# US 10,479,691 B2 · Method for recovering silica from silica-containing plant body using titanium oxide

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- Number: US 10,479,691 B2
- Document ID: US10479691B2
- Status: Granted
- Kind: B2
- Application number: 15/306,765
- Filed: 2015-03-31
- Published: 2017-04-27
- Granted: 2019-11-19
- Earliest claimed: 2014-04-01
- Assignees: Rapas Corporation
- Applicants: Rapas Corporation
- Inventors: Keiko Kitamura; Itsushi Kashimoto; Masahiro Nishimura
- Web page: https://patentgrep.com/patent/US10479691B2

## CPC

- C01B 33/18: Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof (preparation of aerogels by dehydrating gels C01B33/158; treatment to enhance the pigmenting or filling properties C09C)
- B01J 21/063: {Titanium; Oxides or hydroxides thereof}
- B01J 23/72: Copper
- B01J 35/31: Density
- B01J 35/613: {10-100 m2/g}
- B01J 35/633: {less than 0.5 ml/g}
- B01J 35/635: {0.5-1.0 ml/g}
- B09B 3/35: Shredding, crushing or cutting
- B09B 3/40: involving thermal treatment, e.g. evaporation (processes using mineral binders involving a melting or softening step B09B3/29; involving radiation B09B3/50)
- B09B 3/70: Chemical treatment, e.g. pH adjustment or oxidation (involving an extraction step B09B3/80)
- C01G 23/053: Producing by wet processes, e.g. hydrolysing titanium salts
- C01G 23/08: Drying; Calcining {; After treatment of titanium oxide}
- B01J 35/30: characterised by their physical properties
- C01P 2004/32: Spheres
- C01P 2004/51: Particles with a specific particle size distribution
- C01P 2004/60: Particles characterised by their size
- C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer
- C01P 2006/11: Powder tap density
- C01P 2006/12: Surface area
- C01P 2006/14: Pore volume
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B09B: DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; 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 cyanamide C01C3/16; thiocyanates C01C3/20)
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

Rice straw and chaff that are discharged as agricultural waste in large amounts are effectively utilized. The present invention has been completed on the basis of the finding that silica can be recovered with high efficiency by bringing heated titanium oxide into contact with a silica-containing plant body.

## Claims

### Claim 1

A recovery method for silica, comprising bringing heated titanium oxide comprising titanium oxide granules into contact with a silica-containing plant body to obtain said silica, wherein the silica is 98% (wt) or more soluble silica and wherein the titanium oxide granules have the following characteristic (1) or (2):
(1) a particle size distribution in the following range:
titanium oxide granules each having a particle size of 1.2 mm or more account for from 1 wt % to 50 wt %;
titanium oxide granules each having a particle size of from 0.5 mm to 1.2 mm account for from 40 wt % to 90 wt %; and
titanium oxide granules each having a particle size of 0.5 mm or less account for from 1 wt % to 20 wt %; or
(2) a particle size distribution in the following range:
titanium oxide granules each having a particle size of 1.2 mm or more account for from 10 wt % to 60 wt %; and
titanium oxide granules each having a particle size of from 0.5 mm to 1.2 mm account for from 40 wt % to 90 wt %.

### Claim 2 (depends on 1)

A recovery method according to claim 1, wherein the silica-containing plant body is in the absence of any acid pre-treatment and comprises any one of chaff, unhulled rice, straw, and bran.

### Claim 3 (depends on 1)

A recovery method according to claim 1, wherein the contact comprises stirring the silica-containing plant body together with the heated titanium oxide.

### Claim 4 (depends on 1)

A recovery method according to claim 1, wherein a heating temperature of the titanium oxide falls within a range of from 300° C. to 700° C.

### Claim 5 (depends on 1)

A recovery method according to claim 1, wherein the titanium oxide granules have the following characteristics:
(1) the granules each have a substantially spherical shape; and
(2) granules each having a particle diameter of from 0.2 mm to 1.2 mm account for 70% or more of all the granules.

### Claim 6 (depends on 5)

A recovery method according to claim 5, wherein the characteristic “the granules each have a substantially spherical shape” comprises the following characteristics:
(1) an angle at which a granule first starts rolling is from 0.5° to 15.0°; and
(2) an angle at which all the granules finishes rolling is from 2.0° to 30.0°.

### Claim 7 (depends on 1)

A recovery method according to claim 1, wherein the granules each have a specific surface area in a range of from 30 m2/g to 70 m2/g.

### Claim 8 (depends on 1)

A recovery method according to claim 1, wherein the granules each have a tap density in a range of from 1.00 g/mL to 1.80 g/mL.

### Claim 9 (depends on 1)

A recovery method according to claim 1, wherein the granules each have a pore volume in a range of from 0.10 cc/g to 0.60 cc/g.

### Claim 10 (depends on 1)

A recovery method according to claim 1, wherein the titanium oxide granules have the following characteristic:
(1) the titanium oxide granules include titanium oxide granules obtained by drying a sol of titanium oxide to produce a titanium oxide gel, calcining the titanium oxide gel at a temperature in a range of from 450° C. to 850° C., and crushing the calcined product, followed by edge treatment, include particles each having a particle diameter of from 0.5 mm to 1.18 mm at a ratio in a range of from 50 wt % to 95 wt %, and each have a wear ratio of 2.0% or less.

### Claim 11 (depends on 1)

A recovery method according to claim 1, wherein the titanium oxide granules have copper oxide or copper supported thereon.

### Claim 12 (depends on 11)

A recovery method according to claim 11, wherein an amount of the copper oxide to be supported is from 0.5 wt % to 5.0 wt % in terms of copper oxide.

### Claim 13 (depends on 1)

The recovery method according to claim 1, further comprising separating the silica from the heated titanium oxide with a sieve.