The Prayon HDH Process is a clever technology that maximizes the P₂O₅ strength in the acid and produces a high-quality gypsum.
It consists of an attack of the phosphate rock under hemihydrate conditions. Hemihydrate slurry is filtered on a Prayon tilting pan filter to recover the phosphoric acid. Then, the hemihydrate slurry is hydrated to dihydrate under specific process conditions of temperature and acidity defined by Prayon. Dihydrate slurry is filtered on a Prayon tilting pan filter to recover a high-quality calcium sulfate.
Depending on the rock processed, the ex-filter acid strength is typically 40-45% P2O5 and the typical P2O5 recovery efficiency is 98-99%.