Abstract
A pilot-plant process is described that purifies wet-process phosphoric acid for the production of a high-quality urea-ammonium polyphosphate base solution. An intermediate product, crystalline urea phosphate, is produced from urea and merchant-grade (54% P2O5) wet-process phosphoric acid. The urea phosphate crystals contain only about 15 to 20% of the objectionable impurities (iron, aluminum, and magnesium) originally contained in the feed wet-process acid. The urea phosphate crystals are pyrolyzed, converting orthophosphate to polyphosphate with very little energy consumption. The resulting melt is dissolved and neutralized with ammonia to produce 14-29-0 liquid product of high polyphosphate content.
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Hodge, C.A., Motes, T.W. Production of high-quality liquid fertilizers from wet-process acid via urea phosphate. Fertilizer Research 39, 59–69 (1994). https://doi.org/10.1007/BF00750157
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DOI: https://doi.org/10.1007/BF00750157