Production of dicalcium phosphate or monocalcium phosphate

Details Production of dicalcium phosphate or monocalcium phosphate Production of dicalcium phosphate or monocalcium phosphate

2006-09-05

2006-09-05

Langel, Wayne A. (Department: 1754)

Chemistry of inorganic compounds

Phosphorus or compound thereof

Oxygen containing

C423S157300, C423S157400, C423S308000

Reexamination Certificate

active

07101522

ABSTRACT:
A process is provided for the production of dicalcium phosphate form a phosphate source material in which a solution of phosphoric acid is produced by the action of a suitable mineral acid, generally sulphuric acid, on a phosphate source material. Calcium fluoride is precipitated at a pH of between 3.5 and 4.5 followed by hydrolyzing the solution by diluting it with water to a ratio of approximately 1:7 to about 1:10 monocalcium phosphate to water at a temperature of approximately 40 degrees Centigrade to form a primary precipitate containing substantially all of the fluoride present as CaF2together with some dicalcium phosphate and a primary calcium and phosphate containing solution. The primary precipitate is dissolved, the pH adjusted to form 3.5 to 4.5 and the hydrolyzation repeated to form a secondary precipitate containing substantially all of the fluoride present as CaF2together with some dicalcium phosphate and a secondary calcium and phosphate containing solution. The secondary precipitate can optionally, if required, by again processed in the same way to recover more phosphates. The product dicalcium phosphate is recovered from the combined calcium and phosphate containing solutions.

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