Recycling lithium-ion batteries is possible, however the practice is far from perfect. What’s missing is a low-energy and low-cost separation system that selectively recovers electrode materials. The solution according to Michigan Technological University, is a mining technique that has been around for a while, in fact it is more than a century old.
The research suggests technology typically used in the mining industry to help separate metals from ore could be exactly what battery recyclers need.
The researchers used standard gravity separations to separate copper from aluminum, and froth flotation to recover critical materials, including graphite, lithium, and cobalt. MTU assistant professor and chemical engineer Lei Pan points out that this approach is the cheapest one and does not require new infrastructure to be built.
“In this study, froth flotation experiments were carried out with a variety of new and spent lithium-ion batteries using kerosene as the collector. The products were characterized using thermogravimetric and chemical analysis,” notes Pan, who oversaw the research project.
The results found over 90 percent of anode materials were floated in froth layers, while 10–30 percent of cathode materials were floated.
Separability of mixed electrode materials was evaluated using a modified procedure based on release analysis. Results showed that the froth flotation process using kerosene as the collector produced a tailing product having cathode materials of higher purity than those obtained without kerosene.
“For spent lithium-ion batteries, a low purity of cathode materials in tailings might be improved by fine grinding, at which freshly liberated hydrophobic surfaces are exposed and consequently anode materials become floatable,” so the group concludes.
The present result confirms that the froth flotation technique is a viable and versatile technique in producing “high purity” cathode materials from lithium-ion batteries.