GB198024A - Improved process and apparatus for electrolysing fused salts of metals and recovering the metals and acid radicles, and the application of the said process and apparatus to the recovery of valuable constituents from metal bearing ores, and materials - Google Patents

Abstract

198,024. Ashcroft, E. A. Feb. 18, 1922. Electrolytic furnaces.-The electrolysis of fused metallic salts, such as fused chloride of zinc or lead, or a mixture thereof, is effected in an electrolyser provided with a series of closelyspaced electrodes constituting a series of electric couples immersed in the same electrolyte, only the first and last of the electrodes of the series being connected to the external circuit. Fig. 1 shows an electrolyser comprising a refractory container A, or a metal container lined with refractory material, surrounded by a casing of kieselguhr. The electrodes consist of a number of inclined graphite plates B<1> - - B" resting on steps b of fused silica, vitreosil or obsidianite, the steps b for the lowest plate being of graphite. Fused zinc chloride is introduced through an opening a<4> at about 350‹ to 400‹ C. and the temperature of the electrolyte is maintained between 420‹ and 600‹ C., and preferably between 450‹ and 500‹ C., during electrolysis. This may be done by applying external heat in the form of a jacket through which superheated steam, hot air, or hot oil is circulated, by supplying a supplementary alternating current, or by supplying more direct current than is recessed for electrolysis. Zinc flows downwards through the perforations b<2> in the electrodes to the reservoir a<2> which is provided with a tap-hole a<3> and chlorine passes up through the perforations b<3> to the outlet D. A suitable proportion of sodium, potassium, or magnesium chloride may be added to the electrolyte to increase its conductivity. In a modification the electrodes consist of funnel-shaped plates through the centre of which passes a silica tube containing a graphite negative conductor. Fig. 5 shows an electrolyser with a number of saddle shaped electrodes B<1> - - B<9> mounted on refractory partitions, the end electrodes B, B<10> being connected directly to carbon rods E, E<2> which supply the current. The zinc gathers in a number of separate compartments a<2> having outlets a<3>. The saddle-shaped electrodes may be replaced by graphite plates mounted in grooves in the sides of the container A. In every case the electrodes may be corrugated or grooved as desired. The current density used is 2 amps. per square inch of electrode surface. Metallic ores and other metal bearing materials are chlorinated and then subjected to the above process to obtain the pure material.