Title of Invention	"AN IMPROBVED METHOD OF MANUFACTURING Mg-Al AND Mg-Cr SPINEL GRAINS FOR MAKING REFRACTORIES USED IN FERROUS AND NON-FERROUS INDUSTRIES"
Abstract	The invention provides an improved method of manufacturing Mg-Al and Mg-Cr spinel grains for making refractories used in ferrous and non-ferrous industries, comprising the following steps in sequence: (i) wet milling of 65-70% by weight of alumina (Al2O3) and equivalent amounts of Mg(OH)2 for producing 30-35% by weight of MgO in manufacturing Mg-Al spinel grains, and wet milling of 72-77% by weight of chromic oxide (Cr203) and equivalent amount of Mg(OH)2 for producing 23-28% by weight of MgO in manufacturing Mg-Cr spinel grains with addition of the required quantity of water at room temperature in a ball mill using sintered alumina balls as the grinding medium for at least 4 hours to produce a slurry of the said materials in water, (ii) passing the slurry through a filter press to convert the slurry into the form of cakes, (iii) drying the cakes in a dryer at 110 + 10°C for at least 24 hours, (iv) pulverising the cakes into powders in a pulveriser, (v) mixing 10% by weight of a known binder with the powders in a mixer, (vi) converting the mix into the form of briquettes/bricks by pressing the same at a pressure of 1.5t/Cm2 in a press, (vii) drying the briquettes/bricks in a dryer at 110 ± 10°C for at least 24 hours, (viii) firing/ sintering the briquettes/bricks in a furnace/kiln at 1600-1650°C for at least 6 hours, (ix) crushing the briquettes/bricks into particles in a crusher, (x) grinding the particles Into grains in a grinder and (xi) screening the grains into the required size fractions.

Title of Invention

"AN IMPROBVED METHOD OF MANUFACTURING Mg-Al AND Mg-Cr SPINEL GRAINS FOR MAKING REFRACTORIES USED IN FERROUS AND NON-FERROUS INDUSTRIES"

Abstract

The invention provides an improved method of manufacturing Mg-Al and Mg-Cr spinel grains for making refractories used in ferrous and non-ferrous industries, comprising the following steps in sequence: (i) wet milling of 65-70% by weight of alumina (Al2O3) and equivalent amounts of Mg(OH)2 for producing 30-35% by weight of MgO in manufacturing Mg-Al spinel grains, and wet milling of 72-77% by weight of chromic oxide (Cr203) and equivalent amount of Mg(OH)2 for producing 23-28% by weight of MgO in manufacturing Mg-Cr spinel grains with addition of the required quantity of water at room temperature in a ball mill using sintered alumina balls as the grinding medium for at least 4 hours to produce a slurry of the said materials in water, (ii) passing the slurry through a filter press to convert the slurry into the form of cakes, (iii) drying the cakes in a dryer at 110 + 10°C for at least 24 hours, (iv) pulverising the cakes into powders in a pulveriser, (v) mixing 10% by weight of a known binder with the powders in a mixer, (vi) converting the mix into the form of briquettes/bricks by pressing the same at a pressure of 1.5t/Cm2 in a press, (vii) drying the briquettes/bricks in a dryer at 110 ± 10°C for at least 24 hours, (viii) firing/ sintering the briquettes/bricks in a furnace/kiln at 1600-1650°C for at least 6 hours, (ix) crushing the briquettes/bricks into particles in a crusher, (x) grinding the particles Into grains in a grinder and (xi) screening the grains into the required size fractions.

Full Text	The present invention relates to an improved method of manufacturing Mg-Al and Mg-Cr spinel grains for making refractories used in ferrous and non-ferrous industries. The invention relates more particularly to a method of manufacturing Mg-Al spinel grains frlgAl2O4) and Mg-Cr spinel grains (MgCr2O4) at a relatively low temperature and hence at a reduced cost. The existing method of manufacturing Mg-Al apinel grains(MgAl2O4) and Mg-Cr spinel grains (MgCr2O4) requires melting of the ingredients at a high temperature of around 2406 K, and hence the cost of manufacture in the existing method is relatively high.ln recent years the demand for high quality synthetic refractories,such as, those made from Mg-Al and Mg-Cr spinel grains, of increased hardness, reduced thermal conductivity and adequate chemical Inertness has been growing rapidly for applications in the ferrous and non-ferrous industries, necessitating increased production of said spinel grains at a reduced cost. The object of the invention is to provide a method of manufacturing Mg-Al and Mg-Cr spinel grains at a reduced temperature and hence at a reduced cost. The invented method comprises basically wet milling of ingredients such as alumina (Al2O3) or chromic oxide (Sr2O3) and magnesium hydroxide (Mg(OH)2) with water in the required quantity in a ball mill to produce a slurry of the materials, drying the slurry formed in an air oven at 110 + 10°C into lumps/cakes, grinding/pulverising the lumps/cakes into granulated powders of required mesh size such as 30 B.S., mixing the powders with a binder such as a 2% by weight solution of dextrin in water in a mixer, pressing the mix into briquettes/bricks of 2 required sizes at a pressure of around 1.5 t/cm , drying the briquettes/bricks in a dryer at 110 + 10°C, sintering/firing the dried briquettes/bricks in a furnace/kiln at 1600-1650°C, cooling the briquettes/bricks to ambient temperature in natural air, Crushing and grinding the briquettes/bricks into grains of sizes such as -6 B. S. mesh, and screening the grains into required size fractions. 4 A large number of experiments have been performed for optimising the composition of the ingredients used in the invented method of manufacturing the Mg-Al and Mg-Cr spinel grains. Thus the invention provides an improved method of manufacturing Mg-Al and Mg-Cr spinel grains for making refractories used in ferrous and non-ferrous industries, characterised in that the method comprises the following steps in sequence: (i) wet milling of 65-70% by weight of alumina (Al2O3) and equivalent amounts of Mg(OH)2 for 30-35% by weight of MgO for producing Mg-Al spinel grains and 72-77% by weight of chromic oxide (Cr2O3) and equivalent amount of Mg(OH)2 for 23-28% by weight of MgO for producing Mg-Cr spinel grains v/ith required quantity of water at the room temperature in a ball mill using sintered alumina balls as the grinding medium for at least 4 hours to produce a slurry of the said materials in water, (ii) processing the slurry through a filter press to convert the same into the form of cakes, (iii) drying the cakes in a dryer at 110 + 10°C for at least 24 hours, (iv) pulverising the cakes into powders in a pulveriser, (v) mixing 10% by weight of a binder with the powders in a mixer, (vi) converting the mix into the form of briquettes/bricks by pressing the same at a pressure of around 1.5 t/cm2 in a press, (vii) drying the briquettes/bricks in a dryer at 110 + 10°C for at least 24 hours, (viii) firing/sintering the briquettes/bricks in a furnace/kiln at 1600-1650°C for at least 6 hours, (ix) crushing the briquettes/bricks into particles in a crusher, (x) grinding the particles into grains in a grinder and (xi) screening the grains into the required size fractions, such as, +3 to -5 mm, +1 to -3 mm, +0.5 to -1 mm, +O.2 to -0.5, and -0.2 mm or as required. The invention is described fully and particularly with reference to the accompanying drav/ings, in which Figure 1 is a flow diagram of the steps followed in the invented method of manufacturing Mg-Al and Mg-Cr spinel grains. Referring to Fig. 1, raw material 1 i.e. alumina (A1203) and raw material 2 i.e. magnesium hydroxide (Mg(OH)2) or raw material 3, i.e. chromic oxide (Cr2O3) and raw material 2 i.e. magnesium hydroxide (Mg(OH)2) are v/et milled together for 4 hours in a ball mill using sintered alumina balls as the grinding medium with water in the required quantity to produce a slurry of the materials, the slurry is stored in a blunger and is passed through a filter press to produce cakes of the materials, the cakes are dried at 110 + 10°C in a dryer for at least 24 hours, the dried cakes are pulverised into pov/ders in a pulveriser, 9 parts by v/eight of the pulverised powders and 1 part by v/eight of a binder such as 2% by weight of a solution of dextrin in water are mixed in a mixer, the mix is converted into briquettes/bricks in a press at a pressure of around 1.5 t/cm2 , the briquettes/bricks are dried in a dryer at 110 + 10°C for 24 hours, the dried briquettes/bricks are fired/sintered in a furnace/kiln at 1600-1650°C for 6 hours, the fired/sintered briquettes/bricks are crushed into particles in a crusher, the particles are ground into grains in a grinder, the grains are screened into required size fractions by using screens of required mesh sizes and stored as the finished product. Alternatively, instead of pulverising the dried cakes into powders in a pulveriser, these are sintered in a kiln at 1600-1650°C for 6 hours, the sintered cakes are crushed into particles in a crusher, the particles are ground into grains in a grinder, the grains are screened into different size fractions by using screens of required mesh sizes and stored as the finished product. The results of chemical analysis of alumina (Al2O3) and chromic oxide (Cr203) used are presented in Tables I and II respectively, from which it is noted that the said ingredients are of high purity i.e. 99% and above by weight. The magnesium hydroxide (Mg(OH)2) used is of extra high purity of above 99.9% by weight. A typical experiment performed on a pilot scale for optimising the composition of Mg-Al and Mg-Cr spinel grains in the invented method is described below by way of Example. A 5 kg batch containing (by weight) 68% alumina and equivalent amount of Mg{OH)2 for 32% MgO or 74.5% chromic oxide and equivalent amount of Mg(OH)2 for 25.5% MgO with 8 to 12 kg water is milled in a ball mill for 4 hours using sintered alumina balls as the grinding medium to produce a slurry of the materials. The slurry is dried in an oven at 110 ± 10°C for at least 4 hours to be formed into lumps. The lumps are ground into particles in a grinder and screened through a 30 B.S. mesh sieve. 9 parts by weight of the grains are mixed with 1 part by weight of a binder such as 2% by weight of dextrin solution in water and pressed under a pressure of 1.5 t/cm2 and formed into briquettes. The briquettes are dried in an oven at 110 + 10°C for at least 24 hours. The dried briquettes are fired at 1600-1650°C for at least 6 hours in a furnace. The fired briquettes are cooled to ambient temperature in natural air. The cooled briquettes are crushed into particles in a crusher, the particles are ground into grains in a grinder, the grains are screened into the required size fractions by using screens and stored as the finished product. Typical thermo-physical properties of the spinel grains produced are given in Table III, from which it is noted that both Mg-Al and Mg-Cr spinel grains produced in the invented method are of high grain density i.e. 3.31/3.80 gm/cc, low app. grain porosity 2.18/4.07%, low water absorption 0.66/1.08% and high tensile strength 650/450 kg/cm2. The highest temperature used in the invented process being 1600-1650°C against 1800-1900°C used in the conventional method, the cost of manufacture is relatively low in the invented method. Table I Results of Chemical Analysis of Alumina (Al2O3). (Table Removed) Table II: Results of Chemical Analysis of Chromic Oxide (Cr203) used. (Table Removed) Table III; Thermo-physical properties of Mg-Al and Mg-Cr Spinel Grains Produced. (Table Removed) We Claim :- 1. An improved method of manufacturing Mg-Al and Mg-Cr spinel grains for making refractories used in ferrous and non-ferrous industries, characterised in that the method comprises the following steps in sequence : (i) wet milling of 65-70% by weight of alumina (A1203) and equivalent amounts of Mg(OH)2 for 30-35% by weight of MgO for producing Mg-Al spinel grains and 72-77% by v/eight of chromic oxide (Cr2O3) and equivalent amount of Mg(OH)2 for 23-28%by weight of MgO for producing Mg-Cr spinel grains with required quantity of water at the room temperature in a ball mill using sintered alumina balls as the grinding medium for at least 4 hours to produce a slurry of the said materials in water, (ii) processing the slurry through a filter press to convert the same into the form of cakes, (iii) drying the cakes in a dryer at 110 + 10°C for at least 24 hours, (iv) pulverising the cakes into powders in a pulveriser, (v) mixing 10% by weight of binder with the powders in a mixer, (vi) converting the mix into the form of briquettes/bricks by pressing the same at a pressure of around 1.5 t/cm2 in a press, (vii) drying the briquettes/bricks in a dryer at 110 + 10°C for at least 24 hours, (viii) firing/sintering the briquettes/bricks in a furnace/ kiln at 1600-1650°C for at least 6 hours, (ix) crushing the briquettes/bricks into particles in a crusher, (x) grinding the particles into grains in a grinder and (xi) screening the grains into the required size fractions, such as, +3 to -5 mm, +1 to -3 mm, +0.5 to 1 mm, +0.2 to -0.5, and -0.2 mm or as required. 2. The method as claimed in Claim 1, wherein the materials wet milled are (by weight) 67% A120, and 32%MgO for producing Mg-Al spinel grains, and 74.596 Cr2O3 and 25.5% MgO for producing Mg-Cr spinel grains v/ith addition of 160-240% of water therein. 3. The method as claimed in claim 1 or 2, wherein the binder used is a 2% by weight solution of dextrin in water. A. The method as claimed in claim 1, 2 or 3, wherein the dried cakes of the materials produced in step (iii) are sintered in kiln at 1600-1650°C for 6 hours, crushed into particles, in a crusher, ground into grains in a grinder and screened into the size fractions, such as, +3 to-5mm, +1 to -3mm, +0.5 to -1 mm, +0.2 to -0.5, and -0.2 mm or as required. 5. An improved method of manufacturing Mg-Al and Mg-Cr spinel grains for making refractories used in ferrous and non-ferrous industries, substantially as herein described and illustrated in the accompanying drawings.

Full Text

The present invention relates to an improved method
of manufacturing Mg-Al and Mg-Cr spinel grains for making
refractories used in ferrous and non-ferrous industries.
The invention relates more particularly to a method of manufacturing Mg-Al spinel grains frlgAl2O4) and Mg-Cr spinel grains (MgCr2O4) at a relatively low temperature and hence at a reduced cost.
The existing method of manufacturing Mg-Al apinel grains(MgAl2O4) and Mg-Cr spinel grains (MgCr2O4) requires melting of the ingredients at a high temperature of around
2406 K, and hence the cost of manufacture in the existing

method is relatively high.ln recent years the demand for high

quality synthetic refractories,such as, those made from Mg-Al

and Mg-Cr spinel grains, of increased hardness, reduced thermal

conductivity and adequate chemical Inertness has been growing rapidly for applications in the ferrous and non-ferrous
industries, necessitating increased production of said spinel grains at a reduced cost.
The object of the invention is to provide a method of manufacturing Mg-Al and Mg-Cr spinel grains at a reduced temperature and hence at a reduced cost.
The invented method comprises basically wet milling of ingredients such as alumina (Al2O3) or chromic oxide (Sr2O3) and magnesium hydroxide (Mg(OH)2) with water in the required quantity in a ball mill to produce a slurry of the materials, drying the slurry formed in an air oven at 110 + 10°C into lumps/cakes, grinding/pulverising the lumps/cakes into granulated
powders of required mesh size such as 30 B.S., mixing the powders with a binder such as a 2% by weight solution of dextrin
in water in a mixer, pressing the mix into briquettes/bricks of
2 required sizes at a pressure of around 1.5 t/cm , drying the
briquettes/bricks in a dryer at 110 + 10°C, sintering/firing the dried briquettes/bricks in a furnace/kiln at 1600-1650°C, cooling the briquettes/bricks to ambient temperature in natural air, Crushing and grinding the briquettes/bricks into grains of sizes such as -6 B. S. mesh, and screening the grains into required size fractions.
4
A large number of experiments have been performed for optimising the composition of the ingredients used in the invented method of manufacturing the Mg-Al and Mg-Cr spinel grains.
Thus the invention provides an improved method of manufacturing Mg-Al and Mg-Cr spinel grains for making refractories used in ferrous and non-ferrous industries, characterised in that the method comprises the following steps in sequence: (i) wet milling of 65-70% by weight of alumina (Al2O3) and equivalent amounts of Mg(OH)2 for 30-35% by weight of MgO for producing Mg-Al spinel grains and 72-77% by weight of chromic oxide (Cr2O3) and equivalent amount of Mg(OH)2 for 23-28% by weight of MgO for producing Mg-Cr spinel grains v/ith required quantity of water at the room temperature in a ball mill using sintered alumina balls as the grinding medium for at least 4 hours to produce a slurry of the said materials in water, (ii) processing the slurry through a filter press to convert the same into the form of cakes, (iii) drying the cakes in a dryer at 110 + 10°C for at least 24 hours, (iv) pulverising the cakes into powders in a pulveriser, (v) mixing
10% by weight of a binder with the powders in a mixer, (vi)
converting the mix into the form of briquettes/bricks by pressing
the same at a pressure of around 1.5 t/cm2 in a press, (vii)
drying the briquettes/bricks in a dryer at 110 + 10°C for at least 24 hours, (viii) firing/sintering the briquettes/bricks in a furnace/kiln at 1600-1650°C for at least 6 hours, (ix) crushing the briquettes/bricks into particles in a crusher, (x) grinding the particles into grains in a grinder and (xi) screening the grains into the required size fractions, such as, +3 to -5 mm, +1 to -3 mm, +0.5 to -1 mm, +O.2 to -0.5, and -0.2 mm or as required.
The invention is described fully and particularly with reference to the accompanying drav/ings, in which
Figure 1 is a flow diagram of the steps followed in the invented method of manufacturing Mg-Al and Mg-Cr spinel grains.
Referring to Fig. 1, raw material 1 i.e. alumina (A1203) and raw material 2 i.e. magnesium hydroxide (Mg(OH)2) or raw material 3, i.e. chromic oxide (Cr2O3) and raw material 2 i.e. magnesium hydroxide (Mg(OH)2) are v/et milled together for 4 hours in a ball mill using sintered alumina balls as the grinding medium with water in the required quantity to produce a slurry of the materials, the slurry is stored in a blunger and is passed through a filter press to produce cakes of the materials, the cakes are dried at 110 + 10°C in a dryer for at least 24 hours, the dried cakes are pulverised into pov/ders in a pulveriser, 9 parts by v/eight of the pulverised powders and 1 part by v/eight of a binder such as 2% by weight of
a solution of dextrin in water are mixed in a mixer, the mix is converted into briquettes/bricks in a press at a pressure of
around 1.5 t/cm2 , the briquettes/bricks are dried in a dryer at 110 + 10°C for 24 hours, the dried briquettes/bricks are fired/sintered in a furnace/kiln at 1600-1650°C for 6 hours, the fired/sintered briquettes/bricks are crushed into particles
in a crusher, the particles are ground into grains in a grinder,
the grains are screened into required size fractions by using
screens of required mesh sizes and stored as the finished product. Alternatively, instead of pulverising the dried cakes into powders in a pulveriser, these are sintered in a kiln at 1600-1650°C for 6 hours, the sintered cakes are crushed into particles in a crusher, the particles are ground into grains in a grinder, the grains are screened into different size fractions by using screens of required mesh sizes and stored as the finished product.
The results of chemical analysis of alumina (Al2O3) and chromic oxide (Cr203) used are presented in Tables I and II respectively, from which it is noted that the said ingredients are of high purity i.e. 99% and above by weight. The magnesium hydroxide (Mg(OH)2) used is of extra high purity of above 99.9% by weight.
A typical experiment performed on a pilot scale for optimising the composition of Mg-Al and Mg-Cr spinel grains in the invented method is described below by way of Example.
A 5 kg batch containing (by weight) 68% alumina and equivalent amount of Mg{OH)2 for 32% MgO or 74.5% chromic oxide and equivalent amount of Mg(OH)2 for 25.5% MgO with 8 to 12 kg water is milled in a ball mill for 4 hours using sintered alumina balls as the grinding medium to produce a slurry of the materials. The slurry is dried in an oven at 110 ± 10°C for at least 4 hours to be formed into lumps. The lumps are ground into particles in a grinder and screened through a 30 B.S. mesh sieve. 9 parts by weight of the grains are mixed with 1 part by
weight of a binder such as 2% by weight of dextrin solution in
water and pressed under a pressure of 1.5 t/cm2 and formed into
briquettes. The briquettes are dried in an oven at 110 + 10°C for at least 24 hours. The dried briquettes are fired at 1600-1650°C for at least 6 hours in a furnace. The fired briquettes are cooled to ambient temperature in natural air. The cooled briquettes are crushed into particles in a crusher, the particles are ground into grains in a grinder, the grains are screened into the required size fractions by using screens and stored as the finished product.
Typical thermo-physical properties of the spinel grains produced are given in Table III, from which it is noted that both Mg-Al and Mg-Cr spinel grains produced in the invented method are of high grain density i.e. 3.31/3.80 gm/cc, low app. grain porosity 2.18/4.07%, low water absorption 0.66/1.08% and high tensile strength 650/450 kg/cm2.

The highest temperature used in the invented process being 1600-1650°C against 1800-1900°C used in the conventional method, the cost of manufacture is relatively low in the invented method.
Table I Results of Chemical Analysis of Alumina (Al2O3).
(Table Removed)
Table II: Results of Chemical Analysis of Chromic Oxide (Cr203) used.
(Table Removed)
Table III; Thermo-physical properties of Mg-Al and Mg-Cr Spinel Grains Produced.

(Table Removed)

We Claim :-
1. An improved method of manufacturing Mg-Al and Mg-Cr spinel grains for making refractories used in ferrous and non-ferrous industries, characterised in that the method comprises the following steps in sequence : (i) wet milling of 65-70% by weight of alumina (A1203) and equivalent amounts of Mg(OH)2 for 30-35% by weight of MgO for producing Mg-Al spinel grains and 72-77% by v/eight of chromic oxide (Cr2O3) and equivalent amount of Mg(OH)2 for 23-28%by weight of MgO for producing Mg-Cr spinel grains with required quantity of water at the room temperature in a ball mill using sintered alumina balls as the grinding medium for at least 4 hours to produce a slurry of the said materials in water, (ii) processing the slurry through a filter press to convert the same into the form of cakes, (iii) drying the cakes in a dryer at 110 + 10°C for at least 24 hours, (iv) pulverising the cakes into powders in a pulveriser, (v) mixing 10% by weight of binder with the powders in a mixer, (vi)
converting the mix into the form of briquettes/bricks by pressing
the same at a pressure of around 1.5 t/cm2 in a press, (vii) drying
the briquettes/bricks in a dryer at 110 + 10°C for at least 24 hours, (viii) firing/sintering the briquettes/bricks in a furnace/ kiln at 1600-1650°C for at least 6 hours, (ix) crushing the briquettes/bricks into particles in a crusher, (x) grinding the particles into grains in a grinder and (xi) screening the grains into the required size fractions, such as, +3 to -5 mm, +1 to -3 mm, +0.5 to 1 mm, +0.2 to -0.5, and -0.2 mm or as required.

2. The method as claimed in Claim 1, wherein the materials
wet milled are (by weight) 67% A120, and 32%MgO for producing
Mg-Al spinel grains, and 74.596 Cr2O3 and 25.5% MgO for producing
Mg-Cr spinel grains v/ith addition of 160-240% of water therein.
3. The method as claimed in claim 1 or 2, wherein the
binder used is a 2% by weight solution of dextrin in water.
A. The method as claimed in claim 1, 2 or 3, wherein the dried cakes of the materials produced in step (iii) are sintered in kiln at 1600-1650°C for 6 hours, crushed into particles, in a crusher, ground into grains in a grinder and screened into the size fractions, such as, +3 to-5mm, +1 to -3mm, +0.5 to -1 mm, +0.2 to -0.5, and -0.2 mm or as required.
5. An improved method of manufacturing Mg-Al and Mg-Cr spinel grains for making refractories used in ferrous and non-ferrous industries, substantially as herein described and illustrated in the accompanying drawings.

Documents:

3349-del-1998-abstract.pdf

3349-del-1998-claims.pdf

3349-del-1998-correspondence-others.pdf

3349-del-1998-correspondence-po.pdf

3349-del-1998-description (complete).pdf

3349-del-1998-drawings.pdf

3349-del-1998-form-1.pdf

3349-del-1998-form-19.pdf

3349-del-1998-form-2.pdf

3349-del-1998-form-4.pdf

3349-del-1998-gpa.pdf

« Previous Patent

Next Patent »

Patent Number

232190

Indian Patent Application Number

3349/DEL/1998

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

16-Mar-2009

Date of Filing

10-Nov-1998

Name of Patentee

STEEL AUTHORITY OF INDIA LIMITED

Applicant Address

ISPAT BHAWAN, LODI ROAD, NEW DELHI – 110003.

Inventors:

#	Inventor's Name	Inventor's Address
1	JAGDISH PRASAD	RDCIS/SAIL, RACHI, INDIA.
2	TAPAS KUMAR DE	RDCIS/SAIL, RACHI, INDIA.
3	BANSI DHAR CHATTARARJ	RDCIS/SAIL, RACHI, INDIA.
4	MANI SANKAR MUKHOPADHAYAY	RDCIS/SAIL, RACHI, INDIA.
5	KRISHANA CHARAN CHATTERJEE	RDCIS/SAIL, RACHI, INDIA.

PCT International Classification Number

C04B35/043

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA