The disclosure pertains to melamine production coupled to urea production, using a melamine off-gas condenser operating at a pressure of at least 25 bar. In embodiment, carbamate solution from a recovery section of the urea production is supplied to the melamine off-gas condenser. In an embodiment, carbamate solution from melamine mother liquor treatment is supplied to the LP carbamate condenser of the recovery section.

A process for the synthesis of melamine including the purification of the offgas released by the synthesis of melamine by means of a single purification stage (6); in the purification stage (6), the offgas (3) is washed with fresh urea melt and with a recirculated urea melt (8) containing ammonia and melamine precursors (5); said recirculated urea melt is withdrawn from bottom of the single purification stage (6) and cooled in a shell and tube heat exchanger (11), optionally after mixing with the fresh urea melt (15), to a temperature of at least 165 C. preferably in the range 165 C. to 245 C. prior to reintroduction in the purification stage.

A process for the synthesis of melamine including the purification of the offgas released by the synthesis of melamine by means of a single purification stage (6); in the purification stage (6), the offgas (3) is washed with fresh urea melt and with a recirculated urea melt (8) containing ammonia and melamine precursors (5); said recirculated urea melt is withdrawn from bottom of the single purification stage (6) and cooled in a shell and tube heat exchanger (11), optionally after mixing with the fresh urea melt (15), to a temperature of at least 165 C. preferably in the range 165 C. to 245 C. prior to reintroduction in the purification stage.

An integrated process for the synthesis of urea and melamine, wherein urea synthesized in a urea plant is used to produce melamine in a melamine plant connected to the urea plant, according to a high-pressure non-catalytic melamine synthesis process, wherein melamine is synthesized at a pressure higher than urea synthesis pressure and offgas liberated during the synthesis of melamine are returned, as a gas, to the high-pressure synthesis section of the urea plant.

An integrated process for the synthesis of urea and melamine, wherein urea synthesized in a urea plant is used to produce melamine in a melamine plant connected to the urea plant, according to a high-pressure non-catalytic melamine synthesis process, wherein melamine is synthesized at a pressure higher than urea synthesis pressure and offgas liberated during the synthesis of melamine are returned, as a gas, to the high-pressure synthesis section of the urea plant.