Machining device for torsion wing type -structure section and polygonally joined wing

PURPOSE:To raise impurity removing efficiency and crude phosphoric acid purifying efficiency by extracting crude phosphoric acid with an org. solvent; washing the extracted org. solvent layer with an aq. soln. of one or more kinds of sol. salts; and back-extracting the washed layer with water. CONSTITUTION:Wet process crude phosphoric acid is extracted with an org. solvent such as methyl isobutyl ketone. To the extracted org. solvent layer is added an aq. soln. of one or more kinds of sol. salts such as Na2CO3 forming no precipitate together with phosphoric acid and dissolved impurities, and they are stirred to wash the org. layer. The amt. of the sol. salts added is 0.15mol or more, esp. 0.08-0.15 mol as cation to 1mol of phosphoric acid in the layer. The washed org. layer is then back-extracted with water to obtain high purity phosphoric acid. The washed org. layer may be washed with a little water or phosphoric acid.

Mihara Osamu

Papers

Crude phosphoric acid purifying method