Title of Invention	A PROCESS FOR THE PRODUCTION OF ALUMINO-SILICATE HOLLOW SPHERE USEFULL AS AGGREGATES IN INSULATING REFRACTORY CASTABLE PRODUCT
Abstract	Title: A process for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product. In the process of the present invention, different sizes of polymeric spherical beads are given a first coating with chemical admixture followed by a second coating with a mixture of alumino-silicate materials. In the process of the present invention, the polyethylene bead is first coated with a cementitious material which acts as a base for the actual hollow sphere forming material (aluminasilicate). The coated beads are dried at room temperature followed by oven drying. The dried beads are immersed in organic solvent to obtain hollow sphere balls. The hollow sphere balls are subjected to drying followed by firing at high temperatures of the order of 1500 - 1550 °C. After firing at high temperatures, the hollow sphre balls achieved loose bulk density in the range of 0.50 to 0.52 gms/cc. The hollow sphere balls produced by the process of the present invention will find usage as aggregates in manufacturing refractory castable product which provides heat insulation in industrial kilns and furnaces.

Title of Invention

A PROCESS FOR THE PRODUCTION OF ALUMINO-SILICATE HOLLOW SPHERE USEFULL AS AGGREGATES IN INSULATING REFRACTORY CASTABLE PRODUCT

Abstract

Title: A process for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product. In the process of the present invention, different sizes of polymeric spherical beads are given a first coating with chemical admixture followed by a second coating with a mixture of alumino-silicate materials. In the process of the present invention, the polyethylene bead is first coated with a cementitious material which acts as a base for the actual hollow sphere forming material (aluminasilicate). The coated beads are dried at room temperature followed by oven drying. The dried beads are immersed in organic solvent to obtain hollow sphere balls. The hollow sphere balls are subjected to drying followed by firing at high temperatures of the order of 1500 - 1550 °C. After firing at high temperatures, the hollow sphre balls achieved loose bulk density in the range of 0.50 to 0.52 gms/cc. The hollow sphere balls produced by the process of the present invention will find usage as aggregates in manufacturing refractory castable product which provides heat insulation in industrial kilns and furnaces.

Full Text	The present invention relates to a process for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product. The present invention is particularly useful for producing alumino-silicate hollow sphere balls for application as aggregates in insulating refractory castable product which provides heat insulation in industrial kilns and furnaces, thereby saving energy. In the present day hitherto known prior art methods for the production of refractory hollow sphere balls, further references may be drawn to the work of B. Grabham, G. Sargeant,S. Adams, paper presented at UNITECR '89. in Anahem , CA, Nov. 1-5, 1989 and T.N.Venketesan, S.M. Bapat, U.K. patent no 2055787 A, 1981, wherein the polymeric beads of different diameter are coated with fireclay material, dried at 110 °C , heated at around 350 to 400°C for full elimination of polymer, final firing to selected high temperatures to give complete phase stability.The loose bulk density obtained was from 0.64 to 0.72 gm/cc for hollow sphere size of 1 to 5 mm. In another reference paper of J.L.Mendoza and R.F Moore, published in Ceramics. Today-Tomorrows' ceramics edited by P.Vincenzini,Elsevier science Publishers, 1991, it is reported that alumino-silicate hollow sphere balls produced by the hitherto known method posseses apparent density of 0.85 gm /cc for hollow sphere size of 3 to 6 mm. Reference may also be drawn to US patent no. 4,722171(1988) of Blottiere et. al., wherein a method has been described for rronufacturing hollow spheres. In this method metal coating was applied on poly urethane core and that metal coating consists of chemically bonded metal atoms making it a monolithic layer and this coating is not likely to disintegrate in the presence of solvent. The metal was deposited by electroplating on polystyrene cores followed by dissolution of the core by a solvent. However, this method is not applicable to produce refractory (aluminosilicate) hollow sphere. The present day hitherto known prior art methods for the production of hollow sphere balls has the following main drawbacks: 1. Complete elimination of polymer from the coated beads by total burning process requires higher thermal energy. 2. Complete elimination of polymer by burning process creates severe environmental pollution with the evolution of toxic gases. 3. Evolution of higher amount of gases during burning of coated polymeric beads develops stresses and finally may result in defective skin wall. 4. The present day hitherto known prior art methods are not ecofriendly. From the survey of the hitherto known prior art, it is seen that there is a definite need to provide a process for the production of hollow sphere balls, which will address the drawbacks as given herein above. The main object of the present invention fs to provide a process for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product, which obviates the drawbacks of the hitherto known prior art methods as detailed above. Another object of the present invention is to proVide an ecofriendly process for the production of alumino-silicate hollow sphere balls without creating environmental pollution. Yet another object of the present invention is to provide a process wherein removing polymer does not develop any stresses on skin wall. Still another object of the present invention is to provide a process wherein tailor made properties are achieved. A further object of the present invention is to provide a process for producing low dense alumino-silicate hollow sphere balls for application as aggregate in insulating castable. In the present invention there is provided a process for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product. In the process of the present invention, different sizes of polymeric spherical beads are given a first coating with chemical admixture followed by a second coating with a mixture of alumino-silicate materials. In the process of the present invention, a ceramic coating is applied on polyethylene bead, where the individual atoms are not likely to be chemically bonded unless some special procedure is adopted. In the process of the present invention, the polyethylene bead is first coated with a cementitious material which acts as a base for the actual hollow sphere forming material (aluminasilicate). The coated beads are dried at room temperature followed by oven drying. The polymeric material is removed from the alumino-silicatye coated beads by a novel process which is totally free from hazardous environmental pollution. The dried beads are immersed in organic solvent to obtain hollow sphere balls. The hollow sphere balls are subjected to drying followed by firing at high temperatures of the order of" 1 500 - 1550 C. After firing at high temperatures, the hollow sphere balls achieved loose bulk density in the range of 0.50 to 0.52 gms/cc. The hollow sphere balls produced by the process of the present invention will find usage as aggregates in manufacturing refractory castable product which provides heat insulation in industrial kilns and furnaces. Accordingly, the present invention provides a process for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product, which comprises: providing by known methods a first coating of chemical admixture on polymeric spherical beads of different sizes, followed by a second coating with a mixture of alumino-silicate materials to obtain double coated beads; drying the said coated beads at room temperature for a period in the range of 24 to 26 hours, followed by oven drying at a temperature in the range of 100 to 110 °C for a period in the range of 24 to 30 hours to obtain dried double coated beads; immersing the said dried double coated beads in organic solvent to obtain hollow sphere balls; drying the hollow sphere balls at a temperature in the range of 100 to 110 °C for a period in the range of 4 to 5 hours, followed by firing the said hollow sphere balls at a temperature in the range of 1500 to 1550 °C. In an embodiment of the present invention, the polymeric spherical beads of different sizes are in the range of 1.5 to 5.0 mm. In another embodiment of the present invention, the first coating of chemical admixture consists of 0 to 56 vol. % molasses, 0 to 44 vol. % sodium silicate and 33 to 56 vol. % colloidal silica in combination. In still another embodiment of the present invention, the second coating with a mixture of alumino-silicate materials consists of a blended mixture of 74 to 76 wt % calcined clay of below 100 mesh, 7 to12 wt % plastic clay of below 200 mesh,14 to 17 wt % sillimanite sand of below 200 mesh. In yet another embodiment of the present invention, the chemical constituents of both the calcined and plastic clay powders is in the range of AI2O3:35 to 40 wt %, Si02: 55 to 60 wt % and Fe203 below 1.5 wt % . In a further embodiment of the present invention, immersion of the dried double coated beads in organic solvent is for a period in the range of 12 to15 hours. hollow sphere balls at a temperature in the range of 1500 to 1550 °C is In a still further embodiment of the present invention, the firing of the hollow sphere balls at a temperature in the ran for a soaking period in the range of 2 to 3 hours. In the present invention, a process has been described for the production of high quality alumino-silicate hollow sphere balls, wherein by providing a coating, the surface chemistry and surface charge characteristics of polymeric beads and suspension particulates of alumino-silicate minerals have been used. Judicious selection of chemical admixture was necessary to adjust the surface chemistry appropriate for such purpose as well as to obtain strong green bonding between particles. In the present invention, the polymer was removed from the coated beads by dissolution in organic solvent. By this process, more than 95% polymer was found to be dissolved in organic solvent thus mitigating the environmental pollution to a greater extent which was otherwise removed by burning process in the present day method. The skin walls of the hollow sphere balls did not get disintegrated during dissolution of polymers by organic solvent. After drying, the hollow sphere balls were finally fired at a temperature in the range of 1500 to 1550 °C for a soaking period in the range of 2 to 3 hours. The fired hollow sphere balls possess loose bulk density from 0.50 to 0.60 gm/cc for hollow sphere size of 1.5 to 5mm. The novelty of the present invention resides in obtaining defect free low dense alumino-silicate hollow sphere balls having adequate strength. After firing at high temperatures, the hollow sphere balls achieved loose bulk density in the range of 0.50 to 0.52 gms/cc. The hollow sphere balls produced by the novel process of the present invention will find usage as aggregates in manufacturing refractory castable product which provides heat insulation in industrial kilns and furnaces. The novelty of the process of the present onvention has been achieved by the non-obvious inventive steps of providing a double coating, first with a chemical admixture followed by a second coating with a mixture of alumino-silicate materials. This precoating of the polymeric beads by an in situ formed cementitious material acts as a base for the actual hollow sphere forming material (aluminasilicate). The cementitious material which in turn prevents disintegration of the otherwise fragile ceramic material dissolution in a solvent. The following examples are given by the way of illustration of the process of the present invention in actual practice and should not be construed to limit the scope of the present invention. Example - 1 A chemical admixture was prepared by mixing 56 vol.% mollasses,33 vol% colloidal silica and 11 vol % sodium silicate. A blended mixture of alumino-silicate materials was also prepared consisting of 74 wt. % below 100 mesh calcined clay, 12wt. % below 200 mesh plastic clay and 14 wt.% below 200 mesh sillimanite sand. Then 1.5 mm size (diameter) spherical polymeric beads were first coated with the prepared chemical admixture followed by a second coating with the prepared blended mixture of alumino - silicate materials. Then the coated beads were dried first at room temperature for 24 hrs. and then at 110 °C for a period of 24 hrs. and immersed in xylene solvent for a period of 12 hrs. for the dissolution of polymeric material. After removal of polymer , the hollow sphere balls were dried at 110 °C for 4 hrs. & finally heated at 1500° C for 3 hrs. soaking . The heat treated hollow sphere balls were finally tested for loose bulk density, which was found to be 0.50 gm/cc. Example - 2 A chemical admixture was prepared by mixing 56 vol.% molasses and 44 vol.% colloidal silica. A blended mixture of alumino- silicate materials was also prepared consisting of 76 wt. % below 100 mesh calcined clay , 7 wt. % below 20 mesh plastic clay and 17 wt. % below 200 mesh sillimanite sand .Then 5 mm size (diameter) spherical polymeric beads were first coated with the prepared chemical admixture followed by a second coating with the prepared blended mixture of alumino-silicate materials. Then the coated beads were dried at room temperature for 26 hrs. and then atl 10 °C for a period of 30 hrs. and then immersed in toluene solvent for a period of 15 hrs. for the dissolution of polymeric material . After removal of polymers, the hollow sphere balls were dried at 110 °C for 5 hrs. and finally heated at 1550 °C for 2 hrs. soaking. The heat treated hollow sphere balls were finally tested for loose bulk density, which was found to be 0.50 gm/cc. Example- 3 A chemical admixture was prepared by mixing 56 vol. % colloidal silica and 44 vol.% sodium silicate. A blended mixture of alumino-silicate materials was also prepared consisting of 75 wt. % below 100 mesh calcined day , 10 wt.% below 200 mesh plastic clay and 15 wt. % below 200 mesh sillimanite sand.Then 1.5 mm size (diameter) spherical polymeric beads were first coated with this chemical admixture followed by a second coating with the prepared blended mixture of alumino -silicate materials. Then the coated beads were dried first at room temperature for 24 hrs. and then at 110° C for a period of 24 hrs. and immersed in xylene solvent for a period of 12 hrs. for the dissolution of polymeric material . After removal of polymers, the hollow sphere balls were dried at 110°C for 4 hrs. and finally heated at 1500°C for 3 hrs. soaking. The heat treated hollow sphere balls were finally tested for loose bulk density, which was found to be 0.52 gm/cc. The summary of the test results of the above three examples are as follows: (Table Removed) After firing at high temperatures, in the range of 1500 to 1550 °C, the hollow sphere balls achieved loose bulk density in the range of 0.50 to 0.52 gms/cc. The hollow sphere balls produced by the process of the present invention will find usage as aggregates in manufacturing refractory castable product which provides heat insulation in industrial kilns and furnaces. The main advantages of the process of the present invention for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product, are : 1. The process is environmental friendly. 2. The process of removing polymer does not develop any stresses on skin wall. 3. The process achieves tailor made properties. 4. The process produces low dense alumino-silicate hollow sphere balls for application as aggregate in insulating castable . We claim : 1. A process for the production of alumino-silicate hollow sphere balls which comprises : coating of different sizes polymeric spherical beads with chemical admixture such as herein described followed by another coating with a mixture of alumino-silicate; drying the coated beads at room temperature for a period in the range of 24-26 hrs oven drying at 100-110°C for a period in the range of 24 to 30 hrs; immersing the dried beads in organic solvent for dissolution of polymer for a period in the range of 12-15 hrs; drying the bead at 100-110°C for a period in the range of 4-5 hrs; heating the hollow sphere balls at 1500-1550°C for a period in the range of 2-3 hrs to obtain alumino-silicate hollow sphere balls. 2. A process as claimed in claim 1 wherein the chemical admixture used for coating are selected from a mixture of 0-56 vol.% molasses, 0-44 vol.% sodium silicate, and 33-56 vol% colloidal silica in combination. 3. A process as claimed in claim 1 wherein the alumino-silicate materials used for another coating are selected from a blended mixture of 74-76 wt% below 100 mesh calcined clay, 7-12 wt% below 200 mesh plastic clay, 14-17 wt% below 200 mesh sillimanite sand. 4. A process as claimed in claim 1 wherein solvent used for the dissolution of polymer from coated beads is selected from toluene, xylene. 5. A process for the production of alumino-silicate hollow sphere balls substantially as herein described with reference to examples.

Full Text

The present invention relates to a process for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product.
The present invention is particularly useful for producing alumino-silicate hollow sphere balls for application as aggregates in insulating refractory castable product which provides heat insulation in industrial kilns and furnaces, thereby saving energy.
In the present day hitherto known prior art methods for the production of refractory hollow sphere balls, further references may be drawn to the work of B. Grabham, G. Sargeant,S. Adams, paper presented at UNITECR '89. in Anahem , CA, Nov. 1-5, 1989 and T.N.Venketesan, S.M. Bapat, U.K. patent no 2055787 A, 1981, wherein the polymeric beads of different diameter are coated with fireclay material, dried at 110 °C , heated at around 350 to 400°C for full elimination of polymer, final firing to selected high temperatures to give complete phase stability.The loose bulk density obtained was from 0.64 to 0.72 gm/cc for hollow sphere size of 1 to 5 mm.
In another reference paper of J.L.Mendoza and R.F Moore, published in
Ceramics. Today-Tomorrows' ceramics edited by P.Vincenzini,Elsevier
science Publishers, 1991, it is reported that alumino-silicate hollow sphere
balls produced by the hitherto known method posseses apparent
density of 0.85 gm /cc for hollow sphere size of 3 to 6 mm.
Reference may also be drawn to US patent no. 4,722171(1988) of Blottiere et. al., wherein a method has been described for rronufacturing hollow spheres. In this method metal coating was applied on poly urethane core and that metal coating consists of chemically bonded metal atoms making it a monolithic layer and this coating is not likely to disintegrate in the presence of solvent. The metal was deposited by electroplating on polystyrene cores followed by dissolution of the core by a
solvent. However, this method is not applicable to produce refractory (aluminosilicate) hollow sphere.
The present day hitherto known prior art methods for the production of hollow sphere balls has the following main drawbacks:
1. Complete elimination of polymer from the coated beads by total burning process requires higher thermal energy.
2. Complete elimination of polymer by burning process creates severe environmental pollution with the evolution of toxic gases.
3. Evolution of higher amount of gases during burning of coated polymeric beads develops stresses and finally may result in defective skin wall.
4. The present day hitherto known prior art methods are not ecofriendly.
From the survey of the hitherto known prior art, it is seen that there is a definite need to provide a process for the production of hollow sphere balls, which will address the drawbacks as given herein above.
The main object of the present invention fs to provide a process for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product, which obviates the drawbacks of the hitherto known prior art methods as detailed above.
Another object of the present invention is to proVide an ecofriendly process for the production of alumino-silicate hollow sphere balls without creating environmental pollution.
Yet another object of the present invention is to provide a process wherein removing polymer does not develop any stresses on skin wall.
Still another object of the present invention is to provide a process wherein tailor made properties are achieved.
A further object of the present invention is to provide a process for producing low dense alumino-silicate hollow sphere balls for application as aggregate in insulating castable.
In the present invention there is provided a process for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product. In the process of the present invention, different sizes of polymeric spherical beads are given a first coating with chemical admixture followed by a second coating with a mixture of alumino-silicate materials. In the process of the present invention, a ceramic coating is applied on polyethylene bead, where the individual atoms are not likely to be chemically bonded unless some special procedure is adopted. In the process of the present invention, the polyethylene bead is first coated with a cementitious material which acts as a base for the actual hollow sphere forming material (aluminasilicate). The coated beads are dried at room temperature followed by oven drying. The polymeric material is removed from the alumino-silicatye coated beads by a novel process which is totally free from hazardous environmental pollution. The dried beads are immersed in organic solvent to obtain hollow sphere balls. The hollow sphere balls are subjected to drying followed by firing at high temperatures of the order of" 1 500 - 1550 C. After firing at high temperatures, the hollow sphere balls achieved loose bulk density in the range of 0.50 to 0.52 gms/cc. The hollow sphere balls produced by the process of the present invention will find usage as aggregates in manufacturing refractory castable product which provides heat insulation in industrial kilns and furnaces.
Accordingly, the present invention provides a process for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product, which comprises: providing by known methods a first coating of chemical admixture on polymeric spherical beads of different sizes, followed by a second coating with a mixture of alumino-silicate materials to obtain double coated beads; drying the said coated beads at room temperature for a period in the range of 24 to 26 hours, followed by oven drying at a temperature in the range of 100 to 110 °C for a period in the range of 24 to 30 hours to obtain dried double coated beads; immersing the said dried double coated beads in organic solvent to obtain hollow sphere balls; drying the hollow sphere balls at a temperature in the range of 100 to 110 °C for a period in the range of 4 to 5 hours, followed by firing the said hollow sphere balls at a temperature in the range of 1500 to 1550 °C.
In an embodiment of the present invention, the polymeric spherical beads of different sizes are in the range of 1.5 to 5.0 mm.
In another embodiment of the present invention, the first coating of chemical admixture consists of 0 to 56 vol. % molasses, 0 to 44 vol. % sodium silicate and 33 to 56 vol. % colloidal silica in combination.
In still another embodiment of the present invention, the second coating with a mixture of alumino-silicate materials consists of a blended mixture of 74 to 76 wt % calcined clay of below 100 mesh, 7 to12 wt % plastic clay of below 200 mesh,14 to 17 wt % sillimanite sand of below 200 mesh.
In yet another embodiment of the present invention, the chemical constituents of both the calcined and plastic clay powders is in the range of AI2O3:35 to 40 wt %, Si02: 55 to 60 wt % and Fe203 below 1.5 wt % .
In a further embodiment of the present invention, immersion of the dried double coated beads in organic solvent is for a period in the range of 12 to15 hours.
hollow sphere balls at a temperature in the range of 1500 to 1550 °C is
In a still further embodiment of the present invention, the firing of the hollow sphere balls at a temperature in the ran for a soaking period in the range of 2 to 3 hours.
In the present invention, a process has been described for the production of high quality alumino-silicate hollow sphere balls, wherein by providing a coating, the surface chemistry and surface charge characteristics of polymeric beads and suspension particulates of alumino-silicate minerals have been used. Judicious selection of chemical admixture was necessary to adjust the surface chemistry appropriate for such purpose as well as to obtain strong green bonding between particles. In the present invention, the polymer was removed from the coated beads by dissolution in organic solvent. By this process, more than 95% polymer was found to be dissolved in organic solvent thus mitigating the environmental pollution to a greater extent which was otherwise removed by burning process in the present day method. The skin walls of the hollow sphere balls did not get disintegrated during dissolution of polymers by organic solvent. After drying, the hollow sphere balls were finally fired at a temperature in the range of 1500 to 1550 °C for a soaking period in the range of 2 to 3 hours. The fired hollow sphere balls possess loose bulk density from 0.50 to 0.60 gm/cc for hollow sphere size of 1.5 to 5mm.
The novelty of the present invention resides in obtaining defect free low dense alumino-silicate hollow sphere balls having adequate strength. After firing at high temperatures, the hollow sphere balls achieved loose bulk density in the range of 0.50 to 0.52 gms/cc. The hollow sphere balls produced by the novel process of the present invention will find usage as
aggregates in manufacturing refractory castable product which provides heat insulation in industrial kilns and furnaces.
The novelty of the process of the present onvention has been achieved by the non-obvious inventive steps of providing a double coating, first with a chemical admixture followed by a second coating with a mixture of alumino-silicate materials. This precoating of the polymeric beads by an in situ formed cementitious material acts as a base for the actual hollow sphere forming material (aluminasilicate). The cementitious material which in turn prevents disintegration of the otherwise fragile ceramic material dissolution in a solvent.
The following examples are given by the way of illustration of the process of the present invention in actual practice and should not be construed to limit the scope of the present invention.
Example - 1
A chemical admixture was prepared by mixing 56 vol.% mollasses,33 vol% colloidal silica and 11 vol % sodium silicate. A blended mixture of alumino-silicate materials was also prepared consisting of 74 wt. % below 100 mesh calcined clay, 12wt. % below 200 mesh plastic clay and 14 wt.% below 200 mesh sillimanite sand. Then 1.5 mm size (diameter) spherical polymeric beads were first coated with the prepared chemical admixture followed by a second coating with the prepared blended mixture of alumino - silicate materials. Then the coated beads were dried first at room temperature for 24 hrs. and then at 110 °C for a period of 24 hrs. and immersed in xylene solvent for a period of 12 hrs. for the dissolution of polymeric material. After removal of polymer , the hollow sphere balls were dried at 110 °C for 4 hrs. & finally heated at 1500° C for 3 hrs. soaking . The heat treated hollow sphere balls were finally tested for loose bulk density, which was found to be 0.50 gm/cc.
Example - 2
A chemical admixture was prepared by mixing 56 vol.% molasses and 44 vol.% colloidal silica. A blended mixture of alumino- silicate materials was also prepared consisting of 76 wt. % below 100 mesh calcined clay , 7 wt. % below 20 mesh plastic clay and 17 wt. % below 200 mesh sillimanite sand .Then 5 mm size (diameter) spherical polymeric beads were first coated with the prepared chemical admixture followed by a second coating with the prepared blended mixture of alumino-silicate materials. Then the coated beads were dried at room temperature for 26 hrs. and then atl 10 °C for a period of 30 hrs. and then immersed in toluene solvent for a period of 15 hrs. for the dissolution of polymeric material . After removal of polymers, the hollow sphere balls were dried at 110 °C for 5 hrs. and finally heated at 1550 °C for 2 hrs. soaking. The heat treated hollow sphere balls were finally tested for loose bulk density, which was found to be 0.50 gm/cc.
Example- 3
A chemical admixture was prepared by mixing 56 vol. % colloidal silica and 44 vol.% sodium silicate. A blended mixture of alumino-silicate materials was also prepared consisting of 75 wt. % below 100 mesh calcined day , 10 wt.% below 200 mesh plastic clay and 15 wt. % below 200 mesh sillimanite sand.Then 1.5 mm size (diameter) spherical polymeric beads were first coated with this chemical admixture followed by a second coating with the prepared blended mixture of alumino -silicate materials. Then the coated beads were dried first at room temperature for 24 hrs. and then at 110° C for a period of 24 hrs. and immersed in xylene solvent for a period of 12 hrs. for the dissolution of polymeric material . After removal of polymers, the hollow sphere balls were dried at 110°C for 4 hrs. and finally heated at 1500°C for 3 hrs. soaking. The heat treated hollow sphere balls were finally tested for loose bulk density, which was found to be 0.52 gm/cc.
The summary of the test results of the above three examples are as follows:

(Table Removed)
After firing at high temperatures, in the range of 1500 to 1550 °C, the hollow sphere balls achieved loose bulk density in the range of 0.50 to 0.52 gms/cc. The hollow sphere balls produced by the process of the present invention will find usage as aggregates in manufacturing refractory castable product which provides heat insulation in industrial kilns and furnaces.
The main advantages of the process of the present invention for the production of alumino-silicate hollow sphere balls useful as aggregates in insulating refractory castable product, are :
1. The process is environmental friendly.
2. The process of removing polymer does not develop any stresses on skin wall.
3. The process achieves tailor made properties.
4. The process produces low dense alumino-silicate hollow sphere balls for application as aggregate in insulating castable .

We claim :
1. A process for the production of alumino-silicate hollow sphere balls which comprises : coating of different sizes polymeric spherical beads with chemical admixture such as herein described followed by another coating with a mixture of alumino-silicate; drying the coated beads at room temperature for a period in the range of 24-26 hrs oven drying at 100-110°C for a period in the range of 24 to 30 hrs; immersing the dried beads in organic solvent for dissolution of polymer for a period in the range of 12-15 hrs; drying the bead at 100-110°C for a period in the range of 4-5 hrs; heating the hollow sphere balls at 1500-1550°C for a period in the range of 2-3 hrs to obtain alumino-silicate hollow sphere balls.
2. A process as claimed in claim 1 wherein the chemical admixture used for coating are selected from a mixture of 0-56 vol.% molasses, 0-44 vol.% sodium silicate, and 33-56 vol% colloidal silica in combination.
3. A process as claimed in claim 1 wherein the alumino-silicate materials used for another coating are selected from a blended mixture of 74-76 wt% below 100 mesh calcined clay, 7-12 wt% below 200 mesh plastic clay, 14-17 wt% below 200 mesh sillimanite sand.
4. A process as claimed in claim 1 wherein solvent used for the dissolution of polymer from coated beads is selected from toluene, xylene.
5. A process for the production of alumino-silicate hollow sphere balls substantially as herein described with reference to examples.

Documents:

1297-del-2004-abstract.pdf

1297-del-2004-Claims.pdf

1297-del-2004-Correspondence-Others-(20-12-2010).pdf

1297-del-2004-correspondence-others.pdf

1297-del-2004-description (complete).pdf

1297-del-2004-form-1.pdf

1297-del-2004-form-18.pdf

1297-del-2004-form-2.pdf

1297-del-2004-form-3.pdf

1297-del-2004-form-5.pdf

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Patent Number

251741

Indian Patent Application Number

1297/DEL/2004

PG Journal Number

14/2012

Publication Date

06-Apr-2012

Grant Date

30-Mar-2012

Date of Filing

15-Jul-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	KISHORE KUMAR BHATTACHARJEE	CENTRAL GLASS & CERAMIC RESEARCH INSTITUTE, KOLKATA 700 032, INDIA
2	PRADIP KUMAR MONDAL	CENTRAL GLASS & CERAMIC RESEARCH INSTITUTE, KOLKATA 700 032, INDIA
3	SOMNATH MUKHERJEE	CENTRAL GLASS & CERAMIC RESEARCH INSTITUTE, KOLKATA 700 032, INDIA
4	SAKTIMOY DASGUPTA	CENTRAL GLASS & CERAMIC RESEARCH INSTITUTE, KOLKATA 700 032, INDIA
5	SWAPAN KUMAR DAS	CENTRAL GLASS & CERAMIC RESEARCH INSTITUTE, KOLKATA 700 032, INDIA

PCT International Classification Number

C25D 001/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA