Effect of Impurities in Precious Metal Recovery by Electrodeposition-Redox Replacement Method from Industrial Side-Streams and Process Streams

Abstract

The recovery of precious metals (Ag and Au) by electrodeposition-redox replacement (EDRR) method was studied in three different solutions: sulfate based Zn-Fe-Ag solution, chloride based Cu-Fe-Au solution and industrial multimetal chloride solution. The common factor to these solutions is that the base metal is present in g/L scale while the precious metal is present in ppm or lower level. The results showed that the presence of Fe (in g/L scale) decreases the recovery efficiency of precious metals but at the same time, it may lead to selective dissolution of the base metal (Zn or Cu) resulting in the higher purity of the precious metal deposit. Moreover, a successful deposition of Au on carbon nanotube (CNT) films from industrial multi-metal solution was demonstrated.

Electrochemical recovery of tellurium from metallurgical industrial waste

“…Electrochemical measurements were conducted with a standard three-electrode cell set-up comprised of a reference saturated calomel electrode (SCE, B521, SI Analytics, Germany), 0.1-mm-thick (A = 24 cm 2 ) Pt plate as a counter electrode (CE) and 0.1-mm-thick (A = 0.24-0.4 cm 2 ) Pt plate as a working electrode (WE, both Kultakeskus, Finland). The cell set-up was controlled using an IviumStat 24-bit CompactStat potentiostat (Ivium Technologies, The Netherlands) and is described in more detail elsewhere [37][38][39][40][41]. N.B.…”

“…deposition potential (E 1 ), cut-off potential (E 2 ), deposition time (t 1 ), cut-off time (t 2 ) and number of cycles (n). More information about the definition of these parameters has been published earlier [37][38][39][40][41]. Five deposition times, t 1 , were studied in the range of 2-10 s, along with the four deposition potentials, E 1 and three cut-off potentials, E 2 , presented in Table 2.…”

“…In contrast, electrowinning (EW) relies on the direct electroplating of the desired metal element on the electrode surface-by the application of the appropriate potential or current-to produce a surface layer. To date, the EDRR method has been employed for metal reclamation, including Ag recovery from synthetic Zn process solutions [37][38][39], Au recovery from synthetic cyanide-free cupric chloride leaching solutions [39,40] and Pt recovery from synthetic and real industrial nickel solutions [41,42]. Nevertheless, there are no previous reports related to the recovery of Te by EDRR, or even more, combining the electrowinning (EW) and EDRR sequentially to maximise the recovery.…”

A future application of pulse plating – silver recovery from hydrometallurgical bottom ash leachant

“…In order to improve circular economy of metals, it is critical also to consider materials with minor concentrations of valuable metals as secondary raw materials. As a result, the concept of potential raw materials for metal recovery can be expanded also to industrial solid and liquid wastes [1][2]. Municipal solid waste incineration (MSWI) bottom ashes are an excellent example of such a secondary raw material of future from which minor valuable metals could be recovered more efficiently.…”

“…EDRR) provides a promising route to effectively recover very low concentrations (even <1 ppm) of Ag from concentrated Zn solutions [22]. The EDRR method has been previously investigated also to deposit different metals such as, Au, Pt, Pb, and Cu on surfaces from pure synthetic solutions with optimised concentrations [23][24][25][26][27][28][29][30][31][32][33][34] and only very limited studies have been performed on industrially relevant solutions [2,22,35] -and actually, there are no reports demonstrating improved Ag recovery by the EDRR method from municipal bottom ash leaching solutions.…”