Schott Glaswerke

Sigrid Herrmann

Uwe Landau

The electrolytic process for dissolving platinum, platinum metal impurities and/or platinum metal alloys, in particular with contents of Rh, Pd, Ir, Au and Ag, in 6 to 8N aqueous hydrochloric acid is characterized by a dissolution process that takes place in an electrolysis cell subdivided by a cation exchanger membrane into an anode and cathode compartment containing anode and cathode respectively, and, if appropriate, in the presence of platinum metal salts or platinum metal acids, at temperatures between 50.degree. and 110.degree. C., under potentiostatic or voltage-controlled conditions in the range of 2.5 V to 8 V and under a current density of 0.3 to 7.0 A/dm.sup.2. The potential across the anode and the cathode is controlled so that chlorine gas is generated and the anode is contacted with the aqueous hydrochloric acid solution and the chlorine gas in impulse-form.

Electrolytic process for dissolving platinum, platinum metal impurities

The electrolytic process for obtaining platinum of high purity from concentrated hydrochloric acid solutions of a platinum alloy containing Rh, Ir and/or Pd proceeds with simultaneous depletion of noble and base metal impurities from the solution. This electrolysis process takes place in an electrolysis cell having an anode and cathode and subdivided by a teflon cation exchanger membrane under potentiostatic or, voltage-controlled conditions with a potential applied across the anode and cathode of 8 V to 16 V, preferably 11.5 to 12 V, at a current density of 12.5 to 37.5 A/dm.sup.2, preferably 22.5 to 35 A/dm.sup.2, to form a purified platinum-containing solution from which the high purity platinum can be obtained and also platinum alloy metal component deposits on the anode and cathode. The concentrated hydrochloric acid solution of the platinum alloy can have a platinum alloy content of 50 to 700 g/l and total metal impurities of not greater than 5000 ppm.

Electrolytic process for extracting high purity platinum from platinum

The electrolytic process for obtaining platinum of high purity from a concentrated hydrochloric acid solution of contaminated platinum containing base and noble metal impurities includes electrolyzing the hydrochloric acid solution containing the contaminated platinum in an electrolysis cell subdivided by a cation exchanger membrane under potentiostatic or voltage-controlled conditions with a voltage of 2.5 V to 8 V applied across the anode and cathode under a current density of 0.3 to 12.5 A/dm.sup.2 so as to form a refined platinum-containing solution and a platinum alloy metal deposit. The concentrated hydrochloric acid solutions used in the process can have a contaminated platinum content of 50 to 700 g/l and total metal impurities of .ltoreq.5000 ppm. In contrast to the known prior art processes, the process according to the invention operates with minimal requirements in terms of safety technology and equipment, causes a minimal environmental burden and is far less time-consuming and more economical.

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Berlin, Germany

Sigrid Herrmann