Patent Number: 6,251,351

Title: Wet-process technique for refining phosphoric acid

Abstract: A process for purification by multistage countercurrent extraction of wet-process phosphoric acid includes the steps of (a) preparing an aqueous phosphoric acid by decomposition of crude phosphates with sulfuric acid and prepurification thereof; (b) providing an organic solvent mixture consisting of one of (A) a water immiscible solvent and a fully water-miscible solvent or (B) a partially water-miscible solvent and a fully water-miscible solvent; (c) extracting water from the acid by contacting with the solvent mixture in a volumetric ratio of acid to solvent mixture of 1:1 to 1:10 at a temperature of 5 to C.; (d) recovering the fully water-miscible solvent by distillation and washing; (e) recycling the fully water-miscible solvent to step (b) to provide a recycled solvent mixture; and (f) repeating steps (c), (d) and (e) with the recycled solvent mixture to provide a phosphoric acid having a preselected degree of purity.

Inventors: Potencsik; Istvan (Mannheim, DE), Maurer; Alexander (Mannheim, DE)

Assignee: BK Giulini Chinie GmbH & Co., OHG

International Classification: C01B 25/00 (20060101); C01B 25/46 (20060101); C01B 025/16 ()

Expiration Date: 06/26/2018