PURIFIED PHOSPHORIC ACID PRODUCTION PROCESS Russian patent published in 2003 - IPC

FIELD: industrial inorganic synthesis. SUBSTANCE: purified concentrated phosphoric acid is prepared from extraction phosphoric acid for use in production of trade, feed, and food phosphates. Process includes purification performed with liquid organic solvent, post-purification simultaneously with direct-contact concentration of purified acid with gaseous heat carrier in the foamed-bed mode accompanied by blowing away fluorine compounds and circulation of purified phosphoric acid through this bed. Acid is additionally passed through solid adsorbent (pretreated with weak hydrofluoric acid solution) bed within temperature range 20-100 C at adsorbent-to-acid molar ratio 1: (5-10), adsorption stages being alternated with blowing-off stages. Adsorption is carried out either before bringing phosphoric acid into contact with gaseous heat carrier or after said contact. Above-mentioned hydrofluoric acid solution utilized is absorption solution obtained when absorbing with water fluorine gases released in the system. EFFECT: reduced concentration of fluorine, silicon, iron, sulfur, and organic impurities at the same power consumption in fluorine compounds' blowing-off stage. 2 cl, 1 tbl, 3 ex