PROCESSING OF A METAL CONCENTRATE FROM GROUND WASTE PRINTED CIRCUIT BOARDS IN ACIDIC MEDIA USING HYDROGEN PEROXIDE AS OXIDANT

The recovery of precious and base metals from a metal concentrate originating from ground waste printed circuit boards (PCBs) is investigated in this study. The objective is to detail an effective recovery process using acidic media. Methodology consisted of treating samples with sodium hydroxide to eliminate the soldering mask and conducting leaching experiments in acidic conditions, employing hydrogen peroxide as an oxidizing agent. Results demonstrated that base metals could be leached with high efficiency, exceeding 99 wt.%, at approximately 40 °C in different acids—hydrofluoric acid, sulfuric acid, acetic acid, and phosphoric acid—within varying times. In the presence of sulfuric and hydrofluoric acids, lead precipitation occurred, whereas precious metals remained oxidatively unaltered. Moreover, the dissolution of ceramic and fiberglass components was facilitated by the use of hydrofluoric acid. Sequential oxidative treatments enabled the recovery of silver, palladium, and gold from the residual solids. A combination of solvent extraction and precipitation methods were crucial for achieving high yields of leached elements, indicating that while effective leaching in a weak organic acid is feasible, it necessitates a multistage element recovery approach due to the complex composition of PCBs.