# US 2008/0187475 A1 · Process for the Production of Titanium Dioxide Using Aqueous Fluoride

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- Number: US 2008/0187475 A1
- Document ID: US20080187475A1
- Status: Published application
- Kind: A1
- Application number: 11/813,919
- Filed: 2006-01-16
- Published: 2008-08-07
- Earliest claimed: 2005-01-24
- Assignees: Breton SPA
- Inventors: Pavel S. Gordienko
- Web page: https://patentgrep.com/patent/US20080187475A1

## CPC

- C01G 23/053: Producing by wet processes, e.g. hydrolysing titanium salts
- C09C 1/24: Oxides of iron
- C09C 1/3607: {Titanium dioxide}
- C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer
- Y02P 10/20: Recycling
- 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)
- C09C: TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES (treatment of materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone C04B14/00, C04B18/00, C04B20/00); PREPARATION OF CARBON BLACK {; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS}
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A process is described for the production of titanium dioxide by the treatment with ammonium fluoride of titanium ores containing iron; the process comprises the following steps: (a) the titanium ore containing iron is reacted with an aqueous NH4F and/or NH4HF2 solution; (b) the aqueous dispersion thus obtained is filtered with consequent separation of a solid residue and an aqueous solution containing titanium salts; (c) the aqueous solution thus obtained is subjected to hydrolysis, the hydrolysis comprising a first stage at pH 7.0-8.5 and a second stage at pH 10.0-13.0; (d) the aqueous dispersion thus obtained is filtered and the solid residue is subjected to pyrohydrolysis, the pyrohydrolysis comprising a first stage at a maximum temperature of 450° C. and a second stage at a maximum temperature of 1000° C.

## Claims

### Claim at position 1

1-24. (canceled)

### Claim 25

A process for the production of titanium dioxide comprising the following steps:
(a) a titanium ore containing iron is reacted with an aqueous NH4F and/or NH4HF2 solution;
(b) the aqueous dispersion thus obtained is filtered with consequent separation of a solid residue and an aqueous solution containing titanium salts;
(c) the aqueous solution thus obtained is subjected to hydrolysis, the hydrolysis comprising a first stage at pH 7.0-8.5 and a second stage at pH 10.0-13.0;
(d) the aqueous dispersion thus obtained is filtered and the solid residue is subjected to pyrohydrolysis, the pyrohydrolysis comprising a first stage at a maximum temperature of 450° C. and a second stage at a maximum temperature of 1000° C.

### Claim 26 (depends on 25)

A process according to claim 25, wherein step (a) is performed at 100-120° C., preferably about 108° C.

### Claim 27 (depends on 25)

A process according to claim 25, wherein step (a) is performed at a pressure of about 1-2 bar.

### Claim 28 (depends on 25)

A process according to claim 25 wherein step (a) is performed at a pH of about 6.5-7.0.

### Claim 29 (depends on 25)

A process according to claim 25, wherein step (a) has a duration of 40 to 80 minutes.

### Claim 30 (depends on 25)

A process according to claim 25, wherein the aqueous NH4F and/or NH4HF2 solution of step (a) has a concentration of 30-60% by weight, preferably about 45%.

### Claim 31 (depends on 25)

A process according to claim 25, wherein the filtration of step (b) and/or step (d) is performed with meshes having 2-3 nm holes, preferably approximately 2.5 nm holes.

### Claim 32 (depends on 25)

A process according to claim 25, wherein the hydrolysis (c) is performed by the addition of an ammonium hydroxide solution.

### Claim 33 (depends on 25)

A process according to claim 25, wherein the hydrolysis (c) is performed with stirring, the first stage at a speed of 40-60 revolutions/ minute, preferably at about 50 revolutions/minute, the second stage at about 10 revolutions/minute.

### Claim 34 (depends on 25)

A process according to claim 25, wherein the first stage of the hydrolysis (c) is performed at a pH of about 7.5-8.0.

### Claim 35 (depends on 25)

A process according to claim 25, wherein the second stage of the hydrolysis (c) is performed at a pH of about 11-12.

### Claim 36 (depends on 25)

A process according to claim 25, wherein the dispersion obtained from the first stage of the hydrolysis (c) is filtered to give an aqueous solution containing the titanium salt (NH4)2TiF6 and having a (NH4)3FeF6 concentration lower than 0.01% by weight, preferably lower than 0.001%, and a sludge fraction containing ammonium oxyfluorotitanate and (NH4)3FeF6.

### Claim 37 (depends on 36)

A process according to claim 36, wherein said aqueous solution is subjected to the second stage of the hydrolysis (c).

### Claim 38 (depends on 36)

A process according to claim 36, wherein said sludge fraction, upon dissolution, is recirculated in addition to the output flow from step (a).

### Claim 39 (depends on 25)

A process according to claim 25, wherein the first stage of the pyrohydrolysis (d) is performed at about 340-400° C.

### Claim 40 (depends on 25)

A process according to claim 25, wherein the first stage of the pyrohydrolysis (d) is performed at about 360-380° C.

### Claim 41 (depends on 25)

A process according to claim 25, wherein the first stage of the pyrohydrolysis (d) is performed for 1-3 hours, preferably for about 2 hours.

### Claim 42 (depends on 25)

A process according to claim 25, wherein the second stage of the pyrohydrolysis (d) is performed at 700-900° C.

### Claim 43 (depends on 25)

A process according to claim 25, wherein the second stage of the pyrohydrolysis (d) is performed at 750-850° C., preferably at about 800° C.

### Claim 44 (depends on 25)

A process according to claim 25, wherein the second stage of the pyrohydrolysis (d) is performed for 60-180 minutes, preferably for about 90-120 minutes.

### Claim 45 (depends on 25)

A process according to claim 25, wherein the solid residue of step (b) is subjected to pyrohydrolysis at a maximum temperature of 450° C., preferably at 340-400° C.

### Claim 46 (depends on 25)

A process according to claim 25, wherein the solid residue of step (b) is subjected to pyrohydrolysis at 360-380° C.

### Claim 47 (depends on 45)

A process according to claim 45, wherein the pyrohydrolysis is performed for 2-4 hours, preferably for 3 hours.

### Claim 48 (depends on 25)

A process according to claim 25, wherein the titanium ore containing iron is ilmenite, preferably with an average particle size of 0.05-1.5 mm, even more preferably of about 0.1 mm.