Application of indirect non-contact bioleaching for extracting metals from waste lithium-ion batteries

Applying biohydrometallurgy for metal extraction and recovery from mixed and polymetallic wastes such as electronic waste is limited due to microbial inhibition at low pulp densities and substrate (iron and sulfur) limitation. Here, we investigated the application of indirect non-contact bioleaching with biogenic ferric iron and sulfuric acid to extract metals from lithium-ion battery (LIB) waste. Results showed that although a single leach stage at ambient temperature only facilitated low leach yields (<10%), leach yields for all metals improved with multiple sequential leach stages (4 × 1 h). Biogenic ferric leaching augmented with 100 mM H₂SO₄ further enabled the highest leach yields (53.2% cobalt, 60.0% lithium, 48.7% nickel, 81.8% manganese, 74.4% copper). The proposed use of bioreagents is a viable and a more environmentally benign alternative to traditional mineral processing, which could be further improved by appropriate pre-treatment of the LIB waste.