METHOD AND DEVICE FOR RECOVERING ALKALI FROM ALKALI ETCHING SOLUTION

PROBLEM TO BE SOLVED: To recover alkali by a compact device while evading the precipitation of alumina (Al2O3) and the storage of NaCO3and heavy metals, and further, to recover alkali even in an alkali etching solution admixed with a hydrolysis preventive. SOLUTION: This invention is composed of: a...

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Bibliographische Detailangaben
Hauptverfasser:	NOSAKA HIDEO, KAWAHARA TAKUO
Format:	Patent
Sprache:	eng
Schlagworte:	CHEMICAL SURFACE TREATMENT CHEMISTRY CLEANING OR DEGREASING OF METALLIC MATERIAL BY CHEMICALMETHODS OTHER THAN ELECTROLYSIS COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL COATING MATERIAL WITH METALLIC MATERIAL COATING METALLIC MATERIAL COMPOUNDS THEREOF DIFFUSION TREATMENT OF METALLIC MATERIAL INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL INORGANIC CHEMISTRY 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 NON-METALLIC ELEMENTS PERFORMING OPERATIONS PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL SEPARATION TRANSPORTING TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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Beschreibung
Zusammenfassung:	PROBLEM TO BE SOLVED: To recover alkali by a compact device while evading the precipitation of alumina (Al2O3) and the storage of NaCO3and heavy metals, and further, to recover alkali even in an alkali etching solution admixed with a hydrolysis preventive. SOLUTION: This invention is composed of: a first stage where an alkali etching solution of aluminum is introduced into an electrolytic cell 1, and a part of free alkali is separated by an ion exchange membrane electrolytic dialysis process; and a second stage where the alkali etching solution from which a part of the free alkali is separated is hydrolyzed in a separation tank 4, so as to be separated into NaOH and Al(OH)3, and alkali is recovered. It is preferable that, in the first stage, by separating a part of free alkali, the weight ratio between the concentration of the free alkali and the concentration of metal other than alkali metal is controlled to ≤1, and, in the hydrolysis, seed crystals are added. COPYRIGHT: (C)2009,JPO&INPIT