Surface chemistry and flotation strategies of smithsonite: A review

The progressive depletion of high-grade zinc sulfide ores has shifted zinc production toward complex oxide resources, particularly smithsonite. However, the flotation of smithsonite remains highly challenging due to its intrinsic hydrophilicity, surface similarity to gangue minerals, and strong slime-forming tendency. These factors result in excessive reagent consumption, limited selectivity, and poor recovery of fine particles, ultimately restricting process efficiency and sustainability. Although considerable research efforts have been devoted to improving smithsonite flotation, the outcomes are often fragmented and lack systematic evaluation. This review provides a critical synthesis of recent advances in cleaner flotation strategies for smithsonite-rich ores. Key aspects include the interfacial chemistry and surface reactions governing flotation, a comparative assessment of sulfidization and non-sulfidization approaches, and the development of mixed and environmentally friendly collectors. Future research opportunities are also outlined, with particular emphasis on the molecular design of biodegradable selective reagents, the integration of machine learning for reagent system optimization, and the application of micro/nanobubbles to enhance fine particle recovery. Collectively, these developments chart a pathway toward more efficient, selective, and sustainable beneficiation of zinc oxide resources, thereby contributing to a resilient zinc supply for the global low-carbon transition.