Process for combined production of melamine and ammonium nitrate

The production technology of melamine co-produce ammonium nitrate pertains to the technology field of preparing melamine from urea. The invention adopts ammonia as carrier, and flow urea into a melamine reactor, and the impurities are removed from the reacted gas by a filter, and the melamine is desublimated into a solid through an arrestor and turns into crude melamine to be refined; the end gas coming from the arrestor goes through the filter and a second filter, and one part of the end gas comes back to the ammonium after carbon dioxide therein is removed through a compressor and an absorption tower; the other part of the end gas comes into firstly a neutralizer and then an evaporator to be concentrated and crystallized and forms ammonium nitrate(ammonium) finished product. The invention adopts the waste gas of melamine to produce added valued byproduct ammonium nitrate, and the technology can be controlled easily, the process is simple, the invention has good economic and environmental benefits.