Impact of pH and collector concentration on froth flotation of spent lithium-ion battery materials

Lithium-ion batteries (LIBs) are widely used in mobile phones and electric vehicles, but their limited lifespan leads to environmental challenges, particularly due to heavy metal waste. Recycling LIBs is essential for reducing pollution and recovering valuable materials from both the anode and cathode. Froth flotation has emerged as a promising technique for separating these materials, though recovery efficiency and optimal conditions remain unclear. Pretreatment is critical for improving recovery, with pyrolysis being effective for removing organic binders like PVDF and CMC, which are commonly used in LIB electrodes. Pyrolysis, performed at 500°C, decomposes binders and recovers valuable cathode materials such as nickel, cobalt, and aluminum. This study investigates the recovery of graphite (anode) and metal oxides (cathode) in froth flotation by varying collector concentrations (850–2500 g/t) and pH levels (4–9). The highest graphite recovery (90.05%) occurred at a collector concentration of 850 g/t, while the metal oxide recovery was 25.5%. Lower collector concentrations resulted in incomplete anode particle coverage, while higher concentrations reduced selectivity. At pH 7, the best recovery was achieved, with graphite recovery of 94.61% and metal oxide recovery of 24.14%. These findings highlight the importance of pyrolysis pretreatment for binder removal and provide insights into optimizing flotation parameters, enhancing the efficiency and sustainability of LIB recycling processes.