Leaching of NMC industrial black mass in the presence of LFP

Abstract This study focuses on the effect of an emerging source of waste, lithium iron phosphate (LFP) cathode materials, on the hydrometallurgical recycling of the currently dominant industrial battery waste that is rich in transition metals (Ni, Co, Mn, and Li). The effects of the dosage of LFP, initial acidity, and timing of LFP reductant addition were investigated in sulfuric acid (H 2 SO 4 ) leaching ( t = 3 h, T = 60 °C, ω = 300 rpm). The results showed that addition of LFP increased both transition metal extraction and acid consumption. Further, the redox potential was lowered due to the increased presence of Fe 2+ . An initial acidity of 2.0 mol/L H 2 SO 4 with acid consumption of 1.3 kg H 2 SO 4 /kg black mass provided optimal conditions for achieving a high leaching yield (Co = 100%, Ni = 87.6%, Mn = 91.1%, Li = 100%) and creating process solutions (Co 8.8 g/L, Ni 13.8 g/L, Li 6.7 g/L, Mn 7.6 g/L, P 12.1 g/L) favorable for subsequent hydrometallurgical processing. Additionally, the overall efficiency of H 2 O 2 decreased due to its decomposition by high concentrations of Fe 2+ and Mn 2+ when H 2 O 2 was added after t = 2 h, leading to only a minor increase in final battery metals extraction levels.