Process for the purification of an impure phosphoric acid
AssigneeRhone-Poulenc Industries
InventorAlain Leveque
Life of this patent
Estimating the term…
Abstract
An organic phase including both phosphoric acid and sulfuric acid is purified of sulfate ion content by countercurrently washing same with an aqueous liquid in an at least two-stage wash zone, the pH of which having been adjusted with an alkali metal or ammonium compound to a value greater than that as would exist if the washing were effected with the aqueous liquid alone, under the same conditions, and whereby there results a purified organic phase comprising both SO.sub.4 and P.sub.2 O.sub.5 in an amount by weight of SO.sub.4 to P.sub.2 O.sub.5 of less than 50 ppm.
Claims22
A process for the purification of wet process phosphoric acid containing sulfate ion in an amount by weight such that the ratio SO.sub.4 /P.sub.2 O.sub.5 is greater than 50 ppm, comprising countercurrently liquid-liquid extracting an aqueous solution of said wet process phosphoric acid with a water-insoluble organic solvent;
- next, phase separating and countercurrently washing and neutralizing the organic phase effluent of said countercurrent liquid-liquid extraction, in at least two-stages, with an aqueous wash solution of a pH increasing amount of an alkali metal or ammonium compound;
- and thence recovering from said washed organic phase effluent purified phosphoric acid having a content of SO.sub.4 to P.sub.2 O.sub.5 of less than 50 ppm.
A process for the purification of wet process phosphoric acid containing sulfate ion in an amount by weight such that the ratio SO.sub.4 /P.sub.2 O.sub.5 is greater than 50 ppm, consisting essentially of countercurrently liquid-liquid extracting an aqueous solution of 20-60% by weight P.sub.2 O.sub.5 wet process phosphoric acid with a water-insoluble organic solvent;
- next, phase separating and countercurrently washing and neutralizing the organic phase effluent of said countercurrent liquid-liquid extraction, in at least two-stages, with an aqueous wash solution of a pH increasing amount of an alkali metal or ammonium compound;
- and thence recovering from said washed organic phase effluent purified phosphoric acid having a content of SO.sub.4 to P.sub.2 O.sub.5 of less than 50 ppm.
Dependencies are inferred from the claim text.