Urea ammonium sulphate-based composition and method for the manufacture thereof

Abstract

The invention relates to a homogeneous, solid, particulate, urea ammonium sulphate (UAS)-based composition comprising urea ammonium sulphate, a urease inhibitor of the type phosphoric triamide and magnesium sulphate, characterized in that the UAS-based composition comprises 0.02 to 1 weight % of magnesium sulphate, 0.0001 to 1 weight % of the urease inhibitor and about 5 to about 30 weight % of ammonium sulphate. The composition according to the invention has improved properties for reducing ammonia loss by urease activity in the soil and is in particular suitable as a fertilizer. The invention further relates to a method for the manufacture of a homogeneous, solid, particulate urea ammonium sulphate-based composition comprising urea, ammonium sulphate and a urease inhibitor of the type phosphoric triamide, in particular N-(n-butyl) thiophosphoric triamide (nBTPT), as well as to a composition of kit of parts comprising an amount of a) magnesium sulphate; b) a urease inhibitor of the type phosphoric triamide, preferably N-(n-butyl) thiophosphoric triamide (nBTPT); c) optionally, an alkaline or alkaline-forming compound, selected from the group of calcium oxide, zinc oxide, magnesium oxide, calcium carbonate, and mixtures thereof, and d) optionally, one or more anti-caking and/or moisture-repellent and/or anti-dust compounds.

Claims

1. A homogeneous, solid, particulate, urea ammonium sulphate (UAS)-based composition comprising urea ammonium sulphate, a phosphoric triamide urease inhibitor and magnesium sulphate, wherein the UAS-based composition comprises 0.02 to 1 weight % of magnesium sulphate, 0.0001 to 1 weight % of the urease inhibitor and about 5 to about 30 weight % of ammonium sulphate.

2. The urea ammonium sulphate-based composition according to claim 1, wherein the magnesium sulphate is selected from the group consisting of anhydrous, mono-, di-, tri-, tetra-, penta-, hexa-, heptahydrate, and mixtures thereof.

3. The urea ammonium sulphate-based composition according to claim 2, wherein the magnesium sulphate has a purity of >70%.

4. The urea ammonium sulphate-based composition of claim 3 wherein the purity of the magnesium sulphate is >90%.

5. The urea ammonium sulphate-based composition of claim 4 wherein the purity of the magnesium sulphate is >99%.

6. The urea ammonium sulphate-based composition according to claim 1, wherein the ammonium sulphate-based composition further comprises anti-caking and/or moisture-repellent and/or anti-dust material.

7. The urea ammonium sulphate-based composition according to claim 6, wherein the anticaking and/or moisture-repellent material comprises a non-polar material, and is present in the composition at a level of 0.0001 to 1 weight %, relative to the total weight of the composition.

8. The urea ammonium sulphate-based composition according to claim 7, wherein the non-polar material is a liquid organic material selected from the group consisting of an oil, wax, resin and mixtures thereof.

9. The urea ammonium sulphate-based composition according to claim 7, wherein the level of non-polar material in the composition is 0.02 to 0.5 weight %.

10. The urea ammonium sulphate-based composition according to claim 6, wherein the anti-caking and/or moisture-repellent and and/or anti-dust material is applied as a coating to the urea ammonium particulate material.

11. The urea ammonium sulphate-based composition according to claim 1, wherein the urea ammonium sulphate-based composition further comprises an alkaline or alkaline-forming compound, selected from the group consisting of calcium oxide, zinc oxide, magnesium oxide, calcium carbonate, and mixtures thereof.

12. The urea ammonium sulphate-based composition according to claim 11, wherein the weight ratio of alkaline or alkaline-forming compound to magnesium sulphate ranges from 1:20 to 1:2.

13. The urea ammonium sulphate-based composition according to claim 12, wherein the weight ratio of alkaline or alkaline-forming compound to magnesium sulphate ranges from 1:10 to 1:2.

14. The urea ammonium sulphate-based composition according to claim 11, wherein the alkaline or alkaline-forming compound is magnesium oxide.

15. The urea ammonium sulphate-based composition according to claim 1, wherein the urease inhibitor, is present at a level of 0.02 to 0.2 weight %, relative to the total weight of the urea ammonium sulphate-based composition.

16. The urea ammonium sulphate-based composition of claim 15 wherein the urease inhibitor is N-(n-butyl)thiophosphoric triamide.

17. The urea ammonium sulphate-based composition of claim 15, wherein the urease inhibitor is present at a level of 0.03 to 0.06 weight %.

18. The urea ammonium sulphate-based composition according to claim 1, wherein the weight ratio of phosphoric triamide urease inhibitor to magnesium sulphate ranges from 1:20 to 1:1.

19. The urea ammonium sulphate-based composition according to claim 18 wherein the weight ratio of phosphoric triamide urease inhibitor to magnesium sulphate ranges from 1:10 to 1:1.

20. The urea ammonium sulphate-based composition according to claim 1, wherein the UAS is a co-granulated material, and wherein ammonia is neutralized to form ammonium sulphate (AS) in the urea melt or solution to produce UAS, or the UAS is a particulate blend of particulate urea and particulate ammonium sulphate.

21. The urea ammonium sulphate-based composition according to claim 20, wherein the co-granulated material is obtained from: (i) melt mixing molten urea and solid particulate ammonium sulphate, (ii) compacting finely-divided solid urea and ammonium sulphate powders, or (iii) a chemical process for the production of urea from carbon dioxide and ammonia.

22. The urea ammonium sulphate-based composition according to claim 1, wherein the magnesium sulphate is present in the composition at a level of 0.05 to 1 weight %, relative to the total weight of the composition.

23. The urea ammonium sulphate-based composition according to claim 1, wherein the phosphoric triamide urease inhibitor is a compound of formula I: ##STR00004## wherein: X is oxygen or sulphur; R.sub.1 is alkyl, cycloalkeny wherein the urease inhibitor, is present at a level of 0.02 to 0.2 weight %, relative to the total weight of the urea ammonium sulphate-based composition.

24. The urea ammonium sulphate-based composition according to claim 1, wherein the urease inhibitor is N-(n-butyl) thiophosphoric triamide (nBTPT).

25. The urea ammonium sulphate-based composition according to claim 1, wherein the urea ammonium sulphate-based composition is obtained by (i) applying the phosphoric triamide urease inhibitor onto the urea ammonium sulphate-based composition in liquid or in particulate form, (ii) melt-mixing with the urea ammonium sulphate-based compound, or (iii) a combination thereof.

26. The urea ammonium sulphate-based composition according to claim 1, wherein the average particle size (dp50) of the urea ammonium sulphate-based compound in particulate form is between 1 mm and 5 cm, as determined by mesh sieve screening.

27. The urea ammonium sulphate-based composition according to claim 1, wherein the urea ammonium sulphate-based composition comprises about 5 to about 30 weight % of ammonium sulphate, 0.03 to 0.06 weight % of nBTPT, 0.05 to 0.1 weight % of a magnesium sulphate, and 0.015 to 0.03 weight % of magnesium oxide, adding up to 100 weight %, being the total weight of the composition.

28. A method comprising fertilizing a soil with the homogeneous, solid, particulate urea ammonium sulphate-based composition as claimed in claim 1.

29. A method for the manufacture of a homogeneous, solid, particulate, urea ammonium sulphate-based composition according to claim 1, the method comprising the steps of: 1) providing a urea ammonium sulphate material, comprising about 5 to about 30 weight % of ammonium sulphate; 2) providing 0.02 to 1 weight %, relative to the total weight of the composition, of a magnesium sulphate; 3) providing 0.0001 to 1 weight %, relative to the total weight of the composition, of a phosphoric triamide urease inhibitor; 4) optionally, providing 0.001 to 0.5 weight %, relative to the total weight of the composition, of an alkaline or alkaline-forming compound, selected from the group consisting of calcium oxide, zinc oxide, magnesium oxide, calcium carbonate, and mixtures thereof, and 5) optionally, providing coating material, wherein the coating material is able to increase at least the anticaking and/or moisture repellence and/or anti-dust properties of said urea ammonium sulphate-based composition; and 6) adding the components provided in steps 2), 3), 4) and 5) in any order to the component, provided in step 1).

30. The method of claim 29, wherein the phosphoric triamide of step 3) is N-(n-butyl) thiophosphoric triamide.

31. The method of claim 29, wherein the alkaline or alkaline-forming compound is magnesium oxide.

Description

EXAMPLES

Description of Figures

(1) FIG. 1. Ammonia release of a YaraVera® Amidas product comprising 462 ppm nBTPT, treated with several stabilizers (see Table 1).

(2) FIG. 2A. Stability of nBTPT on a YaraVera® Amidas product comprising 462 ppm nBTPT in plastic containers open to air at room temperature after 40 days [A=no stabilizer; B=CaO (2541 ppm); C=MgSO.sub.4 99.5% purity (4957 ppm)].

(3) FIG. 2B. Stability of nBTPT on a YaraVera® Amidas product comprising 462 ppm nBTPT, in bags at 40° C. [A=no stabilizer; B=CaO (2541 ppm); C=MgSO.sub.4 99.5% purity (4957 ppm)] after 8 days.

(4) FIG. 3. Stability of nBTPT on a YaraVera® Amidas product comprising 462 ppm nBTPT using different grades and forms of MgSO.sub.4 and Na.sub.2SO.sub.4, stored in open plastic containers at room temperature for 21 days. [A=no stabilizer; B=CaO (2541 ppm); C=MgSO.sub.4 99.5% purity (4957 ppm); D=MgSO.sub.4 99.999% purity (4957 ppm); E=MgSO.sub.4.7H.sub.2O (10163 ppm); F=Na.sub.2SO.sub.4 (5849 ppm)]

(5) FIG. 4. Stability of nBTPT on a YaraVera® Amidas product comprising 462 ppm nBTPT using different MgSO.sub.4/MgO combinations [A=no stabilizer; B=CaO (2310 ppm); C=MgO (212 ppm); D=MgSO.sub.4>98% grade (4620 ppm); E=MgSO.sub.4>98% grade (924 ppm)/MgO (212 ppm)]

EXPERIMENTAL

(6) 1. Volatilization Measurements (Ammonia Release 2 L Diffusion Kit)

(7) 200 g of UAS product, treated with nBTPT/stabilizer are put in a 2 L plastic container. Through the lid, a Draeger tube is placed for the measurement of vol % ammonia. The Draeger tube turns from yellow to bleu/purple when ammonia is absorbed by the tube. The amount of vol % ammonia released can be followed in time.

(8) 2. nBTPT Measurements

(9) For lab scale experiments, 1.2 kg of solid fertilizer material was added to a lab scale drum. In a next step, the nBTPT/stabilizer material was slowly added. A residence time of 10 minutes was applied and the rotating speed of the drum was consequently the same in each experiment. In case a moisture-repellent coating was added, a nebulizer was used and depending on the order of addition, the moisture-repellent coating was added before or after addition of the nBTPT material. Before use, the moisture-repellent coating was preheated to 80° C. Larger scale experiments with amounts up to 40 kg of fertilizer material were performed in a concrete mixer.

(10) The samples were stored under several conditions, dependent on the type of samples: Bagged at room temperature (18-25° C.) Bagged at 40° C. Open to air at room temperature (18-25° C.)
3. HPLC Analysis of nBTPT-Content

(11) HPLC analysis of nBTPT is done as described in the procedure CEN 15688-2007.

(12) 4. Products

(13) UAS was obtained from Yara as granules YaraVera® Amidas 40-0-0 (product code PA421X).

(14) Solid N-(n-butyl)thiophosphoric triamide was obtained from Sunfit Chemical Co. (China) (CAS-Nr. 94317-64-3), as a white crystalline solid with a melting point of 58-60° C.

(15) MgO technical grade was obtained from Mannekus & Co B.V., Schiedam, The Netherlands (dp(50)=27 μm, +/−90% purity, 2-2.9% CaO, 1.1% SiO2).

(16) CaO technical grade was obtained from VWR International, Oud-Heverlee, Belgium (91.3% pure, 2.7% CaCO.sub.3 and 6% Ca(OH).sub.2), dp(50)=22 μm).

(17) CaCO.sub.3 (limestone powder) was obtained from Nordkalk AB, Finland (98.5% pure, dp(50)=7 μm).

(18) CaSO.sub.4 anhydrous was obtained from Alfa Aesar, Haverhill, USA.

(19) MgSO.sub.4 anhydrous, 99.999%, was obtained from Alfa Aesar, Haverhill, USA.

(20) MgSO.sub.4 anhydrous, >99.5%, was obtained from Alfa Aesar, Haverhill, USA.

(21) MgSO.sub.4 anhydrous, >98%, was obtained from Ekmekciogullari, Turkey.

(22) MgSO.sub.4.7H.sub.2O, >99.5%, was obtained from Merck KGaA, Darmstadt, Germany.

(23) Coating: Moisture-repellent (MR) coating was made according to EP 0768993 A1 (Norsk Hydro ASA) by mixing about 28 weight % of wax, about 68 weight % of oil and about 4 weight % of a resin, applied in an amount of about 0.1-0.5 weight % to the fertilizer. It will be referred herein as NH-coating.

(24) Experiment 1 (Ammonia Release)

(25) Experiment 1 defines the problem. FIG. 1 shows the ammonia release of a YaraVera® Amidas product comprising 462 ppm nBTPT, treated with several stabilizers. The numbers between brackets represent, for each stabilizer compound, the weight ratio of the said stabilizer compound compared to nBTPT.

(26) TABLE-US-00001 TABLE 1 Ammonia release with different stabilizers Example Stabilizer composition A (prior art) MgO (4.3) B (prior art) CaO-G-0554 (5.5) C (prior art) MgO (0.86) D (prior art) none E (prior art) CaCO.sub.3 (9.98) F (prior art) CaSO.sub.4 (12.1) G MgSO.sub.4 (10.7)

(27) Although compounds such as MgO and CaO are mentioned in the prior art document WO2017042194 (Yara International, 2017) as most effective stabilizers for nBTPT in the presence of a urea ammonium sulphate material, these compounds are observed as producing ammonia in the presence of said material, which is an unwanted effect of these stabilizers. Only without stabilizer, and with MgSO.sub.4 and with CaSO.sub.4, there is no ammonia release.

(28) Experiment 2

(29) This experiment was conducted to show the difference between the beneficial effect of the addition of an alkaline or alkaline-forming inorganic or organic compound (CaO—prior art) and MgSO.sub.4 (VWR grade 99.5%) to UAS on the stability of nBTPT in the presence of UAS open to the air at room temperature (FIG. 2A) and in bags at elevated temperature (FIG. 2B). As can be seen, the stabilizing effect of MgSO.sub.4 is comparable with the effect of the prior art compound (CaO), but no ammonia is generated (as shown in FIG. 1).

(30) Experiment 3 (Different Grades)

(31) This experiment shows the effect of the addition of different grades and forms of MgSO.sub.4 and also another sulphate, Na.sub.2SO.sub.4, compared to the prior art compound CaO for open to air storage conditions at room temperature (FIG. 3). All MgSO.sub.4 grades give a comparable nBTPT stability on the YaraVera® Amidas product. This experiment shows that the stabilizing effect of MgSO.sub.4 on nBTPT on UAS is not 100% based on a pH effect (alkaline pH 8.5 for MgSO.sub.4 99.5% versus acidic pH 6.1 for MgSO.sub.4 99.999%) and also not 100% based on the waterbinding effect of anhydrous MgSO.sub.4 as MgSO.sub.4.7H.sub.2O delivers similar nBTPT stability. Na.sub.2SO.sub.4 actually has a negative effect on the stability of nBTPT. This shows the unique stabilizing effect of magnesium sulphate.

(32) Experiment 4 (Effect of Addition of Oxides and Synergetic Effect of MgSO.sub.4 and MgO)

(33) This experiment shows the effect of the addition of a small amount of oxide to the stabilizer. Small amounts of MgSO.sub.4, which have little effect, become very effective in a combination with MgO (see D versus F). The effect is synergetic (see C+D versus F) and not additive. There is almost no difference in stability depending on the method of combining the components of the stabilizer composition (i.e. adding the components one by one in any order/making a pre-mix of the components and adding the pre-mix to UAS). MgO was found more effective than CaO, but it is assumed that any alkaline or alkaline-forming compound, selected from the group of calcium oxide, zinc oxide, magnesium oxide, calcium carbonate, and mixtures thereof, is effective.