| 摘要 |
FIELD: mineral fertilizers. ^ SUBSTANCE: invention relates to manufacturing phosphorus-containing mineral fertilizer, in particular diammonium phosphate, characterized by stable dark coloration and having high commercial success. Process comprises mixing phosphoric acid with sulfuric acid, stepwise neutralization of ammonia with acid mixture to attain NH3/H3PO4 molar ratio 1.4 in presence of coloring organic compounds and then to achieve 1.75, followed by granulation, drying, and two-step cleaning of leaving gases. In the first step, ammonium phosphate pulp and, in the second step, phosphoric acid-containing solution are loaded and resulting absorption fluids are returned into the process. Above-mentioned organic colorant is cane refining syrup (sugar production waste) in amount 7-11 kg per 1 t finished product, which is added to second-step absorption fluid having pH 1.0-2.0. Resulting mixture is routed to neutralization stage. ^ EFFECT: improved uniformity of coloration, improved workability of process. ^ 3 ex |
