There are two main methods for the production of phosphatic compound fertilizers in the world. One is USA method via sulfuric acid. Another is European way on base ofnitric acid. China adopts the second method according to our national conditions.
There will has undissolved substance in the acid hydrolysis solution, and there is no efficient separation technology to remove it. The existing technology only can remove about 10% of the insoluble substance, and this obviously can not meet the separation requirements. In order to solve this problem, now a Chinese team develops “Freezing Nitric Acid Phosphate Fertilizer”technology. It adopts plate filter press and filter aid to separate the insoluble substance and the removal rate can be reach 90% or more.
The frozen nitric phosphate technology has realized the comprehensive utilization of phosphorus resources. The calcium in the phosphate can be used to produce ammonium nitrate calcium. Comparing with existing technology, it do not produce phosphogypsum, which need place for stack. Additionally, it greatly reduced the waste gas for cement producing.