Benckiser-knapsack Gmbh

Bk Ladenburg Gmbh Gesellschaft Fur Chemische Erzeugnisses

Detlev Schober

Guenter Raab

Alexander Maurer

Richard Taenzler

Gudrun Raab

Reinhold Schmitt

Gerold Brachtel

A process for the preparation of a hydroxyapatite, which is suitable as a tooth-cleaning substance, by precipitation from aqueous phosphoric acid and calcium hydroxide solution, in which a calcium-doped phosphoric acid solution is fed to an intensive mixer with a suspension of calcium hydroxide/oxide in a molar ratio of Ca:P=1.667 corresponding to the hydroxyapatite of and reacted there at precipitation temperatures of 60.degree.-100.degree. C., preferably 80.degree.-90.degree. C. and a pH of 4-8, preferably of 6.5-7.5. Also disclosed in a tooth-cleaning substance containing the hydroxyapatite.

Process for the preparation of hydroxyapatite

A process for the preparation of coarse-particle dicalcium phosphate dihydrate having a virtually spherical crystal shape and a particle size range between about 63 and 450 .mu.m, preferably between about 90 and 300 .mu.m, by reacting pure aqueous phosphoric acid with aqueous suspensions of precipitated chalks, wherein an amount of suspension corresponding to the reaction product formed is removed continuously or semicontinuously and the dicalcium phosphate dihydrate is separated off, washed and dried. Also disclosed is coarse-particle dicalcium phosphate dihydrate produced by the above process.

Process for the preparation of coarse-particle dicalcium phosphate

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Frankenthal, Germany

Detlev Schober