Process for the preparation of a powder comprising one or more complexing agent salts

Patent metadata

Field	Value
Publication number	US-9540597-B2
Application number	US-201013501390-A
Country	US
Kind code	B2
Filing date	Oct 11, 2010
Priority date	Oct 12, 2009
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A process for the preparation of a powder comprising one or more complexing agent salts of the general formula

comprises atomizing an aqueous solution comprising the one or more complexing agent salts in the presence of a crystalline fine dust of the same complexing agent salts and a drying step, wherein the concentration of the one or more complexing agent salt is from 10 to 80% by weight, based on the total weight of the aqueous solution, with an upper limit for the average particle diameter of the crystalline fine dust which is lower by at least a factor of 2 than the lower limit of the average particle diameter of the powder obtained after the process, and the fraction of the crystalline fine dust is from 0.1 to 20% by weight, based on the weight of the powder obtained after the process.

First claim

The invention claimed is:

1. A process for preparing a powder comprising at least one methylglycine-N,N diacetic acid complexing agent salt of formula (I):

wherein
R′ is

and
R″ is methyl;
M is, independently, hydrogen, an alkali metal, an alkaline earth metal, ammonium or a substituted ammonium in corresponding stoichiometric amounts, provided that at least one M is not hydrogen;

comprising:
(a) atomizing an aqueous solution comprising a first complexing agent salt of formula (I) in the presence of a crystalline fine dust of a second complexing agent salt of formula (I), to produce a powder, and
(b) drying the powder,

wherein
a concentration of the first complexing agent salt in the aqueous solution is from 10 to 80% by weight, based on a total weight of the aqueous solution;
an upper limit for an average particle diameter of the crystalline fine dust is lower by at least a factor of 2 than a lower limit of an average particle diameter of the powder obtained by the process;
a fraction of the crystalline fine dust is from 0.1 to 20% by weight, based on a weight of the powder obtained in the process; and
the residual moisture of the powder after drying is 6.5 to 14% by weight.

2. The process of claim 1 , wherein the drying occurs in a spray-tower.

3. The process of claim 1 , wherein the drying is a spray-granulation in which, during the atomizing, the aqueous solution is sprayed into a fluidized bed comprising granules of the complexing agent salt of formula (I).

4. The process of claim 2 , wherein, in the spray-tower, a fluidized bed is integrated and an agglomerating spray-drying occurs.

5. The process of claim 1 , wherein the drying is a spray-agglomeration carried out in a mixer with agitated internals, to give an agglomerate which is then fully dried in a further apparatus.

6. The process of claim 1 , wherein the aqueous solution comprises ca. 30 to 50% by weight of the complexing agent salt, and is concentrated in a process upstream of the spray-drying process in a heat exchanger or a thin-film evaporator to ca. 55 to 80% by weight of the complexing agent salt, based on the total weight of the aqueous solution.

7. The process of claim 1 , wherein the drying occurs at a pressure in the range from 0.1 bar absolute to 10 bar absolute.

8. The process of claim 1 , wherein a residence time of the drying is in a range from 10 seconds up to 1 h.

9. The process of claim 1 , wherein the first complexing agent salt of formula (I) and the second complexing agent salt of formula (I) are the same.

10. The process of claim 1 , wherein the first complexing agent salt of formula (I) and the second complexing agent salt of formula (I) are different.

11. The process of claim 9 , wherein at least one M is an alkali metal.

12. The process of claim 11 , wherein each M is an alkali metal, and each M is the same alkali metal.

13. The process of claim 12 , wherein M is sodium and wherein the process produces a methylglycine-N,N-diacetic acid trisodium salt powder with a degree of crystallinity of ≧30% comprising a first crystalline modification with the d values stated below in Angströms at the diffraction angles 2-theta in °:

2-theta (°)
d value (Angströms)

8.4
10.5

9.5
9.3

11.1
8.0

13.2
6.7

13.9
6.35

15.8
5.6

16.5
5.36

16.84
5.26

17.34
5.11

17.67
5.02

18.92
4.69

20.29
4.37

21.71
4.09

22.3
3.98

23.09
3.85

24.74
3.59

25.36
3.51

27.04
3.29

28.28
3.15

29.63
3.01

30.09
2.97

and/or a second crystalline modification with the d values in Angstroms at the respective diffraction angles 2-theta in ° in the X-ray powder diffractogram corresponding to the table below:

2-theta (°)
d value (Angströms)

8.2
10.80

10.5
8.40

15.55
5.70

16.47
5.38

17.09
5.18

18.10
4.90

18.82
4.71

Assignees

• Mrzena Frank
• Menge Ullrich
• Schoenherr Michael
• Heidenfelder Thomas
• Basf Se

Inventors

• Mrzena Frank
• Menge Ullrich
• Schoenherr Michael
• Heidenfelder Thomas

Classifications

• C11D11/02

  Preparation in the form of powder by spray drying · CPC title

• C11D17/06

  Powder; Flakes; Free-flowing mixtures; Sheets · CPC title

• C11D3/33 Primary

  Amino carboxylic acids · CPC title

• C07C229/24

  having more than one carboxyl group bound to the carbon skeleton, e.g. aspartic acid · CPC title

• C11D11/0088

  the liquefied ingredients being sprayed or adsorbed onto solid particles · CPC title