CRUMBLY PHASE COMPOSITION OF METHYLGLYCINE N,N DIACETIC ACID

Abstract

The present invention relates to a crumbly phase composition containing on total weight of the composition (i) 70-87 wt % of organic compounds and salts thereof containing 85 to 100 wt % on total organic compounds and salts thereof of MGDA-Na3, wherein at least 60 wt % of the MGDA-Na3 is crystalline, and (ii) 13-30 wt % of water

The invention furthermore relates to a process to prepare the above composition and a process to prepare crystals of MGDA-Na3 by drying the above composition.

Claims

1. A crumbly phase composition containing on total weight of the composition (i) 70-87 wt % of organic compounds and salts thereof containing 85 to 100 wt % of MGDA-Na3 on total organic compounds and salts thereof, wherein at least 60 wt % of the MGDA-Na3 is crystalline, and (ii) 13-30 wt % of water.

2. The crumbly phase composition of claim 1 containing on total weight of the composition (i) 70-80 wt % of organic compounds and salts thereof containing 85 to 100 wt % of MGDA-Na3 on total organic compounds and salts thereof, wherein at least 60 wt % of the MGDA-Na3 is crystalline, and (ii) 20-30 wt % of water.

3. The crumbly phase composition of claim 1 containing 75-80 wt % of organic compounds and salts thereof on the basis of the total weight of the composition.

4. The crumbly phase composition of claim 1 wherein the organic compounds and salts thereof contain more than 90 wt % of MGDA-Na3 on the basis of total organic compounds.

5. The crumbly phase composition of claim 1 wherein the MGDA-Na3 that is crystalline is at least 75% of crystal type I.

6. The crumbly phase composition of claim 1 containing between 50 and 80% of the L enantiomeric form of MGDA and between 20 and 50% of the D enantiomeric form of MGDA.

7. Process to prepare the crumbly phase composition of claim 1 comprising combining an aqueous composition of MGDA-Na3 and solid MGDA-Na3.

8. Process of claim 7 wherein the aqueous composition contains 35-60 wt % of MGDA-Na3.

9. Process to prepare solid crystalline MGDA-Na3 comprising a step of drying the crumbly phase composition of claim 1.

10. Process of claim 9 wherein the solid crystalline MGDA-Na3 contains 90-100% of crystal type I on total crystal content of MGDA-Na3.

11. Process of claim 9 wherein the process involves as a drying step a step selected from the group of an evaporation step, a step of fluid bed drying, a step of spray drying, a step of thin film drying, a step of drum drying, and a spray granulation step.

12. Process of claim 9 wherein in the process a part of the crystalline product as obtained is recycled and mixed with an aqueous composition containing MGDA-Na3 in an amount to prepare additional crumbly phase composition.

13. Process of claim 9 wherein the process is performed continuously.

14. Solid crystalline MGDA-Na3 product obtained by the process of claim 9 that contains between 50 and 80% of the L enantiomeric form of MGDA and that contains 90-99% crystals of the crystal type I and 1-10% crystals of crystal type III on the basis of the total amount of MGDA-Na3 crystals.

Description

EXAMPLES

Example 1 (Comparative)

[0064] A 50 wt % MGDA-Na3 aqueous slurry was prepared by crystallization evaporation, using MGDA-Na3 seeds of the type I variety. The slurry obtained was concentrated further using a laboratory rotary evaporator (temperature 50° C., pressure 200 mbar). At a concentration of 63 wt %, the slurry transformed into a pasty phase, yielding a sticky film on the wall of flask. Further drying yielded a hard film on the wall that could not be harvested efficiently anymore.

Example 2 (Comparative)

[0065] 77 kg of a 40.7 wt % MGDA-Na3 aqueous solution was charged to a 80 L Vrieco-Nauta conical screw mixer. The solution was concentrated to 50 wt % MGDA-Na3 (jacket temperature: 50-120° C., pressure 100-200 mbar, screw speed 70 rpm). After adding 300 grams of MGDA-Na3 seeds of the type I variety, the slurry obtained was concentrated further. In the range of 60-65 wt % MGDA-Na3 a thixotropic pasty phase was formed, yielding serious fouling problems. The product eventually obtained was one large spheroidal lump of material that could not be processed further.

Example 3

[0066] A crumbly phase composition was prepared by first dosing 17.1 kg of solid MGDA-Na3 (particle size 0.1-1.25 mm), containing solely the type I crystal variety (MGDA-Na3 content 80.8 wt %, crystallinity 75%) to a 50 L Lödige Ploughshare mixer, operated at a rotation speed of 170 rpm, and subsequently dosing 2.9 kg of a 40.7 wt % MGDA-Na3 aqueous solution, during 5 minutes via a dosing pipe. The temperature during mixing was 30-40° C. After dosing, the product (MGDA-Na3 content: 75 wt %) was homogenized for 2 more minutes, before discharging the crumbly phase product.

Example 4

[0067] 50 gram of the crumbly phase as obtained in example 3 was dried in petri-dish overnight in an oven at 90° C. The product obtained showing a MGDA-Na3 content of 81.3 wt %, was slightly caked, but could be easily crumbled, by gently tapping on the cake with a spatula, yielding free flowing particles in the range of 0.5-5 mm. The crystallinity of the product was 80%, showing solely the type I variety.

Example 5

[0068] 500 gram of the crumbly phase as obtained in example 3 was dried using a laboratory rotary evaporator (temperature 80° C., pressure 500 mbar), during 30 minutes. The product obtained showing an MGDA-Na3 content of 82.1 wt %, was a free-flowing powder containing particles in the range of 0.5-3 mm. The crystallinity of the product was 77%, showing predominantly the type I variety and a small amount of a few percent of the type III variety.

Example 6

[0069] 13 kg of the crumbly phase as obtained in example 3 was dried in a 16 L fluid bed drier, during 8 minutes (air temperature 150° C.; product end temperature 90° C.).

[0070] Subsequently the product was milled using an Alexanderwerk friction sieve.

[0071] A free-flowing product was obtained showing an MGDA-Na3 content of 80.1 wt %. The crystallinity of the product was 79%, showing solely the type I variety

[0072] 73 wt % of the product showed a particle size in between 0.5 and 1.5 mm. The bulk density was 850 Kg/m.sup.3.

[0073] Visual inspection using a microscope showed that the majority of the particles had a spheroidal shape (potato-alike).

Example 7

[0074] A crumbly phase composition was prepared by first dosing 16 kg of solid MGDA-Na3 (particle size 0.1-1.25 mm), containing solely the type I crystal variety (MGDA-Na3 content 80.3 wt %, crystallinity 79%) to a 50 L Lödige Ploughshare mixer, operated at a rotation speed of 170 rpm, and subsequently dosing 2.55 kg of a 45.1 wt % MGDA-Na3 aqueous solution, during 5 minutes via a dosing pipe. The temperature during mixing was 45-50° C. After dosing, the product (MGDA-Na3 content: 76.1 wt %) was homogenized for 2 more minutes, before discharging the crumbly phase product.

[0075] The crumbly phase obtained was subsequently processed as described in example 6, yielding a free-flowing product showing an MGDA-Na3 content of 80.3 wt %. The crystallinity of the product was 78%, showing solely the type I variety.

[0076] 68 wt % of the product showed a particle size in between 0.5 and 1.5 mm. The bulk density was 840 Kg/m.sup.3.