# US 2013/0152483 A1 · Method for recovery of cerium oxide

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- Number: US 2013/0152483 A1
- Document ID: US20130152483A1
- Status: Published application
- Kind: A1
- Application number: 13/717,905
- Filed: 2012-12-18
- Published: 2013-06-20
- Earliest claimed: 2011-12-19
- Assignees: Shin-Etsu Chemical Co., Ltd.
- Inventors: Harunobu Matsui; Daijitsu Harada; Masaki Takeuchi
- Web page: https://patentgrep.com/patent/US20130152483A1

## CPC

- C09K 3/1409: {Abrasive particles per se (preparation of diamond C01B32/25)}
- C01F 17/235: Cerium oxides or hydroxides
- C09G 1/02: containing abrasives or grinding agents {(abrasives as such C09K3/14; polishing of semi-conductors H10P52/40)}
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00})
- C09G: POLISHING COMPOSITIONS (French polish C09F11/00); SKI WAXES

## Abstract

A method for recovery of cerium oxide from the abrasive waste composed mainly of cerium oxide arising from the polishing of glass substrates, said method including the steps of (i) adding to the abrasive waste an aqueous solution of a basic substance; (ii) adding to the resulting solution a precipitant, thereby forming precipitates composed mainly of cerium oxide, and removing the supernatant liquid; (iii) adding to the resulting precipitates a solution of an acid substance, thereby making said precipitate slightly acid to neutral; (iv) washing the precipitates with an organic solvent; and (v) drying and crushing the precipitates. The method makes it possible to recycle abrasive waste into a pure abrasive composed mainly of cerium oxide which can be reused to polish synthetic quartz glass substrates for state-of-the-art semiconductor technology relating to photomasks and reticles.

## Claims

### Claim 1

A method for recovery of cerium oxide from the abrasive waste composed mainly of cerium oxide which arises from the polishing of glass substrates, said method comprising the steps of:
(i) adding to the abrasive waste an aqueous solution of a basic substance;
(ii) adding to the resulting solution a precipitant, thereby forming precipitates composed mainly of cerium oxide, and removing the supernatant liquid;
(iii) adding to the resulting precipitates a solution of an acid substance, thereby making said precipitate slightly acid to neutral;
(iv) washing the resulting precipitates with an organic solvent; and
(v) drying and crushing the precipitates.

### Claim 2 (depends on 1)

The method for recovery of cerium oxide of claim 1, wherein the aqueous solution of a basic substance is that of sodium hydroxide having at least pH 12.

### Claim 3 (depends on 1)

The method for recovery of cerium oxide of claim 1, wherein the precipitant is one selected from aluminum sulfate and polyaluminum chloride.

### Claim 4 (depends on 1)

The method for recovery of cerium oxide of claim 1, wherein the acid substance is one selected from acetic acid, carbonic acid, dilute nitric acid, and dilute hydrochloric acid.

### Claim 5 (depends on 1)

The method for recovery of cerium oxide of claim 1, wherein the organic solvent is methanol.