AMMONIUM PHOSPHATE PRODUCTION PROCESS Russian patent published in 2003 - IPC

FIELD: mineral fertilizers. SUBSTANCE: process comprises two-phase ammonia-mediated neutralization of mixture containing non-evaporated phosphoric acid, evaporation and subsequent granulation, drying of product and cleaning of leaving gases. In the first neutralization phase, 20-60% of non-evaporated phosphoric acid (calculated as P₂O₅) is used and ammonization is effected until phosphoric acid contains 1.8- 3.4% of ammonium silicofluoride. Partly ammonized phosphoric acid is evaporated to 10-30% water content and, before the second phase, combined with the rest of non-evaporated phosphoric acid. In the first phase, pH value is maintained 0.7- 1.2 and, in the second phase, in dependence of desired fertilizer product, 4- 4.5 or 6.5-7. EFFECT: simplified leaving gas cleaning stage, avoided fluorine emissions, and reduced incrustation and corrosion of equipment. 2 cl, 3 ex