Fertilizer Manufacture, Diammonium Phosphate Fertilizer from Wet-Process Phosphoric Acid

Separation of ammonium phosphate from ammonium nitrate in sulfate recycle nitric phosphate process

“…Although large TAP crystals formed readily at pH 9 or above and 75°F , filtration rates were very low because of clogging of the filter medium by the precipitated impurities (Blouin et al, 1970). Therefore tests were made of a two-stage ammoniation system similar to that developed by Houston et al (1955) in pilot plant tests of producing diammonium phosphate from wet-process phosphoric acid. In that work ammoniation of the wet-process phosphoric acid to pH 5 at boiling resulted in agglomeration of the impurities to a readily filterable form before the pH was increased for precipitation of the diammonium phosphate.…”

Fertilizer Technology, High-Analysis Fertilizers from Phosphoric Acid and Conventional Ammoniating Materials

“…Houston, Yates, and Haunschild have described a method for removing these impurities by precipitating with ammonia and filtering (9).…”

“…The vacuum crystallizer (9) w'as a cylindrical, cone-bottomed vessel 18 inches in diameter by 6 feet high. Vapors w'ere withdrawn from the top to a barometric condenser.…”

“…In this practice, the zinc carrier may react with the components of the fertilizer during storage prior to use, thus affecting the solubility, and hence the nutrient status, of the trace element. Nikitin and Rainey (9) conducted an investigation of reactions between trace elements and fertilizer salts in which zinc was limited to one carrier, applied at one rate to a single grade of mixed fertilizer, and evaluated after aging for one specified time period. Expansion of each of these variables should provide additional useful information.…”

Production and Use of Liquid Fertilizers

“…However, wet acid is not generally available and the cost of removing impurities may be a significant cost item. Pilot-plant w-ork at TVA (4) has shown that precipitated impurities can be removed from ammonium phosphate solutions by a practical process.…”