Process for the preparation of purified phosphoric solutions from phosphoric acid
AssigneeRhone-Poulenc Industries
InventorsPierre Desire, Jacques Helgorsky
Life of this patent
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Abstract
Process for the preparation of a purified solution of phosphoric acid, which may be partially neutralized, from wet process phosphoric acid, by liquid-liquid extraction by means of a substantially water-immiscible organic solvent. The phosphoric acid is treated in the selected solvent, preferably isobutyl alcohol, in the presence of sulphuric acid, by means of an aqueous solution containing phosphate ions and calcium ions in solution, the sulphate ions are precipitated in the form of calcium sulphate, and suspended in said aqueous solution which is separated from the phosphoric solution. The process is advantageously employed for the continuous preparation of concentrated solutions of monosodium phosphate.
Claims15
A process for the preparation of pure phosphoric acid solutions from impure wet process phosphoric acid with a recovery of at least 95% of the phosphoric acid containing a small amount of sulphuric acid comprising the steps of subjecting the impure phosphoric acid containing water and sulphuric acid to liquid-liquid contact with a substantially water immiscible aliphatic C.sub.4 -C.sub.8 alcohol which extracts most of the phosphoric acid and some of the sulphuric acid and separates from the aqueous phase as a solvent phase, separating the organic solvent phase from the aqueous phase, subjecting the separated organic solvent phase to liquid-liquid contact with an aqueous solution containing phosphate ions and calcium ions to precipitate out SO.sub.4.sup..dbd. as calcium sulphate, subjecting the organic solvent phase which still contains the phosphoric acid in solution to liquid-liquid contact with an aqueous phase whereby the purified phosphoric acid transfers from the organic solvent phase to the aqueous phase, and separating the aqueous phase containing the purified phosphoric acid from the organic solvent phase.
Dependencies are inferred from the claim text.