Powder, method of producing powder and adsorption apparatus

Abstract

The present invention provides that powder is mainly constituted from secondary particles of hydroxyapatite. The secondary particles are obtained by drying a slurry containing primary particles of hydroxyapatite and aggregates thereof and granulating the primary particles and the aggregates. A bulk density of the powder is 0.65 g/mL or more and a specific surface area of the secondary particles is 70 m 2 /g or more. The powder of the present invention has high strength and is capable of exhibiting superior adsorption capability when it is used for an adsorbent an adsorption apparatus has.

1 . Powder including hydroxyapatite, wherein the hydroxyapatite includes secondary particles obtained by drying a slurry containing primary particles and aggregates thereof and granulating the primary particles and the aggregates, and the powder comprising: mainly the secondary particles of the hydroxyapatite,
 wherein a bulk density of the powder is 0.65 g/mL or more and a specific surface area of the secondary particles is 70 m 2 /g or more.   
     
     
         2 . The powder as claimed in  claim 1 , wherein a sphericity of each of the secondary particles of the powder is in the range of 0.95 to 1.00. 
     
     
         3 . The powder as claimed in  claim 1 , wherein the secondary particles consisting the powder are classified so as to have an average particle size of 40±4 μm, wherein when a repose angle of the powder constituted of the classified secondary particles is measured, the repose angle is 27° or lower. 
     
     
         4 . The powder as claimed in  claim 1 , wherein the powder is sintered at a temperature of 700° C. to obtain sintered powder having particles, and then the particles of the sintered powder are classified so as to have an average particle size of 40±4 μm, wherein when a compressive particle strength of the classified particles is measured, the compressive particle strength is over 9.0 MPa. 
     
     
         5 . The powder as claimed in  claim 1 , wherein the powder is sintered at a temperature of 700° C. to obtain sintered powder including particles each having a surface and micropores formed on the surface, wherein an average pore size of the micropores is 0.07 μm or less. 
     
     
         6 . The powder as claimed in  claim 1 , wherein an average particle size of the secondary particles of the powder is in the range of 2 to 100 μam. 
     
     
         7 . A method of producing the powder defined in  claim 1 , the method comprising:
 mixing a first liquid containing a calcium raw material with a second liquid containing a phosphoric raw material to obtain a mixture;   reacting the calcium raw material with the phosphoric raw material with stirring the mixture to obtain the slurry containing the primary particles of the hydroxyapatite and the aggregates thereof;   crushing the aggregates contained in the slurry physically to disperse crushed aggregates in the slurry; and   drying the slurry and granulating the crushed aggregates to obtain the powder mainly constituted from the secondary particles of the hydroxyapatite.   
     
     
         8 . The method as claimed in  claim 7 , wherein the crushing the aggregates physically is performed by a wet-type jet mill method in which the slurry is sprayed under a high pressure to obtain droplets of the slurry and the droplets are crashed to each other. 
     
     
         9 . The method as claimed in  claim 7 , wherein an average particle size of the crushed aggregates is 1 μm or less. 
     
     
         10 . An adsorption apparatus provided with the powder defined in  claim 1  or sintered powder obtained by sintering the powder as an adsorbent.