Copper recovery from waste printed circuit boards using pyrite as the bioleaching substrate

Waste printed circuit boards (WPCBs) can be bioleached for Cu recovery, but lack of substrate for the bioleaching culture. In this study, using pyrite as a bacterial substrate for bioleaching WPCBs and recovering Cu was explored. The results showed that the WPCBs bioleaching using pyrite as the bacterial substrate was feasible. Mechanical crushing was a suitable WPCBs pretreatment method. The optimal WPCBs and pyrite pulp densities were respectively found to be 1.25% (w/v) and 1.0% (w/v), and the suitable nitrogen source ratio ((NH₄)₂SO₄: (NH₄)₂HPO₄) was deemed as 2 g/L: 2 g/L, achieving a Cu²⁺ leaching efficiency of 95.60 ± 1.57% in 14 d. Copper in the bioleaching solution can be directly recovery via electrodeposition. The Cu recovery efficiency in 60 min was up to 92.19 ± 1.35% under the optimal condition that the initial Cu²⁺ concentration and pH were respectively set at 7.34 g/L and 2.75, and the current density was set at 200 A/m². Copper was found as the dominant metal in the cathode deposits, existing in the form of Cu and Cu₂O. This work provided a novel approach for bioleaching WPCBs and recovering Cu.