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 (MSW) near- and far-field blast vibration model, and the Multiple Blasthole Fragmentation (MBF) model. Both MSW and MBF models are built on the fundamentals and empirical aspects of blasting mechanics. The blast vibration at the highwalls from trim blasts was predicted with MSW model. The effects of parameters from the blast design scenarios at the mine site were simulated and optimized designs were proposed based on the MBF and MSW modelling. The MBF model explicitly simulates all blast design parameters. The MSW blast vibration model uses multiple seed waveforms at different distances from a blasthole to a point of interest and is suitable for near-field blast vibration at the highwalls. Through the application of the MBF in conjunction with the MSW, various design scenarios can be explored, and rock fragmentation can be optimized while controlling blast vibration levels. These models have been successfully applied to many open pit mines and quarries around the world.
For a large open pit mine, it is of vital importance to optimize trim blasts. A trim blast is next to the presplit. To minimize the negative impact on the highwall, trim blasts are often loaded with a low powder factor that results in much coarser fragmentation than the production blasts. The coarser fragmentation increases the cost of the downstream operations. On the other hand, trim blasts with a high powder factor could impact the highwall causing the highwall instability.
Over the recent years, Orica developed a unique system for blast optimization projects. The system includes near-field blast vibration monitoring using accelerometers, the multiple blasthole fragmentation (MBF) model, and the multiple seed waveform (MSW) blast vibration model. The three components of the system are used together to improve blast performance at a site.
