The Research Of The Process Of Producing Ammonium Phosphate With Solid-liquid Back-extraction Wet-Process Phosphoric Acid Method

The key problem in the production of use Wet-process phosphoric acid as raw materials to produce high-purity ammonium phosphate is to solve the impurities which introduced in the process of wet-process phosphoric acid production and excess moisture which introduced in the crystallization of ammonium phosphate process, but in current industry widely used method-"phosphoric acid concentration method" and "neutralized slurry concentration process" have not simultaneously solved the two difficulties combines the production process characteristics among the process of ammonium phosphate manufacturing.For these two difficulties, This study use the method of continuous countercurrent extraction to clean raw materials wet process phosphoric acid first, Directly use ammonia anti-extracted the organic solvents which after the phase of organic solvent to create ammonium phosphate crystals, and then use the deposition method to separate the crystal and organic extraction agent, to achieve the aim of the organic extraction agent recycling use and ammonium phosphate’s crystallization.At the course of this study, at first through experiments to confirm the best composition of the mixed extractant, and then orthogonal experiment to explore the extraction of raw materials phosphoric acid purification optimum conditions;In the next place, using different conditions to find the best temperature of solid-liquid back-extraction, and the ammonia dosage, the amount of extractants and concentration of raw materials phosphoric acid process conditions etc,at the end use experiment methond to explore the practicability of the extraction separation of crystals.All experiment results show that the best technological process of producing ammonium phosphate with the solid-liquid back-extraction Wet-Process Phosphoric Acid Method is:Extractants composition is TBP: diluent (volume ratio)=1:1, Raw phosphoric acid concentration is P2O5%=(40%-50%), Dosage of extractants is extractants:raw phosphate≈3:1, Stirring extraction time is about5min, Control of ammonia content is that after anti-extracted the liquid composition of crystallization’s pH≈7, Ammonia stripping-crystallization temperature is15-20℃,after the deposition of ammonium phosphate crystals and the mixed extractants, use about20%compared with the volume of supersaturated solution ethanol to separate the ammonium phosphate crystals and the mixed extractants.Ultimately in the derived ammonium phosphate crystals N%>20%, P2O5%>50%, the P2O5’ one-time utilization of the raw wet-process phosphoric approach50%, the total nutrient of ammonium phosphate is much higher than the standards of ammonium phosphate fertilizer, and the nitrogen and phosphorus content of the ammonium phosphate crystals which under the optimal conditions is close to the industrial DAP (98%) standard.