Removal of fluoride from the acid digestion liquor in production process of nitrophosphate fertilizer

Removal of fluoride in the nitrophosphate process was firstly investigated. Precipitation tests were performed both in pure fluoride solution (H2SiF6 + HF + H2O) and actual acid digestion liquor using KNO3 as precipitant. The results revealed that the addition of KNO3 would remove the fluoride effectively, and the obtained precipitates were the high-purity K2SiF6.