Patent ID: 8628684

Claim:
A process for preparation of a powder, the powder comprising: at least one derivative of glycine-N,N-diacetic acid, at least one derivative of glutamine-N,N-diacetic acid, or a mixture thereof with a degree of crystallinity of ≧30%, the process comprising: concentrating an aqueous solution to obtain a crystal slurry, wherein the aqueous solution comprises the at least one derivative of glycine-N,N-diacetic acid, the at least one derivative of glutamine-N,N-diacetic acid, or the mixture thereof in a concentration range from 20 to 60% by weight, based on a total weight of the aqueous solution, and wherein the crystal slurry has a solids concentration of from 60 to 85% by weight, based on a total weight of the crystal slurry, and ripening the crystal slurry in a paste bunker and then in a thin-film contact dryer, wherein a residence time in the paste bunker and in the thin-film contact dryer is in total ≧15 minutes, and the concentrating occurs in an evaporator with rotating internals, which are arranged at a distance relative to an inside wall of the evaporator of ≦1% of a diameter of the evaporator.