This study investigates graphite separation from Lithium-Ion Battery (LIB) black mass (which is a mixture of anode and cathode materials) via froth flotation coupled with an open-loop recycling approach for the graphite (froth) product. Black mass samples originating from different LIB types were used to produce a carbon-poor and a carbon-enriched fractions. The optimization of the flotation parameters was carried out depending on the black mass chemistry, i.e., the number of flotation stages and the dosing of flotation agents. The carbon-enriched product (with a carbon content of 92 wt.%, corresponding to a recovery of 89%) was subsequently used as a secondary carbon source for refractory material (magnesia carbon brick). Analyses of brick chemistry, as well as thermo-mechanic properties in terms of density, porosity, cold crushing strength (CCS), hot modulus of rupture (HMOR—the maximum bending stress that can be applied to a material before it breaks), and thermal conductivity showed no negative influence on brick quality. It could be demonstrated that flotation graphite can principally be used as a secondary source for non-battery applications. This is a highly valuable example that contributes to a more complete closure of a battery’s life cycle in terms of circular economy.

Recycling of lithium-ion batteries (LIBs) remains challenging due to high energy requirements, losses of key elements like lithium, and the heterogeneity of waste streams arising from different cathode chemistries. This study evaluates multiple recycling methods for LIBs black mass (BM), to recover critical raw materials and other valuable components. Three types of BM including nickel–manganese–cobalt (NMC), lithium iron phosphate (LFP) and a heterogeneous mixture of cell phones and laptops (HL; German: Handy/Laptops), were treated using froth flotation, pyrometallurgy, and biohydrometallurgy and their respective recovery efficiencies were assessed. The flotation results revealed that the HL sample had the lowest mis-recovery of non-ferrous metals into the froth product (around 10%), leading to further flotation only for HL. During screening, 94–99% of iron, phosphorus, and carbon in LFP-type BM were recovered in the fine fraction (<45 µm), while 92–99% of lithium, cobalt, manganese, nickel, and carbon in NMC-type BM were recovered in the same fraction. During precipitation, 99% of iron and 100% of phosphorus were recovered from LFP bioleachates at pH 3, while ~97–100% of dissolved cobalt, manganese, and nickel were recovered from NMC bioleachates. These findings confirm that no single recycling method is optimal for all battery chemistries.