GB315700A - Production of di-ammonium phosphate - Google Patents

Abstract

315,700. Federal Phosphorus Co., (Assignees of Klugh, B. G., and Seyfried, W. R.). July 16, 1928, [Convention date]. Ammonium phosphate. - In preparing di-ammonium phosphate in crystals of uniform size from concentrated phosphoric acid and gaseous ammonia, the heat generated by the neutralization is used to effect evaporation of water from the product. Phosphoric acid of 60-80 per cent strength is mixed with mother liquor from the process to reduce its viscositv and is treated in an insulated acid-proof tank Š with gaseous ammonia admitted through pipes 4. The liquid is agitated by a stirrer 3. Water vapour passes away through an outlet 6. After partial neutralization a further admixture with mother liquor is made, and the mixture is passed into a horizontal rotary cylindrical vessel B, from which air is removed either by a vacuum pump or by displacement by steam or ammonia. Ammonia is admitted through a pipe 15 in quantity sufficient to form di-ammonium phosphate. The solution which first becomes heated to about 100‹ C. is cooled and maintained at about 80‹ C. by water sprayed from a pipe 17. After admission of the ammonia is completed, the solution is allowed to cool slowly to atmospheric temperature, the vessel B being continuously rotated. The slurry is discharged into a filter or centrifuge. The crystals are dried at a temperature below 65‹ C.