IE37684L - Electrolytic cell having a fluid bed electrode - Google Patents

Abstract

1440072 Electrolytically winning or refining metals CJB DEVELOPMENTS Ltd 17 May 1973 [2 June 1972] 25994/72 Heading C7B Metal is electro-deposited on to particles of a fluidized bed cathode within a cathode compartment which is separated from an anode compartment by a flat vertical diaphragm. The cathode compartment has an electrolyte inlet and outlet. In the electroactive region of the cathode compartment (i.e. the portion thereof in which the metal is deposited on the cathode particles), (a) any internal angles at which adjacent structural surfaces meet (including any internal angles formed by surfaces of an electrode for feeding current from the particles are greater than 90 degrees, and (b) there are no horizontal surfaces. In the process, the particles are fluidized by upwardly flowing electrolyte, the rate of electrolyte inflow being sufficient to maintain the height occupied by the particles at least 10% greater than the height of the bed when settled. Particles having metal deposited thereon are removed so as to ensure that any particles having a diameter of one sixth or more of the distance between structural surfaces in the electroactive region of the cathode compartment comprise less than 5 wt. per cent of the particulate bed. The process may be used in the winning of metals from leach liquors, effluents and spent process solutions and may also be used in electrorefining impure Cu, Ni, Sn, Hg, Zn or precious metals. Fig. 2 shows a module of a cell for winning Cu from acidic cupric sulphate catholyte. Modules are placed back to back to form a series of cells, each module comprising the anode compartment 10 of one cell and the cathode compartment 11 of the next cell with a compartment separator 18 between cells and a diaphragm 12 between the compartments of a cell. The cathode compartment contains cathode feeder electrodes 24 and a bed of Cu powder (not shown) which is fluidized by catholyte passing upwardly from perforated pipe 14 through holes 19 in a flow distributer 16. Catholyte is removed from the top of the cathode compartment through a pipe 23 which is slit at 24. The anode compartment 10 contains an anode 29. Anolyte is supplied through pipe 27 and removed through pipe 34. Expanded plastic mesh 30 supports the diaphragm of the adjoining module against the weight of the fluidized bed thereof. Many alternative arrangements are described. Diaphragms may be of anion or cation exchange material. The horizontal crosssection of a cathode compartment may increase with height. Particle sizes may be from 100Ám to 5mm. diameter. A distributer of catholyte to the catholyte compartment may be as illustrated in Fig. 1 (not shown) or may comprise porous plates or static or fluidized particulate beds. A fluidized bed electrode may be operated under conditions of regular or pulsed flow. Feeder electrodes may comprise planar vertical sheets or vertical rods, tubes or bars. The tubes may act as a catholyte flow distributer. The anode may be planar. It may be perforated. It may be of platinized Ti, or of Pb, PbO 2 , Cu or Ni. Details are given of ways of removing cathode particles which have been coated upon. Reference has been directed by the Comptroller to Specifications 1229642, 1203001, 1194181. [GB1440072A]