# US 9,038,931 B2 · Process for preparing aluminium trihydroxide

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- Number: US 9,038,931 B2
- Document ID: US9038931B2
- Status: Granted
- Kind: B2
- Application number: 13/817,454
- Filed: 2011-08-12
- Published: 2013-11-07
- Granted: 2015-05-26
- Earliest claimed: 2010-08-18
- Assignees: Nabaltec AG
- Applicants: Alfred Reimer; Carsten Ihmels; Christian Beer
- Inventors: Alfred Reimer; Carsten Ihmels; Christian Beer
- Web page: https://patentgrep.com/patent/US9038931B2

## CPC

- C08K 7/00: Use of ingredients characterised by shape
- C01F 7/023: Grinding, deagglomeration or disintegration
- C09C 1/407: {Aluminium oxides or hydroxides}
- C09K 21/02: Inorganic materials
- C01P 2004/52: highly monodisperse size distribution
- C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer
- C01P 2006/12: Surface area
- C01P 2006/82: water content
- Y10T 428/2982: Particulate matter [e.g., sphere, flake, etc.]
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- 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})
- 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}
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The invention relates to a process for the milling-drying of a raw mixture containing aluminum trihydroxide having an average particle size D50 in the range from 50 to 130 μm and a specific BET surface area in the range from 0.01 to 0.5 m2/g and containing from 0.1 to 20% by weight of water, based on the raw mixture, which including the steps i) introduction of the raw mixture into a milling-drying apparatus, ii) introduction of a hot air stream having a temperature in the range from 20 to 100° C. into the milling-drying apparatus so as to flow through the milling-drying apparatus and iii) comminution of the aluminum trihydroxide present in the raw mixture in the milling-drying apparatus.

## Claims

### Claim 1

A process for the milling-drying of a raw mixture containing aluminum trihydroxide having an average particle size D50 in the range from 50 to 130 μm and a specific BET surface area in the range from 0.01 to 0.5 m2/g and containing from 0.1 to 20% by weight of water, based on the raw mixture, which comprises the steps
i) introduction of the raw mixture into a milling-drying apparatus,
ii) introduction of a hot air stream having a temperature in the range from 20 to 150° C. into the milling-drying apparatus so as to flow through the milling-drying apparatus and
iii) comminution of the aluminum trihydroxide present in the raw mixture in the milling-drying apparatus.

### Claim 2 (depends on 1)

The process as claimed in claim 1, wherein the raw mixture contains aluminum trihydroxide and from 3 to 15% by weight of water, based on the raw mixture.

### Claim 3 (depends on 1)

The process as claimed in claim 1, wherein the raw mixture contains aluminum trihydroxide having an average particle size D50 in the range from 90 to 110 μm.

### Claim 4 (depends on 1)

The process as claimed in claim 1, wherein the milling-drying apparatus contains a rotor-stator system and the rotor has a circumferential velocity in the range from 20 to 200 m/s.

### Claim 5 (depends on 1)

The process as claimed in claim 1, wherein the aluminum trihydroxide present in the raw mixture has an average residence time in the milling-drying apparatus in the range from 0.01 to 1 second.

### Claim 6 (depends on 1)

The process as claimed in claim 1, wherein steps i), ii) and iii) proceed simultaneously and the process is carried out continuously.

### Claim 7 (depends on 1)

The process as claimed in claim 1, wherein the hot air stream forms a turbulent flow having a Reynolds number of greater than 3000 in the milling apparatus.