A Case Study on Trim Blast Fragmentation Optimization Using the MBF Model and the MSW Blast Vibration Model at an Open Pit Mine in Canada

A project for monitoring, analysis, and modelling trim blasting at an open pit copper/molybdenum mine in Canada in 2021 was conducted using Orica's in-house developed proprietary tools, which includes the accelerometer near-field vibration monitoring system, the Multiple Seed Waveform near-field and far-field blast vibration model, and the multiple blasthole fragmentation model. Both models are built on the fundamentals and empirical aspects of blasting mechanics. They input full blast design parameters and site-specific information from the near-field signature hole blast vibration. The blast vibration at the highwall from trim blasts was predicted with multiple seed waveform blast vibration model. The effects of parameters from the trim blast design scenarios on fragmentation and vibration at the highwall were simulated at the mine site. Improved blast designs for finer fragmentation and controlled vibration were proposed based on the modelling. The multiple blasthole fragmentation model can simulate real blast designs in three dimensions with the actual geometry of the blasted overburden and free faces. The multiple blasthole fragmentation model can explicitly model all blast design parameters, including explosive properties, loading configuration, and delay timing of each explosive charge. The multiple seed waveform blast vibration model uses multiple seed waveforms at different distances from a blasthole and is suitable for near-field blast vibration at the highwalls. Through the application of the two models, various design scenarios can be explored, and rock fragmentation can be optimized while controlling blast vibration levels. These models have been successfully applied to several open pit mines and quarries around the world, including Canada, the United States, and Africa.