Title of Invention	A PROCESS FOR THE PREPARATION OF MICROFINED COATED ALUMINA TRI HYDRATE
Abstract	A process for preparation of microfined coated alumina tri hydrate comprising: drying metallurgical grade alumina tri hydrate by fluidizing to produce dry alumina tri hydrate; coating said alumina tri hydrate with coating reagents; subjecting the said coated alumina tri hydrate to the step of fluidisation for 15 to 60 minutes; pulverizing the said coated alumina tri hydrate to produce microfine product by air classification technique for a period of 60 to 150 minutes to generate heat up to 70-90°C.

Title of Invention

A PROCESS FOR THE PREPARATION OF MICROFINED COATED ALUMINA TRI HYDRATE

Abstract

A process for preparation of microfined coated alumina tri hydrate comprising: drying metallurgical grade alumina tri hydrate by fluidizing to produce dry alumina tri hydrate; coating said alumina tri hydrate with coating reagents; subjecting the said coated alumina tri hydrate to the step of fluidisation for 15 to 60 minutes; pulverizing the said coated alumina tri hydrate to produce microfine product by air classification technique for a period of 60 to 150 minutes to generate heat up to 70-90°C.

Full Text	FIELD OF THE INVENTION: This invention relates to a process for the preparation of microfined coated alumina tri hydrate. BACKGROUND OF THE INVENTION: Alumina tri hydrate processed industrially by Bayer's process is mainly used for making aluminium metal. Microfined surface coated alumina tri hydrate is used for non-metallurgical applications such as fire retardant filler in cable, PVC compound, polymer, plastics etc. Due to surface coating the oil absorption and bulk density of the alumina tri hydrate changes. It becomes a water proofing material and completely floats on water whereas the uncoated alumina tri hydrate sinks in water. Due to these characteristics it is effectively used as fire retardant filler in which the consumption of coated alumina tri hydrate is reduced by 20- 30%. In the present invention, efforts have been made to develop a process for preparation of microfined, coated alumina tri hydrate through online fluidisation followed by microfining process technique, using surface coating reagents in a manner which can be industrially feasible to produce microfined coated alumina tri hydrate (60-100% coated) with median diameter of 3 to 30 micron. OBJECTS OF THE INVENTION: An object of this invention is to propose a process for the preparation of microfined coated alumina tri hydrate; Another object of this invention is to propose a process for online coating of alumina tri hydrate using metallurgical grade alumina tri hydrate. DETAILED DESCRIPTION OF THE INVENTION: According to this invention there is provided a process for preparation of microfine coated alumina tri hydrate comprising: Drying metallurgical grade alumina tri hydrate by fluidizing to produce dry alumina tri hydrate; Coating said alumina tri hydrate with coating reagents during fluidisation; Subjecting the said coated alumina tri hydrate to the step of fluidisation for 15 to 60 minutes; Pulverizing the said coated alumina tri hydrate to produce microfine product by air classification technique for a period of 60 to 150 minutes to generate heat up to 70-90°C. In accordance with the above method, alumina tri hydrate of 150-300 kg is dried through fluidisation process by passing air between 2000-4000 cu. Mt. per hour at 80-150°C using hot air, for 60-150 min. to remove the free moisture. Then the coating reagent of 0.5-2.0% is added to the alumina tri hydrate and a further fluidisation is carried out for 15-60 min. passing hot air under the similar conditions as above. The coated alumina tri hydrate is then microfined in the air classification pulveriser for 60-150 min. during which the particles have disintegrated to generate an internal heat of 70-90°C temperature. This temperature was sufficient to coat the alumina tri hydrate online while micronising. Then it was cooled to the room temperature by natural cooling to obtain the final product. To achieve preparation of microfined, coated alumina tri hydrate the following process parameters were studied: (a) Preparation of coated alumina tri hydrate by fluidisation of alumina tri hydrate of 150-300kg for 60-150 min and then using coating reagent between 0.5-2% for further 15-60 min. (b)The air was passed between 2000-4000 cu.mt. per hour at 80-150°C temperature using hot air. (c) Microfining and online coating of alumina tri hydrate in a air classification pulveriser for 60-150 min. at 70-90°C to get up to 100% coating product having a median diameter between 3-30 micron. Coating reagents are used such as solid stearic acid, dichloro diethyl silane and dichloro dimethyl silane. The typical characteristics of base raw material metallurgical grade alumina tri hydrate along with the specification of final product prepared in this method have been reported in Table-1 and 2 respectively. Commercial grade coating reagents have been used in all the experiments and water used in this invention is tap water. EXAMPLE 250 kg of alumina tri hydrate (with typical characteristics as reported in Table-1) was fluidized by passing hot air at the rate of 3000 cu.mt.per hour for 120 min. at 120°C to remove the free moisture. Subsequently 0.75% of solid stearic acid was added to it and further fluidisation carried out under the same conditions as above for 30min. The coated alumina tri hydrate was microfined in the air classification pulveriser for 120 min. at 80°C. The temperature of 80°C was due to heat generated due to particle disintegration which helped in further online coating of the microfined hydrate. The product was analysed to have a particle size of 5 micron median diameter with 100% coating, water proof properties and oil absorption of 50 ml per 100 gm of product. EXAMPLE 200 kg of alumina tri hydrate (with typical characteristics as reported in Table-1) was fluidized by passing hot air at the rate of 2500 cu.mt. per hour for 90 min. at 90°C to remove the free moisture. Subsequently 0.5% of solid stearic acid was added to it and further fluidisation carried out under the same conditions as above for 15 min. The coated alumina tri hydrate was microfined in the air classification pulveriser for 90 min. at 70°C. The temperature of 70°C was due to heat generated due to particle disintegration which helped in further online coating of the microfined hydrate. The product was analysed to have a particle size of 4 micro median diameter with 90% coating, water proof properties and oil absorption of 45 ml per 100 gm of product. EXAMPLE: 250 kg of alumina tri hydrate (with typical characteristics as reported in Table-1) was fluidized by passing hot air at the rate of 4000 cu.mt. per hour for 90 min. at 100°C to remove the free moisture. Subsequently 1.5% of solid stearic acid was added to it and further fluidisation carried out under the same conditions as above for 30min. The coated alumina tri hydrate was microfined in the air classification pulveriser for 100 min.at 80°C. The temperature of 80°C was due to heat generated due to particle disintegration which helped in further online coating of the microfined hydrate. The product was analysed to have a particle size of 8 micron median diameter with 100% coating, water proof properties and oil absorption of 52 ml per 100 gm of product. WE CLAIM: 1. A process for preparation of microfine coated alumina tri hydrate comprising: drying metallurgical grade alumina tri hydrate by fluidizing to produce dry alumina tri hydrate; coating said alumina tri hydrate with coating reagents during fluidisation; subjecting the said coated alumina tri hydrate to the step of fluidisation for 15 to 60 minutes; pulverizing the said coated alumina tri hydrate to produce microfine product by air classification technique for a period of 60 to 150 minutes to generate heat up to 70-90°C. 2. The process as claimed in claim 1, wherein the fluidisation is carried out maintaining air flow between 2000-4000 cu.mt.per hour. 3. The process as claimed in claim 1, wherein the temperature of air is maintained between 80-150°C. 4. The process as claimed in claim 1, wherein the time of fluidisation during drying is maintained between 60-150 min. 5. The process as claimed in claim 1, wherein the coated reagent quantity is added between 0.5-2% by weight of alumina tri hydrate. 6. The process as claimed in claim 1, wherein further fluidisation is carried out after adding coating reagent under the same condition as in claim 1 and maintain a time of 15-60 min. 7. The process as claimed in claim 1, wherein the microfining time for coated alumina tri hydrate is maintained between 60-150 min. to generate heat up to 70- 90°C, due to particle disintegration and for further online coating of particles. 8. The process as claimed in claim 1, wherein the coating reagent is selected stearic acid, dichloro diethyl silane, dichloro dimethyl silane. 9. The process as claimed in claim 1, wherein microfined, coated alumina tri hydrate of median diameter of 3-30 micron with 90-100% coating is obtained. ABSTRACT Title: A process for the preparation of microfined coated alumina tri hydrate. A process for preparation of microfined coated alumina tri hydrate comprising: drying metallurgical grade alumina tri hydrate by fluidizing to produce dry alumina tri hydrate; coating said alumina tri hydrate with coating reagents; subjecting the said coated alumina tri hydrate to the step of fluidisation for 15 to 60 minutes; pulverizing the said coated alumina tri hydrate to produce microfine product by air classification technique for a period of 60 to 150 minutes to generate heat up to 70-90°C.

Full Text

FIELD OF THE INVENTION:
This invention relates to a process for the preparation of microfined coated
alumina tri hydrate.
BACKGROUND OF THE INVENTION:
Alumina tri hydrate processed industrially by Bayer's process is mainly used for
making aluminium metal. Microfined surface coated alumina tri hydrate is used
for non-metallurgical applications such as fire retardant filler in cable, PVC
compound, polymer, plastics etc. Due to surface coating the oil absorption and
bulk density of the alumina tri hydrate changes. It becomes a water proofing
material and completely floats on water whereas the uncoated alumina tri hydrate
sinks in water. Due to these characteristics it is effectively used as fire retardant
filler in which the consumption of coated alumina tri hydrate is reduced by 20-
30%. In the present invention, efforts have been made to develop a process for
preparation of microfined, coated alumina tri hydrate through online fluidisation
followed by microfining process technique, using surface coating reagents in a
manner which can be industrially feasible to produce microfined coated alumina
tri hydrate (60-100% coated) with median diameter of 3 to 30 micron.
OBJECTS OF THE INVENTION:
An object of this invention is to propose a process for the preparation of
microfined coated alumina tri hydrate;
Another object of this invention is to propose a process for online coating of
alumina tri hydrate using metallurgical grade alumina tri hydrate.

DETAILED DESCRIPTION OF THE INVENTION:
According to this invention there is provided a process for preparation of
microfine coated alumina tri hydrate comprising:
Drying metallurgical grade alumina tri hydrate by fluidizing to produce dry
alumina tri hydrate;
Coating said alumina tri hydrate with coating reagents during fluidisation;
Subjecting the said coated alumina tri hydrate to the step of fluidisation for 15 to
60 minutes;
Pulverizing the said coated alumina tri hydrate to produce microfine product by
air classification technique for a period of 60 to 150 minutes to generate heat up
to 70-90°C.
In accordance with the above method, alumina tri hydrate of 150-300 kg is dried
through fluidisation process by passing air between 2000-4000 cu. Mt. per hour
at 80-150°C using hot air, for 60-150 min. to remove the free moisture. Then the
coating reagent of 0.5-2.0% is added to the alumina tri hydrate and a further
fluidisation is carried out for 15-60 min. passing hot air under the similar
conditions as above. The coated alumina tri hydrate is then microfined in the air
classification pulveriser for 60-150 min. during which the particles have
disintegrated to generate an internal heat of 70-90°C temperature. This
temperature was sufficient to coat the alumina tri hydrate online while
micronising. Then it was cooled to the room temperature by natural cooling to
obtain the final product.

To achieve preparation of microfined, coated alumina tri hydrate the following
process parameters were studied:
(a) Preparation of coated alumina tri hydrate by fluidisation of alumina tri
hydrate of 150-300kg for 60-150 min and then using coating reagent
between 0.5-2% for further 15-60 min.
(b)The air was passed between 2000-4000 cu.mt. per hour at 80-150°C
temperature using hot air.
(c) Microfining and online coating of alumina tri hydrate in a air classification
pulveriser for 60-150 min. at 70-90°C to get up to 100% coating product
having a median diameter between 3-30 micron.
Coating reagents are used such as solid stearic acid, dichloro diethyl silane and
dichloro dimethyl silane.
The typical characteristics of base raw material metallurgical grade alumina tri
hydrate along with the specification of final product prepared in this method have
been reported in Table-1 and 2 respectively. Commercial grade coating reagents
have been used in all the experiments and water used in this invention is tap
water.

EXAMPLE
250 kg of alumina tri hydrate (with typical characteristics as reported in Table-1)
was fluidized by passing hot air at the rate of 3000 cu.mt.per hour for 120 min. at
120°C to remove the free moisture. Subsequently 0.75% of solid stearic acid was
added to it and further fluidisation carried out under the same conditions as
above for 30min. The coated alumina tri hydrate was microfined in the air
classification pulveriser for 120 min. at 80°C. The temperature of 80°C was due
to heat generated due to particle disintegration which helped in further online
coating of the microfined hydrate. The product was analysed to have a particle
size of 5 micron median diameter with 100% coating, water proof properties and
oil absorption of 50 ml per 100 gm of product.
EXAMPLE
200 kg of alumina tri hydrate (with typical characteristics as reported in Table-1)
was fluidized by passing hot air at the rate of 2500 cu.mt. per hour for 90 min. at
90°C to remove the free moisture. Subsequently 0.5% of solid stearic acid was
added to it and further fluidisation carried out under the same conditions as
above for 15 min. The coated alumina tri hydrate was microfined in the air
classification pulveriser for 90 min. at 70°C. The temperature of 70°C was due to
heat generated due to particle disintegration which helped in further online
coating of the microfined hydrate. The product was analysed to have a particle
size of 4 micro median diameter with 90% coating, water proof properties and oil
absorption of 45 ml per 100 gm of product.

EXAMPLE:
250 kg of alumina tri hydrate (with typical characteristics as reported in Table-1)
was fluidized by passing hot air at the rate of 4000 cu.mt. per hour for 90 min. at
100°C to remove the free moisture. Subsequently 1.5% of solid stearic acid was
added to it and further fluidisation carried out under the same conditions as
above for 30min. The coated alumina tri hydrate was microfined in the air
classification pulveriser for 100 min.at 80°C. The temperature of 80°C was due to
heat generated due to particle disintegration which helped in further online
coating of the microfined hydrate. The product was analysed to have a particle
size of 8 micron median diameter with 100% coating, water proof properties and
oil absorption of 52 ml per 100 gm of product.

WE CLAIM:
1. A process for preparation of microfine coated alumina tri hydrate comprising:
drying metallurgical grade alumina tri hydrate by fluidizing to produce dry alumina
tri hydrate;
coating said alumina tri hydrate with coating reagents during fluidisation;
subjecting the said coated alumina tri hydrate to the step of fluidisation for 15 to
60 minutes;
pulverizing the said coated alumina tri hydrate to produce microfine product by
air classification technique for a period of 60 to 150 minutes to generate heat up
to 70-90°C.
2. The process as claimed in claim 1, wherein the fluidisation is carried out
maintaining air flow between 2000-4000 cu.mt.per hour.
3. The process as claimed in claim 1, wherein the temperature of air is
maintained between 80-150°C.
4. The process as claimed in claim 1, wherein the time of fluidisation during
drying is maintained between 60-150 min.
5. The process as claimed in claim 1, wherein the coated reagent quantity is
added between 0.5-2% by weight of alumina tri hydrate.

6. The process as claimed in claim 1, wherein further fluidisation is carried out
after adding coating reagent under the same condition as in claim 1 and maintain
a time of 15-60 min.
7. The process as claimed in claim 1, wherein the microfining time for coated
alumina tri hydrate is maintained between 60-150 min. to generate heat up to 70-
90°C, due to particle disintegration and for further online coating of particles.
8. The process as claimed in claim 1, wherein the coating reagent is selected
stearic acid, dichloro diethyl silane, dichloro dimethyl silane.
9. The process as claimed in claim 1, wherein microfined, coated alumina tri
hydrate of median diameter of 3-30 micron with 90-100% coating is obtained.

ABSTRACT

Title: A process for the preparation of microfined coated alumina tri hydrate.
A process for preparation of microfined coated alumina tri hydrate comprising:
drying metallurgical grade alumina tri hydrate by fluidizing to produce dry alumina
tri hydrate; coating said alumina tri hydrate with coating reagents; subjecting the
said coated alumina tri hydrate to the step of fluidisation for 15 to 60 minutes;
pulverizing the said coated alumina tri hydrate to produce microfine product by
air classification technique for a period of 60 to 150 minutes to generate heat up
to 70-90°C.

Documents:

186-KOL-2009-(04-07-2013)-CORRESPONDENCE.pdf

186-KOL-2009-(04-07-2013)-FORM-1.pdf

186-KOL-2009-(04-07-2013)-FORM-13.pdf

186-KOL-2009-(04-07-2013)-FORM-5.pdf

186-KOL-2009-(11-09-2012)-FORM 13.pdf

186-kol-2009-abstract.pdf

186-kol-2009-claims.pdf

186-KOL-2009-CORRESPONDENCE-1.1.pdf

186-KOL-2009-CORRESPONDENCE-1.2.pdf

186-kol-2009-correspondence.pdf

186-KOL-2009-CORRESPONDENCE1.3.pdf

186-kol-2009-description (complete).pdf

186-KOL-2009-EXAMINATION REPORT.pdf

186-kol-2009-form 1.pdf

186-KOL-2009-FORM 18 1.2.pdf

186-kol-2009-form 18.pdf

186-kol-2009-form 2.pdf

186-KOL-2009-FORM 26.pdf

186-kol-2009-form 3.pdf

186-KOL-2009-FORM 9.pdf

186-KOL-2009-GRANTED-ABSTRACT.pdf

186-KOL-2009-GRANTED-CLAIMS.pdf

186-KOL-2009-GRANTED-DESCRIPTION (COMPLETE).pdf

186-KOL-2009-GRANTED-FORM 1.pdf

186-KOL-2009-GRANTED-FORM 2.pdf

186-KOL-2009-GRANTED-FORM 3.pdf

186-KOL-2009-GRANTED-FORM 5.pdf

186-KOL-2009-GRANTED-SPECIFICATION-COMPLETE.pdf

186-KOL-2009-OTHER.pdf

186-KOL-2009-PETITION UNDER RULE 137.pdf

186-KOL-2009-REPLY TO EXAMINATION REPORT.pdf

186-KOL-2009-REPLY TO EXAMINATION REPORT1.1.pdf

186-kol-2009-specification.pdf

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Patent Number

257022

Indian Patent Application Number

186/KOL/2009

PG Journal Number

35/2013

Publication Date

30-Aug-2013

Grant Date

27-Aug-2013

Date of Filing

03-Feb-2009

Name of Patentee

NATIONAL ALUMINIUM COMPANY LIMITED

Applicant Address

(A GOVERNMENT OF INDIA ENTERPRISE)NALCO BHAWAN, NAYAPALLI, BHUBANESWAR

Inventors:

#	Inventor's Name	Inventor's Address
1	R. S. DHARMAN	C/O NATIONAL ALUMINIUM COMPANY LIMITED(A GOVERNMENT OF INDIA ENTERPRISE) NALCO BHAWAN, PLOT NO. P/1, NAYAPALLI, BHUBANESWAR
2	B. K. SATPATHY	C/O NATIONAL ALUMINIUM COMPANY LIMITED(A GOVERNMENT OF INDIA ENTERPRISE) NALCO BHAWAN, PLOT NO. P/1, NAYAPALLI, BHUBANESWAR
3	P. V. RAMANA MURTHY	C/O NATIONAL ALUMINIUM COMPANY LIMITED(A GOVERNMENT OF INDIA ENTERPRISE) NALCO BHAWAN, PLOT NO. P/1, NAYAPALLI, BHUBANESWAR
4	B. W. HARRY	C/O NATIONAL ALUMINIUM COMPANY LIMITED(A GOVERNMENT OF INDIA ENTERPRISE) NALCO BHAWAN, PLOT NO. P/1, NAYAPALLI, BHUBANESWAR

PCT International Classification Number

A61K8/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA