Recycling of lithium-ion batteries - aspects of mineral engineering

As the global consumption of lithium-ion batteries (LIBs) continues to increase, the need to develop LIB recycling technologies and create a more robust recycling infrastructure has become an important factor in improving and optimizing the way of separating black mass from these batteries for reuse it in the new LIB production. The aim of this thesis is to develop eco-friendly and economical pre-treatment and separation methods before hydrometallurgical extraction, within the framework of purely industrial applicability. Four different LIB pre-treatment options were tested, including discharging for the safety of the whole process, solvent treatment to dissolve the binder in the LIB structure, and grinding to obtain optimum size for the different separation and extraction methods. Discharge in 10% NaCl solution was compared with cryogenic discharge, and cryogenic discharge was found to be more efficient due to both shorter processing time and reliability. For the next step, it was noticed that usage of the N-methyl pyrrolidone (NMP) solution, which has a slow evaporation rate, causes problems in the grinding. Two different grinding methods, dry and cryogenic, were tested and the final products of both methods had a similar composition in < 2 mm fraction. A similar composition was also observed in the > 2 mm fractions as LiCoO2 and graphite in the powder form have adhered onto the coarser grains. Cryogenic discharging and grinding, without solvent treatment, were found to be the best option to obtain black mass in the < 2 mm size fraction, with the contribution of the low temperatures which changes the binder's state from elastic to glassy in the LIB structure. With the final product of the best pre-treatment option, magnetic separation was effective in separating Fe from the product. The electrostatic separation was done with the product in the 0.125 mm to < 2 mm size range, and the flotation was done with the product of < 0.125 mm size. The separation of LiCoO2 and graphite was partially achieved in both methods. Significant Li and Al extraction from the cathode part of spent LIBs (S-LIBs) was achieved by bioleaching.