Effect of thermal pre-treatment of spent lithium-ion batteries on the selective recovery of graphite anode by flotation

• Thermal pre-treatment of LiBs black mass at 400 °C promotes graphite liberation and flotation efficiency. • Microwave-assisted heating enables rapid, uniform processing and cleaner material liberation. • Excessive heating of LiBs black mass generates fines that lower separation efficiency and graphite flotation. • Adding 10 wt% CaO to LiBs black traps fluorine and promotes flotation selectivity against the cathode. The increased use of lithium-ion batteries (LiBs) in electric vehicles (EVs) and other applications due to global efforts to reduce carbon emissions has led to an increase in end-of-life battery production. This has created a demand for efficient recycling methods to control waste and conserve resources. This study investigated the effect of thermal pre-treatment of spent LiBs materials on the liberation of anodic and cathodic materials from the aluminium and copper current collectors and the subsequent graphite recovery by flotation. The samples were pre-treated using a rotating kiln and microwave furnace at temperatures of 200 °C, 400 °C, and 600 °C, with an additional sample containing 10 wt% CaO treated at 400 °C. The results indicated that higher temperatures resulted in the breakdown of the binder, leading to graphite liberation. Specifically, at 600 °C, the anode and cathode materials exhibited significant separation from the Cu and Al current collectors with an almost similar liberation efficiency for both pre-treatment methods. Furthermore, adding 10 wt% CaO to the samples treated at 400 °C significantly lowered the flotation of the cathode materials and improved the flotation selectivity of graphite. The findings indicate that combined thermal pre-treatment with flotation can improve the recycling process, providing a more scalable and environmentally friendly approach to managing the increasing volume of spent LiBs.