From copper ores to e-waste processing: Can urban mining practices be actually integrated into idle capacity in acid-ferric hydrometallurgical facilities?

Sustainable technologies have promoted a sharp increase in copper demand, while copper ore grades are progressively declining and a significant shortfall is predicted in the next 10 years. As copper oxide deposits become scarce hydrometallurgical facilities are prone to become inactive or underutilised in the short term, thus repurposing these plants for processing electronic waste has recently risen discussion considering the higher content of copper (6–27 wt%) in printed circuit boards (PCBs) compared to copper ores (< 1 wt%).

This work revises recent research exploring acid-ferric leaching routes comparable with processes performed conventionally in hydrometallurgical facilities. The adaptability of the operational conditions reported for waste PCB leaching (e.g., temperature, pH, ferric ion concentration, use of microorganisms, solid concentration) into existing hydrometallurgical plants is discussed in terms of copper extraction yield, kinetics, infrastructure availability and compatibility of leachate composition with following solvent extraction (SX) and electrowinning (EW) stages.

The analysis shows that a pretreatment stage would have to be forcibly introduced to reach an efficient metal recovery in stages following leaching (SX-EW). Furthermore, leaching via chemical or biological routes would require precise control of ferric ion concentration, acidic pH, low solid concentration, particle size and dissolution of other metals to obtain copper with high extraction yield (>85 % in hours to days), high purity (>90 %) and low energy consumption. Thus, reactor leaching instead of heap leaching might need to be considered.

Although operational adaptation of conventional hydrometallurgical facilities is possible, reproducible studies at large scale are required to sustain reliable technical–economic analyses.