Leaching of gold and silver from printed circuit board of mobile phones

Abstract

Nowadays there is a wide variety of models, sizes and configurations of mobile phones available for consumption. After the life cycle of this equipment, the recycling and reuse of the precious metals found in the printed circuit boards (PCB) of the mobile phones are principal objectives. Thus, the objective of this work was to characterize the gold and silver present in a PCB and develop a recycling route using alternative reagents for cyanide, such as sodium and ammonium thiosulfate. These reagents are less harmful to the environment and worker health. The first characterization of gold and silver was performed with aqua regia. The results show 86.26g Au/ton of PCBs and 123.85g Ag/ton of PCBs. The second characterization was performed with a commercial cyanide-based reagent and 112.02g Au/ton of PCBs and 26.13g Ag/ ton of PCBs were obtained. A leaching study with solutions based on thiosulfate was performed and an extraction of 9.02g Au/ton of PCBs and 33.88g Ag/ton of PCBs was obtained, compared to characterization results using a cyanide-based reagent.

Electrochemical approaches for selective recovery of critical elements in hydrometallurgical processes of complex feedstocks

“…Other strong leaching systems, such as aqua regia (a 1:3 molar mixture of HNO 3 and HCl) ( Elomaa et al, 2017 ; Petter et al., 2015 ) and cyanide ( Fleming, 1992 ; Montero et al., 2012 ), have also been investigated to extract inert precious metals (e.g., Au) from WPCBs. Aqua regia has shown highly efficient extraction behaviors of Cu, Au, and Ag from WPCBs, but unfortunately, it has severe drawbacks such as environmental and public health concerns, high corrosiveness, volatility, toxic emissions, and low selectivity ( Hsu et al., 2019 ).…”

Determination of Dissolution Rates of Ag Contained in Metallurgical and Mining Residues in the S2O32−-O2-Cu2+ System: Kinetic Analysis

“…Such mineralization is composed mainly of base metal sulfides that make up the ore [31][32][33] such as pyrite (FeS 2 ) associated with quartz (SiO 2 ), as shown in the micrograph on Figure 2. To complete the characterization study, the mineral was analyzed by scanning electron microscopy (SEM) along with energy dispersive X-ray spectrometry (EDS).…”

Recovery of base and precious metals from PCBs (Printed Circuit Boards) in waste electrical and electronic equipment (WEEE)

“…Nowadays, the world is producing more and more electrical and electronic waste. The consumption of electronic equipment is constantly increasing, because with the speed of technological progress, they become obsolete in a relatively short period of time [1,2]. According to [3,4] the amount of computers, phones, televisions and devices being discarded doubled between 2009 and 2014, reaching 42 million tons per year worldwide.…”