Micro- and nanobubble-assisted mineral processing and hydrometallurgy: a new paradigm in sustainable metal extraction and recovery

• Nanobubble (NB) and microbubble (MB) applications in mineral processing and hydrometallurgy. • NBs and MBs generation methods and physicochemical characteristics. • Theoretical and existing techno-economic studies on implementing NB and MB technologies in mineral processing and hydrometallurgy. • Benefits and challenges associated with NB and MB technologies in mineral processing and hydrometallurgy. Recent advances in nanobubble (NB) and microbubble (MB) technologies have introduced novel pathways for enhancing mineral processing and hydrometallurgical operations. Owing to their unique physicochemical properties,such as high surface area, long-term stability, and reactive interfaces,NBs and MBs have shown potential in improving gas–liquid mass transfer, oxidation reactions, and particle-bubble interactions. This review provides a comprehensive analysis of the mechanisms and effects of NBs and MBs in flotation and leaching processes, with an emphasis on the recovery of critical and strategic metals. Generation techniques, stability factors, interaction dynamics with mineral surfaces, and the influence of physicochemical parameters such as pH, temperature, surfactants, and electrolytes are systematically examined. The integration of NBs into hydrometallurgical systems, particularly in oxidant delivery and kinetic enhancement, is critically assessed. Additionally, the review outlines current challenges and modeling approaches to support the scalable application of bubble-assisted mineral processing technologies.