GB801397A - Improvements in or relating to the electrolytic deposition of metals from slurries (or pulps) - Google Patents

Abstract

801,397. Electrolysis. RHOANGLO MINE SERVICES, Ltd. Sept. 19, 1956 [Sept. 20, 1955], No. 26875/55. Class 41. A process for depositing a metal, e.g. copper, from a slurry comprises electrolysing the slurry between two electrodes in the slurry and imparting a rotary motion to all or part of the slurry so that centrifugal force on the slurry is directed away from at least one of the electrodes whereby deposition on that electrode takes place in a zone of clarified liquid, e.g. the slurry may be delivered by a pump tangentially into the annular space separating two concentric electrodes. The centrifugal force produces an acceleration at least equal to that due to gravity. In one embodiment, Fig. 1, a rotor 1 comprising a solid or hollow non-conducting prism of polygonal cross-section is mounted in a vessel 11. Each face of the prism carries a conducting sheet 4 supplied with current by studs 6 and conductors 7 which are connected to a source 10 through a slip-ring 8 on a shaft 9. The vessel 11 is of lead or lead alloy and forms the other electrode, or electrodes may be disposed around the inner surface of the vessel. In a modification, Fig. 4, the rotor comprises a number of concentric electrodes 12, 13 of alternate polarity mounted on a non-conducting body 14, current being supplied via the rotor shaft. Scoops may bridge outer pairs of electrodes at the bottom of the rotor to encourage flow of slurry up and down between the electrodes. In another modification, Fig. 6, a central electrode 17 may be stationary or rotatory and is surrounded by a concentric, non-conducting, perforated or slotted cylindrical rotor 18. An electrode 20 surrounds the rotor 18. In a modification of the Fig. 6 embodiment, a hollow rotor carrying electrodes on its inner surface surrounds a fixed or rotatable central electrode, and in this case the rotor is also the vessel for the slurry. The function of the rotor is to keep solid materials in the slurry away from one electrode, e.g. the cathode, where they would contaminate the deposited metal, and move them to the anode where metal-containing solids are subjected to a reaction which dissolves the metal in the solid for subsequent deposition on the cathode. In one example, the slurry comprises copper in sulphuric acid which bears insoluble copperbearing solids, and in another example the slurry is a calcine, containing copper and cobalt, in sulphuric acid.