Introduction of sequential blasting at Mines Gaspe, Murdochville, Quebec

Abstract Sequential blasting has been introduced at Mines Gaspe to reduce the harmful effects associated with the instantaneously primed blasting method. Three stages of modifications had been tried to improve this method: trials of a rectangular pattern instead of the square one, trials of lengthened hole collars at the perimeter of the blast and trials of increased inter-row delay intervals from 35 to 50 ms. Results showed that improvements to the instantaneously primed blasting method were limited by the probability of increasing the number of bootlegs.
Doing these modifications allowed the definition of a general approach to improvements before the sequential blasting method was introduced. This general approach included: planning of the mining sequence, following up on the drilling, loading and tying-in of each blast, compiling and evaluating blast results, comparing results from one bench to the other and moving along with one change at a time. This approach has permitted the successful introduction of the sequential blasting method in two steps: trials of blast by rows of delayed holes and trials of hole-by-hole blasts. The optimum result has been analyzed by high-speed camera and by computer blast simulations, The actual optimum sequential blast is obtained with a CORDLINE priming system using period 15, permitted in a large drilling pattern, with an inter-sequences delay interval of 230 ms and an inner-sequences delay interval of 50 ms.
While these modifications were being introduced, a careful study of the drilling and blasting costs was made, which showed a sharp reduction of drilling cost per tonne. Even though there was an increased use of packaged slurry the blasting cost per tonne also dropped. The reduction in cost per tonne was explained by the fact that the average energy factor was maintained while the blasting pattern was expanded.
The sequential blasting method, successfully introduced at Mines Gaspe, permits blasts of better quality, reduces the drilling requirements by more than 30% and helps to achieve improved productivity while minimizing costs.
Keywords: Open-pit mining, Blasting, Sequential blasting, Drilling, Computer simulations, Loading
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Publication: CIM Bulletin
Author(s): T.S. GOLOSINSKI, E. McROBERTS, W.F. GILMORE
Keywords: Open-pit mining, Europe, Excavat excavators, Belt conveyors, Belt bridges, Stackers
Issue: 867
Volume: 77
Year: 1984
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Summary: This paper describes the use of electronics for physical measurement and computer analysis in both open-pit and underground mining operations for the ultimate purpose of optimizing production blasts. Techniques in monitoring single borehole blasts using both pressure and vibration sensors to establish in-situ dynamic rock properties are outlined, including characterization of multiple borehole production blasts with regard to stress generation.
Once field derived measurements are computer...
Publication: CIM Bulletin
Author(s): CHRISTOPHER J. PRESTON, NORMAN J. TIENKAMP
Keywords: Open-pit mining, Blast monitoring, Optimization, Seismic monitoring, Computer simulation
Issue: 867
Volume: 77
Year: 1984
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Summary: All optimum pit design studies start from the geological ore reserves inventory, the estimated grades of all blocks of potential ore within the interpreted limits of the deposit. The actual optimization procedure is then carried out on block valuations based on these estimated grades. Thus, the relevance of any pit design can be seen to depend directly on the ore reserve estimation. To insure a proper pit design, a first step would be to use a geostatistical reserve estimation technique such...
Publication: CIM Bulletin
Author(s): ALEXANDRE DESBARATS, MICHEL DAVID
Keywords: Open-pit mining, Geostatistics, Optimum pit design, Selective mining, Kriging, Parametrization
Issue: 867
Volume: 77
Year: 1984
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