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.

Particle crushing is a common phenomenon in granular soils, which can affect the physical and mechanical properties of soils. The index which used to quantify the amount of particle crushing is crucial for the relevant research. Based on Kick's comminution energy consumption theory, size potential regarding as a property of soil and representing the energy of particles in a certain state was defined in this study, and a crushing index was proposed based on it. This index was determined according to a density distribution of particle size that voids the problem of sieving error propagation when using a cumulative grain size distribution curve. The validation of the proposed crushing index showed that it could quantitatively describe the amount of particle breakage, regardless of material, gradation, test type and particle size scale. In addition, the proposed crushing index was considered as a soil property index and could be divided into two categories: the ultimate crushing index and the mobilized crushing index, where the mobilized crushing index is obtained from the ultimate crushing index by replacing the ultimate breakage state with the final breakage state. The test results showed that the mobilized crushing index was equivalent to the input energy ratio between current and final breakage states. This relationship contributes to the understanding of the evolution of the grading curve caused by particle breakage.