GB274913A - Process for electrolytical precipitation of metals - Google Patents

Abstract

274,913. Sundberg, H. E. July 24, 1926, [Convention date]. Void [Published under Sect. 91 of the Acts]. Chromium, tantalum, and other metals and alloys, depositing; oxides, obtaining.-Chromium is deposited by electrolysis of a solution in water, glycerine or pyridine of chromium compounds in one or more states of oxidation. Suitable compounds are oxy-compounds containing hydrogen, boron, carbon, silicon, nitrogen, sulphur, selenium, tellurium or phosphorus, for example, fluoborate, fluosilicate or selenate. Combinations of the metal with ammonium or pyridine or with sulpho-acids or with complex-forming acids such as boron-tartaric acid and those obtained from naphthalene and its derivatives. Chromium may be present in the form of bromo-chromate or iodochromate. Substances may be added which raise the cathode potential by increasing the viscosity or otherwise, for example, glycerine, sugar, emulsifying substances of an oily nature, gelatine, peptone, quinone, dye-stuffs, alkaloids or their oxidation products; the substances may be added in colloidal form. Aluminium, magnesium and other metal compounds may be added to enable deposition to be carried out at low current density. A suitable concentration of hydrogen ions is maintained by addition of bases or weak acids. Insoluble anodes coated with catalyzers such as lead dioxide. or oxides of manganese, cerium, titanium, thorium, osmium or silver, or with gray or black platinum may be employed. The base of the anodes may be of tungsten or tungsten alloys, chromium alloys, ferro-silicon or copper-silicon. Lead silver anodes may also be employed. The chromium content of the electrolyte may be maintained by addition of the compounds specified above or of chromium trioxide, or by periodic replacement of insoluble anodes by chromium anodes, or by the use of chromium anodes in combination with insoluble anodes, or of anodes of predetermined chromium content. When the electrolyte contains chromium in a lower state of oxidation only and no diaphragm is employed, anodes of graphite, chromium, silicon or steel alloys, magnetite, carborundum or other substance having no oxidizing effect should be employed. The electrolyte may be covered by an inert solid or liquid layer. Gas generated at the electrodes may be removed by suction. An auxiliary alternating current may be passed through the electrolyte. The invention is stated to be applicable also to the deposition of metals of groups IV-VII, for example of tantalum from a partially reduced tantalate, and also of alloys and to the anodic precipitation of oxides.