After MAP of agricultural grade was dissolved in water, dissolved impurities crystallized in the presence of chemical reagents, but small impurities and viscous suspension made filtration difficult.

• 把肥料级MAP溶解在水中，加入化学药剂使磷铵中的杂质结晶沉淀并进行溶液的澄清分离，但生成的颗粒细小，溶液黏稠，极难分离。