Patent GB-626636-A (GB)
Title: Improvements in and relating to the production of powder or sponge of metals or metal alloys by electrolytic reduction of metal oxides or other reducible metal compounds
IPC: C25C5/04
Filed: 1946-01-07
Abstract: 626,636. Electrolytic production of metal powders. JOHANSSON, E. H. E. Jan. 7, 1946, Nos. 521 and 522. Convention dates, Jan. 5, 1945, and Dec. 13, 1945. [Class 41] Oxides or other reducible compounds of heavy metals are reduced in an electrolyte comprising one or more molten oxides or hydroxides of alkali or alkaline earth metals, in which the reducible metal compounds, placed between the anode and cathode, or forming the cathode, are difficultly soluble or insoluble. The electrolyte may also contain a halide or a carbonate. The reducible metal compounds may be placed between the anode (which should not be attacked by the electrolyte), and cathode in powder or porous coherent form. In the production of iron powder the vessel 1, Fig. 1, forming the anode may be of iron plate, and the cathode 2 of iron wire, around which is fixed a mass 3 of sintered iron oxides, e.g. Fe 2 O 3  and Fe 3 O 4  The electrolyte 4 consists of molten NaOH. The electrolyser is preferably covered with a tight lid to prevent conversion of the electrolyte to carbonate. In a modification, the vessel forms the cathode and is lined with sintered iron oxides, the anode consisting of an iron wire. In a further modification, the metal compounds are pushed around a wire-shaped cathode which is elongated, e.g. by welding or screwing-on, as it is consumed. The electrolyser in this case may be similarly progressively elongated by flanged or welded cylindrical or conical sections. As the reduction zone is displaced upwardly and the electrolyte is solidified, the vessel is demounted or cut off from below. A cylindrical mass of the reducible metal compounds may also be formed around a wire-shaped cathode provided in the bottom of the electrolyser and kept in position by solid electrolyte. Alloys may be obtained directly by reduction of an oxide mixture; and the metal or alloy may be obtained in sponge rather than powder form. A diaphragm may be used in all cases. Manganese, manganese steel, tungsten, tungsten steel, chromium, chromium steel and chromium nickel steel may be produced. The Specification as open to inspection under Sect. 91 comprises also the embodiment of Fig. 3 (Cancelled), for the production of metal powder from powdered oxides. The electrolyser 9 constitutes the cathode, and the anode con. sists of a rotatable tube 10 provided with four propeller blades 14. An insulated shaft 12 rotatable within the anode tube 10 is also provided with propeller blades 11 and is at the same-potential as the vessel 9. It is stated that during the electrolysis the metal powder is formed in the space between the vessel 9 and the propeller blades 13, At the anode there is formed, in the case of production of iron powder, sodium ferrate, which binds the iron oxides into aggregates which would normally fall down into the iron powder. These aggregates, however, are disintegrated by the propeller blades 13. If the propeller blades 11 are held stationary, they are perforated to permit escape of gas. The propeller devices 11 and 13 are continuously raised to accommodate the powder as it is formed. The shaft 12 may be of non-conductive material; and it is stated that the process may be carried out without the parts 12, 13 and 14. It is also stated that an anhydrous solution, e.g. tetramethyl ammonium hydroxide, may be used as electrolyte in all embodiments. This subject-matter does not appear in the Specification as accepted.