BUSINESS burden’ profile. The true minimum burden profile provides the most accurate face burden profile information by determining the true location of the borehole relative to the blast face. This provides the blaster with the necessary information to adjust explosives loading to these site conditions, reducing the potential for flyrock and airblast while optimizing explosives distribution.
Figure 11 illustrates how the full cycle works. This cycle allows for the most accurate drilling and blast profile information.
An additional part of the programme was the use of an unmanned aerial system( UAS) for dynamic pit mapping. Data gathered from the UAS has been used to track blast patterns, analyse pre- and post-blast performance, and to calculate stripping and stockpile volumes.
Figure 12 is a cross-section from the preblast and post-blast UAS flights. This data can be used to examine muckpile displacement and shape.
Along with muckpile displacement, calculating the in situ blast volume and comparing it to post blast volumes can give you swell factors and help verify actual excavation volumes.
Conclusion
The success of the optimisation programme was due to the systematic changes approach, data tracking to verify the benefits that those changes produced, and the use of advanced systems and technology that made this possible. The advanced systems and technology used in the process included a drill monitoring system, 3-D photogrammetric profiling and advance blast design software, borehole surveys systems, GPS, drill navigation and UAS systems. Originally, these systems and technology were employed short term to help solve specific problems. The value and benefits of these systems and technologies were soon realised, as well as the need for them to be used on an ongoing basis to maintain an optimisation programme.
Because the project was economically successful, it was justifiable to continue to use the advanced technology implemented during the programme.
Special thanks to Charlie Selman of Quarry Services for supporting the programme and supplying the advanced drilling systems and 3-D profiling equipment. n
About the authors
David Stewart is the plant manager at Midsouth Aggregates in Camak, Georgia, in the United States. Tamara Wiseman is the technical service manager for R. A. McClure Inc. in Larkspur, California.
Figure 11
Figure 12
QUARRY SA | JANUARY 2017 _ 15