Oblon, Fisher, Spivak, McClelland & Maier
Solvent extraction method of phosphoric acid
 A method for solvent extraction of phosphoric acid 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 solvent in the presence of sulfuric acid, and which is characterized in that PA0 (a) as said solvent, a solvent in which from 3 to 10 wt. % of water is soluble, is used, and PA0 (b) sulfuric acid is added to a place where the H.sub.3 PO.sub.4 concentration in the aqueous phase is at most 3 mol./l so as to bring the relation between the free sulfuric acid concentration (Y (mol/l)) and the H.sub.3 PO.sub.4 concentration (X (mol/l)) in the aqueous phase of the same place to satisfy the formula EQU 5.0-0.83X.gtoreq.Y.gtoreq.2.5-0.83X PA0 within the range of the H.sub.3 PO.sub.4 concentration in the aqueous phase being from 0.5 to 3 mol/l. 
Toyo Soda Manufacturing Co., Ltd.
C C
C01B C01B
inventional inventional
Yoichi Osamu
Hiraga Watanabe