Method for recovering etchant from etching waste liquid containing iron

Abstract

Method for recovering etchant from etching waste liquid 11 containing iron chloride is disclosed, wherein iron powder is mixed with iron chloride waste solution containing metal ions having a lesser ionization tendency than iron ion in an mixing vessel so as to cause a reaction between the iron powder and the metal ions and remove the precipitated metal from the iron chloride waste solution. The etching waste liquid 11 containing iron chloride or the iron chloride waste liquid which is an intermediate of the etching waste liquid 11 containing iron chloride is supplied to the mixing vessel from the bottom of the mixing vessel, an iron-powder processed liquid which comes up through a fluidized bed is continuously taken out from the mixing vessel and is returned to the bottom portion of mixing vessel so as to form the fluidized bed in the mixing vessel, and metal ions having the lesser ionization tendency than iron ion are removed from the etching waste liquid 11 containing iron chloride or the iron chloride waste liquid to produce the iron-powder processed liquid.