Breakage and fragmentation modelling for underground production blasting applications

A review of breakage and fragmentation modelling literature has shown that only a few methodologies have been specifically developed for applications in underground production blasting. These approaches however, have applied empirical relations that do not adequately consider ring blasting geometries; have failed to appropriately respond to changes in basic design input parameters; and have proposed complex input and calibration requirements. This justified the development of an alternative modelling framework to specifically address the fragmentation prediction problem in underground production blasting. This new modelling approach, designated as “FRAGMENTO”, is introduced in this paper. The basis of FRAGMENTO is a “single ring” deterministic model which can be extended into a stochastic model to simulate of the impact of external operational factors on fragmentation. The single ring component mechanistically models the extent of both near field and mid to far field fractured zones to predict the distribution of rock fragments expected to report to drawpoints. In this paper the response of this key component is evaluated and its practical application demonstrated with the introduction of a methodology to infer critical burden conditions. FRAGMENTO is aimed at the design evaluation stages in an operating mine and for studies at the conceptual, pre-feasibility and feasibility stages of a project, where different drill and blast scenarios and associated costs are still being assessed.