LOW-FLUORINE PHOSPHORIC ACID FERTILIZER AND ITS MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a phosphoric acid fertilizer with less elution of sulfuric acid radical and fluorine. SOLUTION: The environment preservation type phosphoric acid fertilizer is a phosphoric acid fertilizer of quick-acting and slow-acting consisting essentially of water-soluble phosphoric acid and citric acid-soluble phosphoric acid and is characterized by that fluorine content is <=0.2 wt.%, elution quantity of fluorine is <=25 mg/l, preferably <=10 mg/l by a first process in which a raw material consisting essentially of monocalcium phosphate (monocalcium phosphate raw material) obtained from defluorination-treated phosphoric acid is hydrolyzed to phosphoric acid slurry and by a second process in which free fluorine in the slurry is immobilized while pelletizing slurry after adding the monocalcium phosphate raw material and a basic material thereto.