WO2014042494A1

WO2014042494A1 - Method for recycling waste abrasive material containing ceria

Info

Publication number: WO2014042494A1
Application number: PCT/KR2013/008449
Authority: WO
Inventors: 김종필; 조승범; 노준석; 곽익순
Original assignee: 주식회사 엘지화학
Priority date: 2012-09-17
Filing date: 2013-09-17
Publication date: 2014-03-20

Abstract

The present invention relates to a method for recycling a waste abrasive material containing ceria, which effectively removes impurities from the waste abrasive material containing ceria and ensures the safety of a recycling process, thus enabling the suitable recycling of the waste abrasive material containing ceria. The method for recycling waste abrasive material containing ceria comprises: a step of dissolving the waste sludge containing ceria (CeO₂) in a solvent solution comprising (a) a fluoride-based compound of NaHF₂, (NH₄)HF₂ or KHF₂, or (b) a mixture of sodium fluoride of NaF, (NH₄)F or KF and non-hydrofluoric acid-based acid; a step of cleaning the waste sludge containing ceria to remove the impurities containing silica (SiO₂) which were dissolved in the solvent solution; and a step of redispersing and filtering the cleaned waste sludge containing ceria, or drying and firing the cleaned waste sludge containing ceria.

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 relates to a method for regenerating ceria-containing waste abrasives that enables the appropriate regeneration of ceria-containing waste abrasives, while effectively removing impurities contained in ceria-containing waste abrasives.

Background Art

Recently, in the highly information society, we encounter a lot of information every day, and it can be said that the display role is very large as a medium for conveying this information to us. By the way, an alkali-free glass substrate is essentially used for display elements, such as a PDP, LCD, or this ED. The manufacturing method of the glass substrate for display is divided into a fusion method of dropping glass vertically and shaping and a floating method of forming glass like a steel product while pushing the glass horizontally. In general, the floating production method has the advantages of low initial investment cost and the ability to produce large glass substrates. However, since the glass substrates are produced by contacting tin materials during the molding process, the surface flatness and roughness are poor during the production process. It is difficult to produce the original glass as it is as a glass substrate for TV tube or liquid crystal panel. 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. Such characteristics are affected by the surface of the TFT-LCD glass substrate. It is known to receive. To this end, companies that produce glass substrates by the floating method are introducing a polishing process to improve the surface of the glass substrate, 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 have a certain time in glass polishing process. Thereafter, the waste is disposed of as sludge due to a decrease in the polishing efficiency, and thus, several techniques for recycling the abrasive have been investigated.

By the way, in the previously known method of recycling and regenerating ceria-containing abrasives, in order to remove impurities such as silica generated from polishing the glass substrate in the polishing process from the waste sludge, base materials such as NaOH and NH ₄ OH are dissolved. The method of using or the method of using the solvent solution containing hydrofluoric acid has been mainly applied. However, there is a problem in that the silica component contained in the waste slurry is not completely removed when the base material is used as a solvent. In addition, hydrofluoric acid is in a liquid state at room temperature and is an acidic and corrosive substance with strong smoke and toxicity. Therefore, the method using such hydrofluoric acid also has a problem that the economical efficiency and efficiency of the entire process, because the process stability is low, and equipment and conditions for suppressing the smoke is required.

Therefore, the hydrofluoric acid and the like. There is a continuous demand for the development of a process that can effectively and completely remove impurities contained in the waste abrasive materials and properly recycle and recycle the waste abrasive materials without using them. I [contents of invention]

Problem to be solved

Accordingly, the present invention can effectively remove impurities contained in ceria-containing waste abrasives without using hydrofluoric acid, thereby ensuring the stability of the regeneration process. Thus, a method for regenerating ceria-containing waste abrasives which enables proper regeneration of ceria-containing waste abrasives. To provide.

[Measures of problem]

The present invention comprises ceria (Ce0 ₂ ) -containing waste sludge (a) a fluorine-based compound of NaHF ₂ ᅳ (NH ₄ ) HF ₂ or KHF ₂ , or (b) a fluorine salt of NaF, (NH ₄ ) F or KF. Dissolving in a solubilizer solution comprising a mixture of non-fluoric acid; Cleaning the ceria-containing waste sludge to remove silica (SiO ₂ ) -containing impurities dissolved in a solvent solution; And re-dispersing and filtering the washed ceria-containing waste sludge, or drying and calcining. 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, the ceria (CeO ₂ ) containing waste sludge comprises (a) NaHF _2> (NH ₄ ) HF ₂ or a fluorine compound of KHF ₂ or (b) NaF, (NH ₄ ) F or Dissolving in a solvent solution comprising a fluorine salt of KF and a mixture of non-fluoric acid; Cleaning the ceria-containing waste sludge to remove silica (Si0 ₂ ) -containing impurities dissolved in a solvent solution; And redispersing and filtering the washed ceria-containing waste sludge, or drying and calcining.

In the ceria-containing waste abrasive regeneration method according to one 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. The ceria-containing abrasive may be recycled as a slurry (i.e., a regenerated abrasive in slurry) or may be dried and calcined to recover the ceria-containing abrasive as abrasive particles (powder). Powdery recycled abrasives).

In particular, in the regeneration method of one embodiment, as a solvent solution for dissolving impurities derived from the glass substrate or the like, a predetermined (a) fluorine-based compound, a predetermined (b) fluorine salt, and a non-fluoric acid-based compound instead of the previously used hydrofluoric acid A solution containing a mixture of acids is used. At this time, the "non-fluoric acid" used in the regeneration method of the embodiment refers to hydrochloric acid, sulfuric acid, or nitric acid, etc., which do not contain fluorine in its chemical structure, and the acid containing non-fluoric acid or other fluorine, which is conventionally used, is referred to as "non-fluoric acid. Excluded from the category of acidic acid ¹ '. Unless otherwise stated, "non-fluoric acid" is used in the sense described above.

As a result of the experiments of the present inventors, in the case of using a solubilizer solution containing a mixture of (a) a fluorine compound and (b) a fluorine salt and a non-fluoric acid acid, the solvent solution containing hydrofluoric acid is used. Impurities from glass substrates contained in waste sludge and waste abrasives, such as silica (SiO ₂ ) or It has been confirmed that alumina (Al ₂ 0 ₃ ) and the like can be completely dissolved or removed almost completely to near 100%. This is because the predetermined (a) fluorine-based compound, or the mixture of the predetermined (b) fluorine salt and the non-fluoric acid, may exhibit an ionization and dissociation state similar to hydrofluoric acid when dissolved in the solution of the solvent. .

In addition, the predetermined bloso-based compound, the predetermined fluorine salt, and the like have excellent stability as a solid state at room temperature before being added to the solvent solution, and do not substantially exhibit smokeability and toxicity.

Therefore, according to the regeneration method of one embodiment, it is possible to effectively and completely remove impurities contained in the ceria-containing waste abrasive material without using hydrofluoric acid, to ensure the stability of the regeneration process, to suppress the smokeability or toxicity of the solvent solution Since no separate equipment or conditions are required, the efficiency and economics of the entire regeneration process can be further improved.

Hereinafter, with reference to the drawings, a method of regenerating waste ceria-containing waste polishing material of one embodiment will be described in more detail in each step. For reference, FIG. 1 is a view schematically showing an example of a method of regenerating in a slurry state in each step of regeneration of ceria-containing waste abrasive according to one embodiment, and FIG. 2 is a waste-containing ceria-containing abrasive according to one embodiment. Is a diagram schematically illustrating an example of a method of regenerating in a powder state among the regeneration methods.

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 and the like include silica (SiO ₂ ) and alumina (Al ₂ 0 ₃ ) derived from a glass substrate as main impurities, and various organic substances derived from other polishing pads which have undergone polishing. It may be included as.

Therefore, in regenerating the ceria-containing waste sludge and the like, the step of removing the silica and alumina, the step of removing the pad-derived impurities, the surface properties of the ceria-containing abrasive, the particle size distribution and the crystal size, etc. It is necessary to proceed with the adjusting process.

Referring to FIG. 1, in the regeneration method of one embodiment, first, the waste sludge containing ceria (Ce0 ₂ ) comprises (a) NaHF ₂ , (NH ₄ ) HF _2, or a predetermined fluorine-based compound of KHF ₂ , or (b) NaF, (NH ₄₎ F or may be carried out a step for dissolving the agents solution containing the compound of the common bibul acid acid, such as a predetermined fluorine salt, sulfuric acid, nitric acid or hydrochloric acid in KF. As already mentioned above,

A mixture of (a) a fluorine compound and a predetermined (b) fluorine salt with a non-fluoric acid may exhibit an ionization and dissociation state similar to hydrofluoric acid when dissolved in a solution of the solubilizer, and thus the waste sludge and waste abrasive Impurities, such as silica (SiO ₂ ), alumina (Al ₂ O ₃ ), and the like, which are derived from glass substrates contained therein, may be completely or almost completely removed to almost 100%. In addition, such a solvent solution does not substantially dissolve ceria to be recycled as an abrasive from the waste sludge, and suppresses the loss of ceria together with impurities such as silica, thereby greatly increasing the regeneration rate of ceria. Moreover, such fluorine-based compounds, fluorine salts, and the like are solid at room temperature, and do not cause smoke and toxicity such as hydrofluoric acid, and can ensure the stability and safety of the entire regeneration process.

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 or alumina, etc. It can be dissolved by the solvent and separated from the waste sludge, and the ceria to be regenerated in this process is substantially insoluble in the solvent, so that pure ceria can be regenerated at a high regeneration rate.

In a more specific example, the solvent solution is a solvent component that selectively dissolves the silica-containing impurities contained in the ceria-containing waste sludge and does not dissolve the ceria to be regenerated. The above-mentioned (a) fluorine-based compound or (b) It may contain only a mixture of anti-inflammatory and non-fluoric acid, and may be substantially free of other types of solubilizer components such as hydrogen peroxide. When it contains other types of solubilizer components such as hydrogen peroxide, silica containing It is not suitable because it is difficult to selectively dissolve the impurities or some of the ceria to be regenerated may be dissolved.

That is, the (a) fluorine compound or (b) fluorine salt and the mixture of the non-fluoric acid can selectively dissolve the silmoca-containing impurities include those containing fluorine and hydrogen ion generating component together with the hydrofluoric acid and This may be due to similar ionization and dissociation states, but when other types of solubilizer components such as hydrogen peroxide (e.g., other types of solubilizers other than hydrogen ion generating components) are added, similar fluorination and dissociation in the solubilizer solution and It can be predicted because it is difficult to indicate the dissociation state.

On the other hand, considering the amount of impurities such as silica or alumina contained in the waste sludge, the amount of (a) fluorine-based compound or (b) fluorine salt and non-fluoric acid-based acid in the solubilizer solution can be appropriately adjusted. However, in order to effectively remove the silica, alumina and the like and impurities in the waste sludge used for polishing a conventional glass substrate for LCD, the (a) fluorine-based compound is based on the solids content of ceria contained in the waste sludge. about 0.1 to 40 increased _{^0/0, and} black is about 0.5 to 30 parts by weight, or from about ⁰ 1 to 25% by weight, graphite is included this is suitably in an amount of about 3 to 20 parts by weight ⁰ /. Solvent solution. In addition, even when using a mixture of the (b) fluorine salt and non-fluoric acid, the (b) fluorine salt and the non-fluoric acid are each about 0.1 to about 0.1 solids based on the solids content of ceria contained in the waste sludge. 40 parts by weight ⁰ /., or about 0.5 to 30 parts by weight ⁰ /., or may be included in the solution in an amount of from about 1 to about 25 solubilizing increased ^_0/0, or from about 3 to 20 increased ^_0/0.

If the content of each component of the solution of the solvent solution is too low, the removal efficiency of impurities may be lowered. On the contrary, if the content is too high, the amount of raw water may be unnecessarily increased and the washing process may be increased, thereby increasing the amount of waste water.

On the other hand, after dissolving the ceria-containing waste sludge in a predetermined solvent solution, such waste sludge can be washed to remove silica-containing impurities from the waste sludge. At this time, before the cleaning process or during the cleaning process, The method may further include a step of solid-liquid separation by treating the waste sludge treated with the solvent solution by a method such as centrifugation, filtration, or sedimentation.

When the solid-liquid separation 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, deionized water, water or The impurity may be more completely removed through the progress of the cleaning process using other aqueous solvents.

In this case, the centrifugal separation, filtration or sedimentation process may be performed by separating the ceria-containing waste sludge from which impurities are removed by a conventional centrifugation process and the liquid component containing impurities (centrifugal separation process), or the ceria from which the impurities are removed. Sediment containing waste sludge is sedimented to separate liquid components containing impurities (sedimentation process), or filtering and separating liquid components containing impurities from ceria containing waste sludge from which the impurities are removed using a filter or the like (filtration process You can proceed by such a method. It is of course also possible to combine two or more of these during centrifugation _: filtration or sedimentation.

In addition, in the washing step using the aqueous solvent, in order to more effectively wash and remove impurities dissolved in the solvent solution, it can proceed to the aqueous medium adjusted to pH 1 to 4 or pH 10 to 14. In order to properly adjust the pH, an acid or a base may be appropriately dissolved in the water or deionized water and used as a washing liquid.

On the other hand, after the cleaning process, as shown in FIG. 1, the washed ceria-containing waste sludge may be redispersed and filtered, or as shown in FIG. 2, the waste sludge may be dried and calcined. . When the redispersion and filtration process is carried out, the ceria-containing waste abrasive material can be regenerated as a slurry state, for example, as an aqueous slurry state, and when the drying and firing process is performed, the ceria-containing waste abrasive material is polished in the form of abrasive particles (powder). Can play.

In as the dispersion material containing the cleaned ceria waste sludge, based on the solids content of the ceria contained in the waste sludge, the dispersing agent was added at about 0.1 to 5 parts by weight ^_0/0, it can be re-dispersed by using a wet milling have. after, Absolute filter can be used to remove impurities from the back pad or polishing pad included in the waste sludge, and to recycle the waste abrasive in the slurry state. On the other hand, in the drying and firing, first, the water used in the above-described solvent solution treatment process and cleaning process can be dried and removed from the waste sludge from which the impurities are removed, and the waste sludge thus dried It may be dried to have a water content of 1% by weight or less, or about 0-1% by weight ⁰ /.

This drying process may proceed with an oven dryer or compact disc dreyer. Among these, 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 the CD dryer, the CD dryer is used to remove the grains between the abrasive particles (for example, ceria particles) during the drying process. It is possible to suppress the production of macroparticles, thereby suppressing 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 at a temperature of about 100 to 200 ^° C for about 10 to 30 seconds, or on a CD dryer rotated at about 1 to 10 rpm, black to about 5 to 10 rpm, about 100 to 20 CTC Can proceed for about 10 to 30 seconds. 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, ， Drying process may not be done efficiently.

In contrast, when the drying process is performed under optimized conditions, the regenerated ceria-containing regenerated abrasive may have an appropriate average particle size of about 1.0 to 3.0 / im, and the formation of large particles of about 6.0 or more is suppressed, thereby reducing the possibility of scratching. as well, the drying proceeds efficiently water content of about 1 weight ^_0/0 The following abrasive abrasive materials can be obtained easily.

On the other hand, after the drying process described above, as shown in Figure 2, in the presence of a flux containing ammonium salt, alkali metal salt, metal oxide or alkaline earth metal salt, the dried waste sludge is about 800 to 1200 ^° C, or about 800 to 100 (rc, black can be fired at about 800 to 90 C C. Through this firing process, the surface and crystal properties of the ceria-containing abrasive contained in the waste sludge It can be recovered and the polishing rate of the regenerated abrasive can be increased, and impurities such as various organic substances derived from the pad can be removed.

At this time, the flux is from about 1 to 3.0 parts by weight ^_0/0 relative to the weight of the disposed sludge which is reproduced, the black is in the range of about 1 to 2.0 parts by weight ^_0/0, or about 1 to 1.5 parts by weight ⁰ /. Contents coming be used ¾ of have. As the use amount of such flux and the above-described firing temperature are appropriately adjusted, the particle size distribution and crystal size of the reclaimed abrasive are appropriately adjusted to the crystal size of about 1.0 to 3.0 and about 70 to 90 nm, respectively, The generation of particles can be suppressed, so that 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 above-described firing process, the flick may be 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 or barium chloride; It may be a metal oxide such as boron oxide, or two or more selected from them may be used together. According to the use of such flux, after the firing process, the surface characteristics or crystal characteristics of the recycled abrasive can be adjusted to a desirable range.

And, as already described above, the flux may be wet mixed in the previous cleaning step, or dry mixed immediately before the firing process, and may be wet mixed in the cleaning step, as appropriate. In addition, the firing step may be performed for about 1 to 4 hours at the above-mentioned temperature.

Through the progress of the optimized firing process described above, crystals of about 70 to 90 nm A ceria containing regenerated abrasive having a size and an average particle size of about 1.0 to Omi and in which formation of large particles is suppressed can be obtained. If the crystal size or the average particle size is too small, the polishing rate of the recycled abrasive may not be sufficient. On the contrary, if the crystal size or the average particle size is too large, scratches may occur in the polishing process using the recycled 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 is, if necessary or reduce the particle size distribution or grain size of the reproduction abrasives, to proceed further the _yae grinding or classification step to eliminate large particles, and these grinding and classification process are those of ordinary skill in the art You can proceed in a manner well known to For example, the grinding process may be performed using a jet-mill, etc., and the classification process may be performed using a wind classifier such as a cyclone or a sieve for classification.

According to the above-described regeneration method, impurities derived from the glass substrates are removed substantially completely effectively, and stability, stability, and efficiency of the overall processability can be ensured by not using hydrofluoric acid. In addition, by the regeneration method, a ceria-containing regenerated abrasive which not only shows an optimized crystal size and particle size distribution but also suppresses the generation of large particles even before the grinding or classification process can be obtained. Therefore, such ceria-containing regenerated abrasives can be used alone or in combination with new abrasives, and can be recycled for polishing of glass substrates for LCDs, etc., which can contribute greatly to the economics and yield of the process.

【Effects of the Invention】

According to the present invention, there can be provided a method for regenerating ceria-containing waste abrasives, in which the stability of the regeneration process is ensured by effectively removing impurities from the glass substrate contained in the ceria-containing waste abrasives without using hydrofluoric acid. Especially, When the regeneration method of the present invention is applied, no additional equipment or conditions for suppressing the smokeability or toxicity of the dissolving agent solution such as hydrofluoric acid are required, and thus the efficiency and economic efficiency of the entire regeneration process can be further improved.

[Brief Description of Drawings]

1 is a view schematically showing an example of a method of regenerating in a slurry state in the method of regenerating waste material containing ceria according to one embodiment for each step.

2 is a view schematically showing an example of a method of regenerating in a powder state of the regeneration method of ceria-containing waste abrasive according to one embodiment. [Specific contents to carry out invention]

Hereinafter, preferred embodiments are presented to help understand 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

500 g of waste sludge containing ceria (Ce0 ₂ ) with a ceria solid content of 13 weight ⁰ /。 was added to a Nalgene Bottle, NaHF ₂ was added at a concentration of 3 weight ⁰ /。 to the ceria solid content, followed by stirring with a magnetic stirrer. While the silica was dissolved. In order to remove the dissolved silica solution, the resultant was centrifuged with a centrifugal separator (product name: Supra22K, Hanil Seded Co., Ltd.), solid-liquid separation was performed, and the waste sludge was washed with deionized water to remove impurities from glass substrates such as silica and alumina. It was separated and removed from the waste sludge. An ion conductivity analyzer (IC meter, Thermo Scientfic's 3STAR) was used to analyze the degree of cleaning of the sludge. After drying the washed sludge at 105 ^° C in an oven dryer, an inductively coupled plasma emission spectrometer ICP-OES (lnductively Coupled Plasma-Optical Emission Spectrometer, OPTIMA 7300DV, Perkin-lmer) was used to analyze the silica content. And analyzed. The results thus analyzed are shown in Table 1. Example 2: Regeneration of Ceria-Containing Waste Abrasives

The regeneration slurry of Example 2 was obtained in the same manner as in Example 1 except that the amount of NaHF ₂ added was 5 weights ⁰ /. Example 3: Regeneration of Ceria-containing Waste Abrasives

The regeneration slurry of Example 3 was obtained in the same manner as in Example 1 except that the amount of NaHF ₂ added was 10 wt. Example 4 Regeneration of Ceria-Containing Waste Abrasives

The regenerated slurry of Example 4 was obtained in the same manner as in Example 2, except that (NH ₄ ) HF ₂ was added instead of NaHF ₂ . Example 5 Regeneration of Ceria-Containing Waste Abrasives

The regeneration slurry of Example 5 was obtained in the same manner as in Example 2, except that KHF ₂ was added instead of NaHF ₂ . Example 6: Regeneration of Ceria-containing Waste Abrasives

NaHF ₂ instead of Na ₄ F and sulfuric acid, respectively 5% by weight and 5 parts by weight ⁰ /., Except that the addition of an amount of Example 1 to obtain a reproduction abrasive of Example 6 in the same manner. Example 7: Regeneration of Ceria-containing Waste Abrasives

NaHF ₂ instead of the NH ₄ F and the sulfuric acid are respectively 5 weight ⁰ /., And except for the addition of an amount of increase of 5 ^_0/0 in Example 1 to obtain a reproduction abrasive of Example 7 in the same manner. Example 8: Regeneration of Ceria-Containing Waste Abrasives

NaHF ₂ instead of KF and sulfuric acid, respectively 5 in Example 1, with the reproduction of Example 8 in the same manner except that the addition in an amount of ⁰ parts by weight / 5 parts by weight ₀ and ^_0/0 An abrasive was obtained. Comparative Example 1 Regeneration of Ceria-Containing Waste Abrasives

A regenerated abrasive of Comparative Example 1 was obtained in the same manner as in Example 2, except that hydrofluoric acid was used instead of NaHF ₂ . Comparative Example 2: Regeneration of Ceria-Containing Waste Abrasives

A recycled abrasive of Comparative Example 2 was obtained in the same manner as in Example 2, except that sulfuric acid was used instead of NaHF ₂ . Comparative Example 3: Regeneration of Ceria-Containing Waste Abrasives

The regenerated abrasive of Comparative Example 3 was obtained in the same manner as in Example 2, except that Na ₂ F was used instead of NaHF ₂ . Comparative Example 4: Regeneration of Ceria-Containing Waste Abrasives

The regenerated abrasive of Comparative Example 4 was obtained in the same manner as in Example 2, except that NH ₄ F was used instead of NaHF ₂ . Comparative Example 5: Regeneration of Ceria-Containing Waste Abrasives

The regenerated abrasive of Comparative Example 5 was obtained in the same manner as in Example 2, except that KF was used instead of NaHF ₂ . Test Example: Measurement of Properties of Ceria-Contained Recycled Abrasive

1. Determination of the impurities content of silica and alumina: Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) for the analysis of silica content after drying the washed waste sludge at 105 ^° C in Aubon dryer. , OPTIMA 7300DV, Perkin-lmer). The results thus analyzed are shown in Table 1.

TABLE 1

2. Determination of the amount of smoke derived from the solution of the solvent during the regeneration process: In order to analyze the amount of fluorine gas generated by reaction of NaHF ₂ and SiO ₂ , ₂ kg of ceria waste sludge containing 0.15% of Si was placed in a container and weighed 3.3 NaHF _2. The solution was added to a solvent solution containing 。/。 and reacted for 1 hour while stirring. At this time, in order to collect the fluorine gas generated during the reaction, the gas was collected using a 1 L Tedlar Bag (SUPELCO Analytical, USA) in a sealed container. In order to analyze the F gas in the collected gas, it was analyzed using the Quadrupole Mass Spectrometer of Korea Research Institute of Standards and Science. This proves that when NaHF ₂ and silica are used to dissolve silica, unlike fluoric acid, fluorine gas is not fumed and work stability is high.

3. Measurement of Polishing Rate of Recycled Abrasives: The 8th generation glass substrate polishing evaluation of the slurry recycled in the same manner as in Example 2 was carried out in LG Chem's Paju LCD Glass Division production line. As a result, the polishing rate is more than 95% of new abrasives As a result of analyzing the defects generated after polishing, the final inspection defect and OPC (Offline Particle Count) values were implemented more than 80% of new abrasive materials as shown in Table 2 below. . TABLE 2

Claims

[Patent Claims]

[Claim 1]

Ceria (Ce0 ₂ ) containing waste sludge contains (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 Dissolving in a solvent solution comprising a mixture of acids;

Washing the ceria-containing waste sludge to remove silica (Si0 ₂ ) -containing impurities dissolved in a solvent solution; And

Re-dispersing and filtering the dried ceria-containing waste sludge, or drying and calcining.

[Claim 2]

The method for regenerating ceria-containing waste abrasive according to claim 1, wherein the ceria (Ce0 ₂ ) -containing waste sludge contains silica and alumina as impurities.

[Claim 3]

The method for regenerating ceria-containing waste abrasive according to claim 1, wherein the solvent solution is (a) an aqueous solution containing a fluorine compound or (b) an aqueous solution containing a mixture of the fluorine salt and a non-fluoric acid.

[Claim 4]

The method of claim 1, wherein the non-fluoric acid includes at least one selected from the group consisting of hydrochloric acid, nitric acid, and sulfuric acid.

[Claim 5]

The mixture of claim 1, wherein the solubilizer solution is a solubilizer component for selectively dissolving silica-containing impurities contained in the ceria-containing waste sludge and a mixture of the (a) fluorine-based compound or (b) fluorine salt with a biblic acid-based acid. A method for regenerating waste ceria-containing abrasives containing only bay.

[Claim 6]

The method of regenerating ceria-containing waste abrasive according to claim 3, wherein the solvent solution comprises 0.1 to 40% by weight of (a) fluorine-based compound based on the solids content of ceria contained in the waste sludge.

[Claim 7]

4. The method of claim 3 wherein the solubilizing solution is based on the solid content of the ceria contained in the sludge, (b) ceria-containing waste containing a fluoride salt and a content of the bibul acid acid, respectively 0.1 to 40 parts by weight ⁰ /. Recycling method of abrasives.

[Claim 8]

The method of regenerating ceria-containing waste abrasive according to claim 1, further comprising a solid-liquid separation step by centrifugation, filtration or sedimentation before the washing step.

[Claim 9]

The method of claim 1, wherein the washing step is pH 1 to 4 or pH 10 to

14. A method for regenerating ceria-containing waste abrasive which proceeds with a solvent adjusted to 14.

[Claim 10]

The regeneration of the ceria-containing waste abrasive product according to claim 1, wherein the ceria-containing regenerated abrasive material in a slurry state is produced by the redispersion and filtration ^. Way.

[Claim 11]

2. The method for regenerating ceria-containing waste abrasive according to claim 1, wherein the ceria-containing regenerated abrasive in an abrasive powder state is produced by the drying and firing.

[Claim 12] The method of claim 1, wherein the drying step is performed in an oven dryer or a compact disc dryer.

[Claim 13]

The method of claim 1, wherein the drying step is performed at a temperature of 100 to 200 ^° C. in an Aubon dryer or at 1 to 10 rpm in a CD dryer for 10 to 30 seconds.

[Claim 14]

The method of claim 1, wherein the firing step, regeneration of the ceria-containing waste abrasive material is carried out by firing the waste sludge at 800 to 1200 ^° C, in the presence of a flux containing ammonium salt, alkali metal salt, metal oxide or alkaline earth metal salt. Way.

[Claim 15]

15. The waste abrasive according to claim 14, 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 and barium chloride. How to play.

[Claim 16]

15. The method of claim 14, wherein the flux is introduced in the washing step.

[Claim 17]

The method for regenerating ceria-containing waste abrasive according to claim 1, further comprising the step of pulverizing and classifying the ceria-containing regenerated abrasive obtained from the calcined waste sludge after the firing step.

[Claim 18]

18. The method of claim 17, wherein the grinding step is carried out using a jet-mill.

[Claim 19]

The method for regenerating ceria-containing waste abrasive according to claim 1, wherein a ceria-containing regenerated abrasive having a crystal size of 70 to 90 nm and an average particle size of 1.0 to 3.0 is obtained.

[Claim 20]

The method for regenerating ceria-containing waste abrasive according to claim 1, wherein the ceria-containing waste sludge is a gun derived from a ceria-containing abrasive used for polishing a glass substrate.