Case Studies Using the Multiple Blasthole Fragmentation (MBF) Model at Open Pit Mines in Canada

摘要

The multiple blasthole fragmentation (MBF) model developed by Orica models the contributions fromrnmultiple blastholes to fragmentation at any given point in the rock and simulates a production blast withrnthe actual geometry of the blasted overburden and free faces, explosive loading, multiple decking, andrndelay timing of each explosive charge. The model has been successfully applied to several open pit minesrnand quarries around the world, including Canada and the United States. The peak particle velocity (PPV)rninduced in the rock from the explosive detonation is used in the MBF model as the key parameter relatingrnto the size distribution of the rock fragmentation. Relating the PPV to the rock fragmentation is based onrnearlier work relating the particle velocity to the dynamic strain in rock. A recent publication furtherrnrevealed that the PPV is related to the maximum relative displacement that induces three dimensionalrnstrain at a point in the rock. The model can explicitly model most of the blast design parameters includingrnexplosive properties.rnCase studies were conducted at open pit gold/copper mines in Canada in 2016, that included setup of thernfield data collection, data analysis, and establishment of the model for the sites, scenario modeling, fieldrnimplementation and results comparisons against the modeling. The field data analysis was used torncharacterize the rock mass property at the site. The delay timing and burden were selected from thernmodeling and electronic initiations were introduced to implement the recommended timing. Modeling therneffect of different explosive selections was also conducted. Using a target size distribution, blast patternrnmodifications were evaluated in the modeling. The inputs collected in the field tests for the MBF modelrnare also those required by the multiple seed waveform (MSW) blast vibration model. At each site thernMSW modeling was conducted in parallel to the MBF modeling to ensure blast vibrations were underrncontrol while the rock fragmentation was improved.