Process for the preparation of a powder comprising one or more derivatives of glycine-n,n diacetic acid and /or one or more derivatives of glutamine-n,n diacetic acid and methylglycine-n,n diacetic acid trisodium salt powder
Abstract
A process is proposed for the preparation of a powder comprising one or more derivatives of glycine-N,N-diacetic acid and/or one or more derivatives of glutamine-N,N-diacetic acid with a degree of crystallinity of a ≧30%, starting from an aqueous solution comprising the one or more derivatives of glycine-N,N-diacetic acid and/or the one or more derivatives of glutamine-N,N-diacetic acid in a concentration range from 20 to 60% by weight, based on the total weight of the aqueous solution, where the aqueous solution is concentrated in a first process step in an evaporator with rotating internals, which are arranged at a distance relative to the inside wall of the evaporator of ≦1% of the diameter of the evaporator, to give a crystal slurry with a solids concentration in the range from 60 to 85% by weight, based on the total weight of the crystal slurry, and where in a second process step the crystal slurry is left to ripen in a paste bunker and then in a thin-film contact dryer, and where the residence time in the paste bunker and in the thin-film contact dryer is in total a ≧15 minutes.
Claims
exact text as granted — not AI-modified1 - 14 . (canceled)
15 . A methylglycine-N,N-diacetic acid trisodium salt powder with a degree of crystallinity of ≧30%, comprising:
a first crystalline modification with d values in angstroms given below at diffraction angles 2-theta in °:
2-theta (°)
d value (angstroms)
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 optionally a second crystalline modification corresponding with d values in angstroms at respective diffraction angles 2-theta in ° in the X-ray powder diffractogram corresponding to the table below, in each case measured with Cu—K α-radiation with a variable diaphragm adjustment on a primary side and on a secondary side, in a measurement range of 2° to 80° with a step width of 0.01° and a measurement time per angle step of 3.6 seconds on a diffractometer,
2-theta (°)
d value (angstroms)
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
21.00
4.23
21.35
4.16
22.64
3.92
23.69
3.75
24.73
3.60
26.75
3.33
28.93
3.08
29.88
2.99
31.46
2.84
31.88
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