Patent GB-440139-A (GB)
Title: Process and electrolytic cells for the production of alkali metals and alkaline earth metals
IPC: C25C3/02
Filed: 1934-10-31
Abstract: 440,139. Electrolytic production of alkali and alkaline earth metals; electrolytic furnaces. MOLTKEHANSEN, I. J., 65, Avenue Alphonse XIII, Uccle, Brussels. Oct. 31, 1934, No. 31300. Convention date, Oct. 31, 1933. [Class 41] Alkali and alkaline earth metals other than magnesium are obtained by electrolysis of a fused mixture of salts or compounds, one of which is initially decomposed and the other of which reacts with the initial anodic products to set free inert products and to reconstitute the substance initially decomposed ; the electrolysis is carried out in a cell provided with a diaphragm for the separation of anodic and cathodic products and electrodes of metal other than that to be produced. Examples of the substance to be initially decomposed are sodium hydroxide and sodium nitrate or nitrite which may be employed in association with sodamide and sodium carbonate. The electrodes are preferably of metal netting and may be of aluminium, nickel or copper-tin alloy. The final anodic products comprise carbon dioxide, oxygen and ammonia. The materials may be fed to the cell by a funnel situated above the diaphragm down which they trickle principally on the anode side; the funnel may be provided with adjustable heating means. The diaphragms may be metallic or of asbestos, porous cement or magnesia, or of titanium oxide powder with or without admixtures. The diaphragm may also consist of a pair of walls enclosing a layer of sodium carbonate. In one cell described, a central anode compartment containing sodium nitrate is separated by two such diaphragms from outer cathode compartments containing sodamide. The catholyte may contain a paraffin or other organic substance, having a boiling point above 250‹ C. and preferably less dense than sodium, which is rendered conductive by the amide or by colloidal solution therein of graphite. The cathode compartments may be provided with heating tubes or jackets through which a liquid such as paraffin or diphenyl at about 200‹ C. is passed. The cell shown in Fig. 6 comprises a cylindrical diaphragm 33 enclosing a hollow cathode 32. The anolyte consists of caustic soda and sodamide and the catholyte of sodamide and paraffin or other neutral material. Sodium may be removed from the bottom of the hollow cathode or skimmed or siphoned from the top of the cathode chamber according to the density of the catholyte. The cell shown in Fig. 9 comprises double-walled diaphragms 64 enclosing a central anode chamber. Sodium is removed from the cathode compartments by a rotatable tube 66 which may be fixed at the top or bottom according to the density of the anolyte ; the tube 66 may act to compensate for pressure differences between the anode and cathode compartments. Anodic products which have penetrated the cathode compartment may be removed by an orifice 68 and to facilitate this the base of the cell may be inclined as shown at 70 and provided with drainage grooves. An overflow 69 is provided to prevent clogging of the gas exit 65. In another form of cell, the cathode chamber is mounted above a substantially horizontal anode. In another cell the electrodes are of V-section, and slightly inclined to the horizontal, the cathode being nested within the anode.