| 摘要 |
<p>The invention relates to a method for detaching precious metal layers from a correspondingly coated material by dissolving the precious metals in a salt-containing alkali cyanide solution containing oxidizing agents. According to the invention the alkali cyanide solution continuously flows around the material positioned in a dissolution unit (22), preferably contains at least an alkali sulfate, an alkali metaborate and/or a nitroaromatic compound and for obtaining and/or regenerating the oxidizing agent is electrolytically oxidized in a closed circuit in an electrolytic cell (10). The method provided for by the invention there requires minimal quantities of chemicals, which results in correspondingly low recycling costs. If a nitroaromatic compound is used the oxidized solution is stable to such a degree that the dissolution process in the dissolution unit (22) and the oxidizing process in the electrolytic cell (10) can be carried out independently of each other. The precious metals dissolved in the alkali cyanide solution, such as gold, silver, palladium or such like, and/or impurities are preferably separated out electrolytically in the cathode compartment (28) of a further electrolytic cell (26) which chamber is separated from the corresponding anode compartment (30), which is filled with a powerful electrolyte, for example a 10 % potassium hydroxide solution, by a cation exchange membrane (32). Said membrane is preferably coated with a precious metal, notably gold, since this permits extremely high degrees of purity of up to 99 % during separation.</p> |
