一种长效硫铵是双氰胺与硫酸铵为共晶混合物形式存在 ,且双氰胺的含量为硫铵重量的 ( 0 .3～ 4 ) % ,其制备方法是将双氰胺溶解 (用水或氨水 )后 ,用计量泵输入到合成硫酸铵的反应釜中与反应溶液充分混合 ,再按常规技术对反应后溶液进行浓缩、双氰胺与硫酸铵共同结晶、脱水和干 A long-acting ammonium sulfate is a form of eutectic mixture of dicyandiamide and ammonium sulfate, and the content of dicyandiamide is (0.3 ~ 4)% by weight of ammonium sulfate, which is prepared by dissolving dicyandiamide Water or ammonia), with a metering pump input to the synthesis of ammonium sulfate reactor and the reaction solution is well mixed, and then according to conventional techniques after the reaction solution was concentrated, dicyandiamide and ammonium sulfate co-crystallization, dehydration and dry