# US 2010/0076140 A1 · Grinding and Beneficiation of Brucite

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- Number: US 2010/0076140 A1
- Document ID: US20100076140A1
- Status: Published application
- Kind: A1
- Application number: 12/513,502
- Filed: 2007-11-05
- Published: 2010-03-25
- Earliest claimed: 2006-11-06
- Assignees: Imerys Minerals Limited
- Inventors: Mark Barry Windebank; David Robert Skuse; Scott Palm; Jeremy John Hooper
- Web page: https://patentgrep.com/patent/US20100076140A1

## CPC

- C01F 5/14: Magnesium hydroxide
- C09C 1/028: {Compounds containing only magnesium as metal}
- C09K 21/02: Inorganic materials
- H01B 7/295: using material resistant to flame
- C01P 2004/51: Particles with a specific particle size distribution
- C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer
- C01P 2004/62: Submicrometer sized, i.e. from 0.1-1 micrometer
- C01P 2006/12: Surface area
- C01P 2006/60: Optical properties, e.g. expressed in CIELAB-values
- 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
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

The invention provides a method for preparing particulate brucite comprising grinding and beneficiating particulate brucite wherein the ground beneficiated particulate brucite has a d90 of less than or equal to about 6.4 μm as measured by laser light scattering.

## Claims

### Claim 1

A method for preparing particulate brucite comprising grinding and beneficiating particulate brucite wherein the ground beneficiated particulate brucite has a d90 of less than or equal to about 6.4 μm as measured by laser light scattering.

### Claim 2 (depends on 1)

A method according to claim 1, wherein beneficiation of the brucite takes place before and/or during and/or after the particulate brucite is ground.

### Claim 3 (depends on 2)

A method according to claim 2 wherein beneficiation takes place during the grinding process and is provided by the grinding.

### Claim 4 (depends on 1)

A method according to claim 1, wherein the brucite to be ground has a top size of particles which is coarser than a desired top size, and is ground in contact with an aqueous medium in the presence of at least one particulate grinding medium under conditions such that the energy input is in excess of about 20 kWh/tonne, wherein the particulate brucite having a top size of particles which is coarser than the desired top size is present in a weight excess relative to the water of the aqueous medium.

### Claim 5 (depends on 1)

A method according to claim 1, wherein the ground particulate brucite has a d90 less than or equal to about 2 μm as measured by laser light scattering and a d50 less than or equal to about 0.5 μm as measured by laser light scattering.

### Claim 6 (depends on 1)

A method according to claim 1, wherein the ground particulate brucite comprises less than about 0.1 asbestos fibres or other mineral fibres per ml of air at a total dust level of 10 mg/m3.

### Claim 7 (depends on 1)

A method according to claim 1, wherein the ground particulate brucite possesses a moisture pick up value over 7 days of less than about 15%.

### Claim 8 (depends on 7)

A method according to claim 7, wherein the ground particulate brucite possesses a moisture pick up value over 7 days of less than about 6%.

### Claim 9 (depends on 1)

A method according to claim 1, further comprising classifying the particulate brucite including top size particles in a certain size range so as to remove said top size particles in the said certain size range, the method comprising suspending the material in an aqueous medium to form a particulate suspension of the brucite, introducing a stream of the said particulate suspension into a hydrocyclone apparatus to create a vortex flow in the apparatus, and removing from the apparatus a first discharged stream comprising relatively large particles and a second discharged stream comprising relatively small particles, namely small relative to the particles of the first discharged stream, and recovering the classified particulate magnesium hydroxide free of the said top size particles from the second discharged stream.

### Claim 10 (depends on 9)

A method according to claim 9, wherein the said certain size range is from about 15 to about 18 μm as measured by laser light scattering.

### Claim 11 (depends on 9)

A method according to claim 9, wherein the said certain size range is from about 12 to about 18 μm as measured by laser light scattering.

### Claim 12 (depends on 9)

A method according to claim 9, when performed in the absence of a dispersing agent.

### Claim 13 (depends on 1)

A method according to claim 1, wherein the brightness of the particulate magnesium hydroxide is improved, and wherein the beneficiation comprises: dispersing the ground or pre-ground particulate brucite in a fluid carrier medium to produce a dispersion; introducing the dispersion into a magnetic field of sufficient field strength to magnetise ferric components of the particulate brucite; removing the dispersion from the magnetic field and placing the dispersion in sufficiently close proximity to a magnetic or magnetisable material that the said ferric components of the dispersion are concentrated in the vicinity of the magnetic or magnetisable material; and thereafter separating the said concentrated ferric components from the remainder of the dispersion.

### Claim 14 (depends on 1)

A method according to claim 1, further comprising combining said brucite optionally with one or more other particulate inorganic materials in order to provide a particulate filler material for use in a polymeric composition.

### Claim 15 (depends on 14)

A method according to claim 14, wherein the filler is provided for use in the form of a substantially dry powder.

### Claim 16 (depends on 14)

A method according to claim 14, wherein the particulate filler material consists essentially of the ground particulate brucite and one or more other particulate inorganic materials.

### Claim 17 (depends on 14)

A method according claim 14, wherein the one or more other particulate inorganic materials have flame retardant properties and are present with the particulate brucite in a flame-retardant amount.

### Claim 18 (depends on 14)

A method according to claim 14, wherein the filler is present in an amount of between about 1% and about 90%, by weight of the filled polymer composition.

### Claim 19 (depends on 21)

A method according to claim 21, further comprising forming the polymeric composition into an article.

### Claim 20 (depends on 19)

A method according to claim 19, wherein the article is selected from the group consisting of a work surface and a sheath, coating, or housing for an electrical product.

### Claim 21 (depends on 14)

A method according to claim 14, wherein the polymeric composition is formed by mixing the particulate filler material and the other components of the composition, the polymer component being present for the mixing as liquid or particulate solid, and optionally one or more precursors of the polymer.