Solvent extraction method of phosphoric acid

A process for the solvent extraction of a crude phosphoric acid with an organic solvent which comprises counter-currently contacting an impure phosphoric acid solution containing at least 45 wt % of P.sub.2 O.sub.5 with a partially water-miscible organic solvent in the presence of sulfuric acid and recovering a purified phosphoric acid wherein:

• (a) as said organic solvent, a solvent in which from 3 to 10 wt % of water is soluble is used, and
• (b) said sulfuric acid is added at a location wherein the H.sub.3 PO.sub.4 concentration in the aqueous phase is at most 3 moles/liter in an amount so as to bring the relation between the free sulfuric acid concentration and the H.sub.3 PO.sub.4 concentration in the aqueous phase at said location to satisfy the formula
• 5.0-0.83X.gtoreq.Y.gtoreq.2.5-0.83X
• within the range of the H.sub.3 PO.sub.4 concentration in the aqueous phase being from 0.5 to 3 moles/liter.