Porous fired granulated body and method for manufacturing the same

Abstract

A porous fired granulated body is formed by consolidating numerous alumina particles to each other while letting mainly interconnected pores remain in network form across an entire cross section of a granulated body particle ( 11 ). The pores ( 13 ) have an inner diameter controlled by a droplet diameter of a pore forming agent and have numerous precipitated alumina crystals ( 15 ) formed on inner surfaces thereof. Manufacture is performed by spraying the pore forming agent (emulsion) onto a raw material to form a coating layer of the pore forming agent on a surface of the raw material particle and controlling the inner diameter of the pores. A porous fired granulated body of alumina having a high specific surface area and having higher strength for the same specific surface area can thus be provided by a simple manufacturing method.

1 . A porous fired granulated body, formed by consolidating numerous alumina particles to each other while letting mainly interconnected pores remain in network form across an entire cross section of a granulated body particle, and wherein the pores have an inner diameter controlled by a droplet diameter of a pore forming agent and have numerous precipitated alumina crystals formed on inner surfaces thereof. 
     
     
         2 . The porous fired granulated body according to  claim 1 , wherein a content of a soda component (in terms of Na 2 O; the same applies hereinafter) is less than 0.03%. 
     
     
         3 . The porous fired granulated body according to  claim 1 , wherein a mean gap (arithmetic mean) of pores in the granulated body particle is adjusted to be in a range of 0.5 to 50 μm and a biaxial mean diameter (arithmetic mean of major diameters and minor diameters) of the precipitated alumina crystals is 0.1 to 5 μm. 
     
     
         4 . The porous fired granulated body according to  claim 3 , wherein a mean particle diameter (median diameter) of the granulated body particle is 0.1 to 5 mm and a specific surface area (BET method) is 0.1 to 20 m 2 /g. 
     
     
         5 . A method for manufacturing the porous fired granulated body according to  claim 1 , the method for manufacturing the porous fired granulated body comprising: a granulating process of using a tumbling disk granulator, including a rotating plate, to wet-granulate a raw material, constituted of an alumina fine powder, while spraying on liquid agents; and a firing process of firing a granulated body; and
 wherein the granulating process includes respective sub-processes of:   1) a process of performing primary spraying of a crystal precipitating agent on the raw material, loaded from an upper portion side opposite a discharging portion positioned at an obliquely lower portion of the rotating plate and undergoing primary tumbling circulation along an outer peripheral portion of the rotating plate,   2) a process of performing secondary spraying of a pore forming agent on the primary sprayed raw material undergoing secondary tumbling circulation at an inner side of the primary tumbling circulation,   3) a process of performing tertiary spraying of a binder on the secondary sprayed raw material undergoing tertiary tumbling circulation at an inner side of the secondary tumbling circulation, and   4) a process of making the tertiary sprayed raw material progress in granulation growth through further tumbling circulation and be particle-size-adjusted to the granulated body of a required diameter, and   the primary, secondary, and tertiary spraying are respectively performed at tumbling side portions of the primary, secondary, and tertiary tumbling circulations.   
     
     
         6 . The method for manufacturing the porous fired granulated body according to  claim 5 , wherein the raw material is an alumina fine powder with an Na 2 O content of not more than 0.3%. 
     
     
         7 . The method for manufacturing the porous fired granulated body according to  claim 6 , wherein the alumina fine powder is a calcined alumina fine powder with an Na 2 O content of not more than 0.1% and a median particle diameter of 0.1 to 100 μm. 
     
     
         8 . The method for manufacturing the porous fired granulated body according to  claim 5 , wherein a lubricant is added simultaneously in loading the raw material into a loading portion of the rotating plate in a batch or continuously. 
     
     
         9 . A porous fired granulated body, formed by consolidating numerous ceramic particles to each other while letting mainly interconnected pores remain in network form across an entire cross section of a granulated body particle, and wherein the pores have an inner diameter controlled by a droplet diameter of a pore forming agent and have numerous precipitated alumina crystals formed on inner surfaces thereof. 
     
     
         10 . A method for manufacturing the porous fired granulated body according to  claim 9 , the method for manufacturing the porous fired granulated body comprising: a granulating process of using a tumbling disk granulator, including a rotating plate, to wet-granulate a raw material, constituted of a ceramic fine powder, while spraying on liquid agents; and a firing process of firing a granulated body; and
 wherein the granulating process includes respective sub-processes of:   1) a process of performing primary spraying of a crystal precipitating agent on the raw material, loaded from an upper portion side opposite a discharging portion positioned at an obliquely lower portion of the rotating plate and undergoing primary tumbling circulation along an outer peripheral portion of the rotating plate,   2) a process of performing secondary spraying of a pore forming agent on the primary sprayed raw material undergoing secondary tumbling circulation at an inner side of the primary tumbling circulation,   3) a process of performing tertiary spraying of a binder on the secondary sprayed raw material undergoing tertiary tumbling circulation at an inner side of the secondary tumbling circulation, and   4) a process of making the tertiary sprayed raw material progress in granulation growth through further tumbling circulation and be particle-size-adjusted to the granulated body of a required diameter, and   the primary, secondary, and tertiary spraying are respectively performed at tumbling side portions of the primary, secondary, and tertiary tumbling circulations.   
     
     
         11 . A method for manufacturing the porous fired granulated body according to  claim 2 , the method for manufacturing the porous fired granulated body comprising: a granulating process of using a tumbling disk granulator, including a rotating plate, to wet-granulate a raw material, constituted of an alumina fine powder, while spraying on liquid agents; and a firing process of firing a granulated body; and
 wherein the granulating process includes respective sub-processes of:   1) a process of performing primary spraying of a crystal precipitating agent on the raw material, loaded from an upper portion side opposite a discharging portion positioned at an obliquely lower portion of the rotating plate and undergoing primary tumbling circulation along an outer peripheral portion of the rotating plate,   2) a process of performing secondary spraying of a pore forming agent on the primary sprayed raw material undergoing secondary tumbling circulation at an inner side of the primary tumbling circulation,   3) a process of performing tertiary spraying of a binder on the secondary sprayed raw material undergoing tertiary tumbling circulation at an inner side of the secondary tumbling circulation, and   4) a process of making the tertiary sprayed raw material progress in granulation growth through further tumbling circulation and be particle-size-adjusted to the granulated body of a required diameter, and   the primary, secondary, and tertiary spraying are respectively performed at tumbling side portions of the primary, secondary, and tertiary tumbling circulations.   
     
     
         12 . A method for manufacturing the porous fired granulated body according to  claim 3 , the method for manufacturing the porous fired granulated body comprising: a granulating process of using a tumbling disk granulator, including a rotating plate, to wet-granulate a raw material, constituted of an alumina fine powder, while spraying on liquid agents; and a firing process of firing a granulated body; and
 wherein the granulating process includes respective sub-processes of:   1) a process of performing primary spraying of a crystal precipitating agent on the raw material, loaded from an upper portion side opposite a discharging portion positioned at an obliquely lower portion of the rotating plate and undergoing primary tumbling circulation along an outer peripheral portion of the rotating plate,   2) a process of performing secondary spraying of a pore forming agent on the primary sprayed raw material undergoing secondary tumbling circulation at an inner side of the primary tumbling circulation,   3) a process of performing tertiary spraying of a binder on the secondary sprayed raw material undergoing tertiary tumbling circulation at an inner side of the secondary tumbling circulation, and   4) a process of making the tertiary sprayed raw material progress in granulation growth through further tumbling circulation and be particle-size-adjusted to the granulated body of a required diameter, and   the primary, secondary, and tertiary spraying are respectively performed at tumbling side portions of the primary, secondary, and tertiary tumbling circulations.   
     
     
         13 . A method for manufacturing the porous fired granulated body according to  claim 4 , the method for manufacturing the porous fired granulated body comprising: a granulating process of using a tumbling disk granulator, including a rotating plate, to wet-granulate a raw material, constituted of an alumina fine powder, while spraying on liquid agents; and a firing process of firing a granulated body; and
 wherein the granulating process includes respective sub-processes of:   1) a process of performing primary spraying of a crystal precipitating agent on the raw material, loaded from an upper portion side opposite a discharging portion positioned at an obliquely lower portion of the rotating plate and undergoing primary tumbling circulation along an outer peripheral portion of the rotating plate,   2) a process of performing secondary spraying of a pore forming agent on the primary sprayed raw material undergoing secondary tumbling circulation at an inner side of the primary tumbling circulation,   3) a process of performing tertiary spraying of a binder on the secondary sprayed raw material undergoing tertiary tumbling circulation at an inner side of the secondary tumbling circulation, and   4) a process of making the tertiary sprayed raw material progress in granulation growth through further tumbling circulation and be particle-size-adjusted to the granulated body of a required diameter, and   the primary, secondary, and tertiary spraying are respectively performed at tumbling side portions of the primary, secondary, and tertiary tumbling circulations.   
     
     
         14 . The method for manufacturing the porous fired granulated body according to  claim 11 , wherein the raw material is an alumina fine powder with an Na 2 O content of not more than 0.3%. 
     
     
         15 . The method for manufacturing the porous fired granulated body according to  claim 12 , wherein the raw material is an alumina fine powder with an Na 2 O content of not more than 0.3%. 
     
     
         16 . The method for manufacturing the porous fired granulated body according to  claim 13 , wherein the raw material is an alumina fine powder with an Na 2 O content of not more than 0.3%. 
     
     
         17 . The method for manufacturing the porous fired granulated body according to  claim 14 , wherein the alumina fine powder is a calcined alumina fine powder with an Na 2 O content of not more than 0.1% and a median particle diameter of 0.1 to 100 μm. 
     
     
         18 . The method for manufacturing the porous fired granulated body according to  claim 15 , wherein the alumina fine powder is a calcined alumina fine powder with an Na 2 O content of not more than 0.1% and a median particle diameter of 0.1 to 100 μm. 
     
     
         19 . The method for manufacturing the porous fired granulated body according to  claim 11 , wherein a lubricant is added simultaneously in loading the raw material into a loading portion of the rotating plate in a batch or continuously. 
     
     
         20 . The method for manufacturing the porous fired granulated body according to  claim 12 , wherein a lubricant is added simultaneously in loading the raw material into a loading portion of the rotating plate in a batch or continuously.