Claims
- 1. A continuous process for the manufacture of ammonium polyphosphate, comprising a step of forming a mixture consisting essentially of one part of a polyphosphoric acid having an equivalent phosphoric acid content of at least about 110% and from about 0.5 to 3.0 parts of urea by weight, and a step of heating the reactants to a temperature of at least about 150.degree. C. to ammoniate substantially all phosphorus atoms in the polyphosphoric acid, the heating step being carried out under an ammonia atmosphere in a heated extrusion device having an extruder screw which continuously forces the reaction mixture through a reaction barrel.
- 2. The process of claim 1 wherein said polyphosphoric acid has an equivalent phosphoric acid content in the range of 110% to 120%.
- 3. The process of claim 1 wherein said heating step is carried out at least in part by internal heating caused by reaction of said polyphosphoric acid with said urea.
- 4. The process of claim 1 wherein said ammonium polyphosphate has a solubility of less than about 8% in water.
- 5. The process of claim 1 wherein said heated extrusion device provides continuous heating of said extruder screw.
- 6. The process of claim 1 wherein said ammonium polyphosphate has an equivalent phosphoric acid content of from about 115% to about 117%.
- 7. The process of claim 1 wherein said urea is mixed in a quantity of from about 0.8 to 1.2 parts by weight of the polyphosphoric acid.
- 8. The process of claim 1 wherein the reaction mixture is heated at a temperature and for a period sufficient to provide an ammonium polyphosphate which is less than 1% soluble.
- 9. A continuous process for the manufacture of ammonium polyphosphate, comprising continuously feeding to the barrel of a heated screw extruder one part of a polyphosphoric acid having an equivalent phosphoric acid content of at least about 115% and from about 0.8 to 1.2 parts of urea by weight, heating the reactants by a combination of heat created by reaction of the ammonium polyphosphate and heat applied to the heated screw extruder to a temperature above 150.degree. C. under an ammonia atmosphere, and recovering ammonium polyphosphate from the extruder.
- 10. The process of claim 9 wherein said heated extrusion device provides continuous heating of said extruder screw.
- 11. The process of claim 9 wherein said ammonium polyphosphate has an equivalent phosphoric acid content of from about 115% to about 117%.
- 12. The process of claim 9 wherein the reaction mixture is heated at a temperature and for a period sufficient to provide an ammonium polyphosphate which is less than 1% soluble.
Parent Case Info
This is a division of copending application Ser. No. 06/787,429, filed on 10/15/85 now U.S. Pat. No. 4,687,651.
US Referenced Citations (8)
Foreign Referenced Citations (2)
Number |
Date |
Country |
925268 |
May 1973 |
CAX |
49-22318 |
Jul 1974 |
JPX |
Divisions (1)
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Number |
Date |
Country |
Parent |
787429 |
Oct 1985 |
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