Bioleaching: from natural ores to urban mines for sustainability, circularity, and carbon neutrality

Abstract

Securing critical raw materials for net-zero energy systems and green technologies, has become a global priority. This urgency is fuelled by increasing demand, dwindling natural reserves, and rising geopolitical instabilities. Urban waste streams, often rich in metal concentrations than natural ores, are emerging as viable alternative for metal recovery. Bioleaching, a natural process utilising microorganism to mobilise metals from solid mineral matrices, has become increasingly popular as a sustainable and economically attractive alternative to conventional mining of minerals, particularly for low-grade ores and waste-derived feedstocks. The attractiveness of bioleaching lies in low environmental impact and high efficiency, even at low metal concentrations. This review explores different metal-bearing secondary materials containing critical, precious, and rare earth elements (REEs) as potential feedstocks for bioleaching. It traces the evolution of bioleaching from natural ore processing to its growing utility in urban waste valorisation within a circular economy framework. It compares bioleaching process in natural ores versus urban waste, while showcasing recent advancements toward commercial implementation. The review also identifies existing challenges and proposes strategies for improvement. Finally, it articulates bioleaching's potential for integration into a circular economy model, emphasising its role in enabling sustainable metal recovery and achieving carbon neutrality goals