METHOD AND APPARATUS FOR PREPARING PURIFIED PHOSPHORIC ACID FROM PHOSPHORIC ACID AQUEOUS SOLUTION CONTAINING PLURAL METAL IONS

• Main Authors: MAEDA SYOGO, TAKEYAMA TOMOKIYO, ODA AKIYOSHI, KAWASE YASUHITO, MIZUTANI EIICHI
• Format: Patent
• Language: English
• Published: 13.08.2008
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLICMATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASSC23 AND AT LEAST ONEPROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25; NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE

A method and an apparatus for obtaining purified phosphoric acid from a phosphoric acid aqueous solution containing plural metal ions are provided to confirm that an etching process is stable and to reduce supply of a mixed acid aqueous solution acid liquid by keeping the metal ion concentration of the mixed acid aqueous solution tank in less than a predetermined concentration level. A method for obtaining purified phosphoric acid comprises the steps of; mixing inorganic salt with a phosphoric acid aqueous solution containing a plurality of metal ions; mixing an organic poor solvent with phosphoric acid to precipitate inorganic salt crystal, and to precipitate the metal ions; filtering the inorganic salt crystal and liquid-solid separating the inorganic salt crystal; and evaporating the organic poor solvent and water and obtaining refined phosphoric acid.