Process for preparation of calcium hydrogen phosphate anhydride

摘要

An aqueous slurry of CaHPO4.2H2O in a 5-20 Wt% concentration is prepared by the use of the phosphate dihydrate obtained by reaction of NaNH4HPO4.4H2O with CaCl2 in water. After adjustment of the pH of the slurry to 4.5-5.5, the slurry is rapidly heated to 85 DEG -97 DEG C by contact with steam to convert the dihydrate to the anhydride, which is suitable for use in the preparation of fluorescent materials due to its high purity, platy and square crystal shape and uniform particle size.