Composition of a magnesium sulphate-urea compound

Abstract

The present invention relates to compositions containing at least 80% by weight, especially at least 90% by weight, based on the total weight of the composition, of at least one magnesium sulfate-urea compound selected from the compound of the formula (I) and mixtures of the compound of the formula (I) with the compound of the formula (II): [MgSO.sub.4.mCO(NH.sub.2).sub.2.nH.sub.2O] (I), [MgSO.sub.4.xCO(NH.sub.2).sub.2.yH.sub.2O] (II), in which m and x are each in the range from 0.9 to 1.1, n is in the range from 1.9 to 2.1 and y is in the range from 2.9 to 3.1, where the compositions, based on the total weight of the composition, contain less than 10% by weight of free MgSO.sub.4 in the form of the anhydrate or in the form of hydrates of magnesium sulfate and less than 10% by weight of unbound urea. The invention also relates to the production of the compositions and to the use thereof as fertilizers or fertilizer additive.

Claims

1. A composition, comprising: at least 80 wt %, relative to the total weight of the composition, of a magnesium sulfate-urea compound selected from the group consisting of a compound of formula (I) and mixtures of the compound of formula (I) with a compound of formula (II):
[MgSO.sub.4.mCO(NH.sub.2).sub.2.nH.sub.2O](I),
[MgSO.sub.4.xCO(NH.sub.2).sub.2.yH.sub.2O](II), wherein m and x are in the range from 0.9 to 1.1, n is in the range from 1.9 to 2.1 and y is in the range from 2.9 to 3.1, wherein the composition, relative to the total weight of the composition, comprises less than 10 wt % of free MgSO.sub.4 in anhydrous form or in the form of hydrates of magnesium sulfate and less than 10 wt % of unbound urea, and wherein the composition is a solid material and does not deliquesce after 12 hours under ambient conditions.

2. The composition according to claim 1, wherein in formula (I) the variable m has the value 1.0 and the variable n has the value 2.0, and wherein in formula (II) x has the value 1.0 and y has the value 3.0.

3. The composition according to claim 1, wherein the proportion of the compound of formula (I) relative to the total content of compounds of formulas (I) and (II) is at least 90 wt %.

4. The composition according to claim 1, wherein the proportion of the compound of formula (I) relative to the total content of compounds of formulas (I) and (II) is in the range of 20 to lower than 90 wt %.

5. The composition according to claim 1, comprising at least 90 wt %, relative to the total weight of the composition, of the magnesium sulfate-urea compound selected from the group consisting of a compound of formula (I) and mixtures of the compound of formula (I) with compound of formula (II).

6. The composition according to claim 1, wherein the composition, relative to the total weight of the composition, comprises less than 5 wt % of free MgSO.sub.4 in anhydrous form or in the form of hydrates of magnesium sulfate and less than 5 wt % of unbound urea.

7. A process for production of a composition according to claim 1, said process comprising: reacting solid anhydrous magnesium sulfate with solid urea and water at a temperature above 75 C., wherein anhydrous magnesium sulfate, urea and water are used in a mole ratio of magnesium sulfate to urea in the range of 1:0.9 to 1:1.1 and of magnesium sulfate to water in the range of 1:2 to 1:4.

8. The process according to claim 7, wherein the reaction is carried out in a mixing apparatus having at least one rotating mixing implement and wherein adjustment of the grain sizes is achieved during and/or directly after the reaction by increasing the speed of the mixing implements.

9. The process according to claim 7, wherein water is added to a mixture of anhydrous magnesium sulfate and urea.

10. The process according to claim 7, wherein the anhydrous magnesium sulfate is used in the form of a powder, wherein at least 95 wt % of the particles have a diameter of at most 100 m.

11. The process according to claim 7, wherein the urea is used in the form of a powder or granules, wherein at least 95 wt % of the particles have a diameter of at most 1000 m.

12. A process for production of a composition according to claim 1, said process comprising: drying, at a temperature of from 65 to 95 C., a composition comprising at least 80 wt %, relative to the total weight of the composition, of the magnesium sulfate-urea compound of formula II and less than 10 wt % of free MgSO.sub.4 in anhydrous form or in the form of hydrates of magnesium sulfate, and/or less than 10 wt % of unbound urea.

13. A fertilizer or an additive for a fertilizer, comprising: the composition according to claim 1.

14. A nitrogen-magnesium-sulfur fertilizer composition, comprising: a composition according to claim 1, and Epsom salts.

15. A fertilizer composition, comprising: a composition according to claim 1, and least one component selected from the group consisting of an urease inhibitor and a nitrification inhibitor.

16. A process for fertigation of a substrate used in agriculture or horticulture, said process comprising: introducing and/or applying onto said substrate water and a composition selected from the group consisting of i) a composition according to claim 1 and ii) a composition according to claim 1 and Epsom salts; and optionally one or more further fertilizer additives; wherein said introducing and/or applying onto said substrate proceeds in such a way that essentially no excess water is produced.

Description

(1) The inventive composition and the inventive processes will be explained in more detail by the following examples and by FIG. 1 and FIG. 2 as well as Table 4.

(2) FIG. 1: List of the characteristic reflections (expressed as d-values in ngstrm, determined at 298 K using CuK radiation: =1.5413 ) and their relative intensity in the x-ray powder diagram of the compound of formula (I) (MgSO.sub.4.CO(NH.sub.2).sub.2.2H.sub.2O) and of the compound of formula (II) (MgSO.sub.4.CO(NH.sub.2).sub.2.3H.sub.2O). Values: d in ngstrm (1 =0.1 nm), relative reflection intensity is reported relative to the 100% reflection (3%).

(3) FIG. 2: Thermogravimetric diagram of the compound of formula (I).

(4) FIG. 3: Thermogravimetric diagram of the compound of formula (II).

(5) FIG. 4: FTIR spectrum of the compound of formula (I).

(6) FIG. 5: FTIR spectrum of the compound of formula (II).

(7) The x-ray diffraction diagrams were recorded with a type D 8 Advance Diffractometer of the Bruker AXS Co. (298 K, CuK radiation: =1.5413 ), step width: 0.018385738, step duration: 0.2 second, detector: Lynx Eye.

(8) The elemental analyses were performed by:

(9) N determination DIN ISO 13878, TOC determination DIN ISO 1484, Mg/S LUFA [Agricultural Investigation and Research Institute] Association method (K+S 0905.01), H2O determination Karl-Fischer titration.

(10) The thermogravimetric analyses were performed using a Mettler-Toledo TGA/DSC 1 thermogravimetric analyzer.

(11) The IR analyses were performed by means of a standard FTIR spectrometer in the wavelength region of 4000 to 600 cm.sup.1 according to the method of attenuated total reflection (ATR).

EXAMPLE 1

(12) 1000 g (8.31 mol) ground calcined MgSO.sub.4 (anhydrous, grain size <0.1 mm, produced from natural kieserite) was mixed with 499 g (8.31 mol) ground urea (grain size <1.0 mm). To this, 450 g (24.98 mol) water was added within 10 seconds under intensive stirring. Under heating to approximately 87 C., the initially liquid suspension gradually became pasty and within 5 minutes increasingly more solid, until it could no longer be mixed/stirred. After a further 12 hours of standing time (maturation) in air, a colorless solid (MgSO.sub.4.CO(NH.sub.2).sub.2.2H.sub.2O) was obtained. The final weight was 1781 g (8.22 mol), corresponding to a yield of 99%.

EXAMPLE 2

(13) 500 g (2.13 mol) MgSO.sub.4.CO(NH.sub.2).sub.2.3H.sub.2O was dried as a powdery sample for 24 hours at 70 C. in a laboratory drying oven. After drying, a colorless solid was obtained. The final weight was 452.35 g (2.09 mol) MgSO.sub.4.CO(NH.sub.2).sub.2.2H.sub.2O, corresponding to a yield of 98%.

(14) Elemental Analysis:

(15) The theoretically and experimentally determined values of the compounds MgSO.sub.4.CO(NH.sub.2).sub.2.2H.sub.2O and MgSO.sub.4.CO(NH.sub.2).sub.2.3H.sub.2O are presented in the following Table 4.

(16) TABLE-US-00004 TABLE 4 MgSO.sub.4CO(NH.sub.2).sub.22H.sub.2O MgSO.sub.4CO(NH.sub.2).sub.23H.sub.2O theoretical [%] found [%] theoretical [%] found [%] Mg 11.2 11.1 10.4 10.8 SO.sub.4.sup.2 44.4 43.6 41.0 42.5 C 5.5 5.7 5.1 5.2 N.sub.total 12.9 12.8 11.9 12.2 H.sub.2O 16.6 17.2 23.0 20.4

(17) Furthermore, the biuret content of the product MgSO.sub.4.CO(NH.sub.2).sub.2.2H.sub.2O was determined by VDLUFA [Association of Agricultural Investigation and Research Institutes] method II.1, 3.6.1. The values were typically around 0.2% for various production batches and were always below 0.9%.

(18) Thermogravimetric Analysis (TGA):

(19) In the thermogravimetric diagram (FIG. 2), MgSO.sub.4.CO(NH.sub.2).sub.2.2H.sub.2O exhibits a weight loss of around 12% starting at a temperature of approximately 130 C. Further weight losses of 7% are observed starting at approximately 205 C. and up to 260 C. and of 3% starting at approximately 260 C. and up to approximately 290 C. At a temperature of 750 C., essentially anhydrous magnesium sulfate exists. The residual weight of experimentally around 52% (55.6% theoretical) of the starting weight is therefore in good agreement. The thermogravimetric diagram is presented in FIG. 2.

(20) In the thermogravimetric diagram (FIG. 3), MgSO.sub.4.CO(NH.sub.2).sub.2.3H.sub.2O exhibits decomposition starting at a temperature of approximately 90 C., accompanied by a weight loss of approximately 6%. A further weight loss of 11% in two stages is observed starting at approximately 155 C. and up to approximately 210 C. Above 210 C., a steady weight loss is evident. At a temperature of 750 C., essentially anhydrous magnesium sulfate exists. The residual weight of experimentally around 50% (51.4% theoretical) of the starting weight is therefore in good agreement. The thermogravimetric diagram is presented in FIG. 2.

(21) Abbreviations used (IR spectra): m=medium, st=strong, sst=very strong, sh=shoulder, br=broad.

(22) The IR spectrum of MgSO.sub.4.CO(NH.sub.2).sub.2.2H.sub.2O (FIG. 4) exhibits the following bands: 3466 cm.sup.1 (m, br), 3362 cm.sup.1 (m, br, sh), 1672 cm.sup.1 (st), 1603 cm.sup.1 (st), 1483 cm.sup.1 (st), 1138 cm.sup.1 (sst), 1195 cm.sup.1 (sst).

(23) The IR spectrum of MgSO.sub.4.CO(NH.sub.2).sub.2.3H.sub.2O (FIG. 5) exhibits the following bands: 3457 cm.sup.1 (m, sh), 3336 cm.sup.1 (m, br), 3198 cm.sup.1 (m, br), 1672 cm.sup.1 (st), 1638 cm.sup.1 (st), 1603 cm.sup.1 (st), 1483 cm.sup.1 (st), 1086 cm.sup.1 (sst, br).