Calcium phosphates are manufactured by using a very pure grade of phosphoric acid which is reacted with calcium hydroxide derived from limestone. When calcium hydroxide is added to phosphoric acid in the appropriate ratio, dicalcium phosphate (DCP) is precipitated. On the other hand, when acid is added to calcium hydroxide, the precipitate is tricalcium phosphate (TCP) which contains the highest level of calcium content. After drying, the resulting granular grades can be further milled to obtain a powder grade. The ‘milled’ or ‘powder’ grade is typically used in wet granulation processes while the ‘unmilled’ or ‘granular’ grade is used for direct compression.