Metals such as cobalt are particularly strategic since they are present in many high-added-value products. Besides, at the rate of current consumption, specifically of cobalt, the manufacturers are facing risks of shortage for their supply. So, research on these metals' recovery from industrial or urban waste is highly important for the future. Current work focuses on cobalt recovery from Li-ion batteries by precipitation. Literature was evaluated on the various anions allowing to precipitate Co(II), in particular hydroxide, carbonate, and sulfide ions, and the focus was set on the hydroxide way. Simulations were performed using speciation software to highlight the various parameters influencing the precipitation process and the formed species. From simulation results, experiments were carried out in a synthetic solution containing only Co(II).

The growth of the lithium-ion battery industry requires a secure supply of raw materials and appropriate end-of-life management of batteries. In almost five years, global cobalt consumption has increased by nearly 30%, driven mainly by rechargeable batteries. Consequently, several risks have been identified for cobalt, in particular the growing demand for electric vehicles, which could exceed current production. Therefore, research into the recovery of this critical metal, from industrial or urban waste, is particularly important in the years to come. In this study, cobalt is recovered from a lithium-ion battery leachate in hydroxide form. The thermodynamic simulations performed with Visual Minteq showed that it was possible to recover 99.8% of cobalt (II) hydroxide at 25 °C. Based on these results, experiments were conducted to validate the hypotheses put forward and to compare the results obtained with the simulations performed. Experimentally, several operating parameters were studied to determine the optimal conditions for cobalt recovery, in terms of yield, filterability, and selectivity. Results obtained in a batch reactor allowed the determination of the temperature conditions to be applied in continuous reactor. The cobalt (II) hydroxide precipitation in continuous reactor was carried out under different pH conditions. It was then possible to determine the optimal conditions for cobalt recovery in terms of yield and filterability. Results showed that working at pH 9 would effectively meet the desired criteria. Indeed, cobalt recovery is close to 100% and filtration flow rate is three times higher. Results obtained allow a better understanding of cobalt (II) hydroxide precipitation.

As cobalt is a strategic metal essential for the energy and digital transition, the current research work focuses on cobalt recovery from Li‐ion batteries by precipitation. Simulation results allow determination of the cobalt hydroxide precipitation conditions for a complete cobalt recovery. The experimental results show the high impact of temperature on cobalt hydroxide precipitation kinetics and on particle size distribution. Indeed, cobalt recovery is optimal at 25 °C, with a yield of nearly 100 %. However, the simulation results show that it is necessary to be careful about the chosen temperature to avoid coprecipitation of cobalt with manganese. These promising results allow a better understanding of cobalt hydroxide precipitation for a complete recovery from Li‐ion battery leachates.