A novel technology of recovering magnetic micro particles from spent lithium-ion batteries by ultrasonic dispersion and waterflow-magnetic separation

Abstract With the rapid growth of lithium ion batteries (LIBs) market, large Numbers of LIBs are nearing the end of their life cycle. At the same time, large number of magnetic energy metals (MEMs) demand is difficult to meet. It is an urgent demand to recover micro magnetic particles from spent LIBs. However, the aggregates formed by micro particles make it difficult to be separated by mechanical technologies. Existing mechanical separating technologies are limited by strict particle size of larger than 0.075 mm. Chemical technologies can recover micro metallic particles without considering particle size but take the risks of environmental pollution. We developed a technology of ultrasonic dispersion and waterflow-magnetic separation to recover micro magnetic particles from mixed micro particles aggregates. By analyzing the relationship between aggregation energy and size of aggregates, the key factors to destroy the aggregation of micro particles were determined. The optimal parameters of ultrasonic dispersion were obtained by experiments. Under the condition of 20 min ultrasonic time, 200 W ultrasonic power, the maximum recovery rate of cobalt particles was 99.63% ± 0.62% and the purity of cobalt particles was 93.15% ± 0.56%. Combining with the trajectory of particles in waterflow-magnetic separation, key parameters influencing recovery effect were determined. This study provided a new technology for the separation of micro MEMs particles and aggregates.