ABSTRACT
Diammonium phosphate (DAP) has become one of the most extensively used fertilizer materials. Diammonium phosphate can favorably be used in irrigation systems and in the production of liquid or suspension fertilizers, because it is completely soluble in water. The first commercial production of DAP in the United States was started in November 1954 at the Missouri Farmers Association plant at Joplin, Missouri, using the Dorr blunger with free ammoniation taking place in slurry tanks. In the early 1960s Tennessee Valley Authority (TVA) developed what is perhaps today the most widely accepted process for production of granular diammonium phosphate. Although a number of the Dorr-Oliver blunger type plants are still in operation, most recent new plants have been of the TVA type having a preneutralizer for partial ammoniation of the phosphoric acid and completion of ammoniation in a TVA patented rotary ammoniator-granulator instead of a blunger.
