REFINED PHOSPHORIC ACID PRODUCTION PROCESS Russian patent published in 2004 - IPC

FIELD: industrial organic synthesis. SUBSTANCE: process of producing refined concentrated phosphoric acid from extraction phosphoric acid comprises adding sulfuric acid to phosphoric acid ester (38-53% P₂O₅) to concentration of sulfuric acid 3-6 wt % followed by operation including simultaneous concentration, blowing off fluorine compounds, and adsorbing other impurities on solid adsorbents, which operation is accomplished in a single circuit (concentrator-defluorinator - adsorption column - phosphoric acid ester separator) at 96-105^o. At the end of process, residual content of sulfates is eliminated by adding, to phosphoric acid, strontium compounds in amounts to Sr²⁺/SO₄ ^2- in acid equal to 1.07-1.2, provided that strontium compounds are added in the form of suspension and precipitation stage is carried out at the same temperature as in all preceding stages. EFFECT: reduced concentration of fluorine, silicon, iron, aluminum, sulfur, lead, and arsenic compounds to norms for food phosphoric acid and simplified technology due to eliminated organic solvent extraction stage. 2 cl, 1 tbl