Abstract: The breakage characteristics of geotechnical granular materials, represented by broken coal-rock masses in goafs, directly affect their mechanical properties and pore structures. However, conventional breakage rate calculation methods rely on post-test sieving and are therefore unable to capture the real-time evolution of particle breakage during loading. In this study, acoustic emission (AE) monitoring was used to conduct staged loading-unloading compaction tests on broken coal samples. The limitations of conventional breakage quantification methods, including MARSAL’s breakage index, the fractal-dimension method, and HARDIN’s theoretical method, were comparatively analyzed. The results indicate that particle-size loss and structural rearrangement caused by sieving make it difficult for these methods to accurately characterize real-time breakage behavior. On this basis, the number of breakage-related AE events per unit time, defined as the AE event rate, was statistically analyzed during loading, and its distribution characteristics were fitted. The results show that the AE event rate approximately follows a normal distribution. Accordingly, a real-time dynamic breakage-rate calculation method based on AE events was proposed. By integrating the area under the AE event rate-time curve, the proposed method quantifies the breakage potential and enables non-destructive dynamic monitoring of particle breakage. Compared with conventional calculation methods, the AE-based approach can directly obtain the dynamic breakage rate during loading, reduce measurement errors introduced by sieving tests, and continuously characterize the evolution of particle breakage. The findings provide a new approach for the real-time characterization of particle breakage in granular media and offer a reference for the development of dynamic fragmentation mechanics.