Evaluation of Cyrene as a sustainable pre treatment solvent for the effective froth flotation-based separation of fine valuables from spent lithium-ion batteries

Froth flotation is a promising technique to separate the cathode (CAM) and anode active material (AAM) of lithium-ion batteries before downstream recycling processes. However, to ensure effective separation, both CAM and AAM particles must be free of organic binders (i.e., polyvinylidene fluoride) which gives them similar wetabilities. In this work, we propose the green solvent Cyrene dihydroleveglucosenone) as a pre-treatment to remove and possibly recover the polyvinylidene fluoride binder from the NMC-rich black mass. Pristine lithium-nickel-manganese-cobalt oxide (NMC111) and anodic graphite are used to determine the ideal flotation behavior. Pristine powders and black mass were mixed with Cyrene, heated at 100°C for 1 hour, and filtered hot. After flotation, 99.6% of the anodic graphite and only 5% of NMC is recovered in the overflow (O/F) indicating that Cyrene pretreatment does not affect their flotation behavior. For NMC-rich black mass, the NMC recovered in the O/F is reduced to 32.6% from 53.8% in the mechanically pre-treated black mass, demonstrating the potential of Cyrene for effective binder removal.