METHOD OF RECOVERING METALS FROM SCRAP Russian patent published in 1997 - IPC

FIELD: waste disposal. SUBSTANCE: invention relates to recovering metals from scrap originated, e.g. from electronic industry, using iodide leaching. Waste is chemically enriched by successively isolating therefrom heavy, nonferrous metals, and silver, whereas leaching of precious metals is accomplished by agitation technique simultaneously with desorption of iodine from plastic-ceramic basis of enriched scrap. The latter operation is performed by successive treatment with low-acidic iodine-iodide solutions first with elevated iodine concentration to isolate largest part of gold and then with reduced iodine content to after-isolate gold. These solutions are reusable after electrochemical isolation of gold and simultaneous generation of necessary quantity of iodine. Scrap is washed out to remove potassium iodide and iodine bound to insoluble heavy and nonferrous metal iodides using alkali solutions, e.g. production solution after precipitation of gold and simultaneous conversion of insoluble metal iodides into hydroxides followed by water washing performed in combination with electrodialysis treatment of reusable wash waters. EFFECT: enhanced efficiency of metal recovery. 3 cl, 2 tbl