Process for producing ammonium polyphosphate

US5165904A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Thomas Staffel · Grünstadt, DE
• Reinhard Gradl · Hürth, DE
• Wolfgang Becker · Eppstein, DE
• Gregor Fucker · Lechenich, DE

Key dates

• Filing date: Sep 26, 1991
• Grant date: Nov 24, 1992
• Expiry date: Sep 26, 2011

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01B25/405
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

For producing substantially water-insoluble, chain-type ammonium polyphosphate, equimolar quantities of diammonium phosphate and phosphorus pentoxide are reacted at temperatures from 170.degree. to 350.degree. C. in a zone, which effects continuous mixing, kneading and comminution, in the presence of a stream of ammonia gas. In this process, the water is separated from the ammonia gas which leaves the zone and contains water vapor, and the dried ammonia gas is caused to flow again through the zone. A plant for producing substantially water-insoluble, chain-type ammonium polyphosphate can comprise a reactor (1) into which an ammonia feed pipe (8) and pipes for feeding phosphorus pentoxide (6) and diammonium phosphate (7) lead and from which an ammonium polyphosphate discharge pipe (9) and an exit gas pipe (10) start. The exit gas pipe (10) leads into a condenser (13) which is flow-connected via a pump (14) to a heat exchanger (15). An exit gas line (18) which leads into the ammonia feed pipe (8) starts from the heat exchanger (15).