Hydrometallurgical Process for Selective Metals Recovery from Waste-Printed Circuit Boards

Abstract

This paper presents an experimentally-proved hydrometallurgical process for selective metals recovery from the waste-printed circuit boards (WPCBs) using a combination of conventional and time-saving methods: leaching, cementation, precipitation, reduction and electrowinning. According to the results obtained in the laboratory tests, 92.4% Cu, 98.5% Pb, 96.8% Ag and over 99% Au could be selectively leached and recovered using mineral acids: sulfuric, nitric and aqua regia. Problematic tin recovery was addressed with comprehensive theoretical and experimental work, so 55.4% of Sn could be recovered through the novel physical method, which consists of two-step phase separation. Based on the results, an integral hydrometallurgical route for selective base and precious metals recovery though consecutive steps, (i) Cu, (ii) Sn, (iii) Pb and Ag, and (iv) Au, was developed. The route was tested at scaled-up laboratory level, confirming feasibility of the process and efficiencies of metals recovery. According to the obtained results, the proposed hydrometallurgical route represents an innovative and promising method for selective metals recovery from WPCBs, particularly applicable in small scale hydrometallurgical environments, focused on medium and high grade WPCBs recycling.

Kinetic Investigation and Dissolution Behavior of Cyanide Alternative Gold Leaching Reagents

“…The best-known gold solvent is aqua regia. In presence of the oxidant nitric acid, hydrochloric acid forms a soluble tetrachloroaurate complex 5,26–31 . In further notations aqua regia will be counted as halogenic reagent, even though strictly seen it is not.…”

Sustainable Utilization of Metals-Processing, Recovery and Recycling

“…Numerous groups of metals are extracted simultaneously and treated in further steps to be separated optimally from multicomponent systems. For this reason, four papers show an overlap over multiple metal groups, base, precious and critical metals [24][25][26][27].…”

Recovery of Strategic Metals from Waste Printed Circuit Boards with Deep Eutectic Solvents and Ionic Liquids

“…E-waste generated globally is a source of many metals, such as Cu, Zn, Ni, Al, Fe, Pb, and Sn, as well as precious metals (Au, Ag, Pd, and Pt), and rare earth metals (Y, Eu, Ce, Gd, and La) [8][9][10][11]. The most popular methods for recycling metals from WPCBs are the well-known hydrometallurgical and pyrometallurgical processes [12][13][14]. Many reviews have been published in the literature on the current status of extraction methods and perspectives [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28].…”