A process for the purification of the anodes for electrolytic processes, which consists of a base of a film-forming metal and a coating of noble metals, noble metal or noble metal oxides are mixed oxides containing whose

摘要

1,214,579. Fused electrolyte process; Reconstitution of electrodes. CHEMNOR A. G. Feb.28, 1969 [Feb.28, 1968], No.9706/68. Headings C7B and C7E. Anodes comprising a conductive base coated with noble metals (i.e. Au, Ag, Ru, Rh, Pd, Os, Ir, Pt and Re) or compounds thereof are cleaned by immersion in a melt containing a basic material at a temperature above 250‹C, in the presence of an oxidant or oxygen. The base metal of the anodes may be Ti, Zr, Nb, Ta,W, or Bi, the basic material may be NaOH, KOH, LiOH, and the oxidant may be NaNO a or KNO 3 . The bath may also contain NaCl, KCl, Na 2 CO 3 and/or K 2 CO 3 . After treatment in the melt, coating residues may be removed by dilute HCl or H 2 SO 4 or HCl/HNO 3 . The noble metal dissolved in the salt melt may be recovered by making the steel vessel containing the melt an anode, and supplying a cathode whereon the noble metal is collected on passage of D.C., or the melt may be dissolved in water prior to electrolytic recovery of the noble metal.