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Herein, a mechanochemical approach was developed for recover the cobalt and from spent lithium-ion batteries using a high-concentration chloride solution. Effect of parameters on the leaching efficiency of cobalt was studied. 97, 6% of Co was recovered under optimum conditions: rotation speed 500 r/min, S/L ratio: 1:150 g/ml, ball/material ratio 25:1 g/g, milling time 30 min, respectively. The dissolved cobalt was recovered by selective precipitation method to ensure that the recycled Co can be reused for lithium-ion battery production. This research presents a highly efficient and environmentally friendly approach for recovering cobalt from spent LiBs.

Recent observations of Her X-1 with NuSTAR (as well as with INTEGRAL, Swift, and Astrosat) have provided evidence that the nearly 20 yr-long decay of the cyclotron line energy since ∼1994 has ended and that a stable value has replaced the decay. Using the observations of the Hard X-ray Modulation Telescope (Insight-HXMT) performed between 2017 July and 2020 February, we analyze the spectra of Her X-1 in its main-on state, focusing on tracing the evolution of cyclotron line energy. While our analysis of eight main-on observations with Insight-HXMT (two in coordination with NuSTAR) shows significant differences with the results of NuSTAR, two earlier findings are confirmed: the positive correlation between the cyclotron line energy and the X-ray flux (source luminosity) and the constancy of the flux-normalized cyclotron line energy during 2017–2020—albeit with significant uncertainty about the absolute value.