Study on the recovery of graphite from spent carbon cathode via ultrasound-assisted foam flotation

Spent carbon cathode is a kind of solid waste produced by the electrolytic aluminum industry, and it poses a high environmental risk. However, it also contains valuable graphite resources that can be recycled and used as raw materials in industry. In this work, we aimed to enhance the efficient recovery of graphite by introducing ultrasonic waves into the flotation process. Particle size test, inductively coupled plasma (ICP), BET surface area, and other analytical techniques confirmed that ultrasound could promote particle dispersion, clean the surface of minerals, increase the porosity of the graphite surface, and thus strengthen the flotation performance. The results showed that after ultrasonic treatment for 30 min, the recovery rate of graphite increased from 86.22% to 96.24%, the fixed carbon content of tailings decreased from 26.99% to 9.68%, and the fixed carbon content (84.95%) was close to that of conventional flotation (85.32%). Compared with the traditional purification method, this strategy reduces the follow-up cleaning steps of tailings, simplifies the process, reduces the use of chemicals, and features strong market competitiveness and green environmental protection advantages. Additionally, the process is simple and low-cost and can be applied to the recycling of other waste graphite, with potential industrial application prospects.