Patent ID: 7101522
Filing Date: 2006-09-05
Classification: C01B

Abstract:
1. A process for the production of dicalcium phosphate from a phosphate source material comprising the steps of: (a) preparing a solution of phosphoric acid by the action of a suitable mineral acid on a phosphate source material; (b) optionally separating the solution from residual solid materials; and (c) treating the solution with suitable alkaline, calcium material to adjust the pH of the solution to between 3.0 and 4.5; (d) hydrolyzing the solution by diluting it with water to a ratio of approximately 1:7 to about 1:10 monocalcium phosphate to water to form a primary precipitate containing substantially all of the fluoride present as CaF (e) separating the primary precipitate formed in step (d) from the primary calcium and phosphate containing solution; (f) dissolving the primary precipitate with phosphoric acid and repeating steps (c), (d) and (e) containing substantially all of the fluoride present as CaF (g) optionally repeating step (f) one or more times to produce a tertiary, quaternary, etc. precipitate and tertiary, quaternary, etc. calcium and phosphate containing solution; (h) combining the calcium and phosphate containing solutions and adjusting their pH to above about 5.5 to precipitate dicalcium phosphate; and (i) recovering the product dicalcium phosphate.