| 摘要 |
1,248,686. Ammonium polyphosphate; purifying H 3 P0 4 . SWIFT AGRICULTURAL CHEMICALS CORP. 11 Feb., 1969 [25 March, 1968 (2)], No. 7412/69. Heading C1A. Ammonium polyphosphate containing at least 20% non-orthophosphate and 64-85% nitrogen plus P 2 O 5 is produced by mixing NH 3 and H 3 PO 4 under conditions providing a Reynolds number of at least 5000 at a temperature sufficiently high to keep the product molten. The reactants are preferably ananhydrous NH 3 and wet process H 3 PO 4 . As shown in the Figure, H 3 PO 4 at at least 250‹ F. and 200-400 p.s.i.g. and NH 3 at at least 100‹ F. are pumped to a mixing line 3. More NH 3 may be added by line 2<SP>1</SP>. The pressurized mixture is flashed through orifice 3<SP>1</SP> causing intense mixing in reactor 3<SP>11</SP>, this mixing being increased by vibrating blade 3<SP>111</SP>. Reactor 3<SP>11</SP> is at 350-600‹ F. The product is then fed to vessel 5 which releases steam and increases polyphosphate content. The product may be removed or pumped to a heat exchanger 7 to reduce the temperature to about 400‹ F. before transfer to ammoniator 9 where it is reacted with liquid NH 3 at 350‹ F. to 500‹ F. The product of reactor 9 is pumped to a solidifier/granulator 11. The fines from the final stage screening are recycled to the granulator. The Specification refers to the purification of wet process H 3 PO 4 by addition of KCl, KNO 3 or KH 2 PO 4 to precipitate Fe and Al present as M 3 KH 14 (PO 4 ) 8 .4H 2 O and addition of CaCl 2 or CaCO 3 to precipitate SO 4 present as CaSO 4 . |
