ABSTRACT
Since the early 1970s the fluid fertilizer industry has incorporated use of the Tennessee Valley Authority (TV A) pipe reactor process for production of ammonium polyphosphate (APP) solutions by the ammoniation of superphosphoric acid (SPA) [1]. The process is a method of producing fertilizer composed of nitrogen and phosphorus. Nitrogen is supplied to the process in the form of anhydrous ammonia. Phosphorus is supplied as wet-process superphosphoric acid. The only other raw material is water, which is used to dilute the plant nutrients to stable, standard grades of commercial fertilizer. The standard grade manufactured by this process is 10-34-0, which equates to 10% nitrogen, 34% phosphorus pentoxide, and 0% potassium. The 10-34-0 product made through this process of ammoniating superphosphoric acid has a high polyphosphate content (usually over 70% of the P20 5 present as polyphosphate) and because of the simplicity of the process, was readily accepted throughout the fluid fertilizer industry in the United States. Currently, about 1.8 million metric tons of 10-34-0 are produced annually in the United States [2].
