Fluorine-minute removal and how people recover from gypsum waste water discharged from the phosphate fertilizer production

摘要

The treatment of waste water in manufacturing phosphatic fertilizer consists of three processes. First, the calcium fluoride is separated by reacting the waste water with limestone or slaked lime, controlling pH within the range of 3.5-4.0, and precipitating the calcium fluoride under a polymer precipitator, aqueous anionic polyacrylamide solution. Second, P2O5 is recovered by controlling the pH to 10-12 with the addition of slaked lime into the solution. Third, the solution is neutralized by a sulfuric acid concentration.