Patent ID: 6825346
Filing Date: 2004-11-30
Classification: C07D

Abstract:
Process for the production of melamine crystals at high pureness comprising the steps of:feeding a flow comprising substantially pure melt melamine and a flow comprising liquid ammonia as coolant in a crystallisation section; mixing said flow comprising substantially pure melt melamine and said liquid ammonia in said crystallisation section thus obtaining a suspension of melamine crystals in liquid ammonia; feeding said suspension of melamine crystals in liquid ammonia to a thickening section; extracting in said thickening section a portion of said liquid ammonia from said suspension of melamine crystals, thus obtaining a slurry of melamine crystals; recycling to said crystallisation section at least a portion of said liquid ammonia extracted in said thickening section; feeding said slurry of melamine crystals to a separation section in order to remove the liquid ammonia still present and obtain melamine crystals at high pureness substantially free of ammonia.