive (A) is discharged from the bottom of the cyclone tower 88, and the low specific gravity liquid containing the small-diameter foreign matter (B) from the top portion. Discharged.

In addition, the heavy specific gravity liquid in which the abrasive | polishing agent A and the small diameter foreign material B mixed with each other is returned to the tank 72 for cyclones through the circulation piping 90, and it classifies repeatedly by a cyclone. The high specific gravity liquid is stored in the abrasive slurry recovery tank 92 and reused as the abrasive slurry. In addition, the low specific gravity liquid is stored in the small diameter foreign matter tank 94. Thereby, the abrasive (A) can be recovered from the abrasive slurry waste liquid 24 at an efficient and high foreign matter removal rate.

7 shows the present invention in which the abrasive slurry waste liquid 24 is classified by a cyclone 34 of the filtrate 70 after passing through the high pressure jet disperser 30 and the ultrasonic filtration device 32, and the abrasive slurry waste liquid ( The classification performance was examined in comparison with Comparative Example 1 in which 24) was directly classified by the cyclone 34 and Comparative Example 2 classified by the cyclone 34 after passing only the ultrasonic filtration device 32. The classification performance was performed by examining the silica content in the liquid stored in the abrasive slurry recovery tank 92. Here, the silica content contained in the abrasive slurry waste liquid 24 is 195 mg / L, and the silica content in an unused abrasive slurry is approximately 60 mg / L. Therefore, 135 mg / L of silica in the abrasive slurry waste liquid 24 generate | occur | produces by grinding | polishing of the glass substrate 14. As shown in FIG.

As can be seen from FIG. 7, in Comparative Example 1, the silica content was 195 mg / L, and no classification of the abrasive (A) and the small-diameter foreign matter (silica; B) could be performed at all. Moreover, in the comparative example 2, 20 mg / L small diameter foreign material (silica; B) could be removed. In contrast, in the present invention, 98 mg / L small diameter foreign matter (silica; B) could be removed. As a result, the remaining silica became 97 mg / L, and the silica content of the unused abrasive slurry became close.

Thus, the abrasive (A), the small-diameter foreign matter (B) smaller than the particle diameter of the abrasive (A), and the large-diameter foreign matter (C) larger than the particle diameter of the abrasive (A) aggregate and exist as aggregates (D). In order to recover the abrasive A from the abrasive slurry waste liquid 24, it is important to perform each treatment in the high pressure jet disperser 30, the ultrasonic filtration device 32, and the cyclone 34 in the above order.

In addition, although embodiment of this invention demonstrated as an example which collect | recovers the abrasive (A) from the abrasive slurry waste liquid 24 at the time of grinding | polishing the glass substrate 14 with the polisher which used cerium oxide as an abrasive (A), another When an abrasive | polishing agent is used, it is applicable also to the abrasive | polishing agent other than a glass substrate, for example, the abrasive | polishing agent used by the semiconductor substrate.

This invention is especially preferable for recovering cerium oxide from the abrasive slurry waste liquid at the time of grinding | polishing a glass substrate using the abrasive slurry which used cerium oxide as an abrasive.

In addition, all the content of the JP Patent application 2006-222000, the claim, drawing, and the abstract for which it applied on August 16, 2006 is referred here, and it introduces as an indication of the specification of this invention.

Claims (8)

A recovery method for recovering an abrasive from an abrasive slurry waste liquid in which an abrasive, a small diameter foreign substance smaller than the particle diameter of the abrasive, and a large diameter foreign substance larger than the particle diameter of the abrasive are present as an aggregate. A dispersion step of performing mechanical dispersion treatment of the abrasive slurry waste liquid; A filtration step of filtering the dispersion solution to remove the large diameter foreign matter from the dispersion solution; And a classification step of classifying the filtered filtrate with a cyclone and classifying the abrasive and the small-diameter foreign matter in the filtrate. The method of claim 1, And the abrasive is cerium oxide having a particle diameter of 0.5 to 5 µm. The method according to claim 1 or 2, Said dispersion | distribution process is a high pressure collision process which makes the said abrasive slurry waste liquid two or more high pressure jets, and makes the said high pressure jets collide with each other, The abrasive recovery method from the abrasive slurry waste liquids characterized by the above-mentioned. The method according to any one of claims 1 to 3, The filtration step is a method for recovering the abrasive from the abrasive slurry waste liquid, characterized in that when the dispersion is filtered by a filtration filter, an ultrasonic treatment is applied to the dispersion and / or the filtration filter. The method of claim 4, wherein The said filtration process performs the backwash process which backwashes the said filtration filter with backwash water intermittently, The abrasive | polishing agent recovery method from the abrasive slurry waste liquid characterized by the above-mentioned. The method according to any one of claims 1 to 5, In the said dispersion | distribution process, the dispersion | distribution process of abrasive slurry waste liquid is performed repeatedly multiple times, The abrasive | polishing agent recovery method from the abrasive slurry waste liquid characterized by the above-mentioned. The method according to any one of claims 1 to 5, A method for recovering abrasives from abrasive slurry waste liquids, characterized in that in the classification step, the heavy specific gravity solution in which the abrasive and the small-diameter foreign matter are mixed with each other is removed from the cyclone and the classification treatment is repeated. A recovery apparatus for recovering an abrasive from an abrasive slurry waste liquid, A high pressure jet disperser for making the abrasive slurry waste liquid at least two high pressure jets, and for colliding the high pressure jets with each other in a dispersion container; An ultrasonic filter for filtering the dispersion by the filtration filter while applying ultrasonic waves to the dispersion and / or the filtration filter dispersed by the high pressure jet disperser; And a cyclone for classifying the particles in the filtrate filtered by the ultrasonic filter.

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