2025 Rudnik Tin recovery by biohydrometallurgical methods

Tin, although not considered a critical material in all world regions, is a key material for modern technologies. The projected scarcity of tin in the coming decades emphasizes the need for efficient recycling methods to maintain uninterrupted supply chains. This review article focuses on the recovery of tin from low-grade secondary sources, specifically obsolete printed circuit boards (PCBs) and liquid crystal displays (LCDs). In both types of waste, tin occurs in various concentrations and in different chemical forms—a few percent as metal or alloy in PCBs and several hundred ppm as tin(IV) oxide in LCDs. This article presents pretreatment methods to preconcentrate tin and enhance subsequent leaching. It discusses not only conventional acid and alkaline leaching techniques but also the use of complexing agents and the challenges associated with bioleaching. Due to the dilution of the resulting leachates, advanced methods for tin ion separation and preconcentration before final product recovery are shown. Solvometallurgical methods employing deep eutectic solvents or ionic liquids are also discussed; although promising, they still remain under development.