Abstract: The present invention is a method and apparatus for recovering copper (Cu) and regenerating ammoniacal etchant from spent ammoniacal etchant for the process of milling printed circuit boards. The basic steps of the present invention include (a) adding an adequate amount of hydrochloric acid (HCl) into a spent ammoniacal etchant containing copper ions (Cu.sup.2+), ammonium ions (NH.sub.4.sup.+) and chloride ions (Cl.sup.-) to produce an acidified spent ammoniacal etchant having a pH value in the range of between approximately 3 and approximately 6 and having increased concentrations of the ammonium ions (NH.sub.4.sup.+) and the chloride ions (Cl.sup.-) substantially stoichiometrically equivalent to that of the copper ions (Cu.sup.2+), so that all copper (Cu) contained in the acidified spent ammoniacal etchant is substantially precipitated as double salt copper ammonium chloride [(NH.sub.4).sub.2 CuCl.sub.4(S) ]; (b) separating the double salt copper ammonium chloride [(NH.sub.4).sub.2 CuCl.sub.

Abstract: The present invention is a method for separating copper (II) from chromite in a material containing both copper (II) and chromite. The present invention separation method essentially comprises the steps of: (a) extracting the material with a combined hot vapor-liquid phase of volatile carboxylic acid to dissolve the copper (II) as cupric carboxylate, thereby removing the copper (II) from the material; and (b) crystallizing the cupric carboxylate. The present invention method may further comprise the step of reducing the chromite in the remaining material to chromium metal by reduction with hydrogen at about 1500.degree. C. Preferably, the substantially volatile carboxylic acid is acetic acid. The present invention method and apparatus is useful for treatment of exhausted catalyst pellets containing copper (II) and chromite and recovering both copper and chromium in a useful form from the pellets.