Joint recovery of graphite and lithium metal oxides from spent lithium-ion batteries using froth flotation and investigation on process water re-use

Spent lithium-ion batteries (LIBs) contain critical raw materials that need to be recovered and recirculated into the battery supply chain. This work proposes the joint recovery of graphite and lithium metal oxides (LMOs) from pyrolyzed black mass of spent LIBs using froth flotation. Since flotation is a water-intensive process, the quality of the aqueous phase directly impacts its performance. In pursuit of an improved water-management strategy, the effect of process water recirculation on black mass flotation is also investigated. The fine fraction (<90 µm) of the black mass from pyrolyzed and crushed spent LIBs was used. After flotation, 85% of the graphite in the overflow product and 80% of the LMOs in the underflow product were recovered. After flotation with 8 wt% solids, the process water contained about 1,000 mg/L Li and accumulated up to 2,600 mg/L Li after three cycles. The flotation with process water showed no significant impact on the recovery and grade of flotation products, suggesting the feasibility of water recirculation in black mass flotation.