National University of Science and Technology “MISiS”, Moscow, Russia:

L. S. Strizhko, Professor of a Chair of Non-Ferrous Metals and Gold
E. S. Shigin, Post-Graduate Student, e-mail: shigin@bk.ru
S. A. Gavrilov, Post-Graduate Student

Electronic scrap is one of the most valuable types of complex recyclable metallurgical raw materials. Complex recovering of electronic scrap with extraction of non-ferrous and precious metals can make this technological process reasonable and efficient. Implementation of this process is a hard problem, because metals in electronic scrap have different physical and chemical properties and occur in different structural state in connection with different nonmetallic components. This article proposes the method of precious metals recycling from electronic scrap, including smelting scrap with copper and dissolution of obtained alloy under current. There was studied the influence of current characteristic on electrochemical dissolution of collector with the following composition: 90% of Cu, 2,5% of Ag, 0,2% of Au, 1% of Pb, 4% of Ni and 1,5% of Fe. Diffusion of Cu²⁺ through a film as a limiting stage was determined. Critical current density of anode’s passivation was ascertained. Structure of obtained salt films was studied together with influence of sonic waves with frequency of 18 kHz to process. It was found that cavitation effect of ultrasonic oscillation leads to separation of salt film from anode surface. As a result, voltage on the bath is decreased by 0,5 V, which reduces the power consumption by 37%. Analysis of resulting slurry showed the following content: 31,6% of Cu, 58% of Ag and 4,8% of Au. Ultrasonic activation of anode is suggested as a method of intensification for electrochemical dissolution of copper collector with precious metals. It allows to carry out the processing of poorer raw materials with different chemical composition. Obtained data can be used for development and improvement of precious metals recycling technology.

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