Gold Recovery From Printed Circuit Boards of Mobile Phones Scraps Using a Leaching Solution Alternative to Cyanide

Abstract

Currently, the printed circuit boards (PCB) of waste electrical and electronic equipment (WEEE) are attracting interest among researchers for environmental concern reasons and mainly for their content of precious metals such as gold. Thus, this study aims to characterize different types of PCBs from mobile phones in relation to the amount of gold contained, to evaluate alternative leaching agents for the gold (ammonium and sodium thiosulfate) and compare these to commercial stripping (cyanide-based) and then the recovery of gold by the electrometallurgical route. First, the amount of gold was determined. Then, alternative leaching agents were tested under different concentrations and time. A cyanide-based solution was also tested to compare the results. The results showed that the content of gold varied from 142 to 700 g/ton. The cyanide-based solution was able to extract 88% of the gold, while sodium and ammonium thiosulfate extracted 70 and 75% of the gold, respectively. The electrowinning tests showed a 94% recovery of the gold present in thiosulfate solutions.

A natural deep eutectic solvent-based aqueous biphasic system coupled with MoS2 photocatalytic reduction for green recovery of gold from thiosulfate solution

“…5d shows the high-resolution spectra of N 1s in the absence and presence of gold in the NADES-rich phase. It is worth noting that when gold was loaded in the ChCl-Lac-rich phase, the binding energy of N 1s decreased from 402. discussed as an example, and the process of extracting gold using ATPSs can be expressed by eqn (11). Furthermore, the equilibrium constant (K eq ) can be expressed according to eqn ( 12)-( 14) with concentration units of mol L −1 .…”

“…10 Thiosulfate converts metallic gold in ore into the stable complex Au(S 2 O 3 ) 2 3− in solution according to eqn (1). 11 4Au + 8S 2 O 3 2− + O 2 + 2H 2 O = 4Au(S 2 O 3 ) 2 3− + 4OH − …”

Assessment of Pre-Treatment Techniques for Coarse Printed Circuit Boards (PCBs) Recycling

“…The typical copper content is about 10-fold higher compared to the respective metal ores [6]. Similarly, the gold content in PCBs ranges from 140 to 700 g/t, which is much higher than the average gold grade in gold ore deposits [7]. The presence of these valuable metals drives the economics of e-waste recycling.…”

Full Factorial Design for Gold Recovery from Industrial Solutions

“…From an environmental viewpoint, for some metals, scientists estimated [7,8] that nowadays extracting the same amount as a century ago necessitates the removal of about three times more rocks. Therefore, recycling is beneficial from economic and environmental perspectives.…”

“…Therefore, recycling is beneficial from economic and environmental perspectives. Recycling also is a valuable source to recover scarce materials [7,[9][10][11].…”