METHOD OF EXTRACTION OF GOLD AND SILVER FROM POLYMETALLIC RAW MATERIAL Russian patent published in 2005 - IPC

FIELD: hydrometallurgy of noble metals.

SUBSTANCE: the invention is pertaining to the field of hydrometallurgy of noble metals, in particular, to the methods of extraction of gold and silver from various kinds of polymetallic raw materials, composition of which may include copper, nickel, stannum, lead, noncorrosive steel and other metals. The technical result ensures a selective extraction of gold and silver from the current-conducting materials ensuring the high speeds of dissolution of precious metals. The method provides for a treatment of a material placed in the anodic chamber of an electrolyzer and acting as an anode with an acid solution of thiourea (25-100 g/l, pH = 0.5-2.0), passing of a direct current flow and realization of an electrolysis at the temperature of 20-35°C in a controlled potential mode at potential of the anode = +0.380 ÷ +0.420V in respect to a normal hydrogen electrode. The speed of the gold dissolution reaches 0.43 mg/cm² per a minute, silver - 0.37 mg/cm² per a minute. The degree of extraction of gold makes 99.9 %, silver - 99.6 %.

EFFECT: the invention ensures a selective extraction of gold and silver from the current-conducting materials at high speeds of dissolution of precious metals.

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