Development of a recycling process for n

In a governmental funded 3-year research project, a recycling process for nickel-metal hydride batteries (NiMH) has been developed. The discarded batteries are currently utilized in the steel industry as a low-cost nickel source, while cobalt remains unmonetized and rare earth elements are typically lost in the slag. This study identifies that spent NiMH batteries can contain significant concentrations of nickel (36–42%), cobalt (3–4%), and rare earths (8–10%). The batteries are dismantled, processed, and melted in a direct current electric arc furnace, generating a nickel–cobalt alloy and a slag phase that is rich in RE-oxides. The research emphasizes the importance of selecting an appropriate slag system to optimize the separation of the NiCo alloy from rare earth oxides, with various oxidic and halogenic slag systems examined at both laboratory and technical scales. The findings suggest that the CaO–CaF2 slag system exhibits superior melting behavior compared to the CaO–SiO2 system during pilot plant trials. It was observed that nickel and cobalt were predominantly found in the metal phase, while the rare earths were successfully transferred to the slag. Additionally, the study examines the economic viability of the process through scenario calculations.