Abstract: A method for selective dissolution of tin and/or lead- or tin-containing alloys from printed circuit boards is provided comprising contacting a printed circuit board with a solution comprising Ti(IV) and an acid which forms stable and soluble salt of Ti(III), Ti(IV), Sn(II) and Pb(II), under conditions to effect dissolution of substantially all of the Sn and/or Pb- or Sn-containing alloy therefrom, as Sn(II) and/or Pb(II) and recovering from the solution by electrolytic reduction substantially all of the Sn(II) and/or PB(II) species as Sn and/or Pb. After the electrolytic reduction step, the oxidant metal species is regenerated by oxidation and recycled to the first stage of the process.

Abstract: An electrochemical cell is provided for removal of metals such as copper, lead, silver, tellurium, platinum, palladium or nickel from dilute solutions of the metal. The cell comprises a porous tubular support (18) which is provided with a cathode comprising a porous carbon fiber material (19), a current feeder (15) for the cathode, a tubular anode (12) spaced from said cathode, a current feeder (16) for the anode, the anode and the cathode being enclosed by a non-porous outer casing (11). In use the dilute solution from which the metal is to be removed is introduced into the cell through an inlet (13) and flows through the porous carbon fiber cathode to an outlet (14). The cell is useful for removing harmful metals from wastes so that they are environmentally acceptable for disposal and for recovery of valuable metals.

Abstract: An electrochemical cell having dished electrodes received in rectangular frame members, and arranged to form a bipolar stack. Electrolyte inlets and outlets open into plenum chambers defined between the dished electrodes and the frame members. A turbulence promoter substantially fills the flowpath between the electrolyte inlet and electrolyte outlet.