Chemistry of the Melamine Process
Melamine is produced from urea by either non catalytic high-pressure processes or catalytic low-pressure processes, all of which can consist of one or two stages. The net overall reaction is shown below.
Melamine plants are normally integrated in fertilizer complexes, so that the carbon dioxide and ammonia obtained as co-products in both processes are recycled as raw materials for the urea plant, therefore improving the yield and economics of the processes.
Minor by-products are melamine polycondensates and oxiaminotriazines, which account for less than 5% and can be removed by means of several purification techniques. whereby a product with melamine content exceeding 99% can be obtained. The melamine yields, based on urea, are normally in the range of 90-95% of the theoretical according reaction above reported.