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.

Crude phosphoric acid purifying method

PURPOSE:To remove fluorine efficiently and inexpensively from fluorine-contg. phosphoric acid of a prescribed concn. by bringing the acid into contact with a prscribed org. solvent followed by liq.-liq. separation. CONSTITUTION:Fluorine-contg. phosphoric acid of <=45wt% concn. as P2O5 is brought into contact with an org. solvent which does not practically extract phosphoric acid of such a concn., and liq.-liq. separation is carried out to remove the fluorine in the acid. As the org. solvent a regenerated solvent is advantageously used, and it is obtd. by bringing the liq.-liq. separated org. layer into contact with water or a soln. of inorg. salts capable of forming slightly soluble fluoride to remove the fluoride in the org. solvent. Butyl acetate or isopropyl ether is preferably used as the org. solvent. Desirable fluorine-contg. phosphoric acid is primarily purified phosphoric acid obtd. by using the washing water of the solvent in a back extracting process when wet process phosphoric acid is extracted with an org. solvent, and the org. layer is washed and back extracted with water.

Tabei Seikichi

Papers

Crude phosphoric acid purifying method

Defluorinating method of phosphoric acid