Influence of shredder and mill settings on the material recoveries and product qualities of a two-stage mechanical recycling process of automotive lithium-ion batteries

For a two stage shredding and milling process the yield of black mass and the elemental recovery of critical elements Ni and Li s investigated. I can be shown that the quality of the products resulting from the mechanical recycling of lithium-ion batteries significantly depends upon the parameters employed during the shredding process. Modifications to the settings have the potential to exert a considerable impact on the particle size, liberation of composites and de-coating of electrodes. The discharge grid size employed during the first shredding step shows a significant influence on the downstream separation behaviour of the casing material and separator foil. The mill speed utilised during the second comminution step determines the separation achieved between the cathode and anode. A reduction in grid size employed during the first shredding stage results in an increase in black mass yield, although the recovery of the casing is diminished. In total Ni recovery for all setting combinations is similar, a lower recovery in the first shredding step is compensated by a higher recovery after the second comminution. It was observed that an overall increase in the mill speed above 1750 rpm resulted in elevated levels of copper contamination within the black mass. The influence of eleven distinct combinations of shredder and mill settings on the black mass yield and its composition, the recovery of the separator foil and the casing, as well as the separation behaviour of the anode and cathode, were investigated.