WO2014042431A1 - Method for regenerating spent ceria-containing polishing agent - Google Patents

Abstract

The present invention relates to a method for regenerating spent ceria-containing polishing agent, the method allowing the regeneration process, comprising a cleaning process, to be efficient and suppressing re-coagulation of the ceria-containing polishing agent during the cleaning process, while effectively discarding the impurities contained in the spent ceria-containing polishing agent. The method for regenerating the spent ceria-containing polishing agent comprises the steps of: mixing spent ceria(CeO₂)-containing sludge and a solvent containing a fluorine compound, and selectively dissolving silica(SiO₂)-containing impurities contained in the spent sludge; cleaning the spent ceria-containing sludge by passing same through a cross-flow filtration system and selectively discarding the silica(SiO₂)-containing impurities; and drying and sintering the cleaned spent ceria-containing sludge.

Description

 【Specification】

 [Name of invention]

 Regeneration method of ceria-containing waste abrasive

 Technical Field

 The present invention relates to a regeneration method of ceria-containing waste abrasive. More specifically, the present invention is to effectively remove the impurities contained in the ceria-containing waste abrasive material, while improving the efficiency of the regeneration process including a washing process, and of the ceria-containing waste abrasive material that can suppress the re-formation of the ceria-containing abrasive during the washing process It relates to a reproduction method.

 Background Art

Generally, TV CRT tubes and TFT-LCD glass substrates used as liquid crystal panels are produced with poor surface flatness and roughness during the production process. Therefore, using original glass as a TV CRT tube or liquid crystal panel glass substrate is a problem. It is difficult. In particular, the TFT-LCD glass panel used as a liquid crystal panel has been examined in various ways to improve the brightness, viewing angle, and contrast of the product. It is known to receive. To this end, companies producing glass substrates are making efforts to improve the surface of glass substrates, and various glass substrate abrasives are used. Among them, an abrasive containing ceria (Ce0 ₂ ) is widely used as a general abrasive.

 However, such ceria-containing abrasives are disposed of as waste sludge due to a decrease in polishing efficiency after a certain time of glass polishing process. This is because, after a certain time of polishing, the polishing efficiency of the abrasive decreases and agglomeration between the abrasive grains occurs, resulting in a high possibility of scratches. In addition, impurities derived from the polishing pad generated during polishing are introduced into the abrasive slurry to further increase the possibility of scratches.

Because of this, the abrasive needs to be discarded after being used in the polishing process for a certain period of time, which may lower the efficiency or economic efficiency of the process. have. For this reason, some techniques for recycling the abrasive have been studied.

 In the previously known method of recycling and regenerating ceria-containing waste abrasives, a solvent solution containing hydrofluoric acid or hydrogen fluoride compounds is used to dissolve impurities derived from glass substrates such as silica contained in ceria-containing waste sludge, and After separating such impurities from the waste sludge, a method of regenerating the waste sludge and the waste abrasive material through a drying and calcining process is mainly used. In particular, in such a conventional regeneration method, by applying a natural sedimentation method, a filtration method, or a method using a decanter or centrifugal separator in the washing step, the impurities dissolved in the solvent solution while washing the waste sludge are Solid liquid was separated and removed from the waste sludge.

 In the case of the solid-liquid separation and washing method, there is a disadvantage in that the continuous process is impossible and the washing efficiency is lowered so that the yield of the entire regeneration process is lowered. In addition, in the method using the decanter or centrifugal separator, in the process of solid-liquid separation by strong centrifugal force, coagulation between abrasive particles contained in the waste sludge occurs, so that the redispersion process needs to be carried out separately, There was a fear of occurrence of scratches caused by the use of recycled abrasives. In addition, even if the redispersion process is carried out separately, there are disadvantages in that it is difficult to sufficiently remove the large particles and difficult to obtain a desired particle size distribution.

 In addition, even when a conventional filtration method is applied, powders derived from impurities and the like easily accumulate in the filter, and are difficult to remove, thereby shortening the filter life.

 [Contents of the Invention]

 [Problem to solve]

Accordingly, the present invention can effectively remove the impurities contained in the ceria-containing waste abrasive material, and can efficiently regenerate the regeneration process including the washing process, and can suppress the reagglomeration of the ceria-containing abrasive during the washing process. To provide a way to play [Measures of problem]

The present invention comprises the steps of mixing a ceria (Ce0 ₂ ) -containing waste sludge and a solvent solution containing a fluorine-based compound to selectively dissolve the silica (Si0 ₂ ) -containing impurities contained in the waste sludge; Washing the ceria-containing waste sludge while passing through a cross-flow fliltration system to selectively remove the silica (SiO ₂ ) -containing impurities; And drying and firing the washed ceria-containing waste sludge. Hereinafter, a method for regenerating waste ceria-containing waste abrasive according to an embodiment of the present invention will be described in detail.

According to one embodiment of the invention, ceria (CeO ₂ ) containing waste sludge, and a solvent solution containing a fluorine-based compound by mixing, selectively dissolving the silica (Si0 ₂ ) containing impurities contained in the waste sludge; Washing the ceria-containing waste sludge through a cross-flow fliltration system to selectively remove the silica (Si0 ₂ ) -containing impurities; And drying and firing the washed ceria-containing waste sludge.

 In the ceria-containing waste abrasive regeneration method of an embodiment, the ceria-containing waste sludge derived from the waste abrasive is dissolved in a predetermined solution of a solvent to dissolve impurities derived from a glass substrate, and the like. Through the process, the waste abrasive containing ceria can be regenerated into regenerated abrasives.

In particular, in the regeneration method of the embodiment, in the cleaning process, the waste sludge treated with the solvent solution is washed while passing through a cross-flow fliltration system to remove the waste sludge and the solvent solution. The impurities dissolved in the solid-liquid separation, and these impurities are removed. The cross-flow filtration system used at this time includes a predetermined filter in the system, The system refers to a system for filtering a target solution while continuously passing the target solution in a direction perpendicular to the filter through the upper space of the filter. That is, in such a cross flow filtration system, while the target solution passes through the system, impurities in the target solution may be caught by the filter while being continuously contacted with the lower filter, thereby filtering and removing the target solution.

 In the regeneration method of the embodiment, as the cleaning process is performed using the cross flow filtration system, the cleaning process may be performed while continuously passing the waste sludge treated with the solubilizer solution through the cross flow filtration system. Therefore, the regeneration method of one embodiment may continuously process the cleaning and regeneration process. In addition, since the waste sludge treated with the solvent solution continuously passes through the cross-flow filtration system, and the impurities dissolved in the solvent solution are filtered, solid-liquid separated and removed, the impurities are removed and washed efficiently. The yield of the whole regeneration process can be further improved.

 Moreover, as a result of the experiments of the present inventors, it was confirmed that as the cleaning process is carried out using the cross-flow filtration system, abrasive grains during the cleaning process can be suppressed, and as a result, generation of large particles in the recycled abrasive can be greatly reduced. . Therefore, the recycled abrasive obtained by the method of one embodiment can exhibit a desired polishing rate without fear of scratching by the large particles, and greatly reduces the need for additional redispersing, grinding or classifying processes for removing the large particles.

 In addition, in the case of the cross flow filtration system, powder on the filter surface can be easily removed and reused through a back pulse to the filter or the like. Therefore, it is possible to increase the filter life and to more efficiently the cleaning and the entire regeneration process including the same.

As a result, the regeneration method of one embodiment can efficiently remove the impurities contained in the ceria-containing waste abrasive material, and can efficiently regenerate the regeneration process including the cleaning process, and aggregate the ceria-containing abrasive during the cleaning process and generate large particles. Etc. can be suppressed. Hereinafter, with reference to the drawings, a method of regenerating waste containing abrasive ceria of one embodiment will be described in more detail in each step. For reference, FIG. 1 is a view schematically illustrating an example of a method for regenerating waste ceria-containing waste abrasive according to one embodiment, and FIG. 2 is a cross-flow filtration used in a method of regenerating waste-containing abrasion containing ceria according to one embodiment. It is a figure which shows the basic principle and structure of a system typically.

First, the ceria-containing waste abrasive material and the waste sludge derived therefrom, which is the object of the regeneration method of one embodiment, may be derived from a ceria-containing abrasive material used for polishing a glass substrate in a TFT-LCD manufacturing process. Accordingly, the ceria-containing waste sludge or the like contains silica (Si0 ₂ ) and alumina (Al ₂ 0 ₃ ) derived from a glass substrate as main impurities. In addition, the waste sludge and the waste abrasive material may include, as impurities, various polishing pads that have undergone polishing, various organic substances derived from back pads used to support the glass substrate to be polished, and the like (Fe), chromium (Cr). Or other metallic component-containing impurities such as nickel (Ni).

 Therefore, in regenerating the ceria-containing waste sludge and the like, a process of removing such silica and alumina, a process of removing other impurities from the polishing pad, a back pad, or the like and containing a metal component, The process of controlling surface properties, particle size distribution and crystal size is needed.

Referring to FIG. 1, in the regeneration method of one embodiment, first, ceria (Ce0 ₂ ) -containing waste sludge and a dissolving agent solution containing a fluorine-based compound are mixed to selectively select silica (SiO ₂ ) -containing impurities contained in the waste sludge. Melting process can proceed. At this time, the solubilizer solution without substantially dissolved in the ceria to be reproduced as the abrasive material from the waste sludge (e. G., About 0.01 by weight of the ceria content in the waste sludge ⁰ /. Or less, or about 0.001 _^0/0 Dissolve only below), the glass contained in the waste sludge and waste abrasive Substrate-derived impurities, such as silica (Si0 ₂ ), alumina (Al ₂ 0 ₃ ), and the like, are selectively dissolved to allow the silica (Si0 ₂ ) -containing impurities to be nearly black to nearly 100% through subsequent cleaning steps. Can be removed completely As a result, it is possible to increase the removal rate of impurities, to suppress the loss of ceria together with the silica-containing impurities, and to greatly increase the regeneration rate of ceria.

To this end, the solubilizer solution comprises a hydrofluoric acid or hydrogen fluoride compound and a strong base of sodium or potassium hydroxide, or (a) a predetermined fluorine-based compound of NaHF ₂ , (NH ₄ ) HF ₂ or KHF ₂ , or (b) a combination of a predetermined fluorine salt of NaF, (NH ₄ ) F or KF with a non-fluoric acid such as sulfuric acid, nitric acid or hydrochloric acid. In this case, the "non-fluoric acid" refers to hydrochloric acid, sulfuric acid, or nitric acid which does not contain fluorine in its chemical structure, and acids containing hydrofluoric acid, hydrogen fluoride compounds, and other fluorine may be excluded from the category of "non-fluoric acid." Can be. Unless otherwise specified, "non-fluoric acid" is used in the above meaning.

 In such a solvent solution, the hydrofluoric acid or hydrogen fluoride compound is mainly used as a glass etching solution, and may also selectively dissolve impurities such as silica or alumina derived from the glass substrate. Further, the strong base can also selectively dissolve impurities such as silica derived from a glass substrate.

And, in another example of the solvent solution, the (a) NaHF ₂ , (NH ₄ ) HF ₂ or

Fluorine compounds such as KHF ₂ , or (b) fluorine salts such as NaF, (NH ₄ ) F or KF, and a mixture of non-fluoric acid, have an ionization and dissociation state similar to the above-mentioned hydrofluoric acid when dissolved in a solvent solution. Accordingly, the glass substrate-derived impurities contained in the waste sludge and the waste abrasive material, for example, silica (Si0 ₂ ) and alumina (Al ₂ 0 ₃ ), etc., are selectively dissolved to completely or close to 100%. It can be almost completely removed.

Further, the above-mentioned solubilizer solution does not substantially dissolve ceria to be regenerated from the waste sludge as an abrasive, and such ceria can By suppressing the loss with impurities, the regeneration rate of ceria can be greatly increased.

 Therefore, when the ceria-containing waste sludge is treated by dispersing the ceria-containing waste sludge in, for example, an aqueous solution solution, the glass substrate-derived impurities contained in the waste sludge, for example, silica and alumina, are treated. It can be selectively dissolved by the solvent solution and separated from the waste sludge.

At this time, in consideration of the impurity content, such as silica or alumina contained in the waste sludge, the concentration of the fluorine compound, fluorine salt, non-fluoric acid acid or strong base including the hydrofluoric acid or hydrogen fluoride compound in the solubilizer solution can be appropriately adjusted. . However, in order to remove impurities such as silica and alumina effectively from waste sludge used for polishing a conventional glass substrate for LCD, compounds such as hydrofluoric acid, hydrogen fluoride compounds and other NaHF ₂ and fluorine salts such as NaF may be used. It is appropriate that the fluorine-containing compound is included at a concentration of about 0.01 to 20M, or about 0.1 to 15M, or about 1 to 10M in the solvent solution. In addition, the non-fluoric acid-based acid or strong base which may be included together with the hydrofluoric acid, hydrogen fluoride compound, or fluorine salt may be included at a concentration of about 0.01 to 20M, or about 0.1 to 15M, or about 1 to 10M in the solvent solution. If the concentration of each component in the solvent solution is too low, the removal efficiency of the impurities may be lowered, and if the concentration is too high, the amount of the raw material may be unnecessarily increased.

On the other hand, after dissolving the ceria-containing waste sludge, in particular, the silica-containing impurities contained therein in a predetermined solvent solution, such waste sludge may be washed to selectively remove the silica-containing impurities from the waste sludge by solid-liquid separation. . In this case, since the solvent solution does not substantially dissolve ceria to be regenerated from the waste sludge, it is possible to selectively remove and remove only the silica-containing impurities selectively dissolved in the solvent solution through the washing while lowering the loss rate thereof. Particularly, in the regeneration method of one embodiment, the washing process proceeds while continuously passing the waste sludge treated with the solvent solution through a cross-flow fliltration system.

 Referring to FIG. 2, the cross flow filtration system includes a predetermined filter in the system, and the filtration and solid-liquid separation proceed as the waste sludge-containing solution continuously passes in a direction perpendicular to the filter through the upper space of the filter. System. In such a system, the waste sludge-containing solution is continuously contacted with the lower filter while passing through the system, and liquid impurities (eg, silica or alumina, etc.) dissolved in the solvent solution are discharged to the filter and filtered. Solid liquor can be separated and removed and the remaining waste sludge containing high concentrated solution can be withdrawn from the system without exiting through the filter. In addition, the above-described process may be repeated while the highly concentrated solution is circulated and passed again through the cross-flow filtration system and the filter a plurality of times, for example, about 2 to 10 times.

 Through this process, as the cleaning process using the cross flow filtration system proceeds, the above-described cleaning process can be continuously processed to proceed more efficiently. In addition, as described above, since the waste sludge-containing solution continuously passes through the system and contacts the lower filter with a large surface area, impurities dissolved in the solvent solution are filtered, solid-liquid separated and removed, thereby removing and washing impurities. Efficiency and the yield of the whole regeneration process can be improved more. In addition, coarse grains of abrasive grains, formation of macroparticles, and the like can be suppressed during the cleaning process.

On the other hand, in such a cleaning process, the cross-flow fliltration system is a ceramic material such as alumina or zirconia having a filter eye for filtering particles having a particle diameter of about 5 or less and black or about 0.002 to 5 It may include a filter. By the use of such a filter, the abrasive particles in the waste sludge can be filtered and lost by the filter to suppress the reduction of the regeneration yield, and more effectively to remove impurities dissolved in the solvent solution. While completely removable, the life of the filter can be improved.

 In addition, the cross flow filtration system can remove the powder on the surface of the filter through a back pulse to the filter, thereby reducing the accumulation of powder on the filter or shortening the life of the filter, and cleaning and regeneration. The overall process can be made more efficient.

 When the above washing process is performed, the waste sludge and glass substrate-containing impurities such as silica or alumina dissolved in the solvent solution are solid-liquid separated to remove and remove impurities from the waste sludge. In this case, the washing process may be performed by adding a separate washing liquid such as deionized water, water, or other aqueous solvent to the filtration system. In order to more effectively wash and remove impurities dissolved in the dissolving solution, the washing liquid may have a pH of 1 to 1. 4 or a solvent adjusted to pH 10-14. In order to appropriately control the pH, an acid or a base may be appropriately dissolved in the water or deionized water and used as a washing liquid, and the impurities may be more completely removed through the above-described washing process.

 In this cleaning process, the flux to be used in the sintering process to be described later may be added to the waste sludge to be recycled.

On the other hand, as shown in Figure 1, after the cleaning process, the washed ceria-containing waste sludge may be dried. In this drying step, the above-mentioned dissolving agent solution treatment step, and to dry and remove the moisture in the cleaning process from the waste sludge with the impurities have been removed, and this waste sludge drying process conducted from about 1 weight _^0/0 or less, Or dry to have a moisture content of about 0 to 1 weight ⁰ /.

This drying process may proceed with an oven dryer or compact disc dreyer. In particular, the CD dryer is a type of disk type dryer in which the waste sludge is dried on a rotating disk that is heat-supplied. As a result of the use of such a CD dryer, the CD dryer is used to remove the grains between the abrasive particles (for example, ceria particles) during the drying process. Can be suppressed Therefore, it is possible to suppress the generation of macroparticles and to suppress the occurrence of scratches when using the recycled ceria-containing abrasive. Therefore, the said CD dryer can be used more suitably in a drying process. This is expected because the drying in the CD dryer can uniformly transfer heat to the waste sludge with high efficiency.

The drying step is carried out in an oven dryer for about 1 to 30 seconds with a silver of about 100 to 200 ^° C, or on a CD dryer rotated at about 1 to 10 rpm, black to about 5 to 10 rpm, about 100 to 200 ^It can proceed for about 1 to 30 seconds at a temperature of ^° C. If the rotation speed of the CD dryer is too low, or the drying time is too long, there is an increased risk of scratches caused by the generation of coarse particles, and conversely, if the rotation speed is too fast or the drying time is too short, However, the drying process may not be effective.

In contrast, when the drying process is performed under optimized conditions, the recycled ceria-containing regenerated abrasive may have an appropriate average particle size of about 0.5 to 3.0, and the formation of large particles of about 6.0 GPa or more is suppressed, thereby reducing the possibility of scratches. rather, the drying proceeds efficiently the moisture content can be readily obtained the up to about 1 weight ⁰ / playback abrasive.

On the other hand, after the above-described drying process, as shown in Figure 1, in the presence of a flux containing ammonium salt, alkali metal salt, metal oxide, metal oxygen acid or alkaline earth metal salt, the dried waste sludge About 800 to 1200 ^° C, black may proceed to about 800 to 1000 ^° C, or 800 to 900 ^° C. Through the progress of the firing process, the surface characteristics and crystal properties of the ceria-containing abrasive contained in the waste sludge can be restored, thereby increasing the polishing rate of the recycled abrasive and also removing impurities such as various organic substances derived from the pad.

At this time, the force is about 1 to 3.0 weight ⁰ /., Or about 1 to 2.0 weight ⁰ /., Black is about 1 to 1.5 weight ⁰ /. Can be used in amounts. As the use amount of the fleece and the above-described firing temperature and the like are appropriately adjusted, the particle size distribution and the crystal size of the recycled abrasive are appropriately adjusted to the crystal sizes of about 0.5 to 3.0 and about 60 to 90 nm, respectively, The production of particles can be suppressed, the polishing rate of the regenerated abrasive can be adjusted well and the occurrence of scratches due to the generation of the large particles can be suppressed.

 In the calcining process described above, the flux is ammonium salt such as ammonium fluoride, ammonium chloride or ammonium sulfate; Alkali metal salts or alkaline earth metal salts such as sodium chloride, sodium fluoride, sodium hydroxide, potassium chloride, sodium borate or barium chloride; Metal oxides such as boron oxide; Metal oxygen acids, such as boric acid, can also be used, and 2 or more types selected from these can also be used together. According to the use of the flux, after the firing process, the surface characteristics or crystal characteristics of the recycled abrasive may be adjusted to a desirable range. And, as already described above, the flux may be wet mixed by being introduced in a previously cleaned washing step, or dry mixed immediately before the firing process, and may be wet mixed in the washing step as appropriate. In addition, the firing step may be performed for about 1 to 4 hours at the above-mentioned temperature.

Through the above-described optimization of the calcination process, a ceria-containing regenerated abrasive having a crystal size of about 60 to 90 nm and an average particle size of about 0.5 to 3.0 / zm and suppressing the formation of large particles can be obtained. If the crystal size or the average particle size is too small, the polishing of the regenerated abrasive may not be possible. If the crystal size or the average particle size is too large, scratches may occur in the polishing process using the regenerated abrasive or after the firing process. Grinding and classification processes that proceed as needed may be unnecessarily inefficient. Moreover, in order to reduce excessively large particle size or crystal size, when the grinding and classification process is excessively performed, the efficiency of the regeneration process is greatly reduced, and the surface characteristics of the recycled abrasive are rather damaged during the progress of the grinding process. The properties of the recycled abrasive may be degraded. On the other hand, after the progress of the above firing step, the ^decrease, the particle size distribution or grain size of the reproduction abrasive as required and, in order to remove the larger particles, it is possible to proceed further to the grinding or classification process, such grinding and classifying step Can proceed in a manner well known to those skilled in the art. For example, the grinding process may be performed using a jet-mill Get-mill, etc., and the classification process may be performed by using a wind classifier such as a cyclone, a dry classifier, a dipole or a tripole tip. Proceed with a sieve for supply or classification. According to the regeneration method described above, impurities derived from the glass substrates are substantially completely and effectively removed, the entire regeneration process including the cleaning process is continuously processed and the efficiency is improved, the formation of coarse particles of ceria-containing abrasives during the cleaning process, generation of large particles, and the like. This can be suppressed. Therefore, by the above regeneration method, a ceria-containing regenerated abrasive which exhibits excellent properties with excellent efficiency and yield and is suppressed from producing large particles can be obtained. Such ceria-containing regenerated abrasives can be used alone or in combination with new abrasives to be recycled for polishing of glass substrates for LCDs, etc., which can greatly contribute to the economics and yield of the process.

 【Effects of the Invention】

According to the present invention, while effectively removing impurities contained in the ceria-containing waste abrasive material through the cleaning process, the cleaning process and the regeneration process including the same can be efficiently performed in a continuous process, and the size and size of the ceria-containing abrasive material of the cleaning process is increased. Provided is a method for regenerating ceria-containing waste abrasive materials which can suppress the production of particles and the like. ^'

 [Brief Description of Drawings]

 1 is a view schematically showing an example of a method for regenerating waste ceria-containing waste abrasive according to one embodiment for each step.

2 is a view schematically showing the basic principle and configuration of the cross-flow filtration system used in the method for regenerating waste ceria-containing waste abrasive of one embodiment. 3 to 5 after the progress to the cleaning process in Examples 1 to 3, It is a graph which measured the particle size distribution of the obtained recycled abrasive.

 6 to 8 are graphs in which particle size distributions of the recycled abrasives obtained are measured after advancing to the washing step in Comparative Examples 1 to 3. FIG.

 [Specific contents to carry out invention]

 Hereinafter, preferred embodiments will be presented to aid in understanding the invention. However, the following examples are only to illustrate the invention, not limited to the invention only. Example 1 Regeneration of Ceria-Containing Waste Abrasives

4 kg of NaHF ₂ was added to an aqueous waste sludge solution containing ceria (Ce0 ₂ ) containing waste sludge at a solid content concentration of 15% by weight ⁰ /. And dissolved and reacted for 2 hours. Subsequently, the waste sludge-containing solution was passed through a cross flow filtration system (product name: Membralox, Pall) eight times in succession, and the concentration was concentrated to 50 wt% solids once, and additionally deionized water was added. After the cleaning process, it was confirmed that the ion conductivity (IC) value fell from 23mS / cm to 450uS / cm, the silica content was confirmed to be less than 0.05% by weight.

Thereafter, using a CD dryer (product name: CD500, Geumsan Technological Industry), the drying process was carried out for 5 seconds at a temperature of 12C C in the presence of 7rpm. After the drying process, the water content of the waste sludge is confirmed that less than 1 wt. _^0/0. Subsequently, in the presence of an ammonium fluoride 1 part by weight _^0/0 (weight ratio of the first reproduced waste sludge) it was added in the above-described washing step, and then fired for 2 hours, the dried sludge in a 850 ^° C The recycled abrasive of Example 1 was obtained. Yield: 99%; Total cleaning time: 3 hours Example 2: Regeneration of ceria-containing waste abrasive

₂ kg of NaHF ₂ was added to an aqueous waste sludge solution containing ceria (Ce0 ₂ ) containing waste sludge at a solid content concentration of 15% by weight ⁰ /. And dissolved and reacted for 2 hours. Subsequently, the waste sludge-containing solution was passed through a cross flow filtration system (product name: Membralox, Pall) five times in succession, and was concentrated to 50 wt% solids once, and additionally deionized water was added. After this cleaning process proceeds, the conductivity (IC) values followed was confirmed dropped to 30 (iS / cm at 11mS / cm, the residual content of the silica was found to be not more than 0.05 wt. ⁰ /.

Then, using a CD dryer (product name: CD500, Geumsan Tech Industries), the drying process was carried out for 5 seconds at a temperature of 120 ° C. under a rotation of 7 rpm. After the drying step, it was confirmed that the water content of the waste sludge became 1 weight ⁰ /. Or less. Subsequently, in the presence of 1% by weight of ammonium fluoride (relative to the weight of waste sludge subjected to the first regeneration) added in the above-described washing process, the dried waste sludge was calcined at 85 crc for 2 hours to regenerate Example 2 An abrasive was obtained. Yield: 99%; Total cleaning time: 2 hours Example 3: Regeneration of ceria-containing waste abrasive

8 kg of NaHF ₂ was added to an aqueous waste sludge solution containing ceria (Ce0 ₂ ) containing waste sludge at a solid content concentration of 15% by weight ⁰ /. And dissolved and reacted for 2 hours. Subsequently, the waste sludge-containing solution was passed through a cross-filtration system (product name: Membralox, Pall) 10 times in succession, followed by a concentration of 50 wt% solids and supplemented with deionized water. After the cleaning process, it was confirmed that the ionic conductivity (IC) value fell from 45mS / cm to 400yS / cm, the silica content was confirmed to be less than 0.05% by weight.

Thereafter, a drying process was performed for 5 seconds using a CD dryer (product name: CD500, Geumsan Tech Industries) at a temperature of 1201: under a rotation of 7 rpm. After the drying step, it was confirmed that the water content of the waste sludge became 1 weight ⁰ X »or less. Subsequently, in the presence of 1% by weight of ammonium fluoride (relative to the weight of the waste sludge subjected to the first regeneration) added in the above-described cleaning process, the dried waste sludge was 2 at 850 ^° C. Firing for a period of time afforded the recycled abrasive of Example 3. Yield: 99%; Total cleaning time: 5 hours Comparative Example 1: Regeneration of ceria-containing waste abrasive

4 kg of NaHF ₂ was added to an aqueous waste sludge solution containing ceria (Ce0 ₂ ) containing waste sludge at a solid content concentration of 15% by weight ⁰ /. And dissolved and reacted for 2 hours. Thereafter, the waste sludge-containing solution was added to a decanter (product name: DSD25ML, East-West) to proceed with the washing process, and the washing process was repeated five times. In addition, deionized water was additionally added to the concentrated solution every time the cleaning process was performed. After this cleaning process proceeds, the ionic conductivity (IC) values were confirmed dropped at 23mS / cm by 450yS / cm, the residual content of the silica was determined to be 0.05 _^0/0 or less.

 Thereafter, the drying and baking processes were performed in the same manner as in Example 1 to obtain a recycled abrasive of Comparative Example 1. Yield: 70%; Total cleaning time: 48 hours Comparative Example 2: Regeneration of ceria-containing waste abrasive

4 kg of NaHF ₂ was added to an aqueous waste sludge solution containing ceria (Ce0 ₂ ) containing waste sludge at a solid content concentration of 15% by weight ⁰ /. And dissolved and reacted for 2 hours. Thereafter, the waste sludge-containing solution was precipitated by natural sedimentation and then the supernatant was separated. The washing process was repeated five times. In addition, deionized water was additionally added to the concentrated solution every time the cleaning process was performed. After the cleaning process, it was confirmed that the ion conductivity (IC) value dropped from 23 mS / cm to 1000 yS / cm, but the silica content remained 0 1 weight ⁰ /.

Thereafter, the drying and baking processes were performed in the same manner as in Example 1 to obtain a recycled abrasive of Comparative Example 2. Yield: 80%; Total cleaning time: 40 hours Comparative Example 3: Regeneration of ceria-containing waste abrasive A recycled abrasive of Comparative Example 3 was obtained in the same manner as in Comparative Example 2, except that 4 kg of NH ₄ F and hydrogen peroxide were used instead of NaHF ₂ . After the cleaning process, it was confirmed that the ion conductivity (IC) value was dropped from 30mS / cm to 1500yS / cm, but the residual content of silica was 0.2 weight ⁰ /.

 Thereafter, the drying and firing processes were performed in the same manner as in Comparative Example 2 to obtain a recycled abrasive of Comparative Example 3. Yield: 75%; Total cleaning time: 40 hours

 1. After proceeding to the cleaning process of Examples 1 to 3 and Comparative Examples 1 to 3, the particle size distribution of the abrasive was measured with a particle size analyzer (product name: LA950, Horiba) and shown in FIGS. 3 to 5 and 6 to 8, respectively. It was. 3 to 5 and 6 to 8, in Examples 1 to 3, the maximum particle size was not very large, whereas in Comparative Examples 1 to 3, particle spacing occurred during the cleaning process, resulting in about 10 It was confirmed that more large particles were produced.

2. Using the recycled abrasives of Examples 1 to 3 and Comparative Examples 1 to 3, polished the glass polished surface (bottom surface of glass) of 250 mm ^* 220 mm for 5 minutes under the conditions of the top plate pressure of the polishing machine and the bottom plate speed of 100 rpm. After scratches, scratch evaluation was performed with a scratch analyzer (Dr. schenk's equipment). As a result of the evaluation, it was confirmed that no scratches could be visually identified when using the regenerated abrasives of Examples 1 to 3, and that 10000 or more scratches occurred when the regenerated abrasives of Comparative Examples 1 to 3 were used.

Claims

[Patent Claims]  [Claim 1] Mixing ceria (CeO ₂ ) -containing waste sludge and a solution of a fluorine-based compound to selectively dissolve the silica (Si0 ₂ ) -containing impurities contained in the waste sludge; Washing the ceria-containing waste sludge while passing through a cross-flow fliltration system to selectively remove the silica (Si0 ₂ ) -containing impurities; And  Regenerating method of ceria-containing waste abrasive comprising the step of drying and firing the washed ceria-containing waste sludge. [Claim 2] The method of regenerating ceria-containing waste abrasive according to claim 1, wherein the ceria (CeO ₂ ) -containing waste sludge contains silica, alumina and other metal components as impurities. [Claim 3]  The method for producing ceria-containing waste abrasive according to claim 1, wherein the solubilizer solution is an aqueous solution containing a hydrofluoric acid or hydrogen fluoride compound and a strong base of sodium hydroxide or potassium hydroxide. [Claim 4] The solution of claim 1 wherein the solubilizer solution comprises (a) a fluorine-based compound of NaHF ₂ , (NH ₄ ) HF ₂ or KHF ₂ , or (b) a fluorine salt of NaF, (NH ₄ ) F or KF, and a non-fluoric acid-based compound. A method for producing a ceria-containing waste abrasive, which is an aqueous solution containing an acid mixture. [Claim 5] The method of claim 1, wherein the solvent solution is a fluorine-based compound of 0.01 to A method for regenerating ceria-containing waste abrasives, which contains at a concentration of 20 M. [Claim 6]  The method for regenerating ceria-containing waste abrasive according to claim 3 or 4, wherein the solvent solution contains the strong base or non-fluoric acid at a concentration of 0.01 to 20 M. [Claim 7]  The method of claim 1, wherein the cross-flow fliltration system has a filter containing alumina or zirconia that filters particles having a particle diameter of 5 / im or less. [Claim 8]  8. The method of claim 7, wherein the cross flow filtration system removes powder from the surface of the filter through a back pulse to the filter. [Claim 9]  The method of regenerating ceria-containing waste abrasive according to claim 1, wherein the washing step is performed with a solvent adjusted to pH 1 to 4 or pH 10 to 14. [Claim 10]  The method of claim 1, wherein the drying step is performed in an oven dryer or a compact disc dryer. [Claim 111]  The method of claim 1, wherein the drying step is 100 to 100 in an oven dryer 1 to 30 seconds at a temperature of 20 C C or at 1 to 10 rpm in a CD dryer Method of regeneration of waste ceria-containing abrasive polishing during the process. [Claim 12]  The waste containing ceria according to claim 1, wherein the calcining step is carried out by calcining the waste sludge at 800 to 90 (rc) in the presence of a flux including ammonium salt, alkali metal salt, metal oxygen acid, metal oxide or alkaline earth metal salt. Recycling method of abrasives. [Claim 13]  The method of claim 12, wherein the flux comprises at least one selected from the group consisting of ammonium fluoride, ammonium chloride, sodium chloride, sodium fluoride, sodium hydroxide, potassium chloride, ammonium sulfate, boron oxide, barium chloride, boric acid and sodium borate Ceria-containing waste polishing material recycling method. [Claim 14]  The method of regenerating ceria-containing waste abrasive according to claim 12, wherein the flux is introduced in a washing step. . [Claim 15]  The method of regenerating ceria-containing waste abrasive according to claim 1, further comprising, after the firing step, grinding and classifying the ceria-containing recycled abrasive obtained from the calcined waste sludge. [Claim 16] The method of claim 15, wherein the grinding step is performed using a jet-mill Get-mill, the classification step is an EJ-ELBO classifier or classifier using a wind classifier, dry classifier, dipole or tripole Tip Method of regeneration of waste ceria-containing waste abrasive proceeds using a sieve for. [Claim 17]  The method for regenerating ceria-containing waste abrasive according to claim 1, wherein a ceria-containing regenerated abrasive having a crystal size of 60 to 90 nm and an average particle size of 0.5 to 3.0 / zm is obtained. [Claim 18]  The method for regenerating ceria-containing waste abrasive according to claim 1, wherein the ceria-containing waste sludge is derived from a ceria-containing abrasive used for polishing a glass substrate.