Method for producing tri-calcium phosphate

Abstract

A method for producing tri-calcium phosphate admixes water, hydrated lime, and phosphoric acid in a reaction vessel to form a tri-calcium phosphate slurry. The slurry is then placed in physical contact with heated air through a spray head to evaporate water from the slurry. The preferred embodiment of the method utilizes an agitated air dryer.

1 . A method of producing dry marketable hydroxyapatite, commonly known as tri-calcium phosphate, combined from ingredients including water, hydrated lime, phosphoric acid, and acetic acid, comprising: 
 forming a slurry from said ingredients including approximately 72% water by weight and approximately 28% tri-calcium phosphate by weight wherein said tri-calcium phosphate attains an initial moisture content of approximately 30%;    adding to said slurry less than 2% by weight acetic acid for controlling the viscosity of said slurry during the reaction of said ingredients during mixing of said slurry;    placing said slurry within heated air produced by an agitated air system having an agitated air dryer with an inlet and an outlet and at least one spray head located between said inlet and said outlet, said at least one spray head directly applying said slurry within an agitated heated air stream within the air dryer;    maintaining the temperature at said inlet of the air dryer of approximately 550° F. to approximately 650° F., and maintaining the temperature of said air outlet at approximately 190° F. to approximately 210° F.;    using negative air pressure within said agitated air system to move said slurry through said air dryer and to direct said slurry through said at least one spray head in contact with the stream of heated air to evaporate water from said slurry to produce a tri-calcium phosphate having a moisture content less than approximately 2%; and,    said method producing tri-calcium phosphate at a rate of at least 1,300 pounds per hour and at less than 1,500 Btu used per pound.    
     
     
         2 . The method of  claim 1  further comprising: 
 dividing said tri-calcium phosphate produced by said method into two portions;    recycling one of said portions into the step of forming said slurry; and,    packaging the other of said portions for delivery.    
     
     
         3 . The method of  claim 1  further comprising: 
 said air dryer having at least one paddle.    
     
     
         4 . The method of  claim 1  further comprising: 
 forming a slurry including approximately 72% by weight water, approximately 11% by weight hydrated lime, approximately 16% by weight phosphoric acid, and less than 1% by weight acetic acid.    
     
     
         5 . A method of producing dry marketable hydroxyapatite, commonly known as tri-calcium phosphate, combined from ingredients including water, hydrated lime, and phosphoric acid, comprising: 
 forming a slurry from said ingredients including approximately 72% water by weight, and approximately 28% hydrated lime and phosphoric acid by weight, said slurry including tri-calcium phosphate of an initial moisture content of approximately 30%;    placing the slurry in contact with heated air produced by an agitated air system having an agitated air dryer with an inlet and an outlet and at least one spray head between said inlet and said outlet, said at least one spray head directly applying said slurry within said agitated heated air stream within the air dryer;    maintaining the inlet of the air dryer at a temperature of approximately 550° F. to approximately 650° F., and maintaining the outlet of the air dryer at a temperature of approximately 190° F. to approximately 210° F.;    using negative air pressure within said agitated air dryer to move said slurry through said dryer and directing said slurry through said at least one spray head in contact with the stream of heated air to evaporate water from said slurry to produce a tri-calcium phosphate having a moisture content of less than approximately 2%;    splitting said tri-calcium phosphate produced by said method into two portions, returning one of said portions into said slurry, and packaging the other of said portions for delivery; and,    said method producing tri-calcium phosphate, at a rate of at least 1,300 pounds per hour and with less than 1,500 Btu used per pound.    
     
     
         6 . The method of  claim 5  further comprising: 
 said forming said slurry including less than 2% by weight acetic acid.    
     
     
         7 . The method of  claim 5  further comprising said air dryer having at least one paddle.  
     
     
         8 . The method of  claim 5  further comprising: 
 said forming said slurry including hydrated lime and phosphoric acid in similar proportions by weight.    
     
     
         9 . The method of  claim 5  further comprising: 
 said forming said slurry including approximately 11% by weight hydrated lime, approximately 16% by weight phosphoric acid, and less than 1% by weight acetic acid.    
     
     
         10 . A method of producing dry marketable hydroxyapatite Ca 5 (PO 4 ) 3 (OH), also known in trade as tri-calcium phosphate, comprising: 
 forming a slurry including approximately 72% by weight water, approximately 11% by weight hydrated lime, approximately 16% by weight phosphoric acid, and approximately 1% by weight acetic acid for controlling the viscosity of said slurry during the reaction of said ingredients during mixing of said slurry, wherein said slurry contains tri-calcium phosphate of a moisture content of approximately 30%;    placing said slurry within heated air produced by an agitated air system having an agitated air dryer with an inlet and an outlet, at least one paddle, and at least one spray head located between said inlet and said outlet, said at least one spray head directly applying said slurry within an agitated heated air stream within the air dryer;    maintaining the temperature at said inlet of the air dryer of approximately 550° F. to approximately 650° F., and maintaining the temperature of said air outlet at approximately 190° F. to approximately 210° F.;    using negative air pressure within said agitated air system to move said slurry through said air dryer and to direct said slurry through said at least one spray head in contact with the stream of heated air to evaporate water from said slurry to produce tri-calcium phosphate exiting said system having a moisture content less than approximately 2%;    said method producing tri-calcium phosphate at a rate of at least 1,300 pounds per hour and at less than 1,500 Btu used per pound; and,    dividing said tri-calcium phosphate produced by said method into two portions wherein one of said portions is recycled into the step of forming said slurry and wherein the other of said portions is packaged for delivery.