Recovery of Gold as Nanoparticles from Gold-Poor Au-Cu-Cl Solutions

Electrochemical methods for preparing functional surfacestypicallyuse optimized solutions where competing reactions do not need to beconsidered. However, with the increased demand for resource efficiency,selective deposition methods that can make use of more complex solutionsare gaining importance. In this study, we show how gold recovery asnanoparticles from Au-Cu-Cl solutions can be assisted by electrochemicallygenerated Cu1+ species. In the electrochemically assistedreduction (EAR) method, a low-energy electrochemical step is employed,followed by spontaneous gold reduction onto the electrode. The studiedsolutions mimic challenging hydrometallurgical process solutions wherethe ratio of gold (5 ppm) to copper (20 g/L) is low. In addition toselective gold recovery, by controlling the electrochemical pulseparameters, the loss of deposits due to corrosion could be minimized,current efficiency improved from & SIM;0 to >10%, and relativelynarrow particle size distributions achieved (43 & PLUSMN; 10 nm), andthis can be done even at a high (4.5 M) NaCl concentration.

Automated summary

Electrochemical methods are commonly used to prepare functional surfaces using optimized solutions. However, there is a growing need for selective deposition methods that can utilize more complex solutions in order to improve resource efficiency. This study demonstrates how electrochemically generated Cu1+ species can assist in the recovery of gold nanoparticles from Au-Cu-Cl solutions. By employing the electrochemically assisted reduction (EAR) method, the current efficiency can be improved, the loss of deposits due to corrosion can be minimized, and narrow particle size distributions can be achieved, even at high NaCl concentrations.