PROCESS FOR PRODUCING A COATED FERTILIZER

• US 20140255605A1
• Filed: 08/24/2012
• Published: 09/11/2014
• Est. Priority Date: 08/26/2011
• Status: Active Grant

• Current Assignee: Ekompany International B.V. (Kingenta Ecological Engineering Group Co., Ltd.)
• Original Assignee: Ekompany Agro B.V.
• Inventors: Kaathoven Van, Hendrikus Gijsbertus Andrianus, Xuan Bui, Hoa
• Granted Patent: US 9,328,033 B2
• Time in Patent Office: Days
• US Class Current: 427/221
• CPC Class Codes: B01J 2/006 Coating of the granules without description of the process or the device by which the granules are obtained to prevent the granules sticking together B01J2/30
• CPC Class Codes: B01J 2/12 in rotating drums
• CPC Class Codes: C05B 7/00 Fertilisers based essentially on alkali or ammonium orthophosphates C05B11/00 takes precedence
• CPC Class Codes: C05C 1/00 Ammonium nitrate fertilisers
• CPC Class Codes: C05C 9/00 Fertilisers containing urea or urea compounds
• CPC Class Codes: C05D 1/00 Fertilisers containing potassium C05D7/00 takes precedence
• CPC Class Codes: C05G 5/37 layered or coated with a polymer
• CPC Class Codes: C08G 18/10 Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• CPC Class Codes: C08G 18/36 Hydroxylated esters of higher fatty acids
• CPC Class Codes: C09D 175/04 Polyurethanes

Abstract

A process for producing polyurethane coated fertilizer granules having core granules in a rotating drum, wherein the drum has an inlet and an outlet and n application zones arranged along the longitudinal direction of the drum between the inlet and the outlet, n being an integer of at least 2 and wherein each of the application zones is followed by a curing zone. The curing zone after each application zone is arranged to allow an interval of 2-15 minutes, preferably 3-5 minutes, before the application in the successive application zone, wherein the polyol and the isocyanate are applied in the first application zone at a ratio of 0.5-4 wt %, preferably 1-3 wt % of the core granules. The process has the steps of: A) continuously feeding the core granules to the inlet of the rotating drum, thereby providing a flow of the core granules in the direction from the inlet to the outlet, B1) applying a polyol and an isocyanate to the core granules in each of the n application zones, the ratio of hydroxyl groups in the polyol to NCO groups in the isocyanate at the end of each of the application zones being in the range from about 0.9 to about 1.3, B2) reacting the polyol and the isocyanate to form a tack-free polyurethane layer in each of the n curing zones and C) continuously collecting the polyurethane coated fertilizer granules from the outlet.

Claims

1. A process for producing polyurethane coated fertilizer granules comprising core granules in a rotating drum,

wherein the drum comprises an inlet and an outlet and n application zones arranged along a longitudinal direction of the drum between the inlet and the outlet, n being an integer of at least 2 and

wherein each of the application zones is followed by a curing zone,

wherein the curing zone after each application zone is arranged to allow an interval of at least 2 minutes before the application in the successive application zone, wherein a polyol and an isocyanate are applied in the first application zone at a ratio of 0.5-4 wt %, of the core granules, the process comprising the steps of:

A) continuously feeding the core granules to the inlet of the rotating drum, thereby providing a flow of the core granules in the longitudinal direction from the inlet to the outlet,

B1) applying the polyol and the isocyanate to the core granules in each of the n application zones, the ratio of hydroxyl groups in the polyol to NCO groups in the isocyanate at the end of each of the application zones being in the range from about 0.9 to about 1.3,

B2) reacting the polyol and the isocyanate to form a tack-free polyurethane layer in each of the n curing zones and

C) continuously collecting the polyurethane coated fertilizer granules from the outlet,

wherein the polyol is applied first and the isocyanate is applied in a longitudinal position closer to the outlet in the first application zone or the polyol and the isocyanate are applied substantially simultaneously in each of the application zones.

2. The process according to claim 1, wherein n is an integer of between 2 and 15.

3. The process according to claim 1, wherein the curing zone after each application zone is arranged to allow an interval of 2-15 minutes before the application in the successive application zone.

4. The process according to claim 1, wherein the core granules are fed to the inlet of the drum such that the residence time in the drum is 20-90 minutes.

5. The process according to claim 1, wherein the coated polyurethane is 3-20 wt % of the core granules.

6. The process according to claim 1, wherein the polyol and the isocyanate are applied substantially simultaneously in each of the application zones.

7. The process according to claim 1, wherein a catalyst for the reaction of the polyol and the isocyanate is introduced to the drum.

8. The process according to claim 1, wherein the drum is provided with baffles each extending substantially in the longitudinal direction of the drum and having a height of 1-10% of the diameter of the drum.

9. The process according to claim 1, wherein the core granules comprise at least one fertilizer compound comprising urea, potassium sulphate, potassium chloride, ammonium phosphate, ammonium nitrate or a urea containing compounded fertilizer.

10. The process according to claim 1, wherein the polyol and the isocyanate are applied in the first application zone at a ratio of 1-3 wt % of the core granules.

11. The process according to claim 1, wherein the polyol is applied first and the isocyanate is applied in a longitudinal position closer to the outlet in the first application zone.

12. The process according to claim 2, wherein the curing zone after each application zone is arranged to allow an interval of 2-15 minutes before the application in the successive application zone, and wherein the core granules are fed to the inlet of the drum such that the residence time in the drum is 20-90 minutes.

13. The process according to claim 12, wherein the coated polyurethane is 3-20 wt % of the core granules, and wherein the polyol and the isocyanate are applied substantially simultaneously in each of the application zones.

14. The process according to claim 13, wherein a catalyst for the reaction of the polyol and the isocyanate is introduced to the drum, and wherein the drum is provided with baffles each extending substantially in the longitudinal direction of the drum and having a height of 1-10% of the diameter of the drum.

15. The process according to claim 14, wherein the core granules comprise at least one fertilizer compound comprising urea, potassium sulphate, potassium chloride, ammonium phosphate, ammonium nitrate or a urea containing compounded fertilizer, and wherein the polyol and the isocyanate are applied in the first application zone at a ratio of 1-3 wt % of the core granules.

16. The process according to claim 2, wherein the curing zone after each application zone is arranged to allow an interval of 2-15 minutes before the application in the successive application zone, wherein the core granules are fed to the inlet of the drum such that the residence time in the drum is 20-90 minutes, and wherein the coated polyurethane is 3-20 wt % of the core granules.

17. The process according to claim 16, wherein a catalyst for the reaction of the polyol and the isocyanate is introduced to the drum, wherein the drum is provided with baffles each extending substantially in the longitudinal direction of the drum and having a height of 1-10% of the diameter of the drum, wherein the core granules comprise at least one fertilizer compound comprising urea, potassium sulphate, potassium chloride, ammonium phosphate, ammonium nitrate and a urea containing compounded fertilizer, wherein the polyol and the isocyanate are applied in the first application zone at a ratio of 1-3 wt % of the core granules, and wherein the polyol is applied first and the isocyanate is applied in a longitudinal position closer to the outlet in the first application zone.

18. The process according to claim 2, wherein n is an integer of between 2 and 7.

19. The process according to claim 3, wherein the curing zone after each application zone is arranged to allow an interval of 3-5 minutes before the application in the successive application zone.

20. The process according to claim 5, wherein the coated polyurethane is 4-15 wt % of the core granules.