TH52458A - Method of action on the solution of the fertilizer process - Google Patents

Abstract

DC60 (04/05/44) Method for producing solid products containing nitrogen and phosphorus, specifically solid ammonium phosphate and/or urea-ammonium phosphate, in which a solution containing urea and phosphoric acid is heated. Subsequently, water evaporates from this solution, and the urea in this solution decomposes into ammonia and carbon dioxide. Carbon dioxide is released from the reactor along with steam; the ammonia produced neutralizes the phosphoric acid. A suspension containing ammonium phosphate and/or urea-ammonium phosphate is obtained, which is then solidified, dried, crushed, ground, and/or granulated. The final product in such form can be used as fertilizer or as part of compound fertilizers. Method for producing solid products containing nitrogen and phosphorus, specifically solid ammonium phosphate and/or urea-ammonium phosphate, in which a solution containing urea... Phosphoric acid is heated, after which water evaporates from the solution, and the urea in this solution decomposes into ammonia and carbon dioxide. Carbon dioxide is released from the reactor along with steam; the ammonia produced neutralizes the phosphoric acid, resulting in a suspension containing ammonium phosphate and/or urea-ammonium phosphate, which is then solidified, dried, crushed, ground, and/or granulated. The final product in this form can be used as fertilizer or as part of a compound fertilizer.

Claims (19)

1. Method for the production of solid ammonium phosphate and/or urea-ammonium phosphate products from the liquid mother of the urea-phosphate process or from the dust collector solution of the NPK process. This method comprises the following steps: a) Recovering the liquid mother or dust collector solution containing or provided with phosphoric acid to form an aqueous solution containing urea and phosphoric acid; b) Heating and mixing the aqueous solution to remove water by evaporation, breaking down unreactive urea into carbon dioxide and ammonia, evaporating the carbon dioxide and reacting ammonia alone or in combination with unreactive urea with phosphoric acid to form an aqueous suspension of ammonium phosphate and/or urea-ammonium phosphate; and c) Further processing of the aqueous suspension to form solid ammonium phosphate and/or urea-ammonium phosphate products. 2. The method under claim 1 where the molar ratio of nitrogen of urea and phosphorus of phosphoric acid (N/P) in a solution containing urea and phosphoric acid is > 0.85. 3. The method under claim 1 or 2 where the solution containing urea and phosphoric acid is the liquid mother of the urea phosphate process. 4. The method under Claim 1 in which solid carbonates, sulfates, oxides, or chlorides of alkali or alkaline earth metals are added to a reaction mixture to partially neutralize the solution, to emulsify with water, and/or to add nutrients to the final product. 5. The method under Reputation 1 or 2 where a solution containing urea and phosphoric acid is a urea-based NPK process dust collection solution, which contains or is supplemented with phosphoric acid. 6. The method described in claim 1, which specifies that a solution containing urea and phosphoric acid is heated to 50–125°C. 7. The method under claim 6, in which the solution is heated until the moisture content of the formed suspension is 15-20%. 8. The method according to claim 6 or 7, where the solution is heated until the pH of the suspension is 2.5-7. 9. The method under claim 6, in which the solution is heated until the normal ratio of ammonia nitrogen and phosphate phosphorus (N/P) in the suspension is approximately 0.1-1.5:1. 10. Method according to Claim 1 in which, in phase 1, water is evaporated in one or more reactors at approximately 100°C until the moisture content of the suspended solids is <20% and the pH is 3-5, and in phase 2, evaporation is continued in one or more reactors at approximately 110-115°C until the moisture content of the suspended solids is <10% and its pH is approximately 6-6.5. 11. The method under claim 1 in which a suspension of the product containing ammonium phosphate and/or urea-ammonium phosphate is solidified into a layer of thickness 1–30 mm, spread on a steel sheet conveyor belt, which can be heated and/or cooled, and which is heated and/or cooled for a period of 0.01–2 hours, to a final temperature < 50°C. 12. The method under Claim 1 in which the final solid product is dried, crushed, ground and/or granulated. 13. The method under claim 6 in which a solution containing urea and phosphoric acid is heated to 100-115°C. 14. The method under claim 3 in which a solution containing urea and phosphoric acid is heated until the moisture content of the formed suspension is <10%. 15. Method according to claim 3, in which the solution is heated until the pH of the suspension is 4-6.5. 16. The method under claim 3 in which the solution containing urea and phosphoric acid is heated until the molar ratio of ammonia nitrogen and phosphate-phosphorus (N/P) in the suspension is approximately 0.85-1.5:1. 17. The method under claim 3 in which the urea phosphate process is carried out by reacting in an aqueous reaction medium, urea and phosphoric acid to form urea phosphate, separating the urea phosphate from the aqueous reaction medium by crystallization, and discharging the aqueous mother liquid containing unreacted urea and unreacted phosphoric acid. 18. The method under claim 11 in which the suspension of such product is solidified into a layer 10 mm thick, spread on a steel sheet conveyor belt, which is heated and/or cooled for 0.05–0.5 hours. 19. The method under claim 16 in which the solution containing urea and phosphoric acid is heated until the molar ratio of ammonia nitrogen and phosphate-phosphorus (N/P) in the suspension is approximately 1.3–1.4:1.