Progress in bioleaching and its mechanism: a short review

Bioleaching is an environmentally friendly and cost-effective technique for extracting metals from low-grade ores and waste materials. It uses microorganisms to dissolve metals through acidolysis, complexolysis, and redoxolysis, either directly or indirectly. While small-scale studies are conducted in shake flasks, larger applications include heap, vat, and tank systems. Bioleaching is promising for metals such as copper, uranium, and gold; however, it faces several challenges, including slow kinetics, microbial inhibition by toxic metals, reactor design issues, and instability with varying feedstock. To address the challenges, research related to bioleaching focuses on improving microbial strains for higher pulp density, introducing processes through the design of familiar reactors, hybridizing electro-assisted biological systems, and integrating downstream separation for purer products. Advanced tools, such as multi-omics and electrochemical monitoring, are helping to optimize strain selection and process control. Current omics and electrochemical insights have uncovered a multi-layered network of biochemical and biophysical interactions that govern metal solubilisation efficiency, even though the fundamental concepts of acidolysis and redoxolysis remain relevant. It is therefore crucial to incorporate these molecular discoveries into kinetic models to accurately predict and scale up BL systems. Despite its challenges, bioleaching offers a low-energy alternative to traditional metallurgy and has significant potential for sustainable urban mining and the recovery of critical metals.