Production of dicalcium phosphate or monocalcium phosphate

A process for the production of dicalcium phosphate from a phosphate source material comprising the steps of:

• i. preparing a solution of phosphoric acid by the action of a suitable mineral acid on a phosphate source material;
• ii. optionally separating the solution from residual solid materials;
• and,
• iii. treating the solution with suitable alkaline calcium material to adjust the pH of the solution to between 3,0 and 4,5;
• the process being characterized in that further processing comprises the steps of:
• iv. 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 CaF2 together with some dicalcium phosphate and a primary calcium and phosphate containing solution;
• v. separating the primary precipitate formed in step iv from the primary calcium and phosphate containing solution;
• vi. dissolving the primary precipitate and repeating steps iii, iv, and v on the resultant solution to form a secondary precipitate containing substantially all of the fluoride present as CaF2 together with some dicalcium phosphate and a secondary calcium and phosphate containing solution;
• vii. optionally repeating step vi one or more times to produce a tertiary, quaternary, etc precipitate and tertiary, quaternary, etc calcium and phosphate containing solution;
• viii. combining the calcium and phosphate containing solutions and adjusting their pH to above about 5.5 to precipitate dicalcium phosphate;
• and,
• ix. recovering the product dicalcium phosphate.