Addition product of 1-hydroxyethylidene-1,1-diphosphonic acid and ethylenediamine disuccinic acid or a salt thereof, preparation method thereof, and use thereof
An adduct of 1-hydroxyethylidene-1,1-diphosphonic acid and from 0.5 to 10 moles of ethylenediamine disuccinic acid or a salt thereof per mole of 1-hydroxyethylidene-1,1-diphosphonic acid, wherein said adduct is in the form of a solid.