United States Patent (19) (11) 4,411,876 Sherif 45) Oct
United States Patent (19) (11) 4,411,876 Sherif 45) Oct. 25, 1983 54 PROCESS FOR THE MANUFACTURE OF 636182 12/1978 U.S.S.R. .............................. 423A311 TRIMAGNESUM PHOSPHATE OCTAHYDRATE OF HIGH PURTY OTHER PUBLICATIONS Bhaunagary et al., "Preparation of Tricalcium Phos phate by Hydrolysis of Dicalcium Phosphate with Cal (75) Inventor: Fawzy G. Sherif, Stony Point, N.Y. cium Hydroxide", J. Appl. Chem. Biotechnol., (1977), (73) Assignee: Stauffer Chemical Company, 27, 393-398. Westport, Conn. Chemical Abstracts, 81 (12), 71959c. 21 Appl. No.: 454,395 Chemical Abstracts, 78(22) 138447t. Primary Examiner-Edward J. Meros 22 Filed: Dec. 30, 1982 Assistant Examiner-Wayne A. Langel (51) Int. Cl. .............................................. CO1B 25/26 Attorney, Agent, or Firm-Vivienne T. White 52) U.S. Cl. .................................................... 423/311 (58) Field of Search ................................ 423/308, 311 57 ABSTRACT The invention is the production of crystalline tertiary 56) References Cited magnesium phosphate octahydrate having uniform and U.S. PATENT DOCUMENTS perfect crystal shape. The process comprises adding a 991,096 5/1911 Schrödter ........................... 423/31 monomagnesium phosphate solution to a magnesium 2,095,994 10/1937 MacIntire ...... ... 42.331 hydroxide slurry at a sufficient temperature and for a 3,194,632 7/1965 Baniel et al. ........................ 423/311 sufficient time to form the highly pure crystalline prod uct within a specified pH range. FOREIGN PATENT DOCUMENTS 44-4649 2/1969 Japan ................................... 423.31 9 Claims, No Drawings 4,411,876 1 2 phate compatibility of various samples of dicalcium PROCESS FOR THE MANUFACTURE OF phosphate dihydrate, TRIMAGNESUM PHOSPHATE The prior art teaches that dicalcium phosphate dihy OCTAHYDRATE OF HIGH PURITY drate may be stabilized by adding a small amount of an alkali metal pyrophosphate or tertiary magnesium phos BACKGROUND OF THE INVENTION phate to the mother liquor, at a controlled pH, during the preparation of the dicalcium phosphate.
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