IMPROVED UREA-BASED COMPOSITION COMPRISING ELEMENTAL SULPHUR AND METHOD FOR THE MANUFACTURE THEREOF

Abstract

The invention relates to a homogeneous, solid, particulate, urea-based composition comprising elemental sulphur and a urease inhibitor of the type phosphoric triamide, wherein the urea-based composition comprising elemental sulphur is further characterized in that one or more of the following measures applies: a) it comprises 5 weight % or less, relative to the total weight of the composition, of one or more alkaline or alkaline-forming inorganic or organic compounds; or b) it comprises an anticaking and/or moisture-repellent coating. 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-based composition comprising urea, elemental sulphur 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: a) one or more alkaline or alkaline-forming inorganic or organic compounds; b) the urease inhibitor of the type phosphoric triamide in solid particulate or a liquid form, preferably wherein the urease inhibitor is N-(n-butyl) thiophosphoric triamide (nBTPT); c) optionally, one or more anticaking and/or moisture-repellent compounds.

Claims

1-21. (canceled)

22. A homogeneous, solid, particulate urea-based composition comprising urea, elemental sulphur, and a urease inhibitor of the type phosphoric triamide, characterized in that it comprises (i) one or more alkaline or alkaline-forming inorganic compounds at a level of 0.0001 to 5 weight %, relative to the total weight of the composition, wherein the alkaline or alkaline-forming inorganic compound is selected from the group of calcium oxide, zinc oxide, magnesium oxide, calcium carbonate, calcium magnesium carbonate (dolomite), and mixtures thereof, and, (ii) optionally, an anticaking and/or moisture-repellent coating.

23. The urea-based composition according to claim 22, characterized in that the urease inhibitor of the type phosphoric triamide is a compound of formula: ##STR00003## wherein: X is oxygen or sulphur; R.sub.1 is alkyl, cycloalkenyl, aralkyl, aryl, alkenyl, alkynyl, or cycloalkyl; R.sub.2 is hydrogen, alkyl, cycloalkenyl, aralkyl, aryl, alkenyl, alkynyl, or cycloalkyl, or R.sub.1 and R.sub.2 together may form an alkylene or alkenylene chain which may optionally include one or more heteroatoms of divalent oxygen, nitrogen or sulphur completing a 4, 5, 6, 7, or 8 membered ring system; and R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are individually hydrogen or alkyl having 1 to 6 carbon atoms.

24. The urea-based composition according to claim 22, wherein the urease inhibitor is N-(n-butyl) thiophosphoric triamide (nBTPT).

25. The urea-based composition according to claim 22, wherein the urease inhibitor, in particular N-(n-butyl) thiophosphoric triamide (nBTPT), is present at a level of 0.0001 to 1% weight %, preferably 0.02 to 0.2% weight %, most preferably 0.04 to 0.06 weight %, relative to the total weight of the composition.

26. The urea-based composition according to claim 22, wherein the alkaline or alkaline-forming inorganic compound is able to interact with the urease inhibitor, in particular N-(n-butyl) thiophosphoric triamide (nBTPT).

27. The urea-based composition according to claim 22, wherein the alkaline or alkaline-forming inorganic compound is able to interact with reactive sulphur derivatives, such as sulphide.

28. The urea-based composition according to claim 22, wherein the alkaline or alkaline-forming inorganic compound is present in the composition at a level of 0.02 to 1 weight %, most preferably 0.05 to 0.25 weight %, relative to the total weight of the composition.

29. The urea-based composition according to claim 22, wherein the weight ratio of urease inhibitor of the type phosphoric triamide to the one or more alkaline or alkaline-forming inorganic compounds in the composition ranges from 1:20 to 1:1, preferably from 1:15 to 1:1, more preferably from 1:10 to 1:1.

30. The urea-based composition according to claim 22, comprising an anti-caking and/or moisture-repellent coating, wherein the anticaking and/or moisture-repellent coating comprises at least a wax, oil and a resin which is oil-soluble and miscible with wax.

31. The urea-based composition according to claim 22, comprising 50 to 100 weight %, preferably 75 to 100 weight %, more preferably 90 to 100 weight % of urea base material in particulate form, relative to the total weight of the urea composition.

32. The urea-based composition according to claim 22, wherein the urea base material comprises 0.1 to 20 weight % of elemental sulphur, relative to the total weight of the urea base material.

33. The urea-based composition according to claim 32, wherein the urea base material is selected from the group of urea, urea-ammonium sulphate, urea-ammonium phosphate, and any combination thereof.

34. The urea-based composition according to claim 22, wherein the urea-based composition is a composition which comprises a urea base material comprising finely divided sulphur particles in the urea base material, or a urea base material coated with elemental sulphur.

35. A fertilizer, preferably for supporting the growth of agricultural products on a sulphurdeficient soil, comprising the homogeneous, solid, particulate urea-based composition according to claim 22.

36. An animal feed comprising the homogeneous, solid, particulate urea-based composition according to claim 22.

37. A method for the manufacture of a homogeneous, solid, particulate, urea-based composition according to claim 22, the method comprising the steps of: 1) providing a urea base material comprising elemental sulphur; 2) adding a urease inhibitor in solid particulate or a liquid form, preferably wherein the urease inhibitor is N-(n-butyl) thiophosphoric triamide (nBTPT); 3) adding 0.0001 to 5 weight %, relative to the total weight of the composition, of one or more alkaline or alkaline-forming inorganic compounds, wherein the alkaline or alkaline-forming inorganic compound is selected from the group of calcium oxide, zinc oxide, magnesium oxide, calcium carbonate, calcium magnesium carbonate (dolomite), and mixtures thereof; and 4) optionally, applying a coating that is able to increase at least the water repellence and/or anticaking properties of urea ammonium sulphate, preferably wherein said coating is as disclosed in EP 0768993 A1 of which the content is hereby included by reference; (Tropicote); wherein the steps 2), 3) and/or 4) can be interchanged or wherein steps 2), 3) and/or 4) can be performed simultaneously.

38. A kit of parts for addition to a solid particulate urea-based composition comprising urea and elemental sulphur to obtain the homogeneous, solid, particulate, urea-based composition according to claim 22, comprising a) the urease inhibitor of the type phosphoric triamide in solid particulate or a liquid form, preferably wherein the urease inhibitor is N-(n-butyl) thiophosphoric triamide (nBTPT); b) one or more alkaline or alkaline-forming inorganic compounds, wherein the alkaline or alkaline-forming inorganic compound is selected from the group of calcium oxide, zinc oxide, magnesium oxide, calcium carbonate, calcium magnesium carbonate (dolomite), and mixtures thereof; and c) optionally, one or more anticaking and/or moisture-repellent compounds.

39. Method for improving the stability of a urease inhibitor of the type phosphoric triamide, in particular N-(n-butyl) thiophosphoric triamide, (nBTPT) in a urea-based composition comprising urea, elemental sulphur and said urease inhibitor, by: a) addition to the composition of 0.0001 to 5 weight %, relative to the total weight of the composition, of one or more alkaline or alkaline-forming inorganic compounds, wherein the alkaline or alkaline-forming inorganic compound is selected from the group of calcium oxide, zinc oxide, magnesium oxide, calcium carbonate, calcium magnesium carbonate (dolomite), and mixtures thereof; and b) optionally, application of an anticaking and/or moisture-repellent coating onto the particulate urea base material comprising elemental sulphur or urea-based composition.

40. A container comprising the urea-based composition according to claim 22, wherein the head space in said container is less than 1%.

Description

EXAMPLES

Description of Figures

[0085] FIG. 1. Stability of different nBTPT-formulations at various storage conditions, applied on urea versus applied on urea comprising elemental sulphur (ES)% recovery of nBTPT after 98 days of storage under bagged storage conditions at room temperature (20-25 C.), 12 days at 30 C. open to the air, and 12 days at 70 C. in a closed plastic container. [A=urea+500 ppm nBTPT powder; B=urea+9% ES+500 ppm nBTPT powder; C=urea+9% ES+500 ppm Agrotain Ultra (KOCH); left column: Bagged at room temperature; middle column: stored at 30 C. for 12 days; right column: stored at 70 C. for 12 days].

[0086] FIG. 2A. Stability of nBTPT, applied on urea versus applied on urea comprising elemental sulphur (ES) at open storage conditions in nissenhut after 51 days. [D=urea+500 ppm nBTPT powder; E=urea+9% ES+500 ppm nBTPT powder; F=urea+9% ES+500 ppm nBTPT powder+2650 ppm CaO].

[0087] FIG. 2B. Stability of nBTPT, applied on urea versus applied on urea comprising elemental sulphur (ES) at bagged storage conditions in nissenhut after 123 days [D=urea+500 ppm nBTPT-powder; E=urea+9% ES+500 ppm nBTPT powder; F=urea+9% S+500 ppm nBTPT powder+2650 pm CaO].

[0088] FIG. 3. Stability of nBTPT in Amiplus liquid, applied on urea versus applied on urea comprising elemental sulphur (ES) without versus with alkaline stabilizers at open storage conditions in nissenhut, measured after 28 days of storage. [G=urea+Amiplus liquid; H=urea+10.5% ES; I=urea+10.5% ES+2500 ppm CaO; J=urea+10.5% ES+1800 ppm MgO; K=urea+10.5% ES+4464 ppm CaCO.sub.3; L=urea+10.5% ES+3634 ppm ZnO; M=urea+10.5% ES+4500 ppm Et.sub.3N].

[0089] FIG. 4. Stability of nBTPT in Amiplus liquid, applied on urea comprising elemental sulphur (ES) without versus with moisture-repellent coating Tropicote at open storage conditions in nissenhut, measured after 28 days of storage. [N=urea+10.5% ES; 0=urea+10.5% ES+2500 ppm Tropicote].

EXPERIMENTAL

1. Preparation of the Samples

[0090] 1.2 kg of solid fertilizer material was added to a lab scale drum. In a next step, the nBTPT material was slowly added and subsequently followed, if applied, by an alkaline or alkaline-forming inorganic or organic compound. 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.

[0091] For some samples, an accelerated stability test was done after storing these samples at elevated temperatures: [0092] Oven of 30 C., open to air [0093] 70 C. in a closed plastic container

[0094] Typically, a day/night cycle is generated in the nissenhut, with temperature fluctuations between 0 to 42 C. and fluctuations of relative humidity between 20 and 90%, which can be compared with real life storage in silos.

2. HPLC Analysis of nBTPT-Content

[0095] HPLC analysis of nBTPT is done as described in the procedure CEN 15688-2007.

3. Products

[0096] 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.

[0097] Amiplus liquid is a solution of 17.5% w/w N-(n-butyl)thiophosphoric triamide (nBTPT) in propylene glycol with a red colouring agent and is produced and sold by Yara International ASA, Oslo, Norway.

[0098] Urea was obtained from Yara Sluiskil (The Netherlands) as granules YaraVera Urea 46-0-0 (product code PA38M2).

[0099] Urea+ES granules were produced in the urea pilot plant in Yara Sluiskil (The Netherlands). This pilot plant has a batch capacityafter sievingof about 50 kg of on-spec product. It basically consists of a stirred urea preparation vessel with an active volume of about 150 litres and a fluidized bed granulator of the UFT-type, equipped with a spraying nozzle of the spiral-type or HFT-type (EP 1 701 798 B1, Yara International ASA, 2005).

Urea+9% ES:

[0100] 115.71 kg of liquid urea was mixed with 13.0 kg of elemental sulphur in powder form and 1.29 kg of a urea-formaldehyde conditioning agent, UF80 (from Dynea), a mixture of urea/formaldehyde/water in a ratio of 23/57/20) at a temperature of about 130 C. to obtain a melt mix with 10% of sulphur with a melt concentration of 95.2%, after which the resulting mixture was pumped to an active fluidized bed granulator at a granulation temperature of about 101 C., equipped with a spiral nozzle. The injection time was about 13 minutes. The particulate urea-based fertilizer comprising elemental sulphur was discharged from the granulator, sieved and cooled to room temperature.

Urea+10.5% ES:

[0101] 115.93 kg of liquid urea was mixed with 14.3 kg of elemental sulphur in pastille (3-6 mm) form and 1.28 kg of a urea-formaldehyde conditioning agent, UF80 (from Dynea Dynea A, Lillestrom, Norway), a mixture of urea/formaldehyde/water in a ratio of 23/57/20) at a temperature of about 130 C. to obtain a melt mix with 11 weight % of sulphur with a melt concentration of 95.1 weight %, after which the resulting mixture was pumped to an active fluidized bed granulator at a granulation temperature of about 107 C., equipped with a spiral nozzle. The injection time was about 12 minutes. The particulate urea-based fertilizer comprising elemental sulphur was discharged from the granulator, sieved and cooled to room temperature.

Example 1

[0102] Example 1 defines the problem of the invention. The following sample set was prepared with the following compositions:

TABLE-US-00001 Sample (Comparative Example) Raw material urease inhibitor Stabilizer A Urea 500 ppm nBTPT powder none B Urea + 9% S 500 ppm nBTPT powder none C Urea + 9% S 500 ppm Agrotain Ultra none

[0103] This set of samples was stored at room temperature (20-25 C.) in bags and at elevated temperature (30 C. and 70 C., accelerated stability test).

[0104] FIG. 1 shows the stability of nBTPT-formulations (liquid and powder), applied onto urea and onto urea comprising elemental sulphur (ES), under different storage conditions. FIG. 1 shows clearly that in nBTPT formulations, applied onto urea comprising elemental sulphur, the nBTPT degrades fast and the nBTPT level drops even to 0 weight % only in 12 few days of storage at 70 C.

Example 2

[0105] This example shows the beneficial effect of the addition of an alkaline or alkaline-forming inorganic or organic compound on urea comprising elemental sulphur on the stability of nBTPT.

[0106] The following three sample sets were prepared with the following compositions:

TABLE-US-00002 Exp. Raw material urease inhibitor Stabilizer D (Comp.) Urea 500 ppm nBTPT powder none E (Comp.) Urea + 9% S 500 ppm nBTPT powder none F Urea + 9% S 500 ppm nBTPT powder 2650 ppm CaO

[0107] This set of samples was stored in nissenhut (9-39 C./30-81% RH), both bagged and open to air.

[0108] FIG. 2A shows the stability of nBTPT, applied on urea versus applied on urea comprising elemental sulphur (ES) at open storage conditions in nissenhut after 51 days. The addition of CaO has a big beneficial effect: without CaO, the recovery of nBTPT after 51 days open to air is 0%. With CaO, the recovery of nBTPT after 51 days open to air is 89%.

[0109] FIG. 2B shows the stability of nBTPT, applied on urea versus applied on urea comprising elemental sulphur (ES) for bagged storage conditions in nissenhut after 123 days. The addition of CaO has a big beneficial effect: without CaO, the recovery of nBTPT after 123 days of bagged storage drops to about 49%. With CaO, the recovery of nBTPT after 123 days of bagged storage is still about 90%.

Example 3

[0110] A number of samples containing urea, 10.5 weight % of elemental sulphur and 500 ppm of Amiplus liquid as the urease inhibitor were prepared with different stabilizers on lab scale with a lab scale drum. The samples were stored 28 days in open pots in nissenhut.

TABLE-US-00003 Exp. Raw material urease inhibitor Stabilizer G (Comp.) Urea 500 ppm nBTPT as none Amiplus liquid H (Comp.) Urea + 10.5% ES 500 ppm nBTPT as none Amiplus liquid I Urea + 10.5% ES 500 ppm nBTPT as 2500 ppm CaO Amiplus liquid J Urea + 10.5% ES 500 ppm nBTPT as 1800 ppm MgO Amiplus liquid K Urea + 10.5% ES 500 ppm nBTPT as 4464 ppm CaCO.sub.3 Amiplus liquid L Urea + 10.5% ES 500 ppm nBTPT as 3634 ppm ZnO Amiplus liquid M Urea + 10.5% ES 500 ppm nBTPT as 4500 ppm Et.sub.3N Amiplus liquid

[0111] FIG. 3 shows the effect of different stabilizers (CaO, MgO, CaCO.sub.3, ZnO, triethylamine, and the effect of a coating on samples comprising urea, elemental sulphur and nBTPT. The stability was measured after 28 days. As can be seen, the effectivity of the stabilizers and coating after 14 days can be ranked as CaCO.sub.3MgO>CaO>ZnO>Et3N>no stabilizer.

Example 4

[0112] A number of samples containing urea, 10.5 weight % of elemental sulphur and 500 ppm of Amiplus liquid as the urease inhibitor were prepared with and without the addition of moisture-repellent coating Tropicote with a lab scale drum. The samples were stored for 28 days in open pots in nissenhut.

TABLE-US-00004 Exp. Raw material urease inhibitor Coating N Urea + 10.5% ES 500 ppm nBTPT as none (Comp.) Amiplus liquid O Urea + 10.5% ES 500 ppm nBTPT as 2500 ppm Tropicote Amiplus liquid

[0113] FIG. 4 shows the effect of a moisture-repellent coating on samples comprising urea, elemental sulphur and nBTPT. The stability was measured after 28 days of storage. Although the beneficial effect of the coating is small compared to the effect of a alkaline of alkaline-forming component, is it still very significant (about 18% after 28 days for a composition with the coating versus about 9% at day 28 for a composition without the coating).