| 摘要 |
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, wherethe 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 wherein 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. |
