Process for purifying phosphoric acid

In a process for purifying feed wet process phosphoric acid prepared from contact of phosphate rock and sulphuric acid which comprises treating the feed wet process acid with a ketone solvent which is a dialkyl ketone of 5 or 6 carbon atoms to form a crude ketone extract containing at least some of the acid in the feed acid, purifying said crude ketone extract, and then releasing the acid in the purified extract to form aqeous purified phosphoric acid, the improvement which comprises scrubbing said crude ketone extract with water or purified phosphoric acid scrub liquor to produce a scrubbed purified extract, and a used aqueous acid scrub liquor which is all recycled to said contact of wet process phosphoric acid and a ketone, and then contacting said scrubbed purified extract with water or phosphoric acid in a single stage to give a first aqueous product purified phosphoric acid and an acid laden ketone layer which are separated, and then contacting said acid laden ketone layer with water in more than one countercurrent stage to form a second aqueous product purified phosphoric acid and a ketone layer, which are separated, each of the first and second product purified acids containing 35-65% of the phosphoric acid in the scrubbed, purified extract.