In this paper, mechanical stirring and ultrasonic treatment are used to separate graphite electrode materials from copper foils in recycling spent lithium-ion batteries (LIBs). Firstly, the effects of ultrasonic power (60–180 W), ultrasonic time (1–8 min), stirring speed (420–2000 rpm), and stirring time (1–8 min) on the abscission rate of active material on copper foil were studied. It was found that the peeling-off ratio of electrode material under ultrasonic treatment was 91.34% compared with stirring treatment (84.22%). The removal of electrode material from copper foil during stirring was mainly through mechanical scrubbing. As a comparison, the generation of the microjets induced by ultrasound, the local high-temperature and high-pressure environment, and the free radicals during ultrasonic treatment are the key factors to further improve electrode material removal efficiency. An integrated ultrasound-mechanical stirrer technique can achieve a high-efficient separation performance (approximately 100% peeling-off ratio) of anode electrode materials from copper foils. The effects of mechanical stirring speed, temperature, and treatment time on the peeling-off ratios of the ultrasound-mechanical stirrer-assisted system were investigated. Finally, the results of XRF (X-ray fluorescence spectrometer), XRD (X-ray diffraction), and SEM-EDS (scanning electron microscopy coupled with energy dispersive X-ray spectroscopy) showed that the as-separated graphite electrode material had high purity and contained almost no copper foil impurities. Numerical simulation analyses briefly showed that the difference between pressure and ultrasonic temperature changes in the boundary between different anode layers (graphite on copper foil in aqueous solution) was the main effective factor in the considerable separation of graphite from copper anode foil under ultrasonic-assisted delamination.

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The flotation method is widely used for the preliminary beneficiation of aphanitic (microcrystalline) graphite. However, there is limited literature regarding the effects of flotation reagents on the flotation kinetics of aphanitic graphite. In this study, six commonly used flotation kinetic models were used to fit the flotation experimental data of aphanitic graphite. The classical first-order model was found to be most suitable for describing flotation kinetics of aphanitic graphite. The modified flotation rate constant (Km) was then applied to evaluate the effects of collector, frother, and inhibitor on aphanitic graphite flotation kinetics. Compared to diesel oil and terpineol oil, kerosene and 2-octanol produced a greater Km. The highest Km was obtained at an inhibitor dosage of 15 mg/L.

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