Method for producing pure phosphoric acid

Abstract

A method for producing a pure phosphoric acid from a phosphoric acid obtained through a wet process, in a high purity comparable to that from the dry process phosphoric acid, in a simpler manner, at a cheaper cost and more effectively, is provided, which method resides, in one main aspect, in concentrating a phosphoric acid obtained through the wet process, up to a P.sub.2 O.sub.5 content of 30% by weight or higher; treating the resulting phosphoric acid with diisopropylcarbinol to extract a pure phosphoric acid; and back-extracting the pure phosphoric acid in the resulting extract with water, and also resides, in another main aspect, in subjecting a wet process phosphoric acid, to either a step of partially neutralizing said acid with an alkali, ammonia or a salt thereof, followed by adding a water-soluble low boiling organic solvent to said acid, or a step of adding a water-soluble low boiling organic solvent to said phosphoric acid, followed by partially neutralizing with an alkali or ammonia or a salt thereof; separating the resulting precipitate; after distilling off said solvent, treating the resulting solution with an extracting agent comprising diisopropylcarbinol to extract a phosphoric acid; and back-extracting the resulting solution with water.