Fragmentation from Pattern Expansion with Electronic Detonators at the Red Dog Mine

摘要

A blasting project was undertaken at the Teck Alaska Red Dog Mine in 2005 to 2007 to determine theextent that using electronic detonators could increase Semi-Autogenous Grinding (SAG) millthroughput. The results of that project were reported at the 2010 ISEE Annual Conference. This paperis a postscript to that project and provides the fragmentation resulting from the implementation of a 15%pattern expansion using electronic detonators.The measured gyratory crusher fragmentation of 1,250,000 tonnes {metric tons} (1,375,000 tons) of ore,approximately 1/3 of annual production, was used to compare stockpiles constructed from the standardand the expanded geometry shots. In both cases the shots had equilateral geometry, however, thestandard patterns were shot with non-electric detonators using 17 ms inter-hole and 67 ms inter-rowdelays and the expanded patterns were shot with electronic detonators using 0.6 ms/ft (1.9 ms/m) interholeand 5.8 ms/ft (19 ms/m) inter-row delay. Fragmentation uniformity and mean fragment size werefound to be similar between the two patterns. The pattern expansion of 15% effectively annulled theincreased fragmentation effect of the faster inter-hole timing with the electronic detonators. Althoughthe fragmentation improved with the electronic detonators, the magnitude of the fragmentation changewas more modest than that indicated from the earlier work.In implementing the change to electronic detonators it was found that there appeared to be a conceptualerror in the way the vector timing method is put into practice in various software programs. Analternative algorithm is proposed for discussion.