Patent ID: 6891040
Filing Date: 2005-05-10
Classification: C07D

Abstract:
1. A process to recover bosh melamine and oxyaminotriazines (OAT) from the mother liquor of melamine crystallization comprising the following steps: a) adding an alkaline agent to a melamine and OAT containing aqueous solution at high temperature until a pH of a resulting solution reaches a value of at least approximately 11; b) crystallizing at least a portion of the melamine to obtain precipitated melamine by cooling the resulting solution; c) separating and recovering the precipitated melamine from the mother liquor; d) acidifying the mother liquor with a suitable acid to reach a pH of approximately 7 resulting in precipitation of the OAT to obtain a suspension; e) filtering the suspension using tangential filtration to obtain a permeate containing all of the melamine not precipitated in step b) and a retentate comprising an OAT dispersion having an OAT concentration at least fifteen times an original OAT concentration; f) recycling the permeate to recover an amount of melamine not precipitated in step b); and g) recovering OAT from the retentate.