Title of Invention	A PROCESS FOR THE PREPARATION OF POROUS REFRACTORY AGGREGATE .
Abstract	The present invention relates to a process for the synthesis of porous refractory aggregate. The low expansive porous insulating refractory aggregate produced by the present invention can be incorporated in insulating bricks and castable compositions useful in metallurgical industries both in ferrous and non-ferrous sectors to provide insulation in their furnaces as a measure of energy saving. The process steps are: wet grinding and intimate mixing of 50-70 weight percent dry paper pulp, 30-50 weight percent alumino-silicate materials and 300 weight percent of water for a period in the range of 8-10 hours to obtain a ceramic slip, sieving the ceramic slip through 10 mesh BS sieve, drying the slip, compacting the dried powder into shape, drying the shape, sintering the dried shape in a furnace at a temperature in the range of 1200°-1400°C for a period in the range of 2-3 hrs, crushing by known methods to obtain different size porous refractory aggregate.

Title of Invention

A PROCESS FOR THE PREPARATION OF POROUS REFRACTORY AGGREGATE .

Abstract

Full Text	The present invention relates to a process for the synthesis of porous refractory aggregate. The low expansive porous insulating refractory aggregate produced by the present invention can be incorporated in insulating bricks and castable compositions useful in metallurgical industries both in ferrous and non-ferrous sectors to provide insulation in their furnaces as a measure of energy saving. The present day method for the production of porous insulating refractory aggregate utilises raw materials such as perlite, expanded shale for silica based aggregates and expanded fireclay for alumina based aggregates. Sometimes carbon source is used as pore forming agent. Reference may be made to the article of Ken Moody of USA (Industrial minerals, Oct, 1997) wherein typical light weight insulating aggregates used in conventional refractory castable compositions where around 70-80% insulating aggregate is used in addition to other 20-30% raw materials such as clay, high alumina cement bond etc. has been described. Perlite aggregate is a naturally occurring mineral and expanded shale aggregate is produced by firing shale. The drawbacks of such type of aggregates are : a) Limited thermal stability due to the absence of low expansive ceramic phases. b) Impurities (such as alkali, iron oxide) present in perlite and shale aggregate make the bricks and castable product prone to thermal shock. c) Weakness of the aggregate due to their chemistry and non complimentary effect of the calcium aluminate binder used in castable composition. Expanded fireclay and vermiculite aggregate is used to produce alumina based aggregate by firing naturally occurring clay into its expanded form. Again, clay being a naturally occurring mineral, its consistency in quality always varies from one deposit to other which indirectly does not provide bricks and castable product with consistent quality and uniform properties. The literature search does not provide any information regarding simultaneous formation of low expansive synthetic phase and porous structure which may be used as insulating refractory aggregate. The present concept is an unique and new to this branch of technology. The present technology utilises processed pulp waste of paper industries and conversion of it into new usable product. The main object of the present invention is to provide a process for the preparation of low expansive porous refractory aggregate istc which obviates the drawbacks of present existing process as detailed above. Yet another objective of the present invention is to utilise processed paper pulp wajge to provide an insulating aggregate of lower bulk density, higher porosity with extremely fine and uniformly dispersed pores. Accordingly the present invention provides a process for the preparation of porous refractory aggregate which comprises wet grinding and intimate mixing of 50-70 weight percent dry paper pulp, 30-50 weight percent alumino-silicate materials and 300 weight percent of water for a period in the range of 8-10 hours to obtain a ceramic slip, sieving the ceramic slip through 10 mesh BS sieve, drying the slip, compacting the dried powder into shape, drying the shape, sintering the dried shape in a furnace at a temperature in the range of 1200°-1400°C for a period in the range of 2-3 hrs, crushing by known methods to obtain different size porous refractory aggregate. In an embodiment of the present invention the major raw material used may be processed waste paper pulp which contains 50 - 55 weight percent of silica, 28 - 35 weight percent of alumina, 5 - 9 weight percent of magnesium oxide, 1-2 weight percent of calcium oxide, 1-3 weight percent of titanium dioxide. In another embodiment of the present invention the paper pulp may be processed by known methods to make it free from alkali. In yet another embodiment of the present invention, alumino-silicate minerals may be such as kaolin, montmorrillonite, sillimanite sand, kyanite and mixture thereof. In still another embodiment of the present invention compacting of shapes may be done under pressure in the range of 150-170 kg/cm2. In yet another embodiment of the present invention the inmulating aggregate may be done in various size grading to suit specific purposes. The detail process steps of the present invention are i) Intimate wet mixing of 50 to 70 weight percent dry waste paper pulp, 30 to 50 weight percent aluminosilicate minerals with 300 weight percent of water. ii) Sieving the ceramic slip through 10 mesh BS sieve iii) Drying of the slip iv) Compacting of shapes under pressure in the range of 150-170 kg/cm2 by usual method. v) Drying of the shapes vi) Sintering the shapes in a furnace at a temperature in the range of 1200 - 1400°C for soaking period of 2-3 hrs vii) Crushing into various size fractions. The chemical analysis of the waste paper pulp used in the present invention shows the presence of considerable amount of MgO in addition to the SiO2 and A12O3. On sintering the mixture of paper pulp and aluminosilicates, certain proportion of silica, alumina and magnesia gives rise to low expansive synthetic ceramic phase like cordierite (2MgO.2Al2O3.5SiO2) in addition to the formation of hard phase like mullite (3Al2O3.2SiO2 as confirmed by X-ray diffraction. The presence of such low expansive synthetic phases improves the thermal shock resistance of the material significantly. Further, the present invention resides in the formation of porous structure due to cellular structure of waste paper pulp. Such type of material containing source of silica, alumina, magnesia and a pore forming capability is not very common from any single source. The reaction product of waste paper pulp and alluminosilicate minerals in the present invention resulted a light weight material consists of hard particles with a dense skin and cellular structure possessing high thermal shock resistance properties which is also very important and desirable property for the insulating refractory aggregate. ^ The novelty of the process of the present invention lies in the simultaneous formation of low expansive synthetic and porous structure by heating a mixture of processed pulp waste and aluminosilicate materials. The inventive step resides in the starting material, waste paper pulp along with alluminosilicate material which on sintering not only results in providing a novel refractory aggregate having low expansive ceramic phases and porous structure but also utilises an industrial waste. This lightweight material consisting of hard particles with a dense skin and cellular structure provides excellent insulating properties. The presence of low expansive synthetic phase (cordierite) further improves the thermal shock resistance of the material significantly. The following examples are given by the way of illustration and should not be construed to limit the scope of the present invention. Example 1 600 gms of dry processed paper pulp waste, 400 gms of kaolin were thoroughly wet mixed with 3 litters of water for a period of 9 hours. The slip thus produced was sieved through 10 mesh BS sieve and dried. The material was then taken in a mould and pressed at a pressure of 160 kg/cm2 for making samples having dimensions 100mm X 30mm X 30mm rectangular shape. The green samples were then oven dried at about 110°C for 24 hours. The dried samples were sintered in an electric furnace at a temperature of 1350°C for a period of 2 hours. The sintered samples were crushed and graded into -30 +72 mesh ( BS Sieve) fraction. The resultant product characteristics were Loose Bulk Density : 0.80gms/cc Grain Bulk Density : 1.25 gms/cc Example 2 500 gms of dry processed paper pulp waste, 500 gms of kaolin were thoroughly wet mixed with 3 litters of water for a period of 10 hours. The slip thus produced was sieved through 10 mesh BS sieve, dried. The material was then taken in a mould and pressed at a pressure of 170 kg/cm2 for making samples having dimensions 100mm X 30mm X 30mm rectangular shape. The green samples were then oven dried at about 110°C for 24 hours. The dried samples were sintered in an electric furnace at a temperature of 1200°C for a period of 3 hours. The sintered samples were crushed and graded into -8 +16 mesh ( BS Sieve) fraction. The resultant product characteristics were Loose Bulk Density : 0.70 gms/cc Grain Bulk Density : 1.13 gms/cc Example 3 700 gms of dry processed paper pulp waste, 200 gms of kaolin 100 gms of sillimanite sand fines were thoroughly wet mixed with 3 litters of water for a period of 10 hours. The slip thus produced was sieved through 10 mesh BS sieve and dried. The material was then taken in a mould and pressed at a pressure of 170 kg/cm2 for making samples having dimensions 100mm X 30mm X 30mm rectangular shape. The green samples were then oven dried at about 110°C for 24 hours. The dried samples were sintered in an electric furnace at a temperature of 1400°C for a period of 3 hours. The sintered samples were crushed and graded into -72 mesh ( BS Sieve) fraction. The resultant product characteristics were Loose Bulk Density : l.OOgms/cc Grain Bulk Density : 1.23 gms/cc Example 4 600 gms of dry processed paper pulp waste, 200 gms of kaolin 200 gms of kyanite fines were thoroughly wet mixed with 3 litters of water for a period of 10 hours. The slip thus produced was sieved through 10 mesh BS sieve and dried. The material was then taken in a mould and pressed at a pressure of 170 kg/cm2 for making samples having dimensions 100mm X 30mm X 30mm rectangular shape. The green samples were then oven dried at about 110°C for 24 hours. The dried samples were sintered in an electric furnace at a temperature of 1400°C for a period of 3 hours. The sintered samples were crushed and graded into -30 +72 mesh (BS Sieve) fraction. The resultant product characteristics were Loose Bulk Density : 1.05 gms/cc Grain Bulk Density : 1.26 gms/cc The main advantages of the present invention are 1. The present process utilises an unique source of raw materials viz., paper pulp waste to prepare low expansive porous ceramic structure. 2. The present process minimises the environmental pollution problem in paper industries by utilising their pulp waste. 3. The present process produces a product which can be used in the form of aggregate for making usable refractory bricks and castable compositions. We claim: 1. A process for the preparation of porous refractory aggregate which comprises wet grinding and intimate mixing of 50-70 weight percent dry paper pulp, 30-50 weight percent alumino-silicate materials and 300 weight percent of water for a period in the range of 8-10 hours to obtain a ceramic slip, sieving the ceramic slip through 10 mesh BS sieve, drying the slip, compacting the dried powder into shape, drying the shape, sintering the dried shape in a furnace at a temperature in the range of 1200°-1400°C for a period in the range of 2-3 hrs, crushing by known methods to obtain different size porous refractory aggregate. 2. A process as claimed in claim 1 wherein the major raw material used is processed waste paper pulp which contains 50 - 55 weight percent of silica, 28 - 35 weight percent of alumina, 5-9 weight percent of magnesium oxide, 1-2 weight percent of calcium oxide, 1-3 weight percent of titanium dioxide. 3. A process as claimed in claim 1-3 wherein alumino-silicate minerals used is such as kaolin, montmorrillonite, sillimanite sand, kyanite or mixture thereof. 4. A process as claimed in claim 1-4 wherein compacting of shapes is done under pressure in the range of 150-170 kg/cm2. 5. A process for the preparation of low expansive porous refractory aggregate: substantially as herein described with reference to the examples.

Full Text

The present invention relates to a process for the synthesis of porous refractory aggregate.
The low expansive porous insulating refractory aggregate produced by the present invention can be incorporated in insulating bricks and castable compositions useful in metallurgical industries both in ferrous and non-ferrous sectors to provide insulation in their furnaces as a measure of energy saving.
The present day method for the production of porous insulating refractory aggregate utilises raw materials such as perlite, expanded shale for silica based aggregates and expanded fireclay for alumina based aggregates. Sometimes carbon source is used as pore forming agent. Reference may be made to the article of Ken Moody of USA (Industrial minerals, Oct, 1997) wherein typical light weight insulating aggregates used in conventional refractory castable compositions where around 70-80% insulating aggregate is used in addition to other 20-30% raw materials such as clay, high alumina cement bond etc. has been described. Perlite aggregate is a naturally occurring mineral and expanded shale aggregate is produced by firing shale. The drawbacks of such type of aggregates are :
a) Limited thermal stability due to the absence of low expansive ceramic phases.
b) Impurities (such as alkali, iron oxide) present in perlite and shale aggregate make
the bricks and castable product prone to thermal shock.
c) Weakness of the aggregate due to their chemistry and non complimentary effect of
the calcium aluminate binder used in castable composition.
Expanded fireclay and vermiculite aggregate is used to produce alumina based aggregate by firing naturally occurring clay into its expanded form. Again, clay being a naturally occurring mineral, its consistency in quality always varies from one

deposit to other which indirectly does not provide bricks and castable product with
consistent quality and uniform properties.
The literature search does not provide any information regarding simultaneous
formation of low expansive synthetic phase and porous structure which may be used
as insulating refractory aggregate. The present concept is an unique and new to this
branch of technology. The present technology utilises processed pulp waste of paper
industries and conversion of it into new usable product.
The main object of the present invention is to provide a process for the preparation of
low expansive porous refractory aggregate istc which obviates the
drawbacks of present existing process as detailed above.
Yet another objective of the present invention is to utilise processed paper pulp wajge
to provide an insulating aggregate of lower bulk density, higher porosity with
extremely fine and uniformly dispersed pores.
Accordingly the present invention provides a process for the preparation of porous
refractory aggregate which comprises wet grinding and intimate mixing of 50-70
weight percent dry paper pulp, 30-50 weight percent alumino-silicate materials and
300 weight percent of water for a period in the range of 8-10 hours to obtain a
ceramic slip, sieving the ceramic slip through 10 mesh BS sieve, drying the slip,
compacting the dried powder into shape, drying the shape, sintering the dried shape in
a furnace at a temperature in the range of 1200°-1400°C for a period in the range of
2-3 hrs, crushing by known methods to obtain different size porous refractory
aggregate.
In an embodiment of the present invention the major raw material used may be
processed waste paper pulp which contains 50 - 55 weight percent of silica, 28 - 35

weight percent of alumina, 5 - 9 weight percent of magnesium oxide, 1-2 weight
percent of calcium oxide, 1-3 weight percent of titanium dioxide.
In another embodiment of the present invention the paper pulp may be processed by
known methods to make it free from alkali.
In yet another embodiment of the present invention, alumino-silicate minerals may be
such as kaolin, montmorrillonite, sillimanite sand, kyanite and mixture thereof.
In still another embodiment of the present invention compacting of shapes may be
done under pressure in the range of 150-170 kg/cm2.
In yet another embodiment of the present invention the inmulating aggregate may be
done in various size grading to suit specific purposes.
The detail process steps of the present invention are
i) Intimate wet mixing of 50 to 70 weight percent dry waste paper pulp, 30 to 50
weight percent aluminosilicate minerals with 300 weight percent of water.
ii) Sieving the ceramic slip through 10 mesh BS sieve
iii) Drying of the slip
iv) Compacting of shapes under pressure in the range of 150-170 kg/cm2 by usual
method.
v) Drying of the shapes
vi) Sintering the shapes in a furnace at a temperature in the range of 1200 - 1400°C for
soaking period of 2-3 hrs
vii) Crushing into various size fractions.
The chemical analysis of the waste paper pulp used in the present invention shows the
presence of considerable amount of MgO in addition to the SiO2 and A12O3. On
sintering the mixture of paper pulp and aluminosilicates, certain proportion of silica,
alumina and magnesia gives rise to low expansive synthetic ceramic phase like

cordierite (2MgO.2Al2O3.5SiO2) in addition to the formation of hard phase like
mullite (3Al2O3.2SiO2 as confirmed by X-ray diffraction. The presence of such low
expansive synthetic phases improves the thermal shock resistance of the material
significantly. Further, the present invention resides in the formation of porous
structure due to cellular structure of waste paper pulp. Such type of material
containing source of silica, alumina, magnesia and a pore forming capability is not
very common from any single source. The reaction product of waste paper pulp and
alluminosilicate minerals in the present invention resulted a light weight material
consists of hard particles with a dense skin and cellular structure possessing high
thermal shock resistance properties which is also very important and desirable
property for the insulating refractory aggregate. ^
The novelty of the process of the present invention lies in the simultaneous formation of low expansive synthetic and porous structure by heating a mixture of processed pulp waste and aluminosilicate materials. The inventive step resides in the starting material, waste paper pulp along with alluminosilicate material which on sintering not only results in providing a novel refractory aggregate having low expansive ceramic phases and porous structure but also utilises an industrial waste. This lightweight material consisting of hard particles with a dense skin and cellular structure provides excellent insulating properties. The presence of low expansive synthetic phase (cordierite) further improves the thermal shock resistance of the material significantly.
The following examples are given by the way of illustration and should not be construed to limit the scope of the present invention.

Example 1
600 gms of dry processed paper pulp waste, 400 gms of kaolin were thoroughly wet mixed with 3 litters of water for a period of 9 hours. The slip thus produced was sieved through 10 mesh BS sieve and dried. The material was then taken in a mould and pressed at a pressure of 160 kg/cm2 for making samples having dimensions 100mm X 30mm X 30mm rectangular shape. The green samples were then oven dried at about 110°C for 24 hours. The dried samples were sintered in an electric furnace at a temperature of 1350°C for a period of 2 hours. The sintered samples were crushed and graded into -30 +72 mesh ( BS Sieve) fraction. The resultant product characteristics were Loose Bulk Density : 0.80gms/cc Grain Bulk Density : 1.25 gms/cc
Example 2
500 gms of dry processed paper pulp waste, 500 gms of kaolin were thoroughly wet mixed with 3 litters of water for a period of 10 hours. The slip thus produced was sieved through 10 mesh BS sieve, dried. The material was then taken in a mould and pressed at a pressure of 170 kg/cm2 for making samples having dimensions 100mm X 30mm X 30mm rectangular shape. The green samples were then oven dried at about 110°C for 24 hours. The dried samples were sintered in an electric furnace at a temperature of 1200°C for a period of 3 hours. The sintered samples were crushed and graded into -8 +16 mesh ( BS Sieve) fraction. The resultant product characteristics were
Loose Bulk Density : 0.70 gms/cc Grain Bulk Density : 1.13 gms/cc

Example 3
700 gms of dry processed paper pulp waste, 200 gms of kaolin 100 gms of sillimanite sand fines were thoroughly wet mixed with 3 litters of water for a period of 10 hours. The slip thus produced was sieved through 10 mesh BS sieve and dried. The material was then taken in a mould and pressed at a pressure of 170 kg/cm2 for making samples having dimensions 100mm X 30mm X 30mm rectangular shape. The green samples were then oven dried at about 110°C for 24 hours. The dried samples were sintered in an electric furnace at a temperature of 1400°C for a period of 3 hours. The sintered samples were crushed and graded into -72 mesh ( BS Sieve) fraction. The resultant product characteristics were Loose Bulk Density : l.OOgms/cc Grain Bulk Density : 1.23 gms/cc
Example 4
600 gms of dry processed paper pulp waste, 200 gms of kaolin 200 gms of kyanite fines were thoroughly wet mixed with 3 litters of water for a period of 10 hours. The slip thus produced was sieved through 10 mesh BS sieve and dried. The material was then taken in a mould and pressed at a pressure of 170 kg/cm2 for making samples having dimensions 100mm X 30mm X 30mm rectangular shape. The green samples were then oven dried at about 110°C for 24 hours. The dried samples were sintered in an electric furnace at a temperature of 1400°C for a period of 3 hours. The sintered samples were crushed and graded into -30 +72 mesh (BS Sieve) fraction. The resultant product characteristics were Loose Bulk Density : 1.05 gms/cc Grain Bulk Density : 1.26 gms/cc The main advantages of the present invention are
1. The present process utilises an unique source of raw materials viz., paper pulp
waste to prepare low expansive porous ceramic structure.
2. The present process minimises the environmental pollution problem in paper
industries by utilising their pulp waste.
3. The present process produces a product which can be used in the form of aggregate
for making usable refractory bricks and castable compositions.

We claim:
1. A process for the preparation of porous refractory aggregate which comprises wet
grinding and intimate mixing of 50-70 weight percent dry paper pulp, 30-50 weight
percent alumino-silicate materials and 300 weight percent of water for a period in the
range of 8-10 hours to obtain a ceramic slip, sieving the ceramic slip through 10 mesh
BS sieve, drying the slip, compacting the dried powder into shape, drying the shape,
sintering the dried shape in a furnace at a temperature in the range of 1200°-1400°C
for a period in the range of 2-3 hrs, crushing by known methods to obtain different
size porous refractory aggregate.
2. A process as claimed in claim 1 wherein the major raw material used is processed
waste paper pulp which contains 50 - 55 weight percent of silica, 28 - 35 weight
percent of alumina, 5-9 weight percent of magnesium oxide, 1-2 weight percent of
calcium oxide, 1-3 weight percent of titanium dioxide.

3. A process as claimed in claim 1-3 wherein alumino-silicate minerals used is such
as kaolin, montmorrillonite, sillimanite sand, kyanite or mixture thereof.
4. A process as claimed in claim 1-4 wherein compacting of shapes is done under
pressure in the range of 150-170 kg/cm2.
5. A process for the preparation of low expansive porous refractory aggregate:
substantially as herein described with reference to the examples.

Documents:

1202-del-2000-abstract.pdf

1202-del-2000-claims.pdf

1202-del-2000-correspondence-others.pdf

1202-del-2000-correspondence-po.pdf

1202-del-2000-description (complete).pdf

1202-del-2000-form-1.pdf

1202-del-2000-form-19.pdf

1202-del-2000-form-2.pdf

1202-del-2000-form-3.pdf

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Patent Number

220187

Indian Patent Application Number

1202/DEL/2000

PG Journal Number

28/2008

Publication Date

11-Jul-2008

Grant Date

16-May-2008

Date of Filing

26-Dec-2000

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

Inventors:

#	Inventor's Name	Inventor's Address
1	PRADIP MONDAL
2	SOMNATH MUKHERJEE
3	SWAPAN KUMAR DAS
4	GOUTAM BANERJEE
5	SUBRATA DASGUPTA
6	NITYANANDA DHAR

PCT International Classification Number

C04B 14/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA