(513i) Metal Recovery Using Oxalate Chemistry: Recycling of Lithium-Ion Batteries and Refining of Bauxite Ore

Oxalate ion is a bidentate anionic ligand with excellent chelation and complexation properties. Its unique ability to precipitate divalent (M⁺²) metal ions and dissolve monovalent (M⁺)and trivalent (M⁺³) metal ions in aqueous medium is advanatageous for separation of metals. In this poster, the use of oxalate chemistry will be described in detail for two commercially important metal recovery and separation processes. The first application is for the recovery and separation of lithium (Li) and cobalt (Co) from spent lithium-ion battery cathodes. In a single-step digestion process with an oxalate reagent, Li and Co from lithium cobalt oxide (LiCoO₂) can be separated in aqueous and solid phases, respectively. The Li can be precipitated into lithium carbonate (Li₂CO₃) and Co can be converted into cobalt oxide (Co₃O₄) or cobalt hydroxide (Co(OH)₂). To ensure sustainability and no waste is generated in the process, aqueous oxalate reagent used in the digestion was recovered and recycled. The oxalate chemistry was also efficiently used for refining of bauxite ore. Bauxite is a commercially important source for aluminum (Al) and also contains iron (Fe). In the bauxite refining process, closed-loop extraction and separation of Al and Fe from a variety of ores with varying alumina content has been evaluated. The experimental and mechanistic details of both of these processes will be described in detail and potential applications of oxalate chemistry for recovery of the critical metals involving titanium as well as rare earth elements such as samarium and neodymium will also be discussed.