Electrochemical treatment of aluminum-containing solution, e.g. spent aluminum surface treatment or rinsing solution, comprises electrolysis and electrodialysis in a divided cell containing a precious metal, oxide and/or mixed oxide anode

摘要

Electrochemical treatment of aluminum-containing solutions involves electrolysis and electrodialysis in a divided electrolysis cell (3) containing a precious metal, oxide and/or mixed oxide anode (6). Independent claims are given for a process and a cell are claimed for electrochemical treatment of aluminum-containing solutions. The process includes pumping or periodically filling the solution as electrolyte (4) into a chamber (2) of a divided electrolysis cell (3) so that electrochemical reaction of (preferably chromium-containing) solution components occurs at the electrode (6). Other solution components (preferably aluminum and other impurity metal ions) migrate into another electrode chamber (2a) containing an agitated or moving electrolyte and form less soluble metal, hydroxide and/or similar compounds or deposits at a deposition electrode well spaced from the cell separator (5). The current density is 0.1-10 (preferably 2.5-7) A/dm2, the electrolyte in the other electrode chamber (2a) is preferably a mineral acid solution with a minimum conductivity of 0.25 S/m, the cathode preferably consists of a metal, a carbonaceous material or metallized plastic and the anode consists of a precious metal and/or an electrochemically active anode layer of oxide and/or mixed oxide structure preferably of one or more oxides of Ti, Ir, Ta, Ru, Pt, Mn, Pb, Cr, Ag, Sb, Ni and Sn.