Title of Invention	A PROCESS FOR MAKING REACTIVE POZZOLANA FOR USE AS A MINERAL ADMIXTURE IN CEMENT
Abstract	This invention relates to development of a process for making reactive pozzolana for use as a mineral admixture in cement. Particularly, this invention relates to development of a pozzolonaic material comprising of lignocellulosic waste ash and burnt clay. More particularly, this invention relates to preparation of burnt (calcined) clay pozzolona containing ash of lignocellulosic waste by using the lignocellulosic waste as the source of fuel for calcination of the clay. The resultant mixture has improved lime reactivity (higher than specified Indian standard) and also its content of Si02+AL203+Fe203 is higher than specified Indian standard which makes it suitable for use as pozzolana admixture.

Title of Invention

A PROCESS FOR MAKING REACTIVE POZZOLANA FOR USE AS A MINERAL ADMIXTURE IN CEMENT

Abstract

Full Text	This invention relates to development of a process for making reactive pozzolana for use as a mineral admixture in cement. Particularly, this invention relates to development of a pozzolonaic material comprising of lignocellulosic waste ash and burnt clay. More particularly, this invention relates to preparation of burnt (calcined) clay pozzolona containing ash of lignocellulosic waste by using the lignocellulosic waste as the source of fuel for calcination of the clay. The demand of cement is ever increasing. Ordinary (Normal) Portland cement (OPC) clinkers are produced by burning a well proportioned and finely ground raw mix comprising of lime rich materials like limestone and silica and alumina bearing materials like clay, at around 1450 °C temperature. The materials undergo drying, dehydration, de-carbonation etc during the course of heating, and the Products formed react at high temperature to form the major clinker phases. The clinkers are ground with gypsum to obtain the cement. Manufacture of cement is therefore a highly energy consuming process and fuel cost accounts substantially to the cost of the cement. The energy consumption in cement manufacture may be reduced and the production of cement may be increased by mixing ordinary Portland cement with materials having latent hydraulic or pozzolanic property. The cement so produced is known as composite or blended cement. Blended cements have many advantages over ordinary Portland cement. The blended cements exhibit low heat of hydration, improved mechanical strength, increased durability to chemical attack etc. than OPC. Because of these and other reasons like economy in production, elimination of the problems of disposal of some waste materials, reduction of environmental problems associated with disposal of the waste, reduction in emission of CO2 and other green house gasses, conservation of natural resources due to less consumption of limestone etc, the productions and utilization of blended cements are steadily increasing. The materials used for blending with cements are called mineral admixtures, secondary additives, or mineral addition. A variety of naturally occurring substances like volcanic glass, tuff, opaline silica, clay, shale etc. either in raw or in calcined state and many industrial byproducts like fly ash, silica fume etc. Pozzolanic materials are used as mineral admixtures for making composite or blended cement. Pozzolanas are rich in silica and often in alumina. They are sufficiently reactive. The Pozzolanas, when mixed with water and CaO produce C-S-H at ordinary temperature and thereby act as hydraulic cements. Many industrial waste materials like fly ash, rice husk ash are Pozzolanaic and are used in making blended cement. • Rice husk is an agro industrial by Product. The calorific value of husk is around 5000 cal/g. On burning, it produces around 20-25% of its weight as "ash" which is mostly (about 90%) comprised of silica. The Ash containing amorphous silica and having high specific area may be produced by burning husk under controlled condition .The Pozzolanic activity of such ash is superior to burnt clay, fly ash etc. Many cementitious compositions, comprising of controlled burnt rice husk ash, quick/hydrated lime have been reported (Appropriate Technology, Proceeding UNIDO/ESCAP/RCTT/PCSIR joint workshop, Peshawar Pakistan and Bangalore India, 1979). Blended cements prepared using rice husk ash as a mineral admixture can replace higher quantity of cement than any other Pozzolana and impart good strength. (Hwang C.L and Wu D.S " Production of cement containing rice husk" -14 American concrete Institute special publication - 14, edited V.M.Malhotra, 1989, PP 733-765 and Rice husk ash - unique supplementary cementing material, in Advances in concrete technology, CANMET, edited by V.M.Malhotra, 1994,pp 419-444).. Burnt or calcined clay is one of the earliest known pozzolanic materials. It is still in use in places where mineral admixtures like natural pozzolana or industrial waste material like fly ash, blast furnace slag etc are not available. A clay when heated to a suitable temperature undergoes dehydroxylationto form reactive silica and alumina and thereby acts as pozzolana. The calcined clay reacts with lime liberated during hydration of Portland cement and produces C-S-H and C-A-S-H, which are similar to the products of hydration of Portland cement. The calcination temperature varies from clay to clay. Metakaolin formed by calcination of Kaolin clay is generally used as a mineral addition for lended cement production Conversion of Kaolin to Metakaolin involves heating the clay to a temperature of 700-800 °C and therefore consumes considerable amount of thermal energy. The strength characteristics of blended cement containing burnt clay may be improved by mixing the calcined clay with rice husk ash (Saikia P.B, Borthakur P.C, and Baishya N.K in "Effect of mixtures of burnt clay and rice husk ash on blended cement properties" Proceeding 5th NCB International Sem., organised by NCB, New Delhi, pp XI 88-94). The high reactivity of controlled burnt rice husk ash has led to development of various techniques, furnaces for burning husk, (Smith R., "Rice husk ash cement : Progress in development and applications", Intermediate technology Publications Limited, London 1984; Kapur P.C;" Production of reactive Bio silica from the combustion of rice husk in a tube in basket burner, Powder Tech. 44 , 1985,P163, Boating A.A. and Skeete D.A.; Incineration of rice hull for use as a cementitious Materials, the Guyana experience, Cement and Concrete Research, 20(5), 1990 PP 795-802. Sugita S., Yu Q, Shoya M., Tsukinagor Y, and Isojima Y, on the semi industrial Production of highly reactive rice husk ash and its effect on cement and concrete properties, Proc. 10th International conference on chemistry of cement Sweden, 1997 pp 3 ii 109). But in most of the techniques, the calorific value of the husk is lost. The present invention aims at total utilization of the fuel value of the husk in making reactive ash in conjunction with burnt clay pozzolana or using as a blending material in cements. Object of Invention The object of the present invention is to utilize the fuel value of the husk in calcination of a clay to produce a reactive mixture comprising of the calcined clay and rice husk ash to be used as a mineral admixture for preparing blended cement. Statement of invention Accordingly, the present invention provides a process for making a pozzolanic material for use as a mineral admixture in cement which comprises: characterized in mixing clay and powdered rice husk in the weight ratio of 1.0: 0.250 to 1.0: 0.5. homogenizing the dry mixture and then agglomerating the mixture in a disc type nodulizer using a spray of water followed by feeding the agglomerated mixture into a furnace lined with refractory bricks and having provisions for air entry and then firing, raising the temperature to 500 -750 °C by regulating the air entry, followed by cooling and pulverizing the burnt product to a fineness in the range of 8000-9000 cm2 / gm. In an embodiment of the present investigation, powdered kaolin clay and powdered rice husk were mixed in the weight proportion of 1.0:0.2.5 and the mixture after homogenization was nodulized in a disc type nodulizer and fired at a temperature of 750 °C in a vertical furnace and the product after cooling was pulverized to a fineness of 9000 cm2/ gm. In another embodiment the powdered clay and husk were mixed in the weight proportions of 1.0:0.3 or 1.0:0.5 ratio, and the mixtures after homogenization and nodulization was burnt at a temperature of 650-750 °C and the burnt products after cooling was pulverized to 8000 to 8500 cm2/ gm. The invention is illustrated with the following examples, which should not be construed to limit the scope of the investigation. The examples are illustrated with a kaolin clay sample and a locally procured rice husk. The chemical analysis of the clay and rice husk samples used in the examples is shown in Table 1. The proximate analysis and calorific value of the rice husk sample are nrovided in Table 2. Table 1: Analysis of raw materials. (Table Removed) Table 2: Proximate analysis and calorific value of Rice Husk (Table Removed) Example -1 Rice husks were pulverized in a pulverizer to a fineness of less than 200-micron size. It was mixed with powdered kaolin clay in the proportion of 1 kg clay and 0.250 kg rice husk. The mixture was homogenized thoroughly in the dry state and agglomerated to 8-12 mm size nodule in a disc type nodulizer using spray of water. The resultant green nodules were then fed to a vertical furnace, which is internally lined with refractory brick and having provision for entry of air. The green nodules were then fired. The temperature of the mixture was maintained at 650 °C by regulating the airflow. It was then cooled to room temperature by blowing air. The soft and porous resultant products were then ground in a batch type ball mill to a fineness of around 9000 sq.cm/gm. (Blaine). The lime reactivity (pozzolanicity) of the product, so obtained, as determined by the method prescribed in Indian Standard specification No 1727-1960, is 54 kg./cm2 The lime reactivity is much higher than specified in, the Indian standard (minimum of 40 kg./cm2). Example - 2 The clay and powdered rice husk was mixed in the proportions of 1 kg clay and 0.3 kg husk and the green nodules were prepared by following the procedure as discussed in Example 1. The green nodules were then fired and processed further by following the same procedures as outlined in the above example. The fired product was ground in a ball mill posses to obtain a product having fineness of 8500 cm2/ gm and lime reactivity of 68 kg./cm2. Example - 3 Rice husk was pulverized to a fineness of below 200-micron size and mixed with powdered kaolin in the proportion of 1 kg kaolin and 0.5 kg rice husk. The mixture was then homogenized thoroughly in the dry state and then agglomerated in a disc type nodulizer to form of 8-12 mm sized nodules using a spray of water. The green nodules were processed further by following the procedure as outlined in example 1 to obtain a product having fineness of 8300 cm2/gm (Blaine) and lime reactivity of 68 kg/ cm2 The chemical compositions of the various pozzolanic materials obtained in examples 1-3 are presented in Table 3. The total SiO2 + Al2O3 and Fe2O3 of all the mixtures are greater than a minimum 70.0 percent by mass as specified IS 3812 -1981, Specification for fly ash for use as pozzolana and admixture. Table 3: Chemical compositions of the pozzolanic materials as produced in various Examples (Table Removed) The various pozzolanic materials as obtained in different examples were further evaluated as mineral admixtures for making blended cement. For the purpose, Portland cement clinkers produced in a commercial plant was collected and ground with 5 % gypsum to obtain ordinary (normal) Portland cement. Various blended cement compositions containing the Portland cement and 10 and 20% of each of the products obtained in examples 1-3 were prepared. The physical properties of the blended and the parent cement samples were evaluated as per Indian Standard Methods No. (4031 -1967). The results are presented in Table 4. The results shows that the strength of the blended cement compositions are much higher than the parent those of ordinary Portland cement and those specified in Indian standard 4031-1967: for Methods of physical tests for hydraulic cement. Table 4: Physical properties of Blended Cements and Requirements of Ordinary Portland Cement and Portland Pozzolana Cements. Amount of Pozzolanic materials (20%) (Table Removed) Advantage of the present invention • Complete utilization of the fuel value of the husk. • Preparation of ash in conjunction with burnt clay. • Production of burnt clay and reactive ash in situ suitable for utilization as a mineral admixture for cement utilizing the waste materials as the fuel. The co product reactive ash and burnt clay may be blended with Portland cement to obtain blended cement with improved technological properties. We claim: 1. A process for making a pozzolanic material for use as a mineral admixture in cement which comprises: characterized in mixing clay and powdered rice husk in the weight ratio of 1.0: 0.250 to 1.0: 0.5. homogenizing the dry mixture and then agglomerating the mixture in a disc type nodulizer using a spray of water followed by feeding the agglomerated mixture into a furnace lined with refractory bricks and having provisions for air entry and then firing, raising the temperature to 500 -750 °C by regulating the air entry, followed by cooling and pulverizing the burnt product to a fineness in the range of 8000-9000 cm2 / gm. 2. A process as claimed in claim 1, wherein, the nodules are preferably prepared in the size ranges of 8-12 mm. 3. A process as claimed in claims 1-2, wherein, the rice husk possesses a calorific value of 3000-3500 cal/g. 4. A process as claimed in claims l-3,wherein the clay used is a plastic one free from excessive amount of non clay materials like quartz, Feldspar and preferably rich in Kaolinite. 5. A process as claimed in claims 1-4, wherein the firing temperature of the green nodules and cooling of the fired products are preferably effected by blowing ambient air. 6. A process as claimed in claims 1-5, wherein, the temperature of burning of the clay is controlled to effect dehydroxylation of the clay and combustion of carbonaceous material of the husk. 7. A process for making a pozzolanic material for use as a mineral admixture in cement substantially as herein described with reference to the examples.

Full Text

This invention relates to development of a process for making reactive pozzolana for use as a mineral admixture in cement. Particularly, this invention relates to development of a pozzolonaic material comprising of lignocellulosic waste ash and burnt clay. More particularly, this invention relates to preparation of burnt (calcined) clay pozzolona containing ash of lignocellulosic waste by using the lignocellulosic waste as the source of fuel for calcination of the clay.
The demand of cement is ever increasing. Ordinary (Normal) Portland cement (OPC) clinkers are produced by burning a well proportioned and finely ground raw mix comprising of lime rich materials like limestone and silica and alumina bearing materials like clay, at around 1450 °C temperature. The materials undergo drying, dehydration, de-carbonation etc during the course of heating, and the Products formed react at high temperature to form the major clinker phases. The clinkers are ground with gypsum to obtain the cement. Manufacture of cement is therefore a highly energy consuming process and fuel cost accounts substantially to the cost of the cement.
The energy consumption in cement manufacture may be reduced and the production of cement may be increased by mixing ordinary Portland cement with materials having latent hydraulic or pozzolanic property. The cement so produced is known as composite or blended cement. Blended cements have many advantages over ordinary Portland cement. The blended cements exhibit low heat of hydration, improved mechanical strength, increased durability to chemical attack etc. than OPC. Because of these and other reasons like economy in production, elimination of the problems of disposal of some waste materials, reduction of environmental problems associated with disposal of the waste, reduction in emission of CO2 and other green house gasses, conservation of natural resources due to less consumption of limestone etc, the productions and utilization of blended cements are steadily increasing.
The materials used for blending with cements are called mineral admixtures, secondary additives, or mineral addition. A variety of naturally occurring substances like volcanic glass, tuff, opaline silica, clay, shale etc. either in raw or in calcined state and
many industrial byproducts like fly ash, silica fume etc. Pozzolanic materials are used as mineral admixtures for making composite or blended cement. Pozzolanas are rich in silica and often in alumina. They are sufficiently reactive. The Pozzolanas, when mixed with water and CaO produce C-S-H at ordinary temperature and thereby act as hydraulic cements.
Many industrial waste materials like fly ash, rice husk ash are Pozzolanaic and are used in making blended cement. • Rice husk is an agro industrial by Product. The calorific value of husk is around 5000 cal/g. On burning, it produces around 20-25% of its weight as "ash" which is mostly (about 90%) comprised of silica. The Ash containing amorphous silica and having high specific area may be produced by burning husk under controlled condition .The Pozzolanic activity of such ash is superior to burnt clay, fly ash etc.
Many cementitious compositions, comprising of controlled burnt rice husk ash, quick/hydrated lime have been reported (Appropriate Technology, Proceeding UNIDO/ESCAP/RCTT/PCSIR joint workshop, Peshawar Pakistan and Bangalore India, 1979). Blended cements prepared using rice husk ash as a mineral admixture can replace higher quantity of cement than any other Pozzolana and impart good strength. (Hwang C.L and Wu D.S " Production of cement containing rice husk" -14 American concrete Institute special publication - 14, edited V.M.Malhotra, 1989, PP 733-765 and Rice husk ash - unique supplementary cementing material, in Advances in concrete technology, CANMET, edited by V.M.Malhotra, 1994,pp 419-444)..
Burnt or calcined clay is one of the earliest known pozzolanic materials. It is still in use in places where mineral admixtures like natural pozzolana or industrial waste material like fly ash, blast furnace slag etc are not available. A clay when heated to a suitable temperature undergoes dehydroxylationto form reactive silica and alumina and thereby acts as pozzolana. The calcined clay reacts with lime liberated during hydration of Portland cement and produces C-S-H and C-A-S-H, which are similar to the products of hydration of Portland cement. The calcination temperature varies from clay to clay.
Metakaolin formed by calcination of Kaolin clay is generally used as a mineral addition for lended cement production Conversion of Kaolin to Metakaolin involves heating the clay to a temperature of 700-800 °C and therefore consumes considerable amount of thermal energy. The strength characteristics of blended cement containing burnt clay may be improved by mixing the calcined clay with rice husk ash (Saikia P.B, Borthakur P.C, and Baishya N.K in "Effect of mixtures of burnt clay and rice husk ash on blended cement properties" Proceeding 5th NCB International Sem., organised by NCB, New Delhi, pp XI 88-94).
The high reactivity of controlled burnt rice husk ash has led to development of various techniques, furnaces for burning husk, (Smith R., "Rice husk ash cement : Progress in development and applications", Intermediate technology Publications Limited, London 1984; Kapur P.C;" Production of reactive Bio silica from the combustion of rice husk in a tube in basket burner, Powder Tech. 44 , 1985,P163, Boating A.A. and Skeete D.A.; Incineration of rice hull for use as a cementitious Materials, the Guyana experience, Cement and Concrete Research, 20(5), 1990 PP 795-802. Sugita S., Yu Q, Shoya M., Tsukinagor Y, and Isojima Y, on the semi industrial Production of highly reactive rice husk ash and its effect on cement and concrete properties, Proc. 10th International conference on chemistry of cement Sweden, 1997 pp 3 ii 109). But in most of the techniques, the calorific value of the husk is lost. The present invention aims at total utilization of the fuel value of the husk in making reactive ash in conjunction with burnt clay pozzolana or using as a blending material in cements.
Object of Invention
The object of the present invention is to utilize the fuel value of the husk in calcination of a clay to produce a reactive mixture comprising of the calcined clay and rice husk ash to be used as a mineral admixture for preparing blended cement.
Statement of invention
Accordingly, the present invention provides a process for making a pozzolanic
material for use as a mineral admixture in cement which comprises: characterized in mixing clay and powdered rice husk in the weight ratio of 1.0: 0.250 to 1.0: 0.5. homogenizing the dry mixture and then agglomerating the mixture in a disc type nodulizer using a spray of water followed by feeding the agglomerated mixture
into a furnace lined with refractory bricks and having provisions for air entry and then firing, raising the temperature to 500 -750 °C by regulating the air entry, followed by cooling and pulverizing the burnt product to a fineness in the range of 8000-9000 cm2 / gm.
In an embodiment of the present investigation, powdered kaolin clay and powdered rice husk were mixed in the weight proportion of 1.0:0.2.5 and the mixture after homogenization was nodulized in a disc type nodulizer and fired at a temperature of 750 °C in a vertical furnace and the product after cooling was pulverized to a fineness of 9000 cm2/ gm.
In another embodiment the powdered clay and husk were mixed in the weight proportions of 1.0:0.3 or 1.0:0.5 ratio, and the mixtures after homogenization and nodulization was burnt at a temperature of 650-750 °C and the burnt products after cooling was pulverized to 8000 to 8500 cm2/ gm.
The invention is illustrated with the following examples, which should not be construed to limit the scope of the investigation.
The examples are illustrated with a kaolin clay sample and a locally procured rice husk. The chemical analysis of the clay and rice husk samples used in the examples is shown in Table 1. The proximate analysis and calorific value of the rice husk sample are nrovided in Table 2.
Table 1: Analysis of raw materials.
(Table Removed)
Table 2: Proximate analysis and calorific value of Rice Husk

(Table Removed)
Example -1
Rice husks were pulverized in a pulverizer to a fineness of less than 200-micron size. It was mixed with powdered kaolin clay in the proportion of 1 kg clay and 0.250 kg rice husk. The mixture was homogenized thoroughly in the dry state and agglomerated to 8-12 mm size nodule in a disc type nodulizer using spray of water. The resultant green nodules were then fed to a vertical furnace, which is internally lined with refractory brick and having provision for entry of air. The green nodules were then fired. The temperature of the mixture was maintained at 650 °C by regulating the airflow. It was then cooled to room temperature by blowing air. The soft and porous resultant products were then ground in a batch type ball mill to a fineness of around 9000 sq.cm/gm. (Blaine). The lime reactivity (pozzolanicity) of the product, so obtained, as determined by the method prescribed in Indian Standard specification No 1727-1960, is
54 kg./cm2 The lime reactivity is much higher than specified in, the Indian standard (minimum of 40 kg./cm2).
Example - 2
The clay and powdered rice husk was mixed in the proportions of 1 kg clay and 0.3 kg husk and the green nodules were prepared by following the procedure as discussed in Example 1. The green nodules were then fired and processed further by following the same procedures as outlined in the above example. The fired product was ground in a ball mill posses to obtain a product having fineness of 8500 cm2/ gm and lime reactivity of 68 kg./cm2.
Example - 3
Rice husk was pulverized to a fineness of below 200-micron size and mixed with powdered kaolin in the proportion of 1 kg kaolin and 0.5 kg rice husk. The mixture was then homogenized thoroughly in the dry state and then agglomerated in a disc type nodulizer to form of 8-12 mm sized nodules using a spray of water. The green nodules were processed further by following the procedure as outlined in example 1 to obtain a product having fineness of 8300 cm2/gm (Blaine) and lime reactivity of 68 kg/ cm2
The chemical compositions of the various pozzolanic materials obtained in examples 1-3 are presented in Table 3. The total SiO2 + Al2O3 and Fe2O3 of all the mixtures are greater than a minimum 70.0 percent by mass as specified IS 3812 -1981, Specification for fly ash for use as pozzolana and admixture.
Table 3: Chemical compositions of the pozzolanic materials as produced in various Examples

(Table Removed)
The various pozzolanic materials as obtained in different examples were further evaluated as mineral admixtures for making blended cement. For the purpose, Portland cement clinkers produced in a commercial plant was collected and ground with 5 % gypsum to obtain ordinary (normal) Portland cement. Various blended cement compositions containing the Portland cement and 10 and 20% of each of the products obtained in examples 1-3 were prepared. The physical properties of the blended and the parent cement samples were evaluated as per Indian Standard Methods No. (4031 -1967). The results are presented in Table 4. The results shows that the strength of the blended cement compositions are much higher than the parent those of ordinary Portland cement and those specified in Indian standard 4031-1967: for Methods of physical tests for hydraulic cement.
Table 4: Physical properties of Blended Cements and Requirements of Ordinary Portland Cement and Portland Pozzolana Cements.

Amount of Pozzolanic materials (20%)

(Table Removed)
Advantage of the present invention
• Complete utilization of the fuel value of the husk.
• Preparation of ash in conjunction with burnt clay.
• Production of burnt clay and reactive ash in situ suitable for utilization as a
mineral admixture for cement utilizing the waste materials as the fuel.
The co product reactive ash and burnt clay may be blended with Portland cement to obtain blended cement with improved technological properties.

We claim:
1. A process for making a pozzolanic material for use as a mineral admixture in
cement which comprises: characterized in mixing clay and powdered rice husk in the weight ratio of 1.0: 0.250 to 1.0: 0.5. homogenizing the dry mixture and then agglomerating the mixture in a disc type nodulizer using a spray of water followed by feeding the agglomerated mixture into a furnace lined with refractory bricks and having provisions for air entry and then firing, raising the temperature to 500 -750 °C by regulating the air entry, followed by cooling and pulverizing the burnt product to a fineness in the range of 8000-9000 cm2 / gm.
2. A process as claimed in claim 1, wherein, the nodules are preferably prepared in the size ranges of 8-12 mm.
3. A process as claimed in claims 1-2, wherein, the rice husk possesses a calorific value
of 3000-3500 cal/g.
4. A process as claimed in claims l-3,wherein the clay used is a plastic one free from excessive amount of non clay materials like quartz, Feldspar and preferably rich in Kaolinite.
5. A process as claimed in claims 1-4, wherein the firing temperature of the green nodules and cooling of the fired products are preferably effected by blowing ambient air.
6. A process as claimed in claims 1-5, wherein, the temperature of burning of the clay is controlled to effect dehydroxylation of the clay and combustion of carbonaceous material of the husk.
7. A process for making a pozzolanic material for use as a mineral admixture in cement substantially as herein described with reference to the examples.

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Patent Number

277961

Indian Patent Application Number

2234/DEL/2004

PG Journal Number

51/2016

Publication Date

09-Dec-2016

Grant Date

07-Dec-2016

Date of Filing

09-Nov-2004

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	PRAKASH CHANDRA BORTHAKUR	REGIONAL RESEARCH LABORATORY, JORHAT-785006, ASSAM, INDIA
2	DIPAK BORDOLOI	REGIONAL RESEARCH LABORATORY, JORHAT-785006, ASSAM, INDIA

PCT International Classification Number

N/A

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA