Process for the production of coarse-grained, anhydrous calcium monohydrogen phosphate (dicalcium phosphate anhydride) and a device for carrying out the process

US5338524A · kind A · utility

Assignee

• BK Ladenburg GmbH · DE

Inventors

• Alexander Maurer · Hürth, DE
• Guenter Raab · Hemsbach, DE
• Gudrun Raab · Hemsbach, DE
• Hans-Georg Steinert · Eschelbronn, DE
• Richard Taenzler · Hemsbach, DE

Key dates

• Filing date: Dec 23, 1992
• Grant date: Aug 16, 1994
• Expiry date: Dec 23, 2012

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01B25/322
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The present invention provides a process and apparatus for the production of coarse-grained dicalcium phosphate anhydride, at least 95% of which consists of particles with a grain diameter of >45 .mu.m, wherein, at a temperature of 60.degree. to 100.degree. C., a highly reactive calcium component, for example freshly slaked milk of lime or an aqueous slurry or suspension of calcium hydroxide and/or calcium carbonate, is introduced directly into the stirrer zones of a vessel containing aqueous phosphoric acid and having one or more turbulent stirrer zones. An equivalent amount of aqueous phosphoric acid is introduced into another zone of the vessel, the speed of introduction being so regulated that a pH value of 3.0 to 4.5 is obtained in the stirrer zone and the whole batch or a continuously or semi-continuously removed part thereof is cooled to 40.degree. to 60.degree. C. The removed part then is mixed with an additional calcium component, for example milk of lime, to obtain a pH value of from 5.5 to 6.8, the mixture further stirred for 10 to 60 minutes and the resultant course-grained dicalcium phosphate anhydride is filtered off and dried.