Abstract: Energy input during the crushing process is a critical factor determining the liberation efficiency and grinding quality of magnetite ore.However,due to the complexity of influencing factors,the quantitative relationship between energy in put and liberation characteristics remains unclear.This study aims to systematically investigate the effects of impact energy on the breakage characteristics,particle size distribution,fracture morphology,and liberation behavior of magnetite.Drop hammer impact tests were conducted on magnetite particle beds with a specific size fraction (2.00~1.18 mm) and layer thickness (1.45 cm).The particle size distribution of the broken products was statistically analyzed using fractal theory,while the frac ture morphology and liberation characteristics were characterized by scanning electron microscopy (SEM) and an AMICS-Min ing automated mineral analysis system.The results showed that the particle size distribution of the broken products conforms to a fractal pattern,and its fractal dimension (D) exhibits a strong linear positive correlation with specific energy (with a good ness-of-fit R2=0.95),proving it to be an effective indicator for assessing the breakage degree.With increasing impact energy, the fracture mode of magnetite evolves progressively from intergranular fracture through a coupled intergranular-transgranular mode to transgranular fracture.The liberation degree of magnetite follows a unimodal distribution with increasing specific ener gy,reaching a maximum liberation degree of 84.07% in the 0.038~0.019 mm fraction at the optimal specific energy of 0.80 kWh/t,indicating that an appropriate energy input can trigger selective breakage along mineral interfaces,thereby efficiently promoting mineral liberation.This study confirms that precise control of the specific energy to an optimal threshold can maxi mize liberation while suppressing overgrinding,providing a crucial theoretical basis for optimizing energy-efficient comminution processes for magnetite ore.

Key words: fractaldimension,orebreakagecharacteristics,particlesizedistribution,mineral liberation,fracturemorphol ogy