Can bioleaching of critical metals from secondary resources be a sustainable extraction solution?

The demand for critical metals (CMs) has significantly increased due to their indispensable roles in advanced manufacturing. Bioleaching, when coupled with secondary resources, offers a promising alternative that addresses both environmental and economic concerns. This review aims to highlight the potential of environmentally friendly bioleaching technologies and the use of secondary resources for the sustainable extraction of CMs. This review covers: (i) characterization of low-grade waste resources (LGWR) for potential CMs recovery, (ii) current progress in bioleaching of CMs extraction, (iii) a strength-weakness-opportunity-threat (SWOT) analysis of bioleaching for LGWR; (iv) relevant market trends, and (v) a case study on bioleaching of CMs from LGWR. Comprehensive data analysis from 102 peer-reviewed papers indicates that rare earth elements are notably present in red mud (0.13%) and tailings (0.11%). Mutant and mixed cultures were found to be crucial for scaling up due to higher recovery efficiencies with faster processing, addressing industrial demand for time- and cost-efficient solutions. Moreover, SWOT analysis highlighted infrastructure incompatibility and capital cost inertia as key threats, whereas opportunities were achieved around process integration. Ultimately, red mud was found to be a strategic waste in future supply chains due to its high CM content, indicating the direction of future research to meet the demands.