Quarry Southern Africa January 2017 | Page 17

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
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