Apparatus for producing spherical powder, burner for treaitng powder, method for producing spherical powder, spherical oxide powder, and oxide powder

Abstract

There is provided an apparatus for producing a spherical powder, comprising a cylindrical chamber having an axis extending in the vertical direction and a burner 30 provided in the upper part of the chamber to generate a combustion flame in the chamber, characterized in that the aggregate-crushing gas G is injected from the periphery part of the first supply pipe 61 , which constitutes a raw material powder supply route O, into the first supply pipe 61 . This configuration can allow a raw material powder to be supplied to the combustion flame with an aggregate of the raw material powder crushed, and suppress generation of coarse particles or unmelted particles resulting from aggregation of particles. The raw material powder to be supplied to the apparatus for producing a spherical powder may have a treating agent such as stearic acid, or a coupling agent added thereto for preventing aggregation.

1 . An apparatus for producing a spherical powder, comprising: 
 a cylindrical chamber having an axis extending in the vertical direction and    a burner provided in the upper part of the chamber to generate a combustion flame in the chamber, characterized in that    the burner comprises:    a raw material transfer pipe through which a raw material powder is transferred to the combustion flame generated by the burner and    a gas injection part in which a gas is injected from the outer periphery of the raw material transfer pipe into the pipe inside.    
   
   
       2 . The apparatus for producing a spherical powder according to  claim 1 , characterized in that the gas injection part is provided with one or more notches formed on the wall of the raw material transfer pipe.  
   
   
       3 . The apparatus for producing a spherical powder according to  claim 2 , characterized in that a gas passage through which the gas flows is formed on the periphery of the raw material transfer pipe and a gas flows from the one or more notches into the pipe inside.  
   
   
       4 . A burner for treating a powder in which a raw material powder is treated in a predetermined manner using combustion flame, characterized by comprising: 
 a first supply pipe which has an opening at one end and supplies the raw material powder to the combustion flame through the opening,    a second supply pipe which supplies an aggregate-crushing gas for crushing an aggregate of the raw material powder, and    a communication part which communicates the first supply pipe with the second supply pipe to direct the aggregate-crushing gas to the first supply pipe at a predetermined angle.    
   
   
       5 . The burner for treating a powder according to  claim 4 , characterized in that the second supply pipe has a double-layered pipe structure with the first supply pipe stored therein, and the aggregate-crushing gas flows in the space between the first supply pipe and the second supply pipe.  
   
   
       6 . The burner for treating a powder according to  claim 5 , characterized in that the first supply pipe can be detachably attached to the second supply pipe.  
   
   
       7 . The burner for treating a powder according to  claim 4 , characterized in that the predetermined angle is 5° to 85° with respect to the axis of the first supply pipe.  
   
   
       8 . A method for producing a spherical powder by melting a raw material powder in a combustion flame into spheres, characterized in that the method comprises the steps of: 
 transferring the raw material powder to the combustion flame by a carrier gas,    melting the transferred raw material powder in the combustion flame into spheres to obtain a melted product; and    solidifying the melted product by moving the melted product from the combustion flame to the outside thereof, and that    injecting a gas for imparting a shear force to the raw material powder is injected in the transferring step.    
   
   
       9 . The method for producing a spherical powder according to  claim 8 , characterized in that the gas for imparting a shear force is the same kind as the carrier gas.  
   
   
       10 . A method for producing a spherical powder, characterized by comprising the steps of: 
 treating the surface of a raw material powder with a treating agent or a coupling agent, the treating agent made of at least one member selected from the group consisting of a higher fatty acid or a derivative thereof, a higher hydrocarbon and a higher alcohol, and    producing a spherical powder in which the surface-treated raw material powder is put in a combustion flame generated by a burner and melted into spheres, and the raw material powder is moved from the combustion flame to the outside thereof and solidified to obtain a spherical powder.    
   
   
       11 . The method for producing a spherical powder according to  claim 10 , characterized in that the surface treatment step involves mixing the raw material powder with the coupling agent using water as a solvent, and then removing water to treat the surface of the raw material powder.  
   
   
       12 . The method for producing a spherical powder according to  claim 10 , characterized in that the coupling agent is methyltrimethoxysilane.  
   
   
       13 . The method for producing a spherical powder according to  claim 10 , characterized in that the coupling agent is added the raw material powder at 0.1 to 3.0% by weight.  
   
   
       14 . The method for producing a spherical powder according to  claim 10 , characterized in that the surface treatment step involves heating the raw material powder and the treating agent to a predetermined temperature and the stirring the mixture to treat the surface of the raw material powder.  
   
   
       15 . The method for producing a spherical powder according to  claim 10 , characterized in that the treating agent is any of stearic acid, stearic acid amide and hydrogenated castor oil.  
   
   
       16 . The method for producing a spherical powder according to  claim 10 , characterized in that the treating agent is added to the raw material powder at 0.1 to 8.0% by weight.  
   
   
       17 . The method for producing a spherical powder according to  claim 10 , characterized in that in the step of producing a spherical powder, the raw material powder to be put in a combustion flame generated by a burner is dispersed by means for dispersing the raw material powder when the powder is aggregated.  
   
   
       18 . The method for producing a spherical powder according to  claim 17 , characterized in that a gas is injected, at a predetermined angle, to a passage for supplying the raw material powder to the combustion flame in order to disperse the raw material powder, when the powder is aggregated.  
   
   
       19 . A spherical oxide powder characterized in that the spherical oxide powder is produced by treating the surface of a raw material powder with a treating agent or a coupling agent, the treating agent made of at least one member selected from the group consisting of a higher fatty acid or a derivative thereof, a higher hydrocarbon and a higher alcohol; feeding the surface-treated raw material powder to a combustion flame generated by a burner to melt the powder into spheres; moving the raw material powder from the combustion flame to the outside thereof; and solidifying the powder, and that 
 the spherical oxide powder has a mean particle size of 5 μm or less and a largest particle size of 10 μm or less.    
   
   
       20 . An oxide powder which is melted in a combustion flame to obtain a spherical powder, characterized in that: 
 the oxide powder has a surface which is treated with a treating agent or a coupling agent, the treating agent made of at least one member selected from the group consisting of a higher fatty acid or derivative thereof, a higher hydrocarbon and a higher alcohol in order to prevent aggregation, and that    the oxide powder has a mean particle size of 5 μm or less.