Research progress on physical purification technology of graphite

As a critical strategic resource, natural flake graphite’s purification technology directly determines resource-utilization efficiency, making it essential to explore efficient and eco-friendly purification techniques. To systematically investigate the development status and application potential of physical purification technologies for natural graphite, this paper reviews existing physical purification methods, including conventional physical techniques（flotation） and emerging combined technologies（nanobubble technology, ultrasonic-assisted graphite purification, and water jet dissociation technology）. The fundamental principles, advantages, and limitations of each technique are compared and summarized. Furthermore, future development directions of graphite purification technologies are prospected, focusing on raising the upper limit of purification grade, low-cost industrialization, and low-carbon process optimization. Technical breakthroughs in these aspects represent urgent challenges for the advancement of physical graphite purification technologies in China. Accordingly, this paper proposes a novel combined technology: cavitation-flotation coupled graphite purification technology. This multi-stage cyclic treatment process integrates cavitation and flotation. Its basic principle lies in that high-speed rotation of impellers in aqueous media generates cavitation. Forces induced by cavitation act on graphite particles to strip off ash-forming minerals attached to particle surfaces, thereby realizing purification. Preliminary experimental investigations are further performed to compare the purification performance of single flotation and single cavitation-flotation. The results demonstrate superior purification efficacy of cavitation-flotation. Particle-size tests reveal that cavitation treatment exerts fragmentation and exfoliation effects. SEM, XRF, and XRD characterizations further verify the favorable purification performance of cavitation-flotation technology. It is demonstrated that this technology can achieve the goals of purity improvement, process simplification, cost reduction, and environmental friendliness, offering a new insight for addressing challenges in graphite purification.