Freeze-thaw weathering assisted beneficiation of graphite from natural ore resources in cold regions

Freeze-thaw (F-T) weathering can alter the geometry of soils and rocks, imposing severe damage to the Earth's surface. However, it has the potential to favor the beneficiation of mineral resources. In this study, we simulated F-T weathering cycles on the graphite ore from Luobei, a seasonally frozen region in China. The deterioration of the graphite ore caused by F-T weathering was characterized by various means, including the P-wave velocity test, uniaxial compression test, optical microscope, and micro X-ray CT. The results showed that the emergence and propagation of surface defects and cracks in the graphite samples under F-T weathering resulted in weakened mechanical properties of the samples. Moreover, comminution and flotation tests indicated that F-T weathering also amplified the selective liberation between graphite and gangue minerals during crushing and grinding, which contributed to improved separation efficiency and flotation recovery of graphite with significantly reduced chemical usage and energy input. Our study offers a promising strategy for improved and more costefficient beneficiation of graphite ores in cold regions where natural F-T weathering occurs.