In most cases, fine fragmentation is sought for down-stream operations, such as digging, hauling, crushing, and comminution to maximize mineral abstraction and minimizing energy cost. On the other hand, maintaining stable highwalls and undisturbed nearby community from the mine is highly desirable. To obtain fine fragmentation, it is often required to use blast designs with favorable energy concentration through explosive loading or blasthole delay timing. Such blast designs have potential to cause high blast vibration at highwalls or nearby community. A systematic blast optimization requires a desirable fragment size distribution as well as controlled blast vibration at concerned locations. An integral system for accurate monitoring and modeling rock fragmentation and blast vibration is required. All parts of the integral system need to be applied parallel for a successful project.
A unique system has been developed during recent years and applied successfully at many mine sites across the globe. The system consists of a near- and far-field blast vibration monitoring system, the Multiple Blasthole Fragmentation (MBF) model, and the Multiple Seed Waveform (MSW) blast vibration model. The blast vibration monitoring system can record blast vibration from the nearest location possible to blastholes (e.g., 5 m from a blasthole loaded with 300 kg explosives). The nearfield blast vibration carries vital information for modeling rock fragmentation and highwall vibration and provides the site characterization in terms of nearfield response of the rock to the explosive loading. The site characterization is one of the critical inputs to the blast modeling. The MBF model simulates full blast design parameters, multiple blasthole/decking interactions with delay timing, and real blast design geometries. The MSW blast vibration model uses multiple seed waveforms collected at the site as input. The multiple seed waveforms carry more realistic site-specific geology information and blast wave attenuations with distances than a single seed waveform. The MSW model is suitable for both near field (such as highwalls) and far field (e.g., residential houses) vibration predictions. The system is applied integrally for a site to optimize rock fragmentation and productivity while the blast vibration on highwall or residential structures are kept under control. The system is also applicable to underground blast optimizations. This paper presents the system with the case examples.
