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Abstract

High pressure melamine manufacturing process starting from urea with high yields and conversion rates characterized in that it comprises the following steps: a) urea is fed to a reactor essentially containing molten melamine, which reactor operates in continuous and is kept at a temperature in the range of 360 to 420.degree. C. under a pressure higher than 7.times.10.sup.3 KPa and preferably 8.times.10.sup.3 to 9.times.10.sup.3 KPa, while a vigorous mixing is provided by evolving gases; b) liquid reaction product is recovered containing 85 to 95%, preferably 88 to 93% melamine and a gaseous phase is removed containing essentially CO.sub.2 and NH.sub.3 ; c) liquid phase collected in b) is continuously fed, together with fresh NH.sub.3 to a tubular reactor, in which the essentially whole volume is occupied by the liquid phase (plug flow reactor) without any mixing of the reaction product with reactant nor the intermediate products (no 'back mixing'), kept at a temperature of 360 to 450.degree. C. and under a pressure higher than 7.times.10.sup.3 KPa for a residence time sufficient to complete the reaction; d) melamine with a high purity level is collected from the outlet of the tubular reactor.

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First Claim