Production of suspension fertilizers from wet-process orthophosphoric acids

摘要

A process for preparing concentrated, high-grade, nitrogen- phosphate (N--P.sub.2 O.sub.5) base suspension fertilizer from wet- process or other impure orthophosphoric acids. The process involves a new procedure for the direct ammoniation of orthophosphoric acid in stages for production of fluid, high-analysis, N--P.sub.2 O.sub.5 suspension fertilizer with good physical properties. The new process contains a novel method for prevention of settling of crystals in the suspension during vibration, such as that which occurs during shipment. Settling is avoided by producing small, thin crystals of diammonium phosphate through control of the N:P.sub.2 O.sub.5 ratio and temperature in the second and third ammoniation stages.