PRODUCTION OF HIGH-QUALITY LIQUID FERTILIZERS FROM WET-PROCESS ACID VIA UREA PHOSPHATE

A pilot-plant process is described that purifies wet-process phosphori c acid for the production of a high-quality urea-ammonium polyphosphat e base solution. An intermediate product, crystalline urea phosphate, is produced from urea and merchant-grade (54% P2O5) wet-process phosph oric acid. The urea phosphate crystals contain only about 15 to 20% of the objectionable impurities (iron, aluminum, and magnesium) original ly contained in the feed wet-process acid. The urea phosphate crystals are pyrolyzed, converting orthophosphate to polyphosphate with very l ittle energy consumption. The resulting melt is dissolved and neutrali zed with ammonia to produce 14-29-0 liquid product of high polyphospha te content.