FIELD: chemistry.
SUBSTANCE: invention relates to improved method of melamine purification, obtained from synthesis from urea, which includes the following stages: a) conversion of unpurified melamine, which contains admixtures of polycondensates and other side products of synthesis reaction, into solution, with obtaining solution/suspension, where insoluble products are dispersed; b) processing of obtained in such way solution/suspension to remove dissolved CO2, with reduction of its concentration to values lower than 0.5% wt; c) processing of obtained at stage (b) solution/suspension, which has content of CO2 lower than 0.5% wt, with ammonia in quality from 1 to 15%, preferably from 3 to 9% wt, at temperature in range from 110 to 180°C, preferably from 130 to 140°C; d) bringing solution, output from stage (c), in contact with solid catalyst under the same conditions, as at stage (c).
EFFECT: method makes it possible to remove admixtures of polycondensates from water solution with reduction of NH3 consumption.
5 cl, 2 ex
