222 / 2024-03-13 18:50:44

Influence of degree of gas over-saturation on flotation separation performance of electrode materials from lithium-ion batteries

flotation; nanobubbles; agglomeration; settling efficiency;

Abstract: The electrode materials from spent lithium-ion batteries consist of graphite and lithium cobalt oxides (LCO), which cannot be efficiently separated by conventional flotation technique due to fine size distributions of graphite and LCO. In this work, nanobubbles were introduced to the flotation system of electrode materials. Nanobubbles were produced with the method of temperature difference. The different degrees of gas over-saturation in water/slurry were created by increasing temperature of cold water stored in a 4℃ environment at least 72 h to the terminal 20℃, 25℃, 30℃ respectively. It was founded that height and lateral distance of nanobubbles increased with the degree of gas oversaturation of water. Besides, the larger graphite agglomerations were observed to form in the presence of nanobubbles. Settling experiment results show that settling efficiency of graphite decreased as a result of nucleation and formation of nanobubbles and microbubbles on graphite surface. More graphite agglomerations adhered to a captive bubble with aid of nanobubbles than the case of no nanobubbles. The frost of nanobubbles on graphite surface and thus resulting in graphite agglomerations by bridging effect of nanobubbles together should be responsible for the improved flotation performance of electrode materials.



Keywords: flotation; nanobubbles; agglomeration; settling efficiency;