Enhanced bioleaching efficiency of copper from printed circuit boards without iron loss

Abstract

To solve the common problem of Cu bioleaching from waste printed circuit boards (PCBs), a slightly modified bioleaching method was used in this work. This method was concentrated on preventing the iron loss, which would promote Cu bioleaching, reduce FeSO4·7H2O consumption from up to 60 g/L and bring cost savings. Herein, we firstly compared the bioleaching performances between 1.5SO42− system and 1.5S0 system. The results showed that 1.5S0 system was practicable to inhibit the production of Fe(III)-precipitates, and the sustaining low pH should be the main factor for the suppression. Then, different initial content of FeSO4·7H2O was combined with multi-stage bioleaching mode under 1.5S0 system. It was found that 0.25 g/L FeSO4·7H2O was sufficient for bioleaching of Cu from 50 g/L PCBs, the increasing Cu2+ content was achieved by the unsuppressed circulation between Fe2+ and Fe3+. Compared to previous reports, the input quantity of FeSO4·7H2O was reduced remarkably (up to 239 times) and the capital cost of bioleaching could be saved by 37–284 USD m−3. Hence, this work significantly promoted the Cu bioleaching performance through controlling the iron loss, which appears very promising for the development of practical applications.